lib.ajaums.ac.irlib.ajaums.ac.ir/booklist/161349.pdf · march 2007, volume 86, issue 3,pp.169-251...

March 2007, Volume 86, Issue 3,pp.169-251 Research Article Medicare Issues

169 The Effect of Medicare's Prospective Payment System on Patient Satisfaction: An Illustration with Four Rehabilitation Hospitals. Parag K. Shah, MD; Allen W. Heinemann, PhD, ABPP; Larry M. Manheim, PhD

176 ADL Assessment of Nondisabled Turkish Children with the WeeFIM Instrument. Canan Aybay, MD; Gulten Erkin, MD; Atilla H. Elhan, PhD; Hulya Sirzai, MD; Sumru Ozel, MD

183 The Myofascial Trigger Point Region: Correlation Between the Degree of Irritability and the Prevalence of Endplate Noise. Ta-Shen Kuan, MD, MS; Yueh-Ling Hsieh, PhD, RPT; Shu-Min Chen, MD; Jo-Tong Chen, MD, PhD; Wei-Chang Yen, MD; Chang-Zern Hong, MD

190 Evaluation of Two Assessment Tools in Predicting Driving Ability of Senior Drivers. Michael F. Oswanski, MD, FACS; Om P. Sharma, MD, FACS; Shekhar S. Raj, MBBS; Leslie A. Vassar, OTR/L; Kathryn L. Woods, OTR/L; Wendi M. Sargent, OTR/L; Robyn J. Pitock, OTR/L

Book Review 199 Total Knee Arthroplasty.

John A. Schuchmann, MD

Research Article Spinal Cord Injury

200 A Washing Toilet Seat with a CCD Camera Monitor to Stimulate Bowel Movement in Patients with Spinal Cord Injury. Ken Uchikawa, MD; Hidetoshi Takahashi, MD, PhD; Genbu Deguchi, OTR; Meigen Liu, MD, PhD

Book Review 204 Anatomical Guide for the Electromyographer: The Limbs and Trunk.

Ralph M. Buschbacher, MD

Research Article Amputee

205 Body Image in People with Lower-Limb Amputation: A Rasch Analysis of the Amputee Body Image Scale. Pamela Gallagher, PhD; Olga Horgan, PhD; Franco Franchignoni, MD; Andrea Giordano; Malcolm MacLachlan, PhD

216 Noninvasive Ventilation in Children with Spinal Muscular Atrophy Types 1 and 2. Albino Petrone, MD; Martino Pavone, MD; Maria B. Chiarini Testa, MD; Francesca Petreschi, MD; Enrico Bertini, MD; Renato Cutrera, MD, PhD

Commentary Pulmonary

222 Avoiding Respiratory Failure in Neuromuscular Disease: Why Is It Not Done? John R. Bach, MD

Invited Review Nanotechnology

225 Introduction to Nanotechnology: Potential Applications in Physical Medicine and Rehabilitation. Assaf T. Gordon, MD; Greg E. Lutz, MD; Michael L. Boninger, MD; Rory A. Cooper, PhD

Case Report Spinal Cord Injury

242 Spinal Cord Injury Associated with Thoracic Osteoporotic Fracture. Sibel Özbudak Demir, MD; Ceyda Akn, MD; Meltem Aras, MD; Füsun Köseolu, MD

Letters to the Editor 247 RE: RACIAL DISPARITIES IN ACCESS TO CARDIAC REHABILITATION.

Nitin B. Jain, MD, MSPH; Jeffrey N. Katz, MD, MS 247 RE: RACIAL DISPARITIES IN ACCESS TO CARDIAC REHABILITATION.

Patricia C. Gregory, MD; Thomas A. LaVeist, PhD; Crystal F. Simpson, MD, MHS

Visual Vignette 250 A Technique for Ultrasound-Guided Intrathecal Drug-Delivery System

Refills. Mark-Friedrich B. Hurdle, MD; Adam J. Locketz, MD; Jay Smith, MD

Authors:Parag K. Shah, MDAllen W. Heinemann, PhD, ABPPLarry M. Manheim, PhD

Affiliations:From the Rehabilitation Institute ofChicago, Chicago, Illinois (AWH); andthe Institute for Healthcare Studies(PGS, LMM) and Department ofPhysical Medicine and Rehabilitation(AWH, LMM), Feinberg School ofMedicine, Northwestern University,Chicago, Illinois.

Correspondence:Correspondence should be addressed toParag K. Shah, MD, 339 E. ChicagoAvenue, Rm 712, Chicago, IL 60611.Requests for reprints should beaddressed to Allen W. Heinemann,PhD., ABPP, Onterie Center 446 E.Ontario Street Rm 962, Chicago, IL60611.

Disclosures:Supported by the National Instituteon Disability and RehabilitationResearch for a project titled HealthServices Research DRRP on MedicalRehabilitation (H133A030807).

FIM is a trademark of Uniform DataSystem for Medical Rehabilitation, adivision of UB Foundation Activities,Inc.

0894-9115/07/8603-0169/0American Journal of PhysicalMedicine & RehabilitationCopyright © 2007 by LippincottWilliams & Wilkins

DOI: 10.1097/PHM.0b013e31802efff7

The Effect of Medicare’s ProspectivePayment System on PatientSatisfactionAn Illustration with Four Rehabilitation Hospitals

ABSTRACT

Shah PK, Heinemann AW, Manheim LM: The effect of Medicare’s prospectivepayment system on patient satisfaction: an illustration with four rehabilitationhospitals. Am J Phys Med Rehabil 2007;86:169–175.

Objective: To examine the impact of Medicare’s Prospective PaymentSystem (PPS) on patient satisfaction at four inpatient rehabilitation hos-pitals.

Design: Prospective study using a satisfaction survey to examine theeffects of Medicare’s PPS for rehabilitation hospitals. Surveys wereconducted at four affiliated rehabilitation hospitals in the Midwest.

Results: Patient characteristics varied only slightly pre- to post-PPS,and several characteristics were related to overall satisfaction, includingmotor functional gain, discharge to home, and respondent (patient orproxy). A 12-point increase on a 12-item motor function scale resulted in1.13 greater odds (95% CI: 1.04, 1.24) of reporting excellent satisfac-tion. Patient respondents were 1.27 times more likely (95% CI: 1.07,1.50) than proxies to report excellent satisfaction, and patients dischargedhome were 1.65 times more likely (95% CI: 1.31, 2.07) to reportexcellent satisfaction than patients discharged elsewhere. We found anincrease in observed satisfaction from 60.3 to 63.4% (P � 0.05) afterPPS implementation, despite a decrease in motor FIM gain.

Conclusions: Patient characteristics such as motor FIM gain, dis-charge status, and respondent type were significantly associated, althoughonly slightly, with patient satisfaction in inpatient rehabilitation. Percentageof excellent satisfaction improved at these four facilities after PPS imple-mentation, despite declines in motor FIM gain. The improvement may bethe result of numerous ongoing quality-improvement initiatives directed atimproving patient satisfaction at these facilities.

Key Words: Patient Satisfaction, Rehabilitation, Prospective Payment System, HealthPolicy

March 2007 Risk Adjustment in Patient Satisfaction 169

RESEARCH ARTICLE

Medicare Issues

In recent years, many changes have occurred inthe nature of reimbursement and payment for in-patient rehabilitation facilities, commonly knownas rehabilitation hospitals. The most significantchange was the implementation of a ProspectivePayment System (PPS) by The Centers of Medicaidand Medicare Services in 2002. The new paymentplan pays facilities a specific amount per admissionon the basis of a patient’s diagnosis, age, functionalstatus, and comorbidities. This type of reimburse-ment plan creates incentives to reduce length ofstay and amount of services to minimize costs tothe facility. Prior studies about the effect of PPS forpatients with spinal cord injury have shown thataverage length of stay decreased in response toPPS.1 Given potential decreases in length of stayand services, one might expect that other outcomemeasures would also be affected. However, manyfacilities continuously implement programs as partof their quality-improvement initiatives. Theseprograms are often begun in response to a drop ina certain area of satisfaction or in response to ananticipated change in care, such as a decreasedlength of stay. These programs may influence theeffect of changes in length of stay or services ren-dered brought on by PPS. For this reason, thechanges brought on by PPS may not affect satis-faction in the anticipated manner. In this paper, weexamine the effect of PPS on patient satisfaction infour diverse rehabilitation hospitals.

Patient satisfaction is well established as animportant outcome in health care.2–6 From a clin-ical perspective, satisfied patients cooperate morewith treatment regimens and achieve better clini-cal outcomes.7 From a business perspective, satis-fied patients are more likely to be loyal to treat-ment providers and less likely to bring malpracticesuits.8 Patient satisfaction is also identified as a mea-sure of healthcare quality,9,10 and recent efforts havefocused on making these data available to consumers.A 2001 Institute of Medicine report recommendedpublicly reporting patient-satisfaction data as a mea-sure of quality.11 The Rhode Island state legislaturemandated reporting patient-satisfaction data to aidconsumers in selecting healthcare services,12 and twogovernment agencies are developing a survey for pub-lic reporting of patient satisfaction to aid consumerchoice and to measure healthcare quality.13 Asidefrom aiding consumers, measuring patient satisfac-tion is also important for facilities and for the indus-try as a whole. The ability to compare data for varyingpopulations would enable hospitals to evaluate accu-rately the effect of a quality-improvement initiative orother intervention and to compare one hospital withother facilities.

To effectively evaluate the effect of an inter-vention on patient satisfaction, one must control

factors, such as patient characteristics, that mayinfluence patient satisfaction. To normalize popu-lations and detect changes over time, studies ofpatient satisfaction in various types of healthcaresettings have employed control charts, risk adjust-ment, and raw-score analysis.14–16 In this study, wecompare raw scores with risk-adjusted, or pre-dicted, scores. Risk adjustment is necessary be-cause different kinds of patients may respond dif-ferently to satisfaction questions independently ofthe care they receive.17 To isolate the effects of apolicy change that may concurrently affect qualityand change patient sociodemographics, patientcharacteristics must be considered. Previous workon the effect of risk adjusting for different patientand clinical factors has been equivocal. Severalstudies have shown satisfaction is related to ageand clinical status, whereas other studies havenot.4,6,18 Prior studies have demonstrated that pa-tient characteristics account for 2–7% of the vari-ation in satisfaction ratings.17,19,20

The patient and clinical characteristics thataffect satisfaction in other venues of healthcaredelivery may not be the same in rehabilitationcare.21 Rehabilitation patients are recoveringfrom life-changing health events and learninghow to rebuild their lives with skills and abilitiesthat have changed markedly. Clinician expecta-tions are often not for full functional recoverybut for rebuilding a satisfying and meaningfullife. To learn self-sufficiency, management ofchronic diseases, and management of daily activ-ities with a disability, satisfaction with the care apatient is receiving is of critical importance.3,18

A few studies have examined patient character-istics and their relationship to patient satisfac-tion in rehabilitation facilities. Franchignoni etal.3 have reported that functional status was un-related to satisfaction of rehabilitation inpa-tients. This study was conducted at one Italianrehabilitation center and included only 55 pa-tients. In another series of articles that exploredthe relationships between demographic andfunctional status and satisfaction, functionalgains and discharge functional status were foundto have a significant effect on satisfaction inspecific rehabilitation populations.22–25 Specifi-cally, for stroke patients, proxy and patient re-spondents reported satisfaction differently, withproxies reporting lower satisfaction scores. Fur-thermore, persons showing cognitive and motorgain were more likely to be dissatisfied thanpatients showing no gain.23 The discharge set-ting was a significant predictor in a study ofpatients with orthopedic injury, with those pa-tients discharged home about half as likely to bedissatisfied.24 Another study observed that in-creased FIM discharge scores were significant

170 Shah et al. Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

predictors of higher satisfaction in patients withany type of cerebrovascular injury.25

In light of this limited and inconsistent infor-mation, we examined three questions: (1) To whatextent are patient characteristics related to satis-faction? (2) To what extent does adjusting for pa-tient characteristics change satisfaction scores af-ter an intervention that might change satisfactionalong with patient characteristics? (3) What are theeffects of PPS on patient satisfaction in a sample ofdiverse rehabilitation hospitals? We report raw andpredicted scores from patients 1 yr before and 1 yrafter implementation of PPS; then, we apply risk-adjustment techniques, and then we examinechanges in satisfaction.

METHODSRecruitment

The four sites from which patient data wereanalyzed are all affiliated with a midwestern net-work of inpatient and outpatient rehabilitationcenters and have distinct case-mix characteristics.The four rehabilitation hospitals included a free-standing urban hospital with 155 beds (rehabilita-tion hospital A), a 35-bed suburban unit (rehabili-tation hospital B), a 32-bed unit in a ruralcommunity (rehabilitation hospital C), and a 24-bed unit within a level I trauma center (rehabili-tation hospital D). By selection, all patients wereover the age of 18, had a length of stay greater than4 days, and were alive 1 mo after discharge. For thepre- and post-PPS comparison, 3276 patients dis-charged between January 2000 and December 2001were compared with 4806 patients discharged be-tween January 2003 and December 2004. Datafrom 2002 were omitted because that was the yearthat PPS was implemented and a time of transitionfor rehabilitation hospitals. The questionnaire wasadministered by telephone to patients 1 mo afterdischarge. The overall response rate was 55%. Basicdemographic characteristics including age, gender,and admission FIM scores were similar between therespondents and nonrespondents. There was no se-lection or exclusion of any particular medical condi-tion. The subjects closely approximated the overallprevalence of conditions in the chosen rehabilitationhospitals, with approximately 25% with lower-ex-tremity joint replacements and 16% with stroke.

Dependent VariableThe patient-satisfaction instrument used in

the health system contains 18 items that focus onvarious aspects of patient experience and was de-veloped and validated for rehabilitation inpatients.It demonstrates high internal consistency and facevalidity.6 The questionnaire is part of an ongoingquality-assurance initiative administered by the re-

habilitation hospital. For this reason, IRB approvalwas necessary only for the secondary analysis, notfor data collection. All items are rated on a four-point rating scale that ranged from “excellent,” to“good,” “fair,” and “poor.” For analysis, we selecteda single item, “overall satisfaction with care,” be-cause it correlates strongly with the total score andreflects patients’ and proxies’ global perceptions.To compute each facility’s satisfaction score, weused the percentage of patients reporting excellentsatisfaction as our outcome. Percent “excellent” isa commonly reported measure and a goal amongoutcomes managers who strive for excellent rat-ings within their institutions. Also, because satis-faction surveys generally show high levels of satis-faction, differentiating “excellent” from all otheranswers may reduce some of this bias.

Independent VariablesRisk factors that might affect satisfaction were

selected on the basis of a review of the literatureand clinical experience. These included respondenttype (patient vs. proxy), age, gender, functionalgain, and discharge destination. Functional statuswas measured with the FIM,26 a widely used instru-ment that is incorporated in Medicare’s patient-assessment inventory for rehabilitation hospitals.We used motor and cognitive subscores of the FIMbecause they represent two distinct aspects of func-tion.27 The motor FIM subscore is the sum of 12item scores, each rated on a scale of 1–7. For themotor FIM gain score, we omitted tub transferbecause the patient-assessment inventory for inpa-tient rehabilitation facilities does not use thisitem.28 The cognitive FIM subscore is the sum offive items, also on a 1–7 scale. The FIM scores weredivided by the number of items in each category toconstruct a modified motor (motor FIM/12) andcognitive (cognitive FIM/5) FIM score. By con-structing modified scores, the coefficients gener-ated by the regression models indicate the effect ofa 12-point change in the motor score and a 5-pointchange in the cognitive score, or an average of a1-point change in each item within the subscore.

According to Carter and Paddock,29 reportedFIM scores under PPS are likely to be lower be-cause of changes in scoring rules, as opposed totrue changes in patients’ functional status. Scoringchanges under PPS altered the way the admissionFIM was obtained. Previously, the FIM score mea-sured at one point during the first 72-hr period wasused as the admission FIM. Post-PPS scoringchanges included measuring the FIM score at mul-tiple times and taking the lowest FIM score withinthe patient’s first 72 hrs of admission. By conduct-ing multiple measurements, average admissionscores would be expected to go down without therebeing an actual change in functional status. Fur-


thermore, scoring rules changed for certain itemssuch as eating and bowel and bladder function,causing these scores to also drop artificially. Toremove pre-PPS to PPS coding differences, we useda pre-PPS to PPS FIM crosswalk developed usingRasch analysis.30 The pre-PPS FIM scores wereadjusted to be equivalent to post-PPS scores ac-cording to the crosswalk and were then used in themodel.

Statistical AnalysisRisk adjustment of the effect of PPS on patient

satisfaction was achieved using a logistic regres-sion analysis with forced entry of predictors todetermine odds ratios and to evaluate the signifi-cance of risk factors. We generated a model usingall pre-PPS patients; then, using the model, wecomputed a predicted probability of reporting ex-cellent satisfaction for each patient after PPS. Wecompared the pre-PPS scores with the post-PPSobserved scores to measure actual change in satis-faction. Second, we compared the post-PPS pre-dicted scores with post-PPS observed scores toevaluate the magnitude of risk-adjustment effects.

RESULTSTable 1 shows how patient demographic char-

acteristics and functional gains varied across sitesand from before to after PPS. Individual sites variedsomewhat in their patients’ characteristics. Therural rehabilitation hospital (rehabilitation hospi-tal C) had a lower percentage of male respondents(32%), and the mean age of patients at the free-standing rehabilitation hospital (rehabilitationhospital A) was lower than the others. The percentdischarged home changed significantly at only one

site and did not change significantly overall. Meanage increased slightly (66.5 vs. 67.7, t � �3.12,df � 8074, P � 0.01), as did the percentage of proxyrespondents after PPS (29.4 vs. 31.5%, �2 � 4.1,P � 0.05). After adjustment, motor FIM gain de-creased after PPS in all but one of the sites. Con-trary to expectations, cognitive FIM gain increasedin all facilities after PPS.

Table 2 shows odds ratios for the facilities andpatient characteristics for the logistic regressionmodel. Factors that significantly affected satisfac-tion scores included motor FIM gain, respondent,and percentage discharged to home. Patient re-spondents and patients discharged to home hadhigher odds ratios (1.27 and 1.65, respectively)compared with proxy respondents and patients dis-charged to other facilities. A 12-point motor FIMgain was associated with 1.13-fold greater odds ofreporting excellent satisfaction. The suburban andrural facilities had higher odds of reporting excel-lent satisfaction than the urban facility (3.50 and1.65, respectively).

Observed and predicted scores are reported inTable 3. Overall observed satisfaction scores in-creased slightly from 60.3 to 63.4% (t � �2.78,df � 8080, P � 0.01). Predicted scores were calcu-lated using the logistic regression model reportedin Table 2. The variance explained by the model waslow (R2 � 4%); therefore, the predicted score didnot differ much from the observed score (61.3 vs.63.4%). The slight decrease was attributable to thedecrease in patient respondents and the decrease inmotor FIM gain after PPS. Most facilities, with theexception of the rural facility, had higher post-than pre-PPS scores.

TABLE 1 Pre– and post–Prospective Payment System patient characteristics

Site n % MaleMean Age

(SE)Respondent %

PatientMotor FIMGain (SE)

Cognitive FIMGain (SE)

% DischargeHome

Rehabilitation hospital APre 1539 44.5 62.8 (0.48) 71.0 17.5 (0.29) 1.2 (0.90) 88.5Post 2239 43.6 63.2 (0.37) 65.3* 18.9 (0.26)* 3.4 (0.11)* 87.4

Rehabilitation hospital BPre 965 40.3 69.5 (0.43) 66.0 20.1 (0.26) 1.6 (0.10) 86.2Post 1355 41.7 72.2 (0.33)* 70.0* 14.2 (0.24)* 1.8 (0.10) 83.8

Rehabilitation hospital CPre 375 32.3 71.3 (0.74) 79.5 23.1 (0.51) 1.3 (0.16) 91.2Post 756 32.5 71.9 (0.47) 71.3* 22.1 (0.32) 3.7 (0.19)* 94.8*

Rehabilitation hospital DPre 397 37.5 69.5 (0.70) 72.0 22.6 (0.43) 1.5 (0.17) 89.4Post 456 45.0* 69.1 (0.69) 75.4 17.3 (0.43)* 2.5 (0.23)* 86.4

TotalPre 3276 41.0 66.5 (0.29) 70.6 19.5 (0.18) 1.4 (0.06) 88.3Post 4806 41.5 67.7 (0.23)* 68.5* 17.9 (0.16)* 2.9 (0.07)* 87.4

* Boldface, pre–post comparison with P � 0.05.


DISCUSSIONRehabilitation lengths of stay have decreased

in recent years, and it is expected that this trendwill continue with the implementation of PPS.31

An expected consequence of shorter stays is thatpatients’ functional gains will decline along withpatient satisfaction.22–25 However, in this study wefound results to the contrary. Both observed andpredicted satisfaction increased after the imple-mentation of PPS, despite the shorter lengths ofstay and reduced functional gain. Reasons for thisimprovement may be that patients are pleased witha shorter length of stay, or it may be the result ofseveral quality-improvement initiatives that facili-ties undertook to counter the anticipated effects ofPPS. One facility (rehabilitation hospital B) imple-mented a discharge-planning video to help patientsprepare for discharge. This may have influencedthe effect of lowered length of stay. In fact, allfacilities in this study implemented additional dis-charge planning and trained staff on how to com-municate functional goals with patients. Severalfacility-level improvements also occurred, such asexpansions and additions of private rooms. It is

difficult to isolate the effect of PPS on patientsatisfaction, given the concurrent efforts at im-proving patient satisfaction. These results, there-fore, must be interpreted in light of other studiesthat have shown an effect of decreased length ofstay and decreased functional gain. Quality-im-provement initiatives must be studied in isolationto see whether they actually improve satisfaction.Because events in real life do not occur in isolation,one must be prepared to combine results of variousstudies to truly determine the effect of an ongoingchange as large as PPS.

Patient satisfaction is an important outcomefrom both a business perspective and as an indica-tor of quality care. Many hospitals track patientsatisfaction to monitor quality-improvement activ-ities. Owners of multiple hospitals compare patientsatisfaction across facilities and nationally. Clinicaland demographic characteristics vary widely acrossfacilities, reflecting their affiliations and conse-quent referral patterns, geographic locations, andresources. Raw-score analysis does not take intoaccount changing patient characteristics over timewithin a facility. Rehabilitation hospital A is a ter-

TABLE 3 Pre– and post–Prospective Payment System (PPS) observed and predicted excellentsatisfaction

Facility% Excellent Satisfaction

pre-PPS Observed% Excellent Satisfaction

post-PPS Observed% Excellent Satisfaction

post-PPS Predicted

Rehabilitationhospital A

53.3 (50.7–55.8)* 60.8 (58.8–62.9) 54.1 (53.8–54.4)†

Rehabilitationhospital B

65.7 (62.7–68.7) 66.3 (63.8–68.9) 64.3 (63.9–64.6)

Rehabilitationhospital C

81.1 (77.1–85.1)* 67.3 (64.0–70.7) 81.9 (81.6–82.1)†

Rehabilitationhospital D

55.2 (50.3–60.1) 60.7 (56.2–65.2) 53.9 (53.2–54.5)†

Total 60.3 (58.7–62.0)* 63.4 (62.0–64.8) 61.3 (61.0–61.7)†

* Pre-PPS observed significantly different than post-PPS observed with P � 0.01.† Post-PPS predicted significantly different than post-PPS observed with P � 0.01.Boldface, statistically different from the reference value, which is post-PPS observed.

TABLE 2 Logistic regression with demographic risk factors plus motor and cognitive FIM gains

Variables Odds Ratio (95% CI) SE P

Rehabilitation hospital B* 1.65 (1.39–1.96) 0.15 <0.01Rehabilitation hospital C* 3.50 (2.62–4.66) 0.51 <0.01Rehabilitation hospital D 1.00 (0.80–1.26) 0.12 0.99Motor FIM gain/12* 1.13 (1.04–1.24) 0.05 0.01Cognitive FIM gain/5 1.09 (0.97–1.22) 0.06 0.14Age 1.00 (1.00–1.01) 0.00 0.59Gender 0.96 (0.83–1.12) 0.74 0.61Respondent* 1.27 (1.07–1.50) 0.11 0.01Discharge to home* 1.65 (1.31–2.07) 0.19 <0.01

* Boldface, significant with P � 0.05.


tiary free-standing urban hospital that cares forpatients with more severe disabilities, whereas re-habilitation hospital C, a rural rehabilitation unit,had the highest admission FIM scores (data notshown). Respondent types may also vary dependingon primary impairment. Patients with more severedisabilities may not be able to provide self-reportsand are more likely to have a proxy respondent. Thefree-standing rehabilitation hospital (rehabilitationhospital A) had the lowest self-respondent percent-age, and the trauma center and the rural rehabili-tation hospital (rehabilitation hospitals D and C)had the highest proportion of self-respondents,consistent with the patients’ functional status atthese facilities. In this case, the predicted scoresdid not differ greatly from the observed scores.Even if risk adjustment does not significantlychange satisfaction comparisons, it may allowpractitioners to accept the results and minimizearguments that their patients are different.

There is no industry consensus on how tomeasure patient satisfaction or on which factorsshould be included in risk adjustment of patientsatisfaction. The most significant variables in themodel were the facility coefficients themselves,which revealed that facilities vary in patient satis-faction. Other variables such as age, gender, andrespondent type were not significantly related tosatisfaction. It may be that controlling for thesecharacteristics is not necessary for an unbiasedcomparison of patient satisfaction. However, motorFIM gains and home discharge were significantlyrelated to satisfaction. These findings suggest thatpatients are more satisfied if they have increasedfunctional gain and are able to go home ratherthan to another post–acute care facility. The issueof whether functional gains affect satisfaction isdebatable. As discussed in the introduction, manystudies have refuted the point that motor gainincreases satisfaction. In addition, the exclusion oflength of stay as an independent variable lets usidentify the effect of length of stay on satisfactionrather than controlling for the differences.

Because of the small changes in demographiccharacteristics and the small effects of the variables,however, the predicted scores did not vary greatlyfrom the raw scores. Although the differences inpatient characteristics account for some difference inreported satisfaction, they explain very little of thevariance. However, one can imagine that if the differ-ence in characteristics were very large, this couldcause satisfaction scores to be different. The Centersfor Medicare & Medicaid Services’ 75% rule,32 whichstates that 75% of patients in rehabilitation facilitiesmust have one of 13 diagnostic categories, may alterrehabilitation hospitals’ patient diagnostic and socio-demographic characteristics to such a degree such

risk adjustment could significantly affect patient-sat-isfaction scores.

A major limitation of the study is the difficulty ofmeasuring satisfaction reliably. As mentioned before,satisfaction is a complex construct, and it is difficultto assess. A single item was chosen, and although thisitem correlated well with other items, we cannotestimate the reliability of a single item. Our ability togeneralize the results is limited by the small sampleof facilities. Furthermore, all facilities studied share asimilar corporate affiliation, even though they are indifferent communities. The rehabilitation hospitalsstudied share a similar organizational philosophy andare guided by the same values. Care should be takenwhen generalizing these results to all rehabilitation hos-pitals nationally. These differences may not reflect asignificant difference in satisfaction for purposes of con-sumer loyalty or for measures of healthcare quality.

Further research would involve using a largersample of patients to determine the effect of PPS atmany different rehabilitation hospitals. The factorsthat affect satisfaction also need to be clarified.Length of stay, functional gains, and other demo-graphic factors showed a small effect on satisfac-tion, and larger samples would help clarify thisissue. The issue of isolating the effects of a quality-improvement initiative or a new payment systemsuch as PPS can be resolved by measuring specificaspects of satisfaction such as satisfaction withdischarge or satisfaction with teaching. Looking atthese variables specifically as dependent variableswould require further delineation of specific inde-pendent variables.

CONCLUSIONDespite a decrease in motor FIM gains after

PPS, patient satisfaction increased after PPS imple-mentation. Risk adjustment for these characteris-tics had a small effect on overall satisfaction. Therisk of bias in estimating overall satisfaction is suchthat respondent type, discharge to home, and func-tional status should be included in models thatcompare satisfaction across facilities.

ACKNOWLEDGMENTSWe would like to acknowledge insightful com-

ments and helpful suggestions from Ming Zhang,PhD, Trudy Mallinson, PhD, Anne Deutsch, RN, PhD,Deborah Dobrez, PhD, and Elizabeth Durkin, PhD.Funding for this project was provided by the NationalInstitute on Disability and Rehabilitation Researchfor a project titled “Health Services Research DRRPon Medical Rehabilitation” (H133A030807).

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23. Tooth LR, Ottenbacher KJ, Smith PM, et al: Effect of func-tional gain on satisfaction with medical rehabilitation afterstroke. Am J Phys Med Rehabil 2003;82:692–9

24. Mancuso M, Smith P, Illig S, et al: Satisfaction with medicalrehabilitation in patients with orthopedic impairment. ArchPhys Med Rehabil 2003;84:1343–9

25. Ottenbacher KJ, Gonzales VA, Smith PM, Illig SB, FiedlerRC, Granger CV: Satisfaction with medical rehabilitation inpatients with cerebrovascular impairment. Am J Phys MedRehabil 2001;80:876–84

26. Deutsch ABS, Granger CV: The functional independencemeasure. J Rehabil Outcomes Meas 1997;1:67–71

27. Heinemann AW, Linacre JM, Wright BD, Hamilton BB,Granger CV: Measurement characteristics of the FunctionalIndependence Measure. Top Stroke Rehabil 1994;1:1–15

28. Hospital inpatient rehabilitation facilities prospective pay-ment system. Fed Regist 2001;66:41315–430

29. Carter GM, Paddock SM: Preliminary Analyses of Codingand Case Mix Under the Inpatient Rehabilitation FacilityProspective Payment System. Santa Monica, Ca, RANDHealth, 2005

30. Deutsch A, Heinemann AW: Equating Two Versions of theFIM Instrument. Paper presented at Midwest Objective Mea-surement Seminar, Chicago, April 28, 2006

31. Ottenbacher KJ, Smith PM, Illig SB, Linn RT, Ostir GV,Granger CV: Trends in length of stay, living setting, func-tional outcome, and mortality following medical rehabili-tation. JAMA 2004;292:1687–95

32. Medicare Program; Changes to the Criteria for Being Classifiedas an Inpatient Rehabilitation Facility. Federal Register 2004;69(89):25752


Authors:Canan Aybay, MDGulten Erkin, MDAtilla H. Elhan, PhDHulya Sirzai, MDSumru Ozel, MD

Affiliations:From the Department of PhysicalMedicine and Rehabilitation, AnkaraPhysical Medicine and RehabilitationEducation and Research Hospital,Ankara, Turkey (C.A., G.E., H.S.,S.O.); and Department ofBiostatistics, School of Medicine,Ankara University, Ankara, Turkey(A.H.E.).

Correspondence:All correspondence and requests forreprints should be addressed toCanan Aybay, MD, Mektep Sokak, No:18/8, 06600, Kurtulus, Ankara-Turkey.

Disclosures:The use of the WeeFIM instrument tocollect data for this research studywas authorized and conducted inaccordance with the terms of aspecial purpose license granted toLicensee by Uniform Data System forMedical Rehabilitation a division ofUB Foundation Activities, Inc.(UDSmr).

UDSmr, FIM, and WeeFIM areregistered trademarks of the UniformData System for MedicalRehabilitation, a division of UBFoundation Activities, Inc.


DOI: 10.1097/PHM.0b013e31802b8f8d

ADL Assessment of NondisabledTurkish Children with the WeeFIMInstrument

ABSTRACT

Aybay C, Erkin G, Elhan AH, Sirzai H, Ozel S: ADL assessment of nondisabledTurkish children with the WeeFIM instrument. Am J Phys Med Rehabil 2007;86:176–182.

Objective: To evaluate the WeeFIM instrument’s reliability and internalconstruct validity for the Turkish child population.

Design: License was taken from UDSmr to use the WeeFIM instru-ment. For the reliability and validity studies of the Turkish translation of theWeeFIM instrument, 573 Turkish nondisabled children were included inthe study. The reliability of the instrument was assessed by Cronbach’salpha coefficient, intraclass correlation coefficient (ICC), and test–retestreliability. Internal construct validity was assessed by both using Raschunidimensional measurement model and testing for differential item func-tioning for age and gender.

Results: Cronbach � value was 0.99 for motor WeeFIM rating and0.99 for cognitive WeeFIM rating. ICC was 0.81 for motor WeeFIMrating and 0.92 for cognitive WeeFIM rating. The internal constructvalidity of the Turkish translation of the WeeFIM instrument was confirmedby excellent fit to the Rasch measurement model. Two subscales werefound from the principal component analysis of standardized residualcorrelation for items. Among the items, bowel management, bladdermanagement, eating, and comprehension showed considerable levels ofmisfit.

Conclusions: The Turkish translation of the WeeFIM instrument isvalid, reliable, and practical for the Turkish child population. Furtherstudies are required to determine the cross-cultural validity of the instru-ment.

Key Words: WeeFIM, Functional Assessment, Rasch Analysis, Validity, Reliability

176 Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

RESEARCH ARTICLE

Outcomes

Although pediatric evaluation methods are notused as broadly as the methods applied to assessadult rehabilitation, the number of recent studieshas increased. One of the most commonly usedmethods for pediatric functional evaluation is theWeeFIM instrument, a measure of functional inde-pendence in children. It was developed in 1993,arising from the FIM instrument designed to mea-sure severity of disability in adults.1 Recent studieshave demonstrated the reliability and validity of theWeeFIM instrument for both disabled and nondis-abled children and have emphasized that it is anexcellent evaluation method.2,3

The normative samples of the WeeFIM instru-ment for nondisabled American4 and Japanese chil-dren5,6 have been obtained by the studies carriedout before. Studies performed for different popula-tions have emphasized that age, sociocultural andeconomic status of families, and environmentalconditions should be taken into considerationwhen evaluating the independence level of activi-ties of daily living (ADL) of children.5–11

Although ADL and handicap measurementswith proven validation and reliability are availablefor Turkish adults,12–14 there is not any ADL mea-surement method that is valid and reliable forTurkish children. Therefore, we first used theTurkish translation of the WeeFIM instrument in45 children with cerebral palsy (CP) and 41 Turkishnondisabled children as a preliminary study. Wediscovered that all WeeFIM ratings of the childrenwith CP were significantly lower than their non-disabled counterparts in the previous study.15 Wethought that the WeeFIM ratings of the smallgroup of Turkish nondisabled children examined inthe previous study did not reflect normativeWeeFIM ratings of the Turkish child population.Therefore, we decided to conduct a study with alarger case group to prove the validity and reliabil-ity of the WeeFIM instrument in our population.Our purpose was to evaluate the WeeFIM instru-ment’s reliability and internal construct validity forthe Turkish child population.

METHODSSubjects

For the reliability and validity studies, 573Turkish nondisabled children (295 boys and 278girls) aged 7–92 mos without developmental delayswere included in the study. The mean age of thechildren was 39.1 mos (SD 23.9, median 38 mos).The cases were obtained from two health centersavailable in different districts of Ankara. All of themwere nondisabled and attending to these centersfor general health checks and vaccination pur-poses. The purposes and procedures of the study

were explained, and informed consent was obtainedfrom the parents.

The WeeFIM InstrumentThe WeeFIM instrument contains 18 mea-

surement items, divided into six areas: self-care(eating, grooming, bathing, dressing upper body,dressing lower body, toileting), sphincter control(bowel management, bladder management), mo-bility (chair/bed/wheelchair transfer, toilet trans-fer, tub transfer), locomotion (crawling/walking/wheelchair, stair climbing), communication(comprehension, expression), and social cogni-tion (social interaction, problem solving, mem-ory). A seven- level ordinal scoring system rang-ing from 7 (complete independence) to 1 (totalassistance) is used to rate performance. The mini-mum possible total score is 18 (total dependence inall skills); the maximum possible score is 126(complete independence in all skills).1 Because oursample consisted of nondisabled children, we as-sessed the walking task taking into considerationboth crawling and walking, not wheelchair use.

Permission was obtained from the UniformData System for Medical Rehabilitation (UDSmr) touse the WeeFIM instrument. The WeeFIM II Sys-tem Interim Clinical Guide 2003 book was obtainedfrom UDSmr.

Translation Procedure of the WeeFIMInstrument

The original WeeFIM form was translated intoTurkish independently by a physiatrist with ad-vanced English and an English teaching professorwho had lived in the United States. These Turkishtranslations of the WeeFIM instrument were thentranslated back into English by another team thatconsisted of a professional technical translator anda physiatrist who was fluent in English. These textswere compared with each other, and the final Turk-ish translation of the WeeFIM instrument wasformed by a team consisting of four physiatristsand other relevant healthcare professionals special-izing in the field of pediatric rehabilitation.

In the study, one physiatrist performed theWeeFIM instrument by combining direct observa-tion of the children, with the help of the interviewswith primary caregivers consisting of 95.6% moth-ers, 2.6% fathers, and 1.7% other relatives. After 5days, 102 children (55 girls and 47 boys) aged 7–89mos were assessed again by the same physiatrist.

Statistical AnalysisThe scientific quality of the WeeFIM instru-

ment was determined through a range of analysis,which includes tests for reliability and validity. Themotor and cognitive items of the WeeFIM instru-ment were analyzed both together and separately.

March 2007 Turkish Children and WeeFIM Instrument 177

Assessment of ReliabilityThree types of reliability were assessed: inter-

nal consistency, intraclass correlation coefficient(ICC), and the test–retest reliability. One way ofassessing reliability is the consistency or repeat-ability of the measures; this method depends onhow much of the variation in measures is attribut-able to random or chance errors. Internal consis-tency of the Turkish translation of the WeeFIMinstrument was provided by Cronbach’s � coeffi-cient, which is defined as the interrelationship ofitems within a scale. ICC (one-way random-effectmodel) was used as a second way of assessingreliability.16 ICCs are often used as reliability coef-ficients in evaluations of items that are deemed tobe in the same category or class. They are the ratiosof between-rating variance to total variance.17 Al-though the ICCs are defined in terms of propor-tions of variance, it is possible for empirical esti-mates to be negative; the estimates all have upperbounds of 1, but no lower bounds. The test–retestreliability was assessed by Spearman’s correlationcoefficient on 102 nondisabled children.

Assessment of Internal ConstructValidity

Internal construct validity was assessed usingthe Rasch unidimensional measurement model.18–20

The Rasch model is a unidimensional model thatasserts that the easier the item (task), the morelikely it will be passed, and the more able theperson, the more likely they will pass an item (or beable to do a task) compared with a less able person.The Rasch model is now used extensively withinthe medical outcomes field to test the unidimen-sionality of scales, the ways in which their catego-ries function, and whether items are biased for keysubgroups such as age or gender (differential itemfunctioning [DIF]).21,22

The Rasch measurement model transforms or-dinal raw scores into interval measures that areobjective, fundamental, and linear. Rasch measuresprovide more information than the observed rawscores because the former provide sample-free item

difficulties and test-free person measures. The Ra-sch measurement model can also identify items thatare redundant and those that do not fit the model.Two indicators of fit are mean square OUTFIT andmean square INFIT statistics. These statistics aremeasures of how well a WeeFIM item fits to theRasch model. The reasonable item mean squarerange for INFIT and OUTFIT is from 0.6–1.4.

Another important aspect of the internal integ-rity of a scale is the absence of item bias or DIF.23 Ata given level of disability, it is important that theresponse to any item is unaffected by group mem-bership. In the current study, DIF was examined byage and gender. Bonferroni corrections were ap-plied to both fit and DIF statistics because of thenumber of tests undertaken.24 Because of multiplesignificance tests, P values less than 0.008 wereconsidered statistically significant.

Differences among four age groups (6–21, 22–45, 46–62, and 63–100 mos) according to Msall et al.4

for each item were evaluated by Kruskal–Wallis vari-ance analysis. When the P value from the Kruskal–Wallis test statistics was statistically significant, amultiple comparison test was used to determinewhich groups differed from which others.25

Data were analyzed by using SPSS for Win-dows 11.5 and the Rasch model computer programWINSTEPS.26,27

RESULTSMedian WeeFIM ratings and distribution of

gender of the subjects for each age group are pre-sented in Table 1.

ReliabilityCronbach � value was 0.99 for motor WeeFIM

ratings and 0.99 for cognitive WeeFIM ratings. TheICC (one-way random-effect model) was 0.81 for mo-tor WeeFIM ratings and 0.92 for cognitive WeeFIMratings. Test–retest reliability was good, with highcorrelations between the two time points (r � 0.996,P � 0.001 for total; r � 0.995, P � 0.001 for motor;r � 0.987, P � 0.001 for cognitive).

TABLE 1 Characteristics of the subjects

Age Range, mos

Sex Motor RatingMedian

(min–max)

Cognitive RatingMedian

(min–max)

Total RatingMedian

(min–max)M F

7–21 102 91 14 (13–69) 6 (5–23) 19 (18–90)22–45 80 69 68 (25–89) 26 (6–35) 94 (31–121)46–62 52 63 83 (56–91) 30 (16–35) 114 (76–126)63–92 61 55 90 (75–91) 35 (24–35) 125 (100–126)Total 295 278 73 (13–91) 26 (5–35) 98 (18–126)

M, male; F, female; min, minimum; max, maximum.

178 Aybay et al. Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

Internal Construct ValidityInternal Construct Validity of the WeeFIMinstrument by Rasch model

The internal construct validity of the Turkishtranslation of the WeeFIM instrument was con-firmed by its excellent fit to the Rasch measure-ment model. We found two subscales from theprincipal-component analysis of standardized re-sidual correlation for items. Although the stairclimbing, eating, grooming, walking, and bathingitems did not load into any subscale, the remainingmotor items loaded into the first subscale, and allcognitive items loaded into the second subscale.Therefore, we performed Rasch analysis on theWeeFIM instrument and analyzed fit statistics withall 18 items as combined and motor and cognitiveitems as subdivided. Table 2 shows both combinedand separate analyses performed on all 573 nondis-abled children.

For the motor items, bathing, lower dressing,upper dressing, and toileting were difficult items,whereas walking/crawling and stair climbing werethe easiest. The difficulty patterns for the four agegroups were almost identical, except for bowelmanagement and bladder management (Fig. 1).For the cognitive items, memory and problem solv-ing were the more difficult items, whereas compre-hension and expression were easier. The difficultypatterns for the four age groups were almost iden-tical (Fig. 2). Among the items, bowel manage-

ment, bladder management, eating, and compre-hension show considerable levels of misfit, asdetermined by both INFIT and OUTFIT statistics(Table 2).

Internal Construct Validity: DIFThere were statistically significant differ-

ences among the age groups in terms of motoritems. The first age group (7–21 mos) was sig-nificantly different from the other age groups interms of eating, bladder and bowel management,and grooming. The age groups did not presentany statistically significant differences amongthemselves with respect to toileting, dressing thelower body, bed/chair transfer, stair climbing, orwalking. For motor items, there was not anystatistically significant difference among agegroups in terms of gender.

There were statistically significant differencesamong the age groups in terms of cognitiveitems. The first age group was significantly dif-ferent from the second (22– 45 mos), and thethird age group (46 – 62 mos) was significantlydifferent from all age groups in terms of com-prehension. With respect to social interaction,problem solving, and memory items, there wereno significant differences among the age groups.Regarding cognitive items, there were no statis-tically significant differences among age groupsin terms of gender.

TABLE 2 Item difficulties (by logits) and fit statistics for combined and divided items

Items

Item Difficulties (Error) INFIT (MNSQ) OUTFIT (MNSQ)

Combined Divided Combined Divided Combined Divided

Motor ItemsEating 0.79 (0.06) 0.99 (0.06) 1.32 1.48 7.21 9.90Grooming 0.83 (0.06) 1.03 (0.06) 0.70 0.72 0.80 0.99Bathing 1.98 (0.05) 2.17 (0.05) 0.81 0.75 0.90 0.85Upper dressing 1.02 (0.06) 1.22 (0.06) 0.73 0.60 0.57 0.51Lower dressing 1.09 (0.06) 1.29 (0.05) 0.61 0.48 0.50 0.42Toileting 0.95 (0.06) 1.15 (0.06) 0.93 0.73 0.74 0.60Bladder management �0.20 (0.06) �0.07 (0.07) 1.63 1.52 0.97 0.87Bowel management �0.36 (0.06) �0.24 (0.07) 1.83 1.72 0.99 0.86Bed/chair transfer �0.72 (0.07) �0.65 (0.07) 0.79 0.62 0.49 0.43Toilet transfer �0.45 (0.06) �0.34 (0.07) 0.78 0.60 0.50 0.39Tub/shower transfer �0.19 (0.06) �0.05 (0.07) 0.86 0.75 0.59 0.54Walk or wheelchair �3.44 (0.09) �3.73 (0.09) 1.05 0.86 0.31 0.24Stairs �2.54 (0.08) �2.76 (0.09) 0.83 0.90 0.38 0.53

Cognitive ItemsComprehension �0.95 (0.07) �2.97 1.41 1.23 1.66 1.16Expression 0.08 (0.06) �0.56 0.91 0.94 0.90 0.96Social interaction 0.12 (0.06) �0.48 0.83 0.86 0.93 0.80Problem solving 0.92 (0.06) 1.78 0.73 0.87 0.72 0.80Memory 1.07 (0.06) 2.22 0.64 0.81 0.59 0.71

MNSQ, mean square.


DISCUSSIONMsall et al.28 showed that the WeeFIM instru-

ment was a reliable and valid measurement for thefunctional assessment of children aged between 6mos and 7 yrs with CP, Down syndrome, spinabifida, extreme prematurity, and limb deficiency.They also revealed that it is a reliable and validmeasurement method for children aged between 6mos and 12 yrs and that it can be used both duringpreschool and school years. Recent studies havedemonstrated the reliability and validity of theWeeFIM instrument for both disabled and nondis-abled children.2,3 However, the results of the func-tional measurement scales may show variations indifferent countries because of the differences insociocultural behaviors, including feeding, bath-ing, grooming, and toilet habits. To our knowledge,the literature does not contain any studies aboutthe WeeFIM instrument demonstrating the norma-

tive data of the Turkish population. One of ouraims in this study was to fill this gap in the liter-ature.

Heinemann et al.29 and Granger et al.30 ana-lyzed the scale quality of the FIM instrument usingRasch analysis. Tsuji et al.6 used Rasch rating scaleanalysis (RSA) to examine WeeFIM item difficulty.We have also employed Rasch analysis in our studyto establish the internal construct validity of theWeeFIM instrument for Turkish children.

In this study, we found two subscales from theprincipal-component analyses of standardized re-sidual correlation for items. Although all motoritems loaded into the first subscale, all cognitiveitems loaded into the other. Therefore, we per-formed Rasch analysis on the WeeFIM instrumentand analyzed fit statistics with all 18 items ascombined and motor and cognitive items as sub-divided. Chen et al.,31 in a retrospective study on

FIGURE 2 WeeFIM item difficulties for cognitive items (by logits) for nondisabled Turkish children aged 7–92 mos.

FIGURE 1 WeeFIM item difficulties for motor items (by logits) for nondisabled Turkish children aged 7–92 mos.


814 children with disability, applied Rasch RSA tothe data obtained with the WeeFIM instrument.They also identified two dimensions (i.e., motorand cognitive) by principal-component analysis ofthe item residuals. Tsuji et al.,6 in a study theyperformed with the WeeFIM instrument on 225children without any developmental delay, ob-served that when the WeeFIM items were dividedinto two groups of motor and cognitive items tominimize misfit, the degree of misfit was accept-able. Based on these findings, it can be said that theWeeFIM instrument has two dimensions as motorand cognitive.

In the study, the Turkish translation of theWeeFIM instrument’s reliability was good, withexcellent internal consistency and test–retest reli-ability. Internal construct validity was confirmedby good fit to the Rasch measurement model. Wehave observed that for the motor items, bathing,lower dressing, upper dressing, and toileting weredifficult items, whereas walking and stair climbingwere the easiest ones. For the cognitive items,memory and problem solving were more difficultitems, whereas comprehension and expressionwere easier. Our findings are comparable with theresults found with nondisabled Japanese children.Tsuji et al.6 concluded that stair climbing, bed/chair transfer, and walking were the easiest items,whereas grooming, bathing, and bladder controlwere the hardest items for nondisabled Japanesechildren. Chen et al.,31 dividing 814 disabled chil-dren into three age groups (�3, 3–7, and �7 yrs ofage) in their study, reported that the order ofmotor-item difficulty varied across age groups.

The fit statistics conducted in the presentstudy are acceptable, except for eating, bladder andbowel management, and comprehension. Compre-hension seemed to be misfit in the analysis of all 18items, although it did not seem so in motor andcognitive assessments performed separately. Simi-larly, Tsuji et al.6 also found that the comprehen-sion item was a misfit. We can attribute the misfitstatus of the eating item by the fact that children’sdiets become richer as they grow up, which is amore distinct situation, especially in our society.Therefore, it may be more difficult for the con-cerned child to perform eating functions properly,promptly, and reliably using a fork and knife set.On the other hand, if an 18-mo-old baby who hasbeen fed solely on the bottle is able to take his orher bottle alone and self-feed reliably, she or hemay receive a higher-than-expected rating for thistask. In addition, another reason may be the inca-pability of the WeeFIM instrument to investigate,in detail, food types and how the functions areperformed. Wong et al.,9 in a study performed on445 nondisabled Chinese children, have found asignificant correlation between the eating rating of

the WeeFIM instrument and the achievement ageof using chopsticks. They mention that chopsticksuse would make the eating task more difficult.Misfits of this type may be attributed to differentsociocultural contexts.

Misfit status of bladder and bowel manage-ment may be attributable to the fact that thesefunctions are acquired at the age of 2–3 yrs inmany children, and the associated ratings may re-main unchanged despite growing age. In the pre-liminary study we conducted on children with CPand nondisabled children, we found that allWeeFIM ratings except for sphincter controlshowed increases with age in nondisabled chil-dren.15 Bowel and bladder management was alsoreported as a misfit item on the adult FIM instru-ment. Furthermore, as emphasized in earlier studies,this situation may occur because both physiologicand performance (both autonomic and voluntaryneurological control mechanisms for bowel and, es-pecially, bladder management) aspects of these func-tions are rated.6,29–31

The comparison of item difficulty among thefour age groups in this study revealed differences indifficulty levels among some age groups, especiallywith regard to eating and bladder and bowel man-agement. These differences may be related to chil-dren’s ability and task complexity. For example, incontrast to the other items, the eating item seemseasier in the first age group (Fig. 1). This might beexplained by the comfort provided by the use offeeding bottles in this age group. Chen et al.31

reported that only eating and stair climbing itemsshowed misfit in their study conducted on school-age disabled children. They also stated that toilet-ing was the most difficult for toddlers but wasrelatively easier for older children, walking waseasiest for toddlers but was relatively harder forolder children, and grooming was difficult for tod-dlers but was easier for older children. In contrast,the difficulty levels revealed by our study for toi-leting, walking, and transfer activities were similarin all age groups because our sample consisted ofnondisabled children in contrast with Chen’sstudy. Squatting toilets are still common, espe-cially in lower socioeconomic groups in Turkey.However, closet-type lavatories are becoming morecommon in schools and residential dwellings.Therefore, we found no differences among the agegroups regarding the difficulty levels for toilettransfer.

CONCLUSIONRasch analysis of the WeeFIM instrument has

been shown to incorporate two dimensions, one forthe motor items and the other for the cognitiveitems. The Turkish translation of the WeeFIM in-strument is valid, reliable, and practical for the


Turkish child population. The WeeFIM instrumentis convenient for use in pediatric rehabilitation.Further studies are required to determine thecross-cultural validity of the Turkish translation ofthe WeeFIM instrument.

ACKNOWLEDGMENTSThe authors would like to extend their appre-

ciation to the Uniform Data System for MedicalRehabilitation, Center for Functional AssessmentResearch at the State University of New York atBuffalo. The use of the WeeFIM instrument tocollect data for this research study was authorizedand conducted in accordance with the terms of aspecial purpose license granted to the Licensee byUniform Data System for Medical Rehabilitation, adivision of UB Foundation Activities, Inc. (UDSmr).The patient data collected during the course of thisresearch study have been or will be subjected toUDSmr’s standard data processing procedures orare otherwise comparable with data processed byUDSmr.

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31. Chen CC, Bode RK, Granger CV, Heinemann AW: Psycho-metric properties and developmental differences in chil-dren’s ADL item hierarchy: A study of the WeeFIM® instru-ment. Am J Phys Med Rehabil 2005;84:671–9


Authors:Ta-Shen Kuan, MD, MSYueh-Ling Hsieh, PhD, RPTShu-Min Chen, MDJo-Tong Chen, MD, PhDWei-Chang Yen, MDChang-Zern Hong, MD

Affiliations:From the Department of PhysicalMedicine and Rehabilitation, Collegeof Medicine, National Cheng KungUniversity, Tainan, Taiwan (T-SK,S-MC, J-TC, W-CY, C-ZH);Department of Physical Therapy,Hungkuang University, Sha-Lu,Taichung, Taiwan (Y-LH, C-ZH); andDepartment of RehabilitationMedicine, Han-Ming Hospital, Chang-Hua, Taiwan (C-ZH).

Correspondence:All correspondence and requests forreprints should be addressed toChang-Zern Hong, MD, Departmentof Physical Therapy, HungkuangUniversity, 34 Chung-Chie Road, Sha-Lu, Taichung 433, Taiwan.

Disclosures:No commercial party having a directfinancial interest in the results of theresearch supporting this article hasor will confer a benefit upon theauthors or upon any organizationwith which the authors areassociated.


DOI: 10.1097/PHM.0b013e3180320ea7

The Myofascial Trigger Point RegionCorrelation Between the Degree of Irritability and thePrevalence of Endplate Noise

ABSTRACT

Kuan T-S, Hsieh Y-L, Chen S-M, Chen J-T, Yen W-C, Hong C-Z: The myofascialtrigger point region: correlation between the degree of irritability and the preva-lence of endplate noise. Am J Phys Med Rehabil 2007;86:183–189.

Objective: This study was designed to investigate the correlationbetween the irritability of the myofascial trigger point (MTrP) and theprevalence of endplate noise (EPN) in the MTrP region of human skeletalmuscle.

Design: Twenty normal subjects with latent MTrPs and 12 patientswith active MTrPs in the upper trapezius muscles were recruited for thisstudy. The patients reported the subjective pain intensity of the activeMTrP (0–10). The MTrP and an adjacent non-MTrP site were confirmedand marked for the measurement of pressure pain threshold (with apressure algometer) and the prevalence of EPN (with electromyographicrecordings).

Results: The prevalence of EPN in the MTrP regions was significantlyhigher (P � 0.01) in the active MTrPs than in the latent ones. However,no EPN could be found in the non-MTrP region near either the active orthe latent MTrPs. The pain intensity and the pressure pain threshold werehighly correlated with the prevalence of EPN in the MTrP region (r �0.742 and �0.716, respectively).

Conclusions: The irritability of an MTrP is highly correlated with theprevalence of EPN in the MTrP region of the upper trapezius muscle. Theassessment of EPN prevalence in an MTrP region may be applied toevaluate the irritability of that MTrP.

Key Words: Electromyography, Endplate Noise, Muscle, Trigger Point, Pain

March 2007 Endplate Noise and Myofascial Trigger Point 183

RESEARCH ARTICLE

Myofascial Pain

Myofascial trigger point (MTrP) presence ischaracteristic of myofascial pain syndrome.1 AnMTrP has been defined as a highly localized painfulor sensitive spot in a palpable taut band of skeletalmuscle fibers.1 An active MTrP is an irritable spotwith spontaneous pain or pain in response tomovement, and a latent MTrP is a tender spot withpain or discomfort in response to compressiononly.1 Two important characteristics of MTrP arereferred pain and a local twitch response (LTR).LTRs can be elicited by snapping palpation on theMTrP in some muscles, or by needling in almost allcases.1,2 More LTRs can be elicited by needling of ahighly irritable MTrP than a less painful one.3

The mechanism of LTR has been extensivelystudied on the animal model developed by Hongand Torigoe.4 The most tender spot in the ham-string muscle of rabbit could be identified by ob-serving the animal’s behavior. This hyperirritablespot was marked and the animal was anesthetized.It was found that many LTRs (similar to thoseobserved in humans) could be elicited by needlingof this hyperirritable spot, but this was possible invery few or none in the control sites. It was alsofound that LTRs could not be elicited after thetransection of the innervation nerve (sciatic nerve).LTRs could also not be elicited in the hamstringmuscle immediately after transection of the upperthoracic spinal cord, but they recovered almost tothe original level after the spinal shock period(about 2.5 hrs later).5 It has been concluded thatLTR is elicited via the spinal reflex by stimulatingthe sensitive site in the MTrP region. Hong andSimons2 have hypothesized that there are multiplesensitive loci in the MTrP region. Mechanical stim-ulation of this tiny locus can elicit pain, referredpain, and LTR (with high-pressure stimulation,such as needling).2,6 This tiny sensitive site hasbeen defined as a sensitive locus,6 or an LTR locus.2

In 1993, Hubbard and Berkoff7 recorded spon-taneous electrical activity in the MTrP region of theupper trapezius muscle. Similar electrical activitycould also be recorded from the rabbit skeletalmuscles.8 Hubbard and Berkoff7 described this ac-tivity as the action potential generated from theintrinsic muscle fibers when a muscle spindle ismechanically irritated.7 However, this low-ampli-tude electrical activity is similar to the endplatenoise (EPN) rather than action potentials. Afterreviewing old literature, Simons9 concluded thatEPN is a consequence of excessive acetylcholineleakage, which may cause focal contracture in theendplate zone to form the contracture nodule ortaut band.1,9–11 In recent studies, Simons et al.have demonstrated that there is a much higherprevalence of EPN in the MTrP region comparedwith the non-MTrP site in either animals8 or hu-

man subjects.12 The tiny site from which EPN canbe recorded in the MTrP region has been defined asactive locus2 or EPN locus.13

It has been suggested that the amount of sen-sitive loci (LTR loci) in an MTrP region is propor-tionate to the degree of irritability of the MTrP.3,14

However, it is unclear whether the amount of ac-tive loci (EPN loci) is also related to the degree ofirritability of MTrP. This study is designed to in-vestigate the correlation between the prevalence ofEPN loci and the degree of irritability (pain inten-sity, pain threshold) in the MTrP region.

MATERIALS AND METHODSGeneral Design

Normal subjects with latent MTrPs and pa-tients with active MTrPs in one side of the uppertrapezius muscles were included in this study. Pa-tients were initially requested to report the subjec-tive pain intensity of the active MTrP according toa numeric rating scale (0–10). For each subject(either normal subject or patient), pressure painthreshold was measured at both MTrP and non-MTrP sites. Then, the prevalence of EPN was assessedwith needle electromyographic (EMG) recordings inboth the MTrP region and non-MTrP region of theupper trapezius muscle for each subject.

SubjectsTwenty normal subjects (age 43.5 � 11.1) with

latent MTrPs and 12 patients (age 43.7 � 11.9)with active MTrPs in the upper trapezius musclewere recruited for this study. Subjects in bothgroups were matched for age and sex. They allsigned the informed consents as approved by thehuman subject research committee of the NationalCheng Kung University, Tainan, Taiwan. The gen-eral criteria for selection of subjects included (1)no acute or serious medical problems, (2) no neu-rologic disorders other than muscle pain, (3) nocoagulopathy or any other bleeding disorder, (4) noserum hepatitis B or acquired immunodeficiencysyndrome, (5) no pain therapy (pain medications,physical therapy, etc.) for at least 2 wks, and (6) nocognitive impairment or psychiatric disorder.

Identification of MTrPs and Non-MTrPsNormal Subjects with Latent MTrPs

Normal subjects who had latent MTrPs in theupper trapezius muscles in either side or both sideswere recruited. If MTrPs existed in both sides ofupper trapezius muscles, only one side was ran-domly selected for the study. The latent MTrP wasidentified on the basis of the following criteria: (1)a localized tender spot (without spontaneous pain)in a palpable taut band of muscle fibers, and (2)characteristic and consistent referred pain when it

184 Kuan et al. Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

was compressed firmly. As soon as this latent MTrPwas confirmed, it was marked by an investigatorwho did not perform the assessment of pain thresh-old or EPN prevalence.

Patients with Active MTrPsPatients who had active MTrPs in the upper

trapezius muscles in either side or both sides wererecruited. If MTrPs existed in both sides of uppertrapezius muscles, only one side was randomlyselected for this study. The active MTrP was iden-tified on the basis of the following criteria, asrecommended by Simons9: (1) a localized tenderspot in a palpable taut band of muscle fibers, (2)recognized pain (as the usual clinical complaint)when the tender spot was compressed, and (3)characteristic and consistent referred pain. Simi-larly, this active MTrP was marked by the sameinvestigator who marked the latent MTrP.

Localization of Non-MTrPsAfter identification of the MTrP site in each

subject, a control site (non-MTrP site) some dis-tance away from the MTrP site was also marked bythe same investigator who marked the MTrP site.

Subjective Pain Intensity (NumericRating Scale)

Initially, the patient was requested to reportpain intensity of the selected MTrP on the basis ofthe numeric rating scale. The patient was informedof the numeric rating scale from 0 to 10. Zerorepresents no pain at rest or during movement, and10 represents the worst pain ever experienced inone’s life. The other numbers represent differentdegrees of pain level. In general, pain intensitybelow 5 is considered a tolerable level.

Pressure Pain Threshold MeasurementMeasurement of pressure pain threshold on

the MTrP and non-MTrP sites was performed be-fore the EMG recordings. A pressure algometer wasused for this measurement.15 A study by Ohrbachand Gale16 found that pain threshold measurementwith this algometer was reliable and had no signif-icant differences among multiple trials in painfulmuscles. Initially, the algometer was placed on themarked MTrP site, perpendicular to the surface ofthe skin. The pressure of compression was in-creased gradually at a rate of movement approxi-mately 1–2 mm/sec until the subject began to feelany pain or discomfort (for latent MTrPs) or untilthe patient began to feel an increase of pain ordiscomfort (for active MTrPs). At that point, thesubject informed the examiner by saying “yes.” Thecompression stopped as soon as the subject said“yes.” The subject was asked to remember this level

of pain discomfort and to apply the same criterionfor the consecutive measurements. The reading ofpressure (kg/cm2) at that point was considered thepressure pain threshold level. The subject mightdemonstrate pain by pulling away or grimacing,which would indicate that the pain threshold hadbeen exceeded.15 If this was the case, the subjectwould be given instructions again, and a repeat mea-surement would be taken to ensure that the “real”threshold was obtained. Three repetitive measure-ments at an interval of 30–60 secs were performed ateach site. The average values of the three readingswere used for data analysis. The same routine wasalso performed at the control site (non-MTrP site).Two investigators who participated in measuring thethreshold were trained extensively to minimize theintratester and intertester variability. They wereblinded as to whether subjects had latent or activeMTrPs.

Electrophysiological RecordingsEquipment

A four-channel Nicolet EMG machine was usedto record the electrical activity from MTrPs byusing disposable monopolar Teflon-coated EMGneedle electrodes.

SettingsAs shown in Figure 1, the first channel recorded

the electrical activity from the active electrode (ex-perimental needle electrode) in the MTrP region. Thereference needle electrode was placed in a site approx-imately 3–4 cm from MTrP. The second channelrecorded the electrical activity from the control site.For the control recordings, the active recording elec-trode was placed in a non-MTrP region outside theendplate zone. The reference electrode was connectedto the reference electrode of the first channel througha bridge connector (to form a common referenceelectrode). A ground electrode was placed on the skinnear the recording sites. For both channels, the sen-sitivity of recording was set at 20 mV per verticaldivision, and the time-sweep speed was set at 10msecs per horizontal division. The high-frequencyfilter was set at 10 kHz, and the low-frequency filterwas set at 20 Hz.

ProcedureRegarding the assessment of EPN, the preva-

lence of EPN in 24 sites of three needle-insertiontracks in the MTrP region was measured as de-scribed in the previous reports (Fig. 2).8,12 In thisway, only one penetration into the skin was re-quired. We did not measure the amplitude andduration of the EPN because the amplitude andduration varied during needle movement eitherbecause of changes in electrode distance or direct


mechanical injuries to the muscle fibers. In theexperimental study of one MTrP site, the exploringelectrode (active recording needle electrode) wasinserted progressively into the MTrP region. Theneedle was advanced gently and slowly through theleast possible distance (usually 1–2 mm) by simul-taneously rotating the needle to facilitate smoothentry through the tissue. After eight thrusts (ad-vancements of the needle in one track), the needlewas pulled out to the original insertion depth andreinserted in a slightly different direction (a neartrack). This procedure was repeated again to ex-plore a total of 24 thrusts (eight thrusts per inser-tion; three insertions). All occurrences of EPN wererecorded. As soon as an EPN appeared, the needleremained there without further movement. Sam-ple EMG recordings (Fig. 1) were taken until theamplitude of the EPN activity became indistin-guishable from that recorded from the control nee-dle. The time required for the disappearance of

EPN was less than 10 mins, usually 2–3 mins.Advancement of the needle continued after disap-pearance of the EPN. The subject reported the painintensity and feeling when an EPN was recorded.The routine used at the control site (non-MTrPsite) was the same as that used at the MTrP sitewith regard to insertion procedure. The investiga-tor who performed this procedure was blinded as towhether subjects had latent or active MTrPs.

Data AnalysisComparison Between Latent and ActiveMTrPs

The data of pressure pain threshold and prev-alence of EPN in both MTrP and non-MTrP regionwere analyzed for the differences between normalsubjects with latent MTrPs and patients with activeMTrPs according to a t test (pain threshold data) ora Fisher test (EPN data). A P value less than 0.01was considered statistically significant.

FIGURE 2 Schematic of insertion procedure during the assessment of EPN prevalence.

FIGURE 1 Schematic arrangement of electrodes and typical examples of recordings.


Comparison Between MTrP and Non-MTrPSites

The data of pressure pain threshold and prev-alence of EPN in both normal subjects and patientswere analyzed for the differences between MTrPregion and non-MTrP region according to a pairedt test (pain threshold data) or a Fisher test (EPNdata). A P value less than 0.01 was consideredstatistically significant.

Correlation Between the Prevalence of EPNand the Irritability (Pain Intensity orPressure Pain Threshold) in the MTrPRegion

The data of the pain intensity and the averagevalues of three readings for each threshold mea-surement in all subjects (both normal subjects andpatients) were analyzed for their correlation withthe prevalence of EPNs. Pearson linear regressionanalysis was used to analyze statistical significance.

RESULTSLatent MTrP (Normal Subjects) vs.Active MTrP (Patients)

As shown in Table 1, age and sex were fairlymatched for patients and normal subjects. All pa-tients had pain in the MTrP regions, but none hadpain in the non-MTrP regions (with a mean painintensity of 0.0 � 0.0). Every patient reported painlocalized in the shoulder without referral. Themean pressure pain threshold, either at the MTrPsite (1.9 � 0.3 kg/cm2) or at the non-MTrP site(4.1 � 0.6 kg/cm2), was significantly lower (P �

0.01) in the patients with active MTrPs comparedwith the normal subjects with latent MTrPs (3.7 �0.7 and 5.9 � 1.0 kg/cm2, respectively). The prev-alence of EPN in the MTrP regions was also signif-icantly higher (P � 0.01) in the active MTrPs(7.2 � 4.2 per 24 sites) than in the latent MTrPs(2.8 � 1.4 per 24 sites).

MTrP vs. Non-MTrPAs expected, the mean pressure pain threshold

at the MTrP site (3.7 � 0.7 or 1.9 � 0.3 kg/cm2)was significantly lower (P � 0.01) than at thenon-MTrP site (5.9 � 1.0 or 4.1 � 0.6 kg/cm2) foreither latent or active MTrPs. However, no EPNcould be recorded in the non-MTrP region foreither latent or active MTrPs (Table 1).

Prevalence of EPN and Subjective PainIntensity of MTrP

The high correlation (r � 0.742) between theprevalence of EPN and the pain intensity in theMTrP region for all subjects is demonstrated inFigure 3. This was also true when the normalsubjects were excluded from the population foranalysis.

Prevalence of EPN and Pressure PainThreshold of MTrP

For all subjects, the prevalence of EPN washighly inversely correlated (r � �0.716) with thepressure pain threshold (Fig. 4). Similar to a pre-vious study,14 the pain intensity and the pressurepain threshold are also strongly inversely corre-lated.

TABLE 1 Pain intensity, pressure pain threshold, and prevalence of endplate noise (EPN) in themyofascial trigger point (MTrP) region and non-MTrP region

All SubjectsPatients withActive MTrPs

Normal Subjectwith Latent MTrPs

Difference,Normal vs. Patient

P

No. of subjects 32 12 20Male 14 5 9Female 18 7 11

Age 43.5 � 11.2 43.7 � 11.9 43.5 � 11.1Pain intensity (0–10)

MTrP site 2.3 � 3.1 6.2 � 1.3 0.0 � 0.0 �0.01Non-MTrP site 0.0 � 0.0 0.0 � 0.0 0.0 � 0.0

Pressure pain threshold,kg/cm2

MTrP site 3.0 � 1.0 1.9 � 0.3 3.7 � 0.7 �0.01Non-MTrP site 5.3 � 1.2 4.1 � 0.6 5.9 � 1.0 �0.01Difference P � 0.01 P � 0.01 P � 0.01

Prevalence of EPN,no./24 sites

MTrP site 4.6 � 3.6 7.2 � 4.2 2.8 � 1.4 �0.01Non-MTrP site 0.0 � 0.0 0.0 � 0.0 0.0 � 0.0Difference P � 0.01 P � 0.01 P � 0.01


DISCUSSIONThe pathophysiology of the MTrP has become

better understood as a result of recent studies onboth human and animal subjects.2–5,7,8,12,14,17–24

Hong has hypothesized that there are multiplebasic units in an MTrP region.2,6,25 He has specu-lated that each MTrP unit contains a sensitive locus(a minute site from which a LTR can be elicitedwhen this site is mechanically stimulated) and anactive locus (a minute site from which spontaneouselectrical activity can be recorded).2 The sensitivelocus is probably nociceptors (sensory compo-nent),2,20 and the active locus is possibly dysfunc-tional endplates (motor component).2,8,9,12 Spon-taneous electrical activity (EPN) recorded from anactive locus of MTrP has been theorized to beabnormal endplate potentials attributable to exces-sive release of acetylcholine,2,8,9,12 with the exces-sive acetylcholine release responsible for the for-mation of taut bands, which contain MTrPs.2,8,9 Inan electron microscopic study,11 remarkable short-ening of the sarcomeres in a contraction nodule(probably in or near the endplate zone) with

lengthening of the sarcomeres outside the nodulewas observed in some fibers (taut fibers). The totallength of these muscle fibers was unchanged, butthe tension of the muscle fibers was increased (tautband).

In previous studies, it has been suggested thatthe irritability of an MTrP is closed related to theLTR loci in the MTrP region.3–6 The pressure painthreshold can be used for the assessment of MTrPirritability.14–16 In this study, we have demon-strated the high correlation between the irritability(measured with pain intensity and pressure painthreshold) and the prevalence of EPN loci in anMTrP region of upper trapezius muscle. It is ourexperience during EMG examination that when theEMG needle approaches a painful locus, EPN fre-quently can be recorded from this site. Therefore,an EPN locus may be in the immediate vicinity ofan LTR locus. However, it is unclear whether everyEPN locus in the MTrP region is closely connectedwith an LTR locus. Because the irritability of MTrPis related to the prevalence of both LTR loci andEPN loci, it is very likely that the vast majority ofEPN loci are connected with LTR loci. Stated dif-ferently, in most endplates in the MTrP region,there are nociceptors (free nerve endings, as ob-served in animal study20) in the nearby region. Ithas also been demonstrated that free nerve endingswere frequently found near the sites from whichEPN could be recorded.21 However, this does notindicate any neural connection between an EPNlocus and an LTR locus.

It has been suggested that MTrP formation isrelated to a central mechanism on the basis of thestudies on referred pain24 and LTRs.5,19 However,the mechanism of the connection between EPNloci and LTR loci is unknown. The correlationbetween them is possibly attributable to a periph-eral interaction rather than a central sensory con-nection. It is possible that the persistent contrac-ture of taut band may cause hypoxia and ischemiain the local region (within the endplate zone),which subsequently cause the release of inflamma-tory substance to sensitize the nociceptors (LTRloci).1 This is the peripheral sensitization of anMTrP. Gunn26 also suggested that local contractionof the muscle fibers (local depolarization withoutaction potentials) may cause hypersensitivity ofnociceptors. Therefore, the sensitivity of the noci-ceptors (irritability of MTrP) seems closely relatedto the prevalence of EPN, which could be related tothe degree of local depolarization.

In conclusion, the irritability of an MTrP in theupper trapezius muscle is closely related to theprevalence of EPN in this MTrP region. In futureresearch, assessment of EPN prevalence may beused for the estimation of MTrP irritability.

FIGURE 4 The correlation between the prevalence ofendplate noise (EPN) and pressure painthreshold (PPT) of myofascial triggerpoints (MTrPs).

FIGURE 3 The correlation between the prevalence ofendplate noise (EPN) and subjective painintensity (PI) of myofascial trigger points(MTrPs).


REFERENCES1. Simons DG, Travell JG, Simons LS: Travell & Simons’s

Myofascial Pain and Dysfunction: The Trigger Point Man-ual. Vol. 1, ed 2. Baltimore, Williams & Wilkins, 1999

2. Hong C-Z, Simons DG: Pathophysiologic and electrophysi-ologic mechanism of myofascial trigger points. Arch PhysMed Rehabil 1998;79:863–72

3. Hong C-Z, Kuan T-S, Chen J-T, et al: Referred pain elicitedby palpation and by needling of myofascial trigger points: acomparison. Arch Phys Med Rehabil 1997;78:957–60

4. Hong C-Z, Torigoe Y: Electrophysiologic characteristics oflocalized twitch responses in responsive bands of rabbitskeletal muscle fibers. J Musculoskelet Pain 1994;2:17–43

5. Hong C-Z, Torigoe Y, Yu J: The localized twitch responsesin responsive bands of rabbit skeletal muscle fibers arerelated to the reflexes at spinal cord level. J MusculoskeletPain 1995;3:15–33

6. Hong C-Z: Lidocaine injection versus dry needling to myo-fascial trigger point: the importance of the local twitchresponse. Am J Phys Med Rehabil 1994;73:256–63

7. Hubbard DR, Berkoff GM. Myofascial trigger points showspontaneous needle EMG activity. Spine 1993;18:1803–7

8. Simons DG, Hong C-Z, Simons LS: Prevalence of sponta-neous electrical activity at trigger spots and at control sitesin rabbit skeletal muscle. J Musculoskelet Pain 1995;3:35–48

9. Simons DG: Clinical and etiological update of myofascialpain from trigger points. J Musculoskelet Pain 1996;4:93–121

10. Simons DG: Diagnostic criteria of myofascial pain caused bytrigger points. J Musculoskelet Pain 1999;7:111–20

11. Simons DG, Stolov WC: Microscopic features and transientcontraction of palpable bands in canine muscle. Am J PhysMed 1976;55:65–88

12. Simons DG, Hong C-Z, Simons LS: Endplate potentials arecommon to midfiber myofascial trigger points. Am J PhysMed Rehabil 2002;81:212–22

13. Hong C-Z: New trends in myofascial pain syndrome (invitedreview). Zhonghua Yi Xue Za Zhi (Taipei) 2002;65:501–12

14. Hong C-Z, Chen Y-N, Twehous D, et al: Pressure threshold

for referred pain by compression on the trigger point andadjacent areas. J Musculoskelet Pain 1996;4:61–79

15. Fischer AA: Pressure threshold meter: its use for quantifi-cation of tender spots. Arch Phys Med Rehabil 1986;67:836–8

16. Ohrbach R, Gale EN: Pressure pain thresholds, clinicalassessment, and differential diagnosis: reliability and valid-ity in patients with myogenic pain. Pain 1989;39:157–69

17. Chen J-T, Chen S-M, Kuan T-S, et al: Phentolamine effecton the spontaneous electrical activity of active loci in amyofascial trigger spot of rabbit skeletal muscle. Arch PhysMed Rehabil 1998;79:790–4

18. Gerwin RD, Shannon S, Hong C-Z, et al: Identification ofmyofascial trigger points: interrater agreement and effect oftraining. Pain 1997;69:65–73

19. Hong C-Z, Yu J: Spontaneous electrical activity of rabbittrigger spot after transection of spinal cord and peripheralnerve. J Musculoskelet Pain 1998;6:45–58

20. Hong C-Z, Chen J-T, Chen S-M, et al: Histological findingsof responsive loci in a myofascial trigger spot of rabbitskeletal muscle from where localized twitch responsescould be elicited. Arch Phys Med Rehabil 1996;77:962

21. Hong C-Z, Chen J-T, Chen S-M, et al: Sensitive loci in amyofascial trigger point region are related to sensory nervefibers. Am J Phys Med Rehabil 1997;76:172

22. Kuan T-S, Lin T-S, Chen J-T, et al: No increased neuro-muscular jitter at rabbit skeletal muscle trigger spot spon-taneous electrical activity sites. J Musculoskelet Pain 2000;8:69–82

23. Kuan T-S, Chen J-T, Chen S-M, et al: Effect of botulinumtoxin on endplate noise in myofascial trigger spots of rabbitskeletal muscle. Am J Phys Med Rehabil 2002;81:512–20

24. Mense S,: Considerations concerning the neurobiologicalbasis of muscle pain. Canadian J Physiol Pharmacol 1991;69:610–6

25. Hong C-Z: Pathophysiology of myofascial trigger point.J Formos Med Assoc 1996;95:93–104

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Authors:Michael F. Oswanski, MD, FACSOm P. Sharma, MD, FACSShekhar S. Raj, MBBSLeslie A. Vassar, OTR/LKathryn L. Woods, OTR/LWendi M. Sargent, OTR/LRobyn J. Pitock, OTR/L

Affiliations:From the Toledo Hospital/The ToledoChildren’s Hospital, Toledo, Ohio(M.F.O., O.P.S., S.S.R.); and TotalRehab at Flower Hospital, Sylvania,Ohio (L.A.V., K.L.W., W.M.S., R.J.P.).

Correspondence:All correspondence and requests forreprints should be addressed toMichael F. Oswanski, MD, FACS,Medical Director, Trauma ServicesDepartment, The Toledo Hospital/TheToledo Children’s Hospital, 2142North Cove Boulevard, Toledo, Ohio43606.

Disclosures:The Ohio State Department of PublicSafety provided funding for thisstudy. The authors have no conflictsof interest associated with this study.


DOI: 10.1097/PHM.0b013e31802b7de5

Evaluation of Two Assessment Toolsin Predicting Driving Ability of SeniorDrivers

ABSTRACT

Oswanski MF, Sharma OP, Raj SS, Vassar LA, Woods KL, Sargent WM, PitockRJ: Evaluation of two assessment tools in predicting driving ability of seniordrivers. Am J Phys Med Rehabil 2007;86:190–199.

Objective: To evaluate Motor Free Visual Perceptual Test (MVPT)and Clock Drawing Task (clock test) as quick assessment tools in pre-dicting driving capability of senior drivers for an on-road driving test.

Design: Senior drivers (�55 yrs) referred for evaluation and recommen-dation for license renewal were given the MVPT, clock test, and an on-roaddriving test. Receiving operating characteristic (ROC) analysis and stepwisemultivariate logistic regression (SMLR) were used to develop a probabilitymodel to differentiate between capable and incapable senior drivers.

Results: Data for 232 seniors who had completed all written tests andthe on-road driving test were analyzed. Of the 232 seniors, 131 (56%)were classified as capable and 101 (44%) as incapable drivers on theroad test. Mean scores for capable and incapable drivers were MVPT32.0 � 4.0 vs. 28.4 � 4.6 and mean clock test score 3.5 � 0.8 vs.2.7 � 1.2, and mean processing time was 7.1 � 6.5 vs. 10.6 � 5.5.The means of the three measurements were significantly different be-tween the two groups (P value �0.001). ROC curve analysis revealed anoptimal cut point of �32 for MVPT score with 60% sensitivity and 83%specificity. The optimal cut point for clock test scores is �3 with 70%sensitivity and 65% specificity. The optimal cut point for processing timesis �6.27 secs with 60% sensitivity and 80% specificity. SMLR showedthat the most significant predictor of seniors’ driving capabilities are theMVPT test scores and clock test scores.

Conclusion: MVPT and clock test tools are significant predictors ofdriving capability on an on-road driving test.

Key Words: Motor Free Visual-Perception Test (MVPT), Clock-Drawing Task (ClockTest), Processing Time, Cognitive Testing, Senior Drivers


RESEARCH ARTICLE

Cognitive

Driving is an activity requiring complex sen-sory, perceptual, cognitive, behavioral, and motorskills. Crash rates increase steadily in senior driv-ers after the age of 60 yrs.1–5 Age-associated dis-eases and changes in physiologic function oftencombine synergistically to impair driving ability.3,4

Senior drivers use automobiles for 90% oftheir outings.6 It is expected that there will be athreefold increase of senior drivers in the next fewdecades.6 By the year 2020, one of five aging babyboomers will be 65 yrs or older, and nearly half ofthese people will be more than 75 yrs old.7

Senior drivers have a higher rate of accidentsper mile than all other age groups, with the excep-tion of the teenage group.1,8 The actual number ofcrashes senior drivers are involved in as a group isno higher than that of the general driving popula-tion because seniors drive fewer miles. When crashrates of senior drivers are adjusted for actual milesdriven, their rate is higher than any age group,with the exception of drivers under the age of 25yrs.1,9–18 Senior driver crash rates per 100,000miles driven are double those of the younger co-horts. Senior drivers also differ from younger agegroups in the types of crashes they are involved in.Studies indicate that crashes involving senior driv-ers are more likely to occur at intersections and atlow speeds, and they are five times more likely toinvolve two or more vehicles, with a higher fre-quency of fatality.19–22

Research is currently being conducted to makeall aspects of driving safer and to determine howsenior drivers with disabilities or unsafe drivers canbe trained to drive safely. Some senior drivers whohave deficiencies identified and corrected can be-come safe drivers.1 It is a challenge to safety offi-cials to separate safe from unsafe drivers. The di-vision of motor vehicles offices in most states arenot adequately equipped to perform this task effec-tively.1

PHYSIOLOGIC CHANGESVision is very important for most of the sensory

contributions during driving. With advancing years,multiple visual functions start to decline.4,20,23,24

Static visual acuity for licensing is a widely acceptedstandard. It is dynamic visual acuity (clarity of visionfor objects moving relative to the observer) thatshows a strong and consistent relationship to driv-ing.25,26 There is a gradual progressive age-relateddecline in the nasal and temporal visual fields in thefifth decade.25–27

Advancing age causes increased difficulty innight driving.26 Changes in age-associated lensprotein and increased lens density cause increasedscatter of light.26 The time required for glare re-covery also increases with age.20,28 Increased lens

density and decreased pupil size reduce illumina-tion reaching retinal photoreceptors. Adaptation todarkness occurs more slowly in senior drivers.Higher levels of contrast are required to visualizeobjects adequately under conditions of low illumi-nation.20,28,29

Other factors that influence the visual systemcan result in several ocular diseases with additionalreversible or progressive visual impairments.26 Someocular diseases, including diabetic retinopathy, cor-neal diseases, cataracts, glaucoma, and age-relatedmacular degeneration, can impede safe driving.

Hearing loss attributable to advancing age cancause high-frequency loss, which impairs the per-ception of important driving cues such as horns,sirens, and/or train whistles.3,23,29–31 Driving isalso affected by age-related decline in musculoskel-etal function (including decreases in strength, flex-ibility, coordination, or dexterity).3,23,29,30

Age-related vision deterioration, decline inhearing and cognitive processing, and decreasedlimb strength and range of motion present specialchallenges to senior drivers, especially when driv-ing at night, through intersections, on freeways,and in highway work zones.

Dynamic visual acuity (the ability to see movingobjects) and scotopic visual acuity (the ability to seeobjects in dim light), contrast sensitivity (objects thatdo not stand out sharply from their background), orperipheral vision (objects that seem in the outeredges of visual field) are some components of goodvisual health essential for driving. In addition, atten-tion, visual spatial skills, memory, information pro-cessing, and quick decision making are critical cog-nitive components for driving.2 Ongoing endeavorsby the automobile industry to add more safety fea-tures to motor vehicles such as multiple air bags andnavigational warning devices will benefit all agegroups of drivers.3,6

It would be beneficial for division of motorvehicles offices to use simple, inexpensive screen-ing tools to differentiate capable from incapabledrivers. Few states require repeated written androad tests for license renewal. Visual screening islimited to static visual acuity testing in almost allstates.6

OBJECTIVESThe objective of this study was to evaluate the

Motor Free Visual Perceptual Test (MVPT) and theClock Drawing Task (clock test) as quick assess-ment tools in predicting driving capability of seniordrivers for an on-road driving test.

MATERIALS AND METHODSSubjects/Participants

The subjects were 255 senior drivers, (�55 yrsof age) referred for a driver’s evaluation at a reha-

March 2007 Predicting Driving Ability of Senior Drivers 191

bilitation center from September 1999 to October2001 in northwest Ohio and southeast Michigan.Most of these subjects were from within the greaterToledo area (218/255). These subjects were referredfor a driver’s evaluation at a rehabilitation centerbased on unsafe behaviors observed by law enforce-ment officers, including those that form a basis forcitations; accidents; physician referral; referral byrelatives; and self-referral. Senior drivers’ demo-graphic information such as age, gender, place ofresidence, reason for referral, and details of citation(if that was the reason for referral) were also col-lected. These subjects were given two paper-and-pencil tests of cognitive functioning: the clock testand the MVPT.

The evaluator screened the subjects for anypreexisting medical conditions that would legallypreclude them from driving, such as visual hom-onymous hemianopsia (a primary visual impair-ment inadequately improved by corrective lenses),class IV cardiac status, and uncontrolled seizures.9

Clock TestThe clock test is designed to quickly assess

visual–spatial construction, visual perception, andabstract conceptualization19,22,30–33 using threesubtests: clock drawing, clock setting, and clockreading. The clock test measures the subject’s levelof cognitive impairment and helps differentiate be-tween normal elderly individuals and those suffer-ing from dementia.29,30,32–34 There were conflict-ing results from another study that had limitationsin detecting mild or early dementia, which wasclinically detectable.35

The four-point method of clock drawing taskby Pfizer, Inc.36 that is currently being used by theTriAD (Three for the Management of Alzheimer’sDisease: The Clinician, Patient, and Caregiver Alli-ance) was selected because it is easy to administerand easy to score. It requires only a paper and apencil and is less ambiguous than conventionalclock drawing tests.

The clock test provides well-defined, specificscoring criteria that ensure greater efficiency andreliability. Errors are broken down into the followingcomponents: (1) omissions, (2) distortions, (3) mis-placements, (4) preservations, (5) substitutions, (6)additions, and (7) rotations.

The test subjects are instructed to draw theface of a clock and place the hands of the clock atnumbers 10 and 11. The scores are given using thefour-point system.36

The clock test was more sensitive than theclock drawing alone.32 It was based on a normativesample of elderly subjects aged 55 and older. Infor-mation from a large clinical sample was alsoused.29 The four-point scoring system for the clocktest tool by Pfizer36 was used because it has high

sensitivity and specificity (average 85%) and has ahigh level of interrater and test–retest reliabilityand predictive validity. It takes 5–10 mins to ad-minister this test, including hand scoring for eachcomponent. The four-point scoring system wasused for the clock test in this study.

MVPTThe MVPT assesses a subject’s visual percep-

tual ability, with no motor involvement needed tomake a response. It is especially useful for individ-uals who have learning, motor, or cognitive dis-abilities.9–11,22 Five categories of visual perceptionare measured: spatial relationships, visual closure,visual discrimination, visual memory, and figureground.

MVPT standards are based on a nationally rep-resentative sample that included senior drivers.Another feature of the MVPT is that the responsetime is standard, which is often useful in rehabili-tation settings. The test format is visual multiplechoice. There are 36 testing plates. The subject getsa point for each correct answer (Table 1). Theprocessing time is measured by the response timefor each plate viewed by the senior driver. Thestandard response time for the age group �50–69yrs is 3–5.4 secs; for the age group �70–80 yrs, itis 4.5–7.1 secs for each plate viewed. The recordedresponse times in seconds are added and divided by36, which gives the total processing time.

This task requires viewing all pictures/figuresand looking for shapes and consistencies. The testprovides a perceptual quotient and a perceptual agescore. The MVPT takes approximately 25 mins toadminister. In our study, average time to completethe MVPT was also evaluated as a predictor ofdriving capability. Scoring is extremely easy be-cause raw scores can be quickly converted to stan-dard scores and percentile ranks. Response-timedata identify whether an individual’s responses aresignificantly delayed.12

The scores for this test range from 0 to 36,with a higher score indicating better visual percep-tion. A maximum score of 36 indicates no errors.For the purposes of this study, raw scores were theprimary outcome of interest because driving, re-gardless of age, requires specific visual perceptionskills.9 Both the clock test and MVPT have beenused as screening tools to determine whether sub-jects are fit to undergo an on-road evaluation.9,29,32

In this study, MVPT was administered first,followed by the clock test. The on-road test wasdone on a different day in most of the seniordrivers. The evaluator reviewed each driver’s MVPTand clock test scores before taking the driver forthe on-road test.

192 Oswanski et al. Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

On-Road Driving Test

The senior driver evaluation program is acopyrighted, standardized program of the OhioState University Medical Center, Office of Geriat-rics and Gerontology, administered through a li-cense agreement with the Office of Geriatrics andGerontology, the Ohio State University Health Sci-ences Center. The Lucas County Older Driver Eval-uation Program was funded in part by the OhioDepartment of Public Safety/NHTSA.

Three occupational therapists are trained asdriver evaluators/trainers by the Ohio Departmentof Public Safety. Each occupational therapist isrequired to take a 40-hr course and additional 40hrs of training to train/evaluate handicapped sub-jects. The MVPT was done first because subjectstend to get tired after some time and are unable toperform other tests. For consistency, only one eval-uator conducted the on-road tests.

In the on-road test, the subject was allowed toget the feel of the car in the parking lot and thentake it for a standard test drive. Each subject wasexpected to drive 17 miles in city traffic, highwaytraffic, and in residential areas, with 12 left turns,5 right turns, 7 straight-through intersections,stop signs, and red lights at intersections withflashing red light or orange lights. They were ob-served for staying on course and within the lanesand lane changes, keeping within speed limits, andnoting speed bumps. They were also taken to a busyparking lot, where each subject had to locate aparking spot and park with the car aligned cor-rectly, then pull out of the parking lot. They weregiven three chances to correct themselves if theydid not align the car correctly the first time.

Data AnalysisA commonly used and accepted level of certainty

of 95% was set before the running of statistical com-parisons. This standard preset level of certainty, orconfidence, represents the likelihood that the resultsare true or correct and not attributable to randomchance. For the result to be true, the alpha should beless than 0.05. The actual level of significance for anyobtained statistic is a P value �0.05.

�2 analysis was used to evaluate the relation-ship between the categorical variables and forwardexact test used for 2 � 2 categorical variables.One-way analysis of variance was used to comparethe continuous variable means within the groups.ROC curve analysis, stepwise logistic regressionanalysis, and Hosmer–Lemeshow goodness-of-fitpredicted probability tests were also performed. Allstatistical analyses were performed using Statisti-cal Package for the Social Sciences, (SPSS) version10.1 (SPSS Inc., Chicago IL).

Both the clock test and the MVPT were in-cluded in the model to identify their usefulness aspredictors of the driving abilities of senior drivers(capable vs. incapable of driving) and to determinewhether they could be used as quick indicators thata subject might need a more expensive, traditionaldriving test. The results of these subjects werediscussed in a group meeting with a board-certifiedgeriatrician and occupational therapists. The sub-jects’ test scores were used to categorize thesesubjects as capable or incapable drivers.

RESULTSTwo hundred fifty-five senior drivers were re-

ferred for evaluation and recommendation for li-cense renewal. Referrals of these subjects werebased on various violations or behaviors contribut-

TABLE 1 The motor free visual perception test

Test Tasks Points

Visual discriminationtasks 1–3

● Orientation and composition of figure 3● The patient is given a book with images. The task is to look at a

figure and identify the same kind at the bottom of the page from A–DVisual memory: tasks

4–8 (5-secexposure)

● Figure ground 5● To pull information to foreground from background information

Visual discrimination:tasks 9–13

● Identifying shapes and figure ground information 5

Visual memory: tasks14–21

● To look at picture for 5 secs and identify figure on the next page in adifferent sequence

8

Visual closure: tasks22–32

● This test is like connecting the dots. Patient looks at a picture,mentally completes the picture, and states what was missing

11

Visual discrimination:tasks 33–36

● This task requires viewing the picture of all figures and looking forshapes’ consistency. The test provides a perceptual quotient and aperceptual age score

4

The 36-point task of the Motor Free Visual Perception Test is based on a national representative sample.


ing to accidents. After excluding 23 subjects whodid not complete all of the tests, data were analyzedfor 232 senior drivers, who completed the MVPT,clock test, and on-road driving test.

There were 82 reported violations in 48 (59%)males and 34 (41%) females. In violations, femalesvs. males were no yield at stop: 24 vs. 17%; turningacross traffic: 17 vs. 4%; running a red light: 9 vs.13%; speeding: 3 vs. 15%. Other violations, includ-ing wrong way, yellow light, lane changes, slowspeed, rear ending, and illegal U turn, were lessfrequent, with similar numbers in both genders(Table 2). No statistical analysis was done on vio-lations (including gender).

ROC analysis and multivariate logistic regres-sion were used to develop a predicted probabilitymodel to differentiate between senior drivers’ ca-pabilities. Subjects were categorized into twogroups: 131 (56%) were capable drivers and 101(44%) were found to be incapable drivers on theroad test. The mean scores of the three measure-ments (MVPT score, clock test score, and process-ing time) in the capable vs. incapable drivers weresignificantly different between the two groups,with a P value �0.001 (Fig. 1, Table 3 and 4).

ROC curve analysis revealed that the optimalcut point for the MVPT score was �32 to yield 60%sensitivity with a confidence interval of 50.7–67.7and 83% specificity and a confidence interval of74.4–89.9, with a positive likelihood ratio of 3.53and a negative likelihood ratio of 0.49. The optimalcut point for the clock test score was �3 to yield70% sensitivity with a confidence interval of 59.5–76.0 and 65% specificity and a confidence intervalof 55.4–74.4, with a positive likelihood ratio of 1.97and a negative likelihood ratio of 0.49. The optimalcut point for the processing time was �6.27 secs toyield 61% sensitivity with a confidence interval of52.6–69.5, and 79% specificity with a confidence

interval of 70.0–86.6, with a positive likelihoodratio of 2.95 and a negative likelihood ratio of 0.49.

Stepwise multivariate logistic regression and theHosmer–Lemeshow test of goodness fit were used toarrive at a predicted probability of driving capability.Figure 2 shows the relationship between predicteddriving capability with MVPT score and clock test.MVPT score and clock test score were significantpredictors of seniors’ driving capabilities.

DISCUSSIONDriving is a controlled task involving cogni-

tion and operational, tactical, and strategic func-tion.37 Senior drivers experience gradual declinesin the sensory system, perceptual skills, and cog-nitive functioning with advancing age. Many se-niors experience anxiety performing new tasks be-cause of associated impairments, such as excessiverisk-taking behavior, poor judgment, confusion,diminished frustration tolerance, and emotionalinstability.38

Road tests evaluate practical driving skills andare a standard method of assessing driving compe-tence. This study was designed to evaluate two off-road assessment tools that can be used to identifyat-risk senior drivers before an on-road evaluation.The MVPT and the clock test were chosen to identifyat-risk subjects. Senior drivers were referred to arehab center for a driving diagnosis before recom-mending continuation of independent driving. Thetraditional way to diagnose driving capability is toadminister a standard driving test. Several diagnostictools have been sought as a replacement or an ad-junct. However, earlier studies tested these tools in-dividually.3,9–11,19,22,29,31,34 Although the results wereencouraging, these tools cannot be used indepen-dently with reliable certainty.

This study was designed to evaluate the ef-fectiveness of two simple assessment tools that

TABLE 2 Violations in senior drivers as reported by law enforcement officers

Behavior Accidents Violations Observations Total Males Females

Wrong way 0 1 0 1 (1) 1 (2) 0 (0)No yield/stop 5 8 3 16 (19) 8 (17) 8 (24)Ran red light 3 3 3 9 (10) 6 (13) 3 (9)Yellow light 1 0 1 2 (3) 1 (2) 1 (3)Turning across traffic 3 3 2 8 (10) 2 (4) 6 (17)Lane change 1 1 3 5 (6) 3 (6) 2 (5)Slow speed 0 0 2 2 (3) 1 (2) 1 (3)Speeding 2 6 0 8 (10) 7 (15) 1 (3)Rear-ending 5 3 0 8 (10) 5 (10) 3 (9)Illegal U-urn 1 1 0 2 (3) 1 (2) 1 (3)Slide on ice 2 1 0 3 (4) 3 (6) 0 (0)Miscellaneous 6 7 4 17 (20) 9 (19) 8 (24)Driving on closed road 0 1 0 1 (1) 1 (2) 0 (0)Total reported cases 29 35 18 82 (100) 48 (100) 34 (100)

Percentages in parenthesis. Other referrals were 150 (72 males and 78 females).


can be easily administered in an office setting.The clock test and the MVPT were included inthe model to identify whether they were usefulpredictors of driving diagnosis of senior drivers(capable vs. incapable of driving) and whether

they could be used as quick assessment toolsbefore recommending continuation of indepen-dent driving.

Traffic violations may vary by age group. Se-niors, as a group, are highly cited in violations for

TABLE 3 Analysis of MVPT score, clock score, and processing time in capable and incapablesenior drivers

Tests n MeanStandardDeviation

StandardError

95% ConfidenceInterval for Mean

Minimum MaximumLowerBound

UpperBound

MVPT scoreIncapable 101 28.37 4.595 0.457 27.46 29.27 14 36Capable 131 32.03 3.997 0.340 31.36 32.70 6 36Total 232 30.48 4.622 0.299 29.89 31.07 6 36

Processing time scoreIncapable 101 10.5771 5.46446 0.54373 9.4984 11.6559 2.34 36.03Capable 131 7.1667 6.49005 0.55448 6.0702 8.2632 1.70 55.10Total 232 8.6140 6.29469 0.40802 7.8102 9.4178 1.70 55.10

Clock test scoreIncapable 101 2.77 1.159 0.114 2.54 2.99 0 4Capable 131 3.50 0.843 0.073 3.35 3.65 0 4Total 232 3.18 1.057 0.069 3.04 3.31 0 4

MVPT, Motor Free Visual Perceptual Test.

FIGURE 1 MVPT score 32.0 � 4.0 vs. 28.4 � 4.6.


failure to obey signs, failure to yield right of way,improper turns (particularly left turns), and illegalpassing.8 Senior drivers have a tendency to makeerrors of omission (such as failure to read trafficsigns or obey traffic lights) and demonstrate diffi-culty in maneuvers requiring a series of rapid judg-ments.4,27,39,40 A recent study showed that seniordrivers fail to yield at stop signs and fail to yield to

right of way.41 One study indicated that older fe-male drivers have a higher incidence of trafficviolations and have driving difficulty with increas-ing age.42

Carr et al.43 analyzed the Fatality Analysis Re-porting System from January 1990 to December2000 to identify crashes based on age group (i.e.,25–64, 65–74, 75–84, and �85 yrs). Their study

FIGURE 2 Relationship between predicted driving capability and visual score (MVPT) and clock score.

TABLE 4 Analysis of MVPT score, clock score, and processing time between groups and withingroups of capable and incapable senior drivers

Sum of Squares df Mean Square F P value

MVPT scoreBetween groups 783.574 1 783.574 43.181 0.000Within groups 4300.665 231 18.146Total 5084.240 232

Processing time scoreBetween groups 676.208 1 676.208 18.313 0.000Within groups 8714.465 231 36.926Total 9390.673 232

Clock test scoreBetween groups 31.064 1 31.064 31.405 0.000Within groups 231.462 231 0.989Total 262.525 232

Significant difference between two groups (capable vs. incapable) for the three scores (MVPT, processing time, and clocktest).


showed that in-person license renewal in seniordrivers significantly lowered fatality rates.43

In this report, all subjects used the standarddriving route, contrary to another report in whichonly 78% of subjects used a standard drivingroute.44

The current study analyzed MVPT, the clocktest, and processing time scores. Fifty-six percent(131/232) of seniors were classified as capable driv-ers, with higher MVPT scores and clock test scoresand lower processing time. Fourty-four percent(101/232) of the seniors tested were found to beincapable drivers with lower MVPT scores andclock test scores and higher processing time on thestandardized on-road driver evaluation tests. (Table3). The means of the three measurements weresignificantly different between the two groups (P �0.001; Table 4).

The mean MVPT score in this study was 32.0 �4.0 vs. 28.4 � 4.6 (capable vs. incapable drivers),with 60% sensitivity and 83% specificity. The meanprocessing time was 7.1 � 6.5 vs. 10.6 � 5.5 secs,with 61% sensitivity and 79% specificity.

A recent study compared Cognitive BehavioralDriver’s Inventory (CBDI) scores for clients whopassed and failed a driving evaluation. This studyexamined Cognitive Behavioral Driver’s Inventory,MVPT, Bells test, and on-road driving test results.38

The results of the on-road tests showed that 54% ofsubjects passed their driving evaluations, 34%failed, and 12% were advised to take lessons and bereevaluated.38 The mean MVPT score in the passgroup was 32.92; for the fail group, it was 29.89,with processing times of 4.63 and 6.11 in the failgroup.38

Earlier studies indicated a cutoff MVPT score of�30 as the best predictor of a pass or fail on theon-road test; this cutoff is well accepted.9,45 The clocktest score cutoff of �3 is the best predictor.36 Theclock test used in this study has a very simple four-point scoring system,36 whereas other tests have scor-ing systems with high score numbers. Because eachassessment tool uses a slightly different scoring sys-tem, comparisons cannot be made.33

The findings of earlier studies provide a guidefor clinicians to identify the screening tool that canpredict at-risk senior drivers. However, the find-ings indicate that different approaches may be re-quired to accurately address the specific needs ofeach diagnostic group.38

A working group of researchers from theUnited States and Canada are exploring the possi-bility of forming consensus guidelines on the basiccomponents of off-road and on-road driving assess-ment.46,47 These guidelines will include key com-ponents that should be part of a standard assess-ment for determining the driving ability of seniordrivers. The use of these guidelines will help stan-

dardize the assessment process regardless of whichcenter subjects visit for their driving evaluation.44

Physicians should periodically look for any cog-nitive changes in their patients because thesechanges can impact their driving skills over time.48 A6- to 12-mo repeat cognitive test should be plannedby the physician. The AMA recommends two cogni-tive tests to identify at-risk senior drivers.49

For senior drivers who perform poorly on off-road tests, a recommendation to an occupationaltherapy specialist is warranted for performance-based road testing.50 On-road evaluations by reha-bilitative facilities are expensive ($200–$500) andmay not be covered by medical insurance.51 Forhigh-risk drivers, referral to the division of motorvehicles office can be considered for in-person li-cense renewal.52

Implications of the StudyThis study provides easy-to-administer tools to

healthcare providers to screen and identify at-riskdrivers. Consensus guidelines, the MVPT, and theclock drawing tasks will be effective assessmenttools to evaluate senior drivers for on-road tests.

Limitations of the StudyThis was a retrospective analysis done on a

variety of referrals. The study was not designed toprospectively analyze senior driver capability withand without underlying neurological conditions.Possible factors that may have reduced the associ-ation found between the MVPT, clock test scores,and on-road performance are limitations related tothe evaluator’s knowledge of the test scores beforeadministration of the on-road test. Gender differ-ences were not analyzed in this study.

CONCLUSIONThe current study indicates that the MVPT and

the clock test tools were significant predictors ofdriving capability of senior drivers for an on-roaddriving test.

These tests have the potential to identify at-risk drivers. Physicians could use these simple,inexpensive tools (clock test and MVPT) in theirclinical setting as screening tools before recom-mending seniors for independent driving.

ACKNOWLEDGMENTSThe authors thank Linda Mauger, Program

Manager Office of Geriatric and Gerontology, OhioState University; Shirley Mickens, Secretary, TotalRehab at Flower Hospital; Christine McKean, Man-ager of Communications at The Toledo Hospital;and Yahya Daoud, Jobst Vascular Center for theirhelp with the study and preparation of the manu-script.


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34. Royall DR, Mulroy AR, Chiodo LK, Polk MJ: Clock drawingis sensitive to executive control: a comparison of six meth-ods. J Gerontol B Psychol Sci Soc Sci 1999;54:P328–33

35. Richardson HE, Glass JN: A comparison of scoring proto-cols on the Clock Drawing Test in relation to ease of use,diagnostic group, and correlations with Mini-Mental StateExamination. J Am Geriatr Soc 2002;50:169–73

36. Powlishta KK, et al: The Clock Drawing Test is a PoorScreen for Very Mild Dementia. New York, Pfizer, 1997

37. Michon JA: A critical view of driver behavior models. Whatdo we know, what should we do? in Evans L, Schwing R(eds): Human Behavior and Traffic Safety. New York, Ple-num Press, 1985, pp 485–524

38. Bouillon L, Mazer B, Gelinas I: Validity of the cognitivebehavioral driver’s inventory in predicting driving outcome.Am J Occup Ther 2006;60:420–7

39. Powlishta KK, Von Dras DD, Stanford A, et al: The clock-drawing test is a poor screen for very mild dementia. Neu-rology 2002;59:898–903

40. Benekohal RF, Resende P, Shim E: Highway OperationsProblems of Elderly Drivers in Springfield Illinois. HighwaySafety Information System (HSIS) summary report. Depart-ment of Transportation, 1992

41. National Highway Traffic Safety Administration. TrafficSafety Facts 2000. Older Population. Washington, DC, Na-tional Highway Traffic Safety Administration, 2001

42. Cook LJ, Knight S, Olson LM, et al: Motor vehicle crashcharacteristics and medical outcomes among older driversin Utah, 1992-1995. Ann Emerg Med 2000;35:585–91

43. Carr DB, Duchek JM, Meuser TM, Morris JC: Older adultdrivers with cognitive impairment. Am Fam Physician2006;73:1029–34

44. Korner-Bitensky N, Bitensky J, Sofer S, Man-Son-Hing M,Gelinas I: Driving Evaluation Practices of Clinicians Work


ing in the United States and Canada. July/August 2006;60:428–34

45. Simms B: Perception and driving: Theory and practice. Br JOccup Ther 1985;48:363–6

46. Korner-Bitensky N, Gelinas I, Man-Son-Hing M Marshall S:Recommendations of the Canadian Consensus Conferenceon driving evaluation in older drivers. P & OT in Geriatrics2005;23:123–44

47. Stephens B, McCarthy DP, Marsiske M, et al: SummaryReport: International Older Driver Consensus Conference.Gainsville, FL, University of Florida National Older DriverResearch and Training Center, 2004

48. 22. Duchek JM, Carr DB, Hunt L, et al: Longitudinal drivingperformance in early-stage dementia of the Alzheimer type.J Am Geriatr Soc 2003;51:1342–7

49. Freund B, Gravenstein S, Ferris R, Shaheen E: Evaluatingdriving performance of cognitively impaired and healthyolder adults: a pilot study comparing on-road testing anddriving simulation. J Am Geriatr Soc 2002;50:1309–10

50. Dubinsky RM, Stein AC, Lyons K: Practice parameter: riskof driving and Alzheimer’s disease (an evidence-basedreview): report of the quality standards subcommittee of theAmerican Academy of Neurology. Neurology 2000;54:2205–11

51. Fox GK, Bashford GM: Driving and dementia: balancingpersonal independence and public safety. Med J Aust 1997;167:406–7

52. Grabowski DC, Campbell CM, Morrisey MA: Elderly licen-sure laws and motor vehicle fatalities. JAMA 2004;291:2840–6

BOOK REVIEW

Total Knee ArthroplastyBy Richard D. Scott, MD. 148 pages. Published 2006by Saunders-Elsevier, Philadelphia, PA, 1st Edition.$189.00. ISBN 0721639488.

The author has performed nearly 4000 primary kneereplacements and has taught more than 500 orthopedicresidents and arthroplasty fellows his surgical tech-niques. This book provides detailed instruction in theauthor’s total knee arthroplasty procedures. Surgicaltechniques are presented in the text and in the includedDVD. The intended audience is primarily orthopedicresidents or fellows, but the text would also be of interestto others who commonly participate in the care of pa-tients who have undergone total knee arthroplasty.

The book contains 19 chapters. The first chapterreviews the history of total knee arthroplasty, with afocus on the procedures and materials developed inBoston, Massachusetts. Very well illustrated chaptersfollow that provide detailed instruction in the surgicalprocedures for a routine total knee arthroplasty as wellas for complicated cases—varus or valgus deformity,knee stiffness, contracture, following osteotomy, forrheumatoid arthritis, and for bone stock deficiency. Uni-compartmental knee arthroplasty is discussed as well as

when bilateral procedures are indicated. Surgical com-plications are reviewed.

The book contains over 300 high-quality color sur-gical photographs, drawings, and radiographs illustrat-ing the various steps of the surgical procedures. Thenarrated DVD demonstrates a total knee arthroplasty, aunicompartmental arthroplasty, and a lateral release forvalgus.

Discussion of rehabilitative care is brief. The textdoes include a final chapter of frequently asked ques-tions by patients about total knee arthroplasty. Usefulpatient-education material is found in this four-pagechapter.

Overall, this is a well-illustrated and detailed surgi-cal instruction guide for orthopedists in training.Physiatrists who work extensively with total knee arthro-plasty patients would find it useful as a reference book toexpand their knowledge of the surgical techniques usedduring these procedures.

Rating: �� for the average physiatrist; �� forthe orthopedist in training

John A. Schuchmann, MDTemple, Texas

March 2007 Book Reviews 199

Authors:Ken Uchikawa, MDHidetoshi Takahashi, MD, PhDGenbu Deguchi, OTRMeigen Liu, MD, PhD

Affiliations:From the Department ofRehabilitation Medicine, NationalHospital Organization, MurayamaMedical Center, Tokyo, Japan (KU,GD); and the Department ofRehabilitation Medicine, KeioUniversity School of Medicine, Tokyo,Japan (HT, ML).

Correspondence:All correspondence and requests forreprints should be addressed to KenUchikawa, 2-37-1 GakuenMusashimurayama, Tokyo 208-0011,Japan.


DOI: 10.1097/PHM.0b013e3180320edf

A Washing Toilet Seat with a CCDCamera Monitor to Stimulate BowelMovement in Patients with SpinalCord Injury

ABSTRACT

Uchikawa K, Takahashi H, Deguchi G, Liu M: A washing toilet seat with a CCDcamera monitor to stimulate bowel movement in patients with spinal cord injury.Am J Phys Med Rehabil 2007;86:200–204.

Objective: The objective was to study the effectiveness of a modifiedwashing toilet seat equipped with a CCD camera monitor and an elec-tronic bidet to facilitate precise hitting of the anal area with water streamsto stimulate bowel movement in patients with spinal cord injury (SCI).

Design: There were 20 subjects, all of whom had traumatic SCI, wereat least 5 mos post acute injury, and could change their position on thetoilet seat while watching the monitor. Stimulation of bowel movement withthe modified toilet seat was provided for a maximum of 30 mins. Successor failure to induce bowel movement was evaluated as related to injurylevel, ASIA impairment scale, and ability to voluntarily increase anorectalpressure, measured with a manometory.

Results: Bowel movement was successfully induced in 15 of the 20patients (75%). Success was not related significantly to injury level, ASIAimpairment scale, or ability to voluntarily squeeze. Compared with theirusual manner of bowel management, for which they spent more than 30mins, time needed for successful bowel movement was shortened in 11of 13 patients. No complications were observed.

Conclusions: This preliminary study suggests that our newly modifiedwashing toilet seat with a monitoring system could be a useful alternativefor bowel management in patients with SCI.

Key Words: Bowel Dysfunction, Defecation, Anal Sphincter, Rectal Stimulation


RESEARCH ARTICLE

Spinal Cord Injury

Together with bladder dysfunction, bowel dys-function poses a major problem in patients withspinal cord injury (SCI). Its successful manage-ment, although very important, is often very diffi-cult to achieve. Problems related to defecation,which vary from fecal incontinence to chronic con-stipation, may have grave implications for the pa-tients’ reintegration into society.1–3 In the Stock-holm SCI study, 41% of participants rated boweldysfunction as a moderate to severe life-limitingproblem.4 In another study, 41% of patients withSCI spent more than 1 hr, and 12.5% spent morethan 2 hrs per bowel-evacuation episode.5

There have been several studies reported in theliterature describing countermeasures for these bowelproblems. Bisacodyl suppository, enema, and stool soft-eners are commonly used as laxative agents.6 How-ever, they are sometimes ineffective, and hemor-rhoids or rectal abscesses can occur among thosewho use primarily suppositories and enemas rou-tinely. Christensen et al.7 have described the enemacontinence catheter (ECC) and Malone antegradecontinence enema (MACE). The ECC is a catheterwith an inflatable balloon; the catheter is insertedinto the rectum, and the balloon is inflated to holdit there. The rate of success with the ECC is re-ported to be 57%. The MACE is a simple operativeprocedure that brings out the appendix to skinlevel to form an appendicostomy. Through thestoma, patients can introduce a catheter and ad-minister an enema. Overall success with the MACEwas found in 87% of patients.

Puet et al.8,9 have described pulsed irrigationevacuation, which uses intermittent, rapid pulsesof warm water to break up stool impactions andstimulate peristalsis. The pulsed irrigation evacua-tion has been reported to be a safe and effectivemethod of treating impactions. These devices, how-ever, require assistance for administration, and theECC and MACE entail the potential risk of bowelperforation when inserting a catheter into the ano-rectum or stoma.

To avoid these complications and to facilitateself-management of bowel care by the patient, wedeveloped a less invasive procedure for rectal stim-ulation that uses a washing toilet seat equippedwith a CCD camera monitor. The purpose of thisstudy is to test the effectiveness of our modifiedbowel-care system to counter these difficult bowelproblems in patients with SCI.

METHODSWe recruited 20 patients with traumatic SCI

who received inpatient care at the SCI units ofMurayama Medical Center in Tokyo, Japan, duringthe period from November 2002 to September2003. The study design was a single test per sub-

ject. All of them were males, and their mean agewas 46.3 yrs (SD � 17.9, range � 18–73). The levelof injury was cervical in 11 patients, thoracic in 7patients, and lumber in 2 patients. The impairmentlevel, as classified according to the American Spi-nal Injury Association (ASIA),10 was A in eightpatients, B in four patients, C in four patients, andD in four patients. The patients were at least 5 mospost acute injury and could independently transferto the toilet seat and change their position on itwhile watching the CCD monitor. The study wasapproved by the institutional ethics review board ofour facility. The purpose and procedures of thestudy were fully explained, and informed consentwas obtained from the participants.

The newly developed procedure to induce bowelmovement uses a washing toilet seat equipped withan electronic bidet (Hygiene toilet seat, DL-GT30, Pa-nasonic, Japan), a CCD camera (KPC-S20CB, KT&CCorp., Korea), and a light (DOP-151 Asahi electricCorp., Japan) (Fig. 1). The electronic bidet provideswater flow. The water stream is pulsatile and adjust-able and can deliver 0.55 liters of water and 0.6 litersof air per minute maximally. To facilitate preciselocation of the anorectal area, we devised a washingtoilet seat equipped with a CCD camera monitor. Bywatching the monitor, the patients could accuratelydirect the water stream toward the anal area. Themaximum duration of stimulation was set at 30 mins,and the maximum power of the water stream that thetoilet seat could provide was used for stimulation.After 30 mins, the amount of residual stool in therectum was examined using digital evacuation. Duringthe study period, the participants kept taking stimulantlaxatives (senna, magnesium oxide, alosenn, sennoside)if they were prescribed, but suppositories and enemaswere discontinued.

To evaluate anorectal functions, anorectal ma-nometry was performed in 18 patients. In left lat-eral decubitus position, a balloon catheter was in-serted 15 cm deep from the anal canal, and it waspulled out slowly. First, we measured anal restingpressure, which represented the internal analsphincter pressure, and then we assessed squeezepressure at the external anal sphincter level duringvoluntary contraction. We expected that the waterstream was likely to have invaded into the analcanal if voluntary contraction was difficult and ifsphincter tone was reduced, which was likely tohave caused reflex defecation. Then, we studied therelationship between the success of bowel evacua-tion and the ability to voluntarily squeeze. Werelated success or failure to induce bowel evacua-tion with injury level, ASIA impairment scale with�2 test, and the ability to voluntarily increase ano-rectal pressure measured with anorectal manome-try with a forward exact probability test. All analy-ses were performed with Statcel (OMS, Saitama), a

March 2007 A Washing Toilet Seat 201

statistical software program for Windows, and thelevel of significance was set at P � 0.05.

RESULTSFigure 2 shows the usual manner of bowel care

practiced by our study participants. Sixteen pa-tients (80%) used rectal suppositories, three (15%)used enemas, and one (5%) used Valsalva maneu-vers. Fifteen of the 20 patients (75%) also usedmanual evacuation in addition to a routine bowelprogram. As illustrated in Figure 3, seven patients(35%) spent less than 30 mins for usual defecation,12 (60%) spent 30–60 mins, and one (5%) spentmore than 60 mins. Fourteen of the 20 patients(70%) could not direct the water stream preciselyto the anorectal area without the use of the mon-itor. All patients in the ASIA impairment levels Aand B (n � 12) and two of the four level C patientsbelonged to this category. On the other hand, twoof the four level C patients and all of the level Dpatients could direct the water stream to the ano-rectal area without the monitor.

With their usual manner of bowel care, bowelmovement was induced within 30 mins in seven

patients, from 30–60 mins in 12 patients, and inmore than 60 mins in one patient. In contrast,bowel movement was successfully induced with ourmodified device within 30 mins [average time � 17mins (range 3–28)] in 15 of the 20 patients (75%).Time needed for bowel management with our mod-ified device was shorter than that with patients’usual manner of bowel care (�2 for independencetest, P � 0.01). Time required for successful bowelmovement was shortened in 11 of 13 patients(85%) who had spent more than 30 mins with theirusual manner of bowel management. However, re-sidual stools were found in 8 of the 15 patients.

The success of defecation was not related signif-icantly with injury level (P � 0.69) or ASIA impair-ment scale (P � 0.44) (�2 for independence test).

The manometric results showed that the aver-age internal anal sphincter pressure was 25.4 mmH2O (SD 14.0, range 4–51), and the average exter-nal anal sphincter pressure was 43.3 mm H2O (SD

FIGURE 2 Usual bowel-care methods used by theparticipants (n � 20).

FIGURE 3 Time spent for bowel evacuation withroutine bowel programs (n � 20). Thir-teen patients (65%) spent more than 30mins for usual defecation.

FIGURE 1 System of a washing toilet seat with a CCD camera monitor. By watching the monitor, the patientscould accurately direct the water stream toward the anal area. A, whole image; B, close-up of CCDcamera and light.

202 Uchikawa et al. Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

33.9, range 4–127). In 6 of the 18 patients (33.3%),the average external anal sphincter pressure elic-ited with voluntary squeezing was higher than theresting internal anal sphincter pressure (83.3 mmH2O [range 51–127] vs. 29.5 mm H2O [range5–51]). The success rate of defecation in patientswho could voluntarily squeeze (three of the sixpatients, 50%) did not significantly differ from thatin patients who could not voluntarily squeeze (10of the 12 patients, 83.3%; forward exact probabilitytest, P � 0.13). No complication was observedduring the bowel-care procedure using this device,and 15 of the 20 patients (75%) who could success-fully induce bowel movement with the devicewanted to try it again.

DISCUSSIONAs far as we know, our study is the first that

examined the effects of a washing toilet seat with amonitor to stimulate bowel movement in personswith SCI. In the able-bodied population, waterstream into the rectum is likely to stimulate bowelmovement and induce defecation. However, it isdifficult for patients with SCI who have completeor incomplete loss of anal sensation to preciselydirect a water stream to the anorectal area. Tofacilitate precise location of the anorectal area, wedevised a washing toilet seat equipped with a CCDcamera monitor. By watching the monitor, thepatients could accurately direct a water stream tothe anal area. Anorectal stimulation can initiatereflex defecation and activate anorectal inhibitoryreflex to cause relaxation of the internal analsphincter. Enemas also can cause reflex defecationand increase bowel peristalsis with water streaminto the rectum. In our study, the effect of anenema with a water stream to promote defecationwas considered stronger than that of anorectalstimulation.

The success rate to induce bowel movementwith our method in this preliminary study was 75%(15 of the 20 patients), which was higher than thatwith ECC (57%) and slightly lower than that withMACE (87%).7 Although this study was for a singletrial, and effectiveness of our method’s long-term usewas not investigated, our new method can achievebowel management at least as successfully as thosemore invasive methods can. Success was not relatedto injury level or ASIA impairment scale.

As for manometric studies, Tjandra et al.11 andLynch et al.12 have reported that patients with SCIpresenting with severe bowel symptoms had loweranal canal pressures than healthy controls. In thepatient group, the mean resting anal canal pres-sure and maximum squeeze anal canal pressurewere 46 (10–100) mm Hg and 76 (30–120) mm Hgcompared with 62 (50–70) mm Hg and 138 (100–180) mm Hg in healthy controls.11 Although we did

not compare pressure in patients with SCI withthat of healthy controls, our data indicate that theresting anal pressure and squeeze anal canal pres-sure were lower than normal values previouslyreported.

We expected that water stream was likely tohave invaded into the anal canal if voluntary con-traction was difficult and sphincter tone was re-duced, which was likely to have caused reflex def-ecation. However, the success rate of defecation inpatients who could voluntarily squeeze (three of sixpatients, 50%) did not significantly differ from thatin patients who could not voluntarily squeeze (10of 12 patients, 83.3%). This might indicate thatbowel movement in patients with SCI does notdepend on anal sphincter pressure alone. However,the statistical nonsignificance was more likely tohave been caused by the small sample size in thepresent study, and a larger study is needed.

Regarding complications, the risk of bowelperforation must be considered when using ECC orMACE. For manual evacuation, hemorrhoids asso-ciated with defecation and anorectal injury are ma-jor complications. In contrast, our device only ap-plies water to the anal area, and it is unnecessary toinsert anything such as a rectal suppository, en-ema, or catheter into the rectum. This may be oneimportant reason why we experienced no compli-cations in this preliminary study.

As for the time needed to induce bowel move-ment, 41% of the patients spent more than 1 hr,and 12.5% spent more than 2 hrs for bowel evac-uation with their usual method of bowel care. Withour new method, it was shortened to less than 30mins. However, we must note that in 8 of the 15patients who succeeded in inducing bowel move-ment with our device within 30 min, residualstools were found. This indicates that more than 30mins may be needed to completely empty the rec-tum. This is an area for future research.

In conclusion, although this study was a pilotstudy, and residual bowel stools were found ineight patients, our newly devised bowel-manage-ment system, which uses a washing toilet seat witha CCD camera monitor, successfully induced bowelmovement in 75% of the patients with SCI in lesstime than was needed for their routine manner ofbowel management using a suppository or enema.No complications were observed with this method,and it would be a useful adjunct in their bowel care.

REFERENCES1. Harari D, Sarkarati M, Gurwitz JH, McGlincheny-Berroth

G, Minaker KL: Constipation-related symptoms and bowelprogram concerning individuals with spinal cord injury.Spinal Cord 1997;35:394–401

2. Stone JM, Nino-Murcia M, Wolfe VA, Perkash I: Chronicgastrointestinal problems in spinal cord injury patients: aprospective analysis. Am J Gastroenterol 1990;85:1114–9

March 2007 A Washing Toilet Seat 203

3. Glickman S, Kamm MA: Bowel dysfunction in spinal-cord-injury patients. Lancet 1996;347:1651–3

4. Levi R, Hulting C, Nash M, Seiger A: The Stockholm spinalcord injury study: 1. Medical problems in a regional SCIpopulation. Paraplegia 1995;33:308–15

5. De Looze D, Van Laere M, De Muynck M, Beke R, Elewaut A:Constipation and other chronic gastrointestinal problems inspinal cord injury patients. Spinal Cord 1998;36:63–6

6. Han TR, Kim JH, Kwon BS: Chronic gastrointestinal prob-lems and bowel dysfunction in patients with spinal cordinjury. Spinal Cord 1998;36:485–90

7. Christensen P, Kvitzau B, Krogh K, Buntzen S, Laurberg S:Neurogenic colorectal dysfunction—use of new antegrade andretrograde colonic wash-out methods. Spinal Cord 2000;38:255–61

8. Puet T, Jackson H, Amy S: Use of pulsed irrigation evacu-ation in the management of the neuropathic bowel. SpinalCord 1997;35:694–9

9. Puet T, Phen L, Hurst DL: Pulsed irrigation enhancedevacuation: new method for treating fecal impaction. ArchPhys Med Rehabil 1991;72:935–6

10. Maynard FM Jr, Bracken MB, Creasey G, et al: InternationalStandards for Neurological and Functional Classification ofSpinal Cord Injury. American Spinal Injury Association.Spinal Cord 1997;35:266–74

11. Tjandra JJ, Ooi B-S, Han WR: Anorectal physiologic testingfor bowel dysfunction in patients with spinal cord lesions.Dis Colon Rectum 2000;43:927–31

12. Lynch AC, Anthony A, Dobbs BR, Frizelle FA: Anorectalphysiology following spinal cord injury. Spinal Cord 2000;38:573–80

BOOK REVIEW

Anatomical Guide for the Electromyographer: The Limbs and TrunkBy Aldo O. Perotto, MD. 362 pages. Published 2005 byCharles C. Thomas Publisher, Ltd., Springfield, IL,4th Edition. $65.95 (hardcover; ISBN 0398075778);$45.95 (softcover; ISBN 0398075786).

This is the fourth edition of a series begun by Edward F.Delagi, MD, Aldo Perotto, MD, John Iazzetti, MD, andDaniel Morrison, MD.

Obviously, in a book such as this one, the main subjectmatter does not change, and there is a lot of repetitionfrom previous editions. Nevertheless, the book is thor-oughly updated and does include some new informationthat is very valuable. This book, as most electromyopgra-phers already know, contains descriptions of needle local-ization for many different muscles. For most muscles thatare routinely tested in electromyography, the practitionerobviously does not need to look things up in a referencebook, but occasionally a muscle needs to be tested that isnot routinely tested, so a book such as this one is extremelyvaluable in looking at the techniques that are available.

I was very impressed with this book. It is a greatreference manual. There are numerous small sections

such as hand, forearm, arm, shoulder joint, etc. Thismakes looking up muscles easy. For each muscle, thereis a useful description of the innervation path. What isparticularly useful is that it does not just give the endnerve that innervates the muscle, but the entire course,through the plexi as indicated. The book’s inclusion ofthe origin and insertion of each muscle is also useful.There is additional information on pitfalls, and there arecomments on how to test each muscle, as well as theelectrode-insertion technique. For each muscle, there isalso a cross-sectional view that shows where the musclestands in relation to the other anatomic structures. Thequality of those cross-sectional figures is not as nice asthe other anatomic drawings that show the musclecourse.

Compared with other books of its type, this guidecontains more information; this also makes it a bitlarger and less portable. Some of the extra information isnot always needed. On balance, though, it is a solid work.

Rating: �� Ralph M. Buschbacher, MDIndianapolis, Indiana

204 Book Reviews Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

Authors:Pamela Gallagher, PhDOlga Horgan, PhDFranco Franchignoni, MDAndrea Giordano,Malcolm MacLachlan, PhD

Affiliations:From the Faculty of Science andHealth, School of Nursing, DublinCity University, Dublin, Ireland (PG);Department of Clinical Psychology,University of Liverpool, Liverpool, UK(OH); Department of OccupationalRehabilitation and Ergonomics (FF)and Unit of BioengineeringRehabilitation Institute of Veruno,Salvatore Maugeri Foundation,Clinica del Lavoro e dellaRiabilitazione, IRCCS, Veruno,Novara, Italy (AG); School ofPsychology, University of Dublin,Trinity College, Dublin, Ireland (MM);and Dublin Psychoprosthetics Group,Dublin, Ireland (PG, MM).

Correspondence:All correspondence and requests forreprints should be addressed to Dr.Pamela Gallagher, Faculty of Scienceand Health, School of Nursing,Dublin City University, Dublin 9,Ireland.


DOI: 10.1097/PHM.0b013e3180321439

Body Image in People withLower-Limb AmputationA Rasch Analysis of the Amputee Body Image Scale

ABSTRACT

Gallagher P, Horgan O, Franchignoni F, Giordano A, MacLachlan M: Bodyimage in people with lower-limb amputation: a Rasch analysis of the amputeebody image scale. Am J Phys Med Rehabil 2007;86:205–215.

Objective: The aim of this study was to examine the psychometricproperties of the Amputee Body Image Scale (ABIS) through Raschanalysis, investigating the quality of its rating categories and its reliabilityand validity.

Design: The ABIS (20 items; ratings of 1–5) and Trinity AmputationProsthesis Experience Scales (TAPES) were administered by post andcompleted by 145 people with a lower-limb amputation and currentlywearing a prosthesis.

Results: According to Rasch analysis and expert review, some re-sponse categories were collapsed and six items were deleted. The re-maining 14 items created a revised ABIS (ABIS-R) rated with a three-level rating scale. ABIS-R fitted the unidimensional construct that the scalewas intended to measure and demonstrated good reliability (Cronbach’salpha and person separation reliability � 0.87), targeting, and internalconstruct validity. Moreover, the correlations with the nine TAPES sub-scales (in particular, r � �0.54 with the general adjustment, r � �0.43with the social activity restriction, and r � �0.40 with social adjustment)supported the convergent validity of ABIS-R.

Conclusions: The 14-item ABIS-R demonstrates good psychometriccharacteristics for measuring body image disturbances in people withlower-limb amputation. These preliminary results suggest the generaladequacy of the new instrument and provide a good foundation on whichfurther validation and psychometric studies of the ABIS-R can be con-ducted.

Key Words: Amputation, Body Image, Psychometrics, Rasch Analysis

March 2007 Rasch Analysis of ABIS 205

RESEARCH ARTICLE

Amputee

Psychosocial factors have recently been demon-strated to influence the prosthetic rehabilitation ofindividuals with an amputation.1–9 Consequently,the psychological impact of amputation and thesubsequent fitting of a prosthesis needs to be takeninto consideration in conjunction with the physicalimpact to enhance the prosthetic experience andoutcomes for the user and to lead to enhancedhealth and quality of life. For example, there are anumber of images for the person who has experi-enced an amputation to adjust to: the “complete”or familiar body before the limb loss, the trauma-tized body, the healing body, and the extended body(i.e., a body supplemented with prosthetic devicesand, if necessary, mobility aids). Each of theseimages may be accompanied by phantom sensa-tions and/or phantom limb pain (i.e., sensationsand/or pain in the part of the body that has beenamputated). Rybarcyzk et al.10 proffer that the per-son has to adapt to an image of him- or herselfwithout the amputated limb while reconcilingthree images of his or her body: before the limbloss, without a prosthesis, and with a prosthesis.Body image anxiety has been found to be signifi-cantly related to depression,11,12 poorer perceivedquality of life,11,12 lower levels of self-esteem,12 higherlevels of general anxiety,13 lower levels of prosthesissatisfaction,12 and lower levels of participation inphysical activity.14 According to Horgan and Ma-cLachlan,3 adaptation to a changed body image is apotential measure of psychosocial adjustment to am-putation. Therefore, it is an important construct thatshould be included in a clinical assessment.

However, to be adequately able to investigatebody image concerns in people with an amputationand to explore its relationship with psychosocialadjustment, it is important to have a psychometri-cally sound instrument that will facilitate the de-velopment of a solid evidence base on which to setup appropriate interventions. The AmputationBody Image Scale (ABIS) developed by Breakey12

has been proposed as one such instrument. It com-prises 20 items that assess how a person with anamputation perceives and feels about his or herbody experiences. In the original paper outliningits development, acceptable content validity, inter-nal consistency, and convergent validity were dem-onstrated using classical test theory, and signifi-cant positive correlations were found between theperception of body image (using the ABIS) andpsychosocial well-being (more specifically, anxiety,depression, self-esteem, and life satisfaction).12 Inaddition, Murray and Fox15 observed moderate tohigh negative correlations between body image dis-turbance as measured by the ABIS and prosthesissatisfaction. The validity of the ABIS was also sup-ported by Wetterhahn et al.,14 who found a signif-

icant correlation between six subscales of the Mul-tidimensional Body–Self Relations Questionnaire16

and the ABIS. To the best of our knowledge, theseare the only published studies using the ABIS. Assuch, many issues related to the structure andmain psychometric properties of the scale still needto be examined.17,18 In particular, it was consideredworthwhile to further investigate (a) content valid-ity (i.e., that it covers all parts of the universe ofcontent and reflects the relative importance of eachpart, and that it is free from the influence of factorsthat are irrelevant to the purpose of the measure-ment), and (b) the rating-scale structure.

Recently, there has been a growing trend inthe field of rehabilitation to implement Rasch anal-ysis to facilitate the development and validation ofquestionnaires.19–23 Rasch analysis provides psy-chometric information that is not given by classicaltest theory,23–24 examining, among other things,(a) how the rating scale is being used; (b) thevalidity of a measure by evaluating the fit of indi-vidual items to the latent trait: it postulates that ifthe ability in responding to items on an ordinalscale is explained by an underlying unidimensionalconstruct, the hierarchy of difficulty of the items isexpected to match the hierarchy of ability of thesubjects (i.e., more able subjects are more likely topass more difficult items) within a probabilisticmodel; and (c) whether the pattern of item diffi-culties is consistent with the expectations of theconstruct and, hence, provides an adequate de-scription of the range and hierarchical relationshipof the variable. Indeed, Andresen25 recommendsRasch analysis as a method for assessing scalingproperties in addition to traditional psychometriccriteria for reviewing and assessing surveys andquestionnaires for disability outcomes research.

To facilitate the availability of a psychometri-cally robust measure of body image in people withan amputation, the aim of this study was to per-form an in-depth validation of the basic measure-ment properties of ABIS12 through Rasch analysis,investigating the quality of their rating categoriesand the validity (unidimensionality and internalconstruct validity) and reliability of the instru-ment.

METHODSProcedure and Sample

After ethical approval from two national limb-fitting centers in Ireland, hospital charts of poten-tial participants were reviewed. A preselection cri-terion included a requirement that the participantswith loss/absence of a limb be at least 18 yrs old. Acover letter, the questionnaire, and a stamped, ad-dressed envelope were sent to all participants. A

206 Gallagher et al. Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

short reminder card was sent 2 wks after the initialmailing to nonrespondents. There was no incentiveor reimbursement for participation.

One hundred ninety-one people returned com-pleted questionnaires. Of these 191 respondents,145 indicated that they had had a lower-limb am-putation and were currently using a prosthesis.These respondents were included in the study. Thecharacteristics of the sample (n � 145) are out-lined in Table 1. As can be seen, the sample waspredominantly male, with the prevalent cause ofamputation being peripheral vascular disorder,diabetes/peripheral vascular disorder, or accident/trauma. In addition, the most common level ofamputation was below the knee. These character-istics are consistent with the general population ofpeople with lower-limb amputations in the West-ern world.

MeasuresABIS

The ABIS12 comprises 20 items (see Appendix)that assess how an amputee perceives and feelsabout his or her body experiences. Participants areasked to indicate their responses to the questionsusing a rating scale of 1 (none of the time) to 5 (allof the time). Three questions (3, 12, and 16) arereverse scored. The scale produces scores thatrange from 20 to 100, with high scores indicatinghigh body image disturbance.

Trinity Amputation and ProsthesisExperience Scales

As well as requesting demographic and disabil-ity-related data regarding gender, age, cause andtype of amputation, length of time living with theprosthesis, and degree of prosthetic use, the TrinityAmputation and Prosthesis Experience Scales(TAPES) consist of nine subscales.7 There are threepsychosocial subscales: general adjustment (e.g., Ihave adjusted to having an artificial limb), socialadjustment (e.g., I don’t mind people asking aboutmy artificial limb), and adjustment to limitation(e.g., Being an amputee means that I can’t do whatI want to do). Each of these subscales contains fiveitems, which are measured along a five-point rat-ing scale (strongly disagree, disagree, neither agreenor disagree, agree, strongly agree). Scores rangefrom 5 to 25, with higher scores indicating greaterlevels of adjustment. The TAPES also containsthree activity-restriction subscales: functional ac-tivity restriction (e.g., walking 100 yards), socialactivity restriction (e.g., visiting friends), and ath-letic activity restriction (e.g., sport and recreation).Each of these activity-restriction subscales con-tains four items, which are measured along a three-point scale (not at all limited, limited a little, lim-ited a lot). Scores range from 3 to 12, with higherscores being indicative of greater activity restric-tion. There are three additional subscales assessingsatisfaction with the prosthesis, measured along afive-point scale (very dissatisfied, dissatisfied, nei-ther dissatisfied nor satisfied, satisfied, very satis-fied). The functional satisfaction subscale containsfive items (e.g., reliability), with a potential scorerange of 5–25. There are four items in the aestheticsatisfaction subscale (e.g., color), with a potentialscore range of 4–20. Because weight satisfactioncontains only one item, scores in this subscalerange from 1 to 5. Higher scores in each of thesatisfaction subscales are indicative of greater sat-isfaction with the prosthesis. Each of the psychos-ocial, activity-restriction, and satisfaction scalesdemonstrate high internal reliability using Cron-bach’s alpha (range, 0.75–0.89) and good face, con-tent, construct, and predictive validity.7

The TAPES also looks at the experience ofphantom limb pain, residual limb pain, and othermedical problems not related to the amputation.Each of the aforementioned is subdivided intoquestions relating to (1) whether that type of painis experienced (2), how often it is experienced, (3)how long each episode lasts, (4) how the level ofpain can be described, and (5) the extent to whichit interferes with their daily lives. This section ofthe TAPES also incorporates two items requestingrespondents to rate their general health and phys-

TABLE 1 Sample characteristics

Frequency Percentage

GenderMale 99 68.3Female 46 31.7

Type of amputationBelow knee 73 50.3Through knee 3 2.1Above knee 52 35.9Bilateral 17 11.7

Cause of amputationPVD 40 27.6Diabetes/PVD 38 26.2Accident/trauma 37 25.5Infection 8 5.5Cancer 7 4.8Clot 4 2.8Other 11 7.6

Mean SD

Age, yrs 60.5 17.4Length of time since

amputation, mos81.4 143.4

PVD, peripheral vascular disorder.


ical capabilities, using a five-point scale (very poor[1] to very good [5]).

Statistical AnalysisA three-stage process was used to investigate

the basic psychometric properties of the ABIS:1) Using SPSS version 11 (SPSS 11 for Win-

dows, SPSS Inc., Chicago IL), internal consistencyand homogeneity of the original 20 items wereexamined by calculating:

a) Cronbach’s coefficient alpha. It has beensuggested that this should be above 0.70 but nothigher than 0.90,26–27 because it is important tostrike a balance between satisfactory internal con-sistency and an instrument that is too homogenousand thus measures a very restricted aspect of aphenomenon.17,28

b) Item–total correlations. Spearman rank cor-relation coefficients (rs) were used to examine thedegree to which each item was correlated with thetotal score, omitting that item from the total. Theusual rule of thumb is that an item should corre-late with the total score with a r � 0.2027;

c) Kaiser Meyer Olkin measure of samplingadequacy (both global and for each item). The levelof homogeneity of the matrix of item scores wasinvestigated through comparison of the magni-tudes of the correlation coefficients observed withthose of the partial correlation coefficients. KaiserMeyer Olkin values greater than 0.6 are soughtbecause values less than this indicate that one ormore items should not be included in the factoranalysis, because they do not belong to the sameuniverse shared by the other variables.29

d) Principal-component analysis. To test theunidimensionality of the measure, the amount ofvariance explained by the first principal componentand the extent to which the first eigenvalue waslarger than the second and third ones is examined.It has been suggested that when the first compo-nent accounts for 40% of the total variance, it canbe said that a set of items is measuring a singledimension.30,31

2) Rasch analysis: The matrix of single rawscores for each subject was subjected to the rating-scale model through the WINSTEPS software(WINSTEPS, Chicago, IL) to estimate the followingissues:

a) Rating-scale diagnostics. To investigatewhether the rating scales of the questionnaire werebeing used in the expected manner, the followingcriteria (suggested by Linacre32) have been adoptedto judge this parameter: (1) at least ten cases percategory; (2) regular distribution of category use;and (3) monotonic increase in both average mea-sures across rating-scale categories and thresholds.Thresholds (sometimes also called step calibra-tions) are the points at which the probability of a

response of either the category below and the nextcategory are equally likely; that is, they representthe transition from the category below to the nextcategory; (4) category outfit mean square valuesless than 2; and (5) thresholds differences greaterthan 1.4 and less than 5.

Until all these criteria were met, categorieswere combined according to specific guidelines,and several categorizations have been compared,looking not only at above indicators of categorydiagnostics but also at various reliability and valid-ity indices.24 Only the final solution is reported onin the results.

b) Validity. After the check and revision of therating scale, validity was analyzed by evaluating thefit of the individual items to the latent trait (uni-dimensionality), as well as by examining whetherthe pattern of item difficulties was consistent withthe expectation of the construct. Depending on thestring of responses provided by a particular sampleof subjects on a particular sample of items, theRasch model estimates (1) goodness of fit of themodel (fit statistics). Information-weighted (infit)and outlier-sensitive (outfit) mean-square statistics(MnSq) for each item were calculated (similarly toa �2 analysis) to test whether there were items thatdid not fit with the model expectancies. Accordingto the literature, items are deemed to have anacceptable fit to the model when the MnSq isgreater than 0.6 and less than 1.4.24,33 Items out-side this range were considered misfitting (MnSq �1.4) or overfitting (MnSq � 0.6) (see also below); (2)the level of difficulty achieved by each item on aninterval scale (item difficulty) and where each in-dividual subject fits along the continuum (subjectability). Item difficulty and patient ability are ex-pressed (on a common interval scale) in logits, thenatural logarithm of the odds of mutually exclusivealternatives (e.g., pass vs. fail, or higher responsevs. lower response).24,34,35 It is reported that asample size of about 100 persons will estimate itemdifficulty with an alpha of 0.05 to within 0.5logits.36

c) Reliability. The final set of items satisfyingboth the model fit requirements and an expertreview were evaluated in terms of “separation” (G),defined as the ratio of the true spread of the mea-sures with their measurement error.24 The itemseparation index indicates an estimate (in standarderror units) of the spread or separation of itemsalong the measurement construct; the person sep-aration index provides the same for persons (de-scribing the number of performance levels the testmeasures in a particular sample). A separation of2.0 is considered good and enables the distinctionof three groups or strata (high, average, low) (num-ber of distinct strata � (4G � 1)/3), defined assegments whose centers are separated by distances


greater than can be accounted for by measure-ment error alone.34,35 A related index is the reli-ability of these separation indices, indicating thedegree of confidence we can place in the consis-tency of our estimates (range � 0–1; coefficients�0.80 are considered good, and coefficients �0.90are excellent).24

3) Construct validity: Both the original 20-item ABIS and the new Rasch-refined version of thescale (known as ABIS-R) were correlated with theTAPES using Spearman’s correlation coefficient toassess their convergence issues.27,28 It is expectedthat the ABIS and ABIS-R will correlate positivelywith each of the activity-restriction subscales onthe TAPES—that is, body image disturbance willbe associated with higher levels of restriction inathletic, social, and functional activity restriction.It is expected that the ABIS and ABIS-R will cor-relate negatively with each of the satisfaction andadjustment subscales of the TAPES—that is, bodyimage disturbance will be associated with lowerlevels of functional, weight, and aesthetic satisfac-tion and lower levels of general, social, and limita-tion adjustment. Aside from the significance levelof the correlations, r � 0.25 indicates little rela-tionship, and r from 0.25 to 0.50 suggests a fairdegree of relationship.28

RESULTSInternal Consistency/Homogeneity

The Cronbach’s coefficient alpha of the origi-nal ABIS was 0.90. The item-to-total correlationcoefficients (rs) ranged from 0.30 (item 7) to 0.74(item 11). The overall Kaiser Meyer Olkin measureof sampling adequacy was 0.87. The Kaiser MeyerOlkin statistics for each individual item found onthe diagonal of the antiimage correlation matrixwere all greater than 0.6, as required29: they rangedfrom 0.94 (item 8) to 0.73 (item 15). Principal-component analysis showed that four factors hadeigenvalues greater than 1.0, and the first factor(eigenvalue � 7.40) explained 37% of variance,whereas the second (eigenvalue � 1.61) and third(eigenvalue � 1.28) factors explained only smalladditional amounts of variance (9 and 6%, respec-tively). The scree test identified only the first factorbefore the “break.” The internal consistency indi-ces and the large amount of variance accounted forby the first principal factor indicated that the testwas sufficiently unidimensional30 to be submittedto Rasch analysis.

Rasch AnalysisRegarding rating-scale diagnostics, the rating

categories of 2 (rarely), 3 (some of the time), and 4(most of the time) did not comply with the setcriteria for category functioning (average mea-sures, thresholds, etc.) (Fig. 1A).

The model meeting all the established criteriaand with the best person separation and reliabilitywas the one that collapsed into a unique categorylevel 2 with 3, and level 4 with 5 of the ABIS, thusproducing a new three-level rating scale (0 � noneof the time, 1 � sometimes, and 2 � most/all of thetime). Figure 1B shows category probability curvesafter collapsing the categories.

After the phase of rating-scale modification,the Rasch analysis showed that 15 ABIS items fittedthe unidimensional construct that the scale wasintended to measure (Table 2). Items 2, 19, 17, and16 were misfitting (MnSq � 1.4), and item 11 wasoverfitting (MnSq � 0.6).

Regarding the hierarchic ordering of items,Figure 2A shows the distribution map of subjectability and item difficulty of the items, according tothe Rasch model. In the original 20-item scale (Fig.2A), item measures ranged from –1.63 (item 19) to�1.33 logits (item 5), and person-ability measuresranged from –3.00 to �4.19 logits. In the short-ened 14-item version without misfitting and over-fitting items or item 7 (which was deleted forcontent reasons; see Discussion) (ABIS-R), itemmeasures ranged from –1.47 (item 12) to �1.23logits (item 5) (Fig. 2B), and person-ability mea-sures ranged from –3.21 to �3.99 logits.

In the 14-item ABIS-R, the item separationindex was 4.59 (item separation reliability �0.95), the person separation index was 2.33, andthe person separation reliability (which is anal-ogous to Cronbach’s alpha) was 0.84.

Correlations of ABIS (20 Items) andABIS-R (14 Items) with TAPES

As can be seen in Table 3, there is a significantnegative correlation between both ABIS andABIS-R and each of the following TAPES subscales:aesthetic, weight, and functional satisfaction; andgeneral, social, and limitation adjustment. There isalso a significant positive correlation between theABIS, ABIS-R, and functional and social activityrestriction.

DISCUSSIONBeing cognizant of the person’s body image

after amputation is an important aspect of ongoingpostamputation care, and its inclusion as part of acomprehensive outcome measurement merits con-sideration. However, because such measurementsneed to demonstrate robust psychometric proper-ties, this study used Rasch analysis to improve thevalue of the ABIS by refining its rating scale, dis-tinguishing items belonging to the same construct(unidimensionality), verifying the expected diffi-culty hierarchy of its items, examining the extentto which the items are of appropriate difficulty for


the sample (targeting), and analyzing reliability interms of both internal consistency and separation.

Internal ConsistencyThe internal consistency of ABIS was found to

be satisfactory according to multiple tests fromclassical test theory.27,28 Furthermore, despite thereduction of six items, the ABIS-R showed an ac-

ceptable value (0.84) of person separation reliabil-ity, which is analogous to Cronbach’s alpha.24

Rasch AnalysisRegarding the rating-scale diagnostics, the

ABIS showed some disordered thresholds. Thiscontradicts the usual interpretation of categories(i.e., that they represent the sequence of the most

FIGURE 1 Category probability curves of ABIS. The y-axis represents the probability (0–1) of responding to oneof the rating categories, and the x-axis represents the different performance values (person measureminus the item measure) in logits. The 0 curve declines as the subject’s ability increases; the crossingpoint (where 0 and 1 are equally probable) is the first threshold. The same applies for the other curves.The plot should look (as in panel B) like a range of hills. A, Original scale with five categories (1 �none of the time, 2 � rarely, 3 � some of the time, 4 � most of the time, and 5 � all of the time).B, Revised scale after collapsing some categories (1¡ 0 � none of the time; 2 � 3 ¡ 1 � sometimes;and 4 � 5 ¡ 2 � most/all of the time).

Apparent from Figure 1A is that the probability of using the central categories 2–4 is never higherthan receiving other ratings. Conversely, in Figure 1B, it can be seen that the probability of selectingone of the three revised rating categories is now a clear function of the level of body imagedisturbance expressed by the individual in x-axis.


likely outcomes) and suggests that respondentswere not able to distinguish their abilities as finelyas envisaged by the five response categories (i.e.,more categories existed in the scale than wereneeded to describe the construct).19,22 In particu-lar, category diagnostics evidenced the inability ofrespondents to appreciably discern between cate-gories 2 (rarely) and 3 (some of the time) andbetween categories 4 (most of the time) and 5 (allof the time) and later confirmed the appropriate-ness of collapsing them into two single categoriesindicating “sometimes” and “most/all of the time.”This modification makes sense, eliminates the re-dundancy of underused rating categories, and en-sures that each rating category is distinct from theothers.24,32 Similar problems and solutions withscales using adjectival descriptions of frequencyand discrete responses have been illustrated byBond and Fox24 (p 166) and Zhu.37

Four ABIS items proved to be “misfitting”:their values suggested erratic response patterns.The misfitting could have been attributable—among other reasons—to their being part of an-other construct, being poorly written, or being toosensitive to confounding factors.23,24 We used a

careful approach to item deletion that was basednot only on the criterion of Rasch fit statistics butalso on expert analysis of the item content andpresentation, to guarantee the face, content, andclinical validity of the shortened scale.38 Thatstated, we suggest the elimination of the four mis-fitting items (because of their major threat to va-lidity) for both statistical and content reasons.They are:

● Item 2: “I avoid wearing shorts in public becausemy prosthesis would be seen”; and item 17: “Iwear baggy clothing in an attempt to hide myprosthesis.” The wearing of clothes may be influ-enced by factors other than body image. This taskis also sensitive to cultural and environmental(including geographical) factors.

● Item 16: “I like the appearance of my stumpanatomy.” It is possible that the way in whichthis item is phrased may render it sensitive toconfounding factors; for instance, a significantproportion of people experience stump pain.39

However, the shape and appearance of the resid-ual limb is a potentially important aspect of bodyimage, and this element is retained in item 20,which remains in the ABIS-R.

● Item 19: “It is important that my prosthesis andremaining anatomy of my affected limb are thesame size as the other limb.” We do not thinkthat the element of “body size distortion” is asrelevant to people with an amputation, nor is it asignificant part of their concept of body image.

One item was “overfitting” (MnSq � 0.60)—that is,open to interpretation as redundant or failing todiscriminate persons with different levels of abi-lity.23,24 Overfitting items contribute little extrainformation beyond that provided by other items inthe scale.22 However, the decision to remove, re-tain, or substitute overfitting items should be madeon the basis of clinical reasoning. In our opinion,because the aspects covered in the overfitting item(item 11: “The loss of my limb makes me think ofmyself as disabled”) are also covered by remainingitems, we would suggest removing it from thescale. Indeed, concerns about the reduction offunctional capabilities are also found in items 4, 9,13, and 15 (see Appendix). Furthermore, we sug-gest the removal of item 7 (“I experience a phan-tom limb”) on conceptual grounds. Because themajority of people with an amputation experiencephantom limb pain, this item is unlikely to distin-guish between people who are and are not experi-encing body image disturbance. Moreover, thisitem was that with the lowest item–total correla-tion (r � 0.30), and some authors consider assatisfactory only a correlation of 0.40 or higher.40

TABLE 2 Item calibrations (measure) withstandard errors (SE) and infit andoutfit mean-square statistics (MnSq)for the 20 items of Amputee BodyImage Scale, in order of misfit

ItemNumber Measure SE

InfitMnSq

OutfitMnSq

2 �1.29 0.17 1.57* 1.3319 �1.63 0.18 1.48* 1.3316 �0.92 0.16 1.39 1.46*17 0.86 0.15 1.41* 1.2515 0.21 0.15 1.08 1.327 0.11 0.15 1.06 1.245 1.33 0.16 1.21 1.21

12 �1.13 0.16 1.14 1.1913 �0.52 0.15 1.01 1.1820 1.16 0.15 1.12 1.183 0.57 0.15 1.00 1.12

10 �0.17 0.15 1.04 0.9514 �0.09 0.15 1.03 0.99

8 0.97 0.15 0.81 0.8518 0.73 0.15 0.75 0.766 0.86 0.15 0.71 0.679 �0.17 0.15 0.70 0.674 �0.59 0.15 0.66 0.641 0.09 0.15 0.65 0.61

11 �0.37 0.15 0.57* 0.57*

Each item estimate can be regarded as the balance pointfor the response distribution across that item’s categories.The higher the item estimate, the more difficult that itemwas for the group to endorse (higher scores). Items 3, 12,and 16 are reverse scored. Misfitting and overfitting valuesare marked by asterisks.


Despite the considerable item reduction fromABIS, the ABIS-R showed a large logit range inperson ability (7.20 logits, from –3.21 to �3.99)and a reasonable logit range of item difficulty (2.70

logits, from –1.47 to �1.23) (Fig. 2B); this indi-cates a great spread of both person measures (asdefined by the selected items) and item difficulties(as characterized by the sample under study). Av-

FIGURE 2 Person-ability and item-difficulty maps of the ABIS (A) and ABIS-R (B). In each map, the doublevertical line represents the measure of the variable, with the units of measurement on the scale(logits, the natural logarithm of the odds of mutually exclusive alternatives; e.g., pass vs. fail, orhigher response vs. lower response). The lefthand column locates the individual person’s performancealong the variable: each person is indicated by an “X.” The righthand column locates the itemdifficulty measures along the variable (the difficulty estimate represents the mean calibration of thethreshold parameters according to the rating-scale model, with values opposite those from Table 2).Each item is indicated by its number (see Appendix); fitting items are in bold. The top of the scalerepresents greater body image disturbance (patient measure) and greater item difficulty (higher itemraw score). By convention, the average difficulty of items in the test is set at 0 logits (and indicatedwith M=); items with negative signs are easier than average, and those with positive signs are harderthan average. Accordingly, a candidate with average ability is indicated with M.


erage person ability (M) was also at the same levelas average item difficulty (M=), which denotes thatthe instrument was well matched to the sampleunder study. Moreover, person abilities are nor-mally distributed along the continuum, and itemstap well into a range of levels of body image dis-turbances, without significant redundancy or con-siderable gap in their difficulty estimates (Fig. 2B).Finally, no floor or ceiling effects have been found.In addition, the reliability values indicate thatABIS-R has an acceptable internal consistency(particularly for making group comparison) and ahigh ability to define a distinction hierarchy ofitems and persons along the measured construct.Items were distributed into more than six difficultystrata, and their high separation reliability (0.95)indicates that high confidence can be placed in thereplicability of item placement across other sam-ples. Furthermore, items of ABIS-R were able todistinguish three levels of body image disturbances(absent, low, high) in this sample of people with alower-limb amputation. Overall, these findingsshow that ABIS-R presents a series of sound psy-chometric properties.

The pattern of the item difficulty estimates inthe righthand columns of Figure 2B also provides adescription of some characteristics of feelings andconcerns about body image in this population, asdefined by the ABIS-R questions. For example,items in the upper part of the column (e.g., item13: “When I am walking, people notice my limp”;item 4: “It concerns me that the loss of my limbimpairs my body’s functional capabilities in variousactivities of daily living”; and items 10 and 14:

“. . . I avoid situations where my physical appear-ance can be evaluated by others”) are more likely toobtain higher ratings (i.e., answers in category 1[sometimes] and 2 [more/all of the time]) thanitems in the lower part of the column (e.g., items 5and 20: “I avoid looking into a full-length mir-ror . . .”) or in the upper part but reverse scored(e.g., item 12: “I like my physical appearance whennot wearing my prosthesis). Several characteristicsof this ordering are consistent with clinical expe-rience and support the face validity of the itemhierarchy. For example, the physical appearancewhen not wearing a prosthesis (item 12), the con-cerns about the impairment of body’s functionalcapabilities in various activities of daily living pro-duced by a limb loss (item 4), and the worries that“people notice my limp, when I’m walking” (item13) are expected to be potential sources of distressfor people with lower-limb amputations. On thecontrary, the avoidance of looking into a full-length mirror in order not to see one’s own pros-thesis (item 5) or stump anatomy (item 20) isexpected to be infrequent in most people with alower-limb amputation. In addition, the two pairsof similar items (items 5 and 20; items 10 and 14)occurred in the expected order of difficulty (Fig.2B).

Construct ValidityThe revised scale still contains items that re-

late to affective (e.g., item 1), cognitive (e.g., item18), and behavioral (e.g., item 10) components ofbody image as outlined by Breakey12 (See Appen-dix). The validity of the ABIS-R was also affirmed in

TABLE 3 Correlation between the original Amputee Body Image Scale (ABIS) and revisedAmputee Body Image Scale (ABIS-R) and each of the Trinity Amputation ProsthesisExperience Scales (TAPES) subscales

ABIS 20 ABIS-R

Aesthetic satisfaction subscale (n � 119) r � �0.27 R � �0.22P � 0.005* P � 0.05*

Weight satisfaction subscale (n � 121) r � �0.23, R � �0.23,P � 0.01* P � 0.01*

Functional satisfaction subscale (n � 120) r � �0.41, R � �0.37,P � 0.0001* P � 0.0001*

Athletic activity-restriction subscale (n � 114) r � 0.17, R � 0.19,P � 0.07 P � 0.05*

Functional activity-restriction subscale (n � 113) r � 0.30, R � 0.31,P � 0.001* P � 0.001*

Social activity-restriction subscale score less work (n � 120) r � 0.40, R � 0.43,P � 0.0001* P � 0.0001*

General adjustment subscale (n � 126) r � �0.57, R � �0.54,P � 0.0001* P � 0.0001*

Social adjustment subscale (n � 123) r � �0.44, R � �0.40,P � 0.0001* P � 0.0001*

Adjustment to limitations subscale (n � 116) r � �0.30 R � �0.26P � 0.001* P � 0.005*


that similar relationships between the originalABIS and the ABIS-R with the TAPES subscalesemerged despite the reduction in items. The rela-tionships between the ABIS-R and each of theTAPES subscales were also in the hypothesizeddirection.

The moderate correlations between the ABIS-Rand the “prosthesis satisfaction” subscales of theTAPES are not surprising and are consistent withthe findings of Murray and Fox.15 As the prosthesisplays an important cosmetic and social role, inaddition to a functional role, it is expected that agreater level of satisfaction with the prosthesis isassociated with lower levels of body image distur-bance. This association can be better appreciated ifclient satisfaction is considered as a concept relatedto the extent to which the features of prostheticcare received meet the client’s expectations, and ifbody image is considered as the portion of one’sself-concept that involves attitudes and experiencespertaining to the body that influence the individ-ual’s subjective well-being. Thus, the personalbackground expectations and their perceived de-gree of fulfillment might be the shared underlyingvariable.

The association between ABIS-R and the activ-ity-restriction subscales of TAPES was also in theexpected direction; that is, lower levels of bodyimage disturbance were associated with lower lev-els of activity restriction. This finding is consistentwith Wetterhahn et al.,14 who identified a positiverelationship between regular participation in phys-ical activity and body image among people withlower-limb amputations. Furthermore, Fisher andHanspal41 recorded a significant correlation be-tween body image and mobility in younger peoplewith traumatic amputations. Indeed, Van Deusen42

postulated that body image distortion interfereswith body movements that are necessary for dailyactivities to be performed. Finally, the correlationbetween the ABIS-R and the psychosocial adjustmentsubscales of the TAPES confirms the relationshipbetween the body images of people with amputationsand psychosocial adjustments to leg amputationsfound by Rybarcyzk et al.,11 Breakey,12 and Murrayand Fox.15

CONCLUSIONThe 14-item ABIS-R demonstrates good psy-

chometric characteristics for measuring body im-age disturbances in people with lower-limb ampu-tations. Although these preliminary results suggestthe adequacy of the new instrument, further stud-ies are needed to analyze the actual performance ofthe new response structures and to confirm itsmeasurement properties in other samples, therebyadding clinical validity to the instrument. Further-more, a reasonable next step would be to assess

whether ABIS-R items have different levels of dif-ficulty (differential item functioning) on the basisof a sample characteristic such as gender or am-putation level.

APPENDIXAmputation Body Image Scale (ABIS). The 20-

item questionnaire that, in the original version,was scored by a five-level ordinal scale (1 � none ofthe time, 2 � rarely, 3 � some of the time, 4 �most of the time, 5 � all of the time). Three of thequestions (3, 12, and 16) are reverse scored. The 14items of the shortened version (ABIS-R) are inbold, and their new scoring is 0 � none of the time,1 � sometimes, and 2 � most/all of the time.

1. Because I am an amputee, I feel more anxiousabout my physical appearance in social situa-tions than when I am alone.

2. I avoid wearing shorts in public because myprosthesis would be seen.

3. I like my overall physical appearance whenwearing my prosthesis.

4. It concerns me that the loss of my limb impairsmy body’s functional capabilities in variousactivities of daily living.

5. I avoid looking into a full-length mirror inorder not to see my prosthesis.

6. Because I am an amputee, I feel anxious aboutmy physical appearance on a daily basis.

7. I experience a phantom limb.8. Since losing my limb, it bothers me that I no

longer conform to society’s idea of normalappearance.

9. It concerns me that the loss of my limb impairsmy ability to protect myself from harm.

10. When I am not wearing my prosthesis, I avoidsituations where my physical appearance canbe evaluated by others (e.g., I avoid socialsituations, swimming pool or beach activities,etc.).

11. The loss of my limb makes me think of myselfas disabled.

12. I like my physical appearance when not wear-ing my prosthesis.

13. When I am walking, people notice my limp.14. When I am wearing my prosthesis, I avoid

situations where my physical appearance canbe evaluated by others (e.g., I avoid any socialsituations, and/or I avoid swimming pool orbeach activities etc.).

15. People treat me as disabled.16. I like the appearance of my stump anatomy.17. I wear baggy clothing in an attempt to hide my

prosthesis.


18. I feel I must have four normal limbs to bephysically attractive.

19. It is important that my prosthesis and remain-ing anatomy of my affected limb are the samesize as the other limb.

20. I avoid looking into a full-length mirror inorder not to see my stump anatomy.

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Authors:Albino Petrone, MDMartino Pavone, MDMaria B. Chiarini Testa, MDFrancesca Petreschi, MDEnrico Bertini, MDRenato Cutrera, MD, PhD

Affiliations:From the Respiratory Unit (AP, MP,MBCT, FP, RC) and NeuroscienceDepartment (EB), Bambino GesuChildren Hospital, Research Institute,Rome, Italy.

Correspondence:All correspondence and requests forreprints should be addressed toAlbino Petrone, Respiratory Unit,Bambino Gesu Children Hospital,Research Institute, Rome, Piazza S.Onofrio 4, 00165 Rome (Italy).


DOI: 10.1097/PHM.0b013e31802ef774

Noninvasive Ventilation in Childrenwith Spinal Muscular Atrophy Types1 and 2

ABSTRACT

Petrone A, Pavone M, Chiarini Testa MB, Petreschi F, Bertini E, Cutrera R:Noninvasive ventilation in children with spinal muscular atrophy types 1 and 2.Am J Phys Med Rehabil 2007;86:216–221.

Objective: Our aim was to assess the efficacy of noninvasive ventila-tion (NIV) for the treatment of thoracoabdominal asynchrony during sleepin children with spinal muscular atrophy (SMA) types 1 and 2.

Design: Nine subjects underwent assessment for sleep apnea/hypop-nea index (AHI), mean oxyhemoglobin saturation (SpO2), oxygen desatu-ration index, transcutaneous carbon dioxide tension (tcpCO2), and meanphase angle during sleep as a measure of thoracoabdominal coordination.A second sleep study was performed with use of NIV.

Results: The nine patients (7 mos of age, range 2–33) had a baselineAHI of 2.1 events per hour (range 0.5–55.8), oxygen desaturation indexof 3.7 events per hour (range 1.6–46.1), mean tcpCO2 of 46 mm Hg(range 37–60), and phase angle of 127 degrees (range 72.7–151.7).Comparing baseline and NIV sleep studies, we found significant improve-ment in oxygen desaturation index (P � 0.010), mean tcpCO2 (P �0.001), and phase angle (P � 0.001). For five patients, phase-angleimprovement became significant when using high-span bilevel positiveairway pressure (PAP).

Conclusions: NIV improved sleep breathing parameters and thoraco-abdominal coordination during sleep in SMA types 1 and 2. Phase-angleimprovement correlated with bilevel PAP pressures. Phase angle may beuseful for the evaluation and monitoring of therapeutic interventions suchas NIV.

Key Words: Spinal Muscular Atrophy, Respiratory Inductive Plethysmography, Non-invasive Ventilation, Thoracoabdominal Coordination, Sleep Apnea, Phase Angle


RESEARCH ARTICLE

Pulmonary

Spinal muscular atrophy (SMA) is an autosomalrecessive congenital disease of the anterior horncells of the spinal cord and the cranial nerves. It ischaracterized by weakness, with proximal musclesmore affected; restrictive respiratory insufficiency;and absence of deep-tendon reflexes.1 This disorder isthe leading hereditary cause of infant mortality.2,3

SMA is stratified into five types based on se-verity of muscle weakness. SMA type 1 (Werdnig–Hoffmann disease) patients never attain the abilityto sit independently; with conventional manage-ment, they usually die before age 2. Patients withSMA type 2 at least temporarily attain the ability tosit unsupported, but they also usually develop re-spiratory failure during childhood. Patients withSMA type 3 at least temporarily attain the ability towalk, and types 4 and 5 are adult onset.4–6 Use ofrespiratory muscle aids can greatly prolong sur-vival for many patients with SMA types 1 and 2.7–9

In patients with SMA, intercostal muscles areseverely involved with relative sparing of the dia-phragm. The intercostal muscle weakness is respon-sible for a funnel-shaped chest and pectus excavatum,paradoxical breathing, and diminished cough flowsthat result in atelectasis and bronchopulmonary in-fections. Respiratory muscle asynchrony increasesthe work of breathing and reduces tidal volume.6,9

Paradoxical movements of the rib cage andabdomen are also seen physiologically during REMsleep in normal infants but decrease by age 3, andin otherwise normal children during obstructivesleep apneas.10,11 The SMA children have moreasynchronous (paradoxical) breathing during ac-tive and quiet sleep than healthy controls12 andalso when they are awake. In our previous study,we reported that both inspiratory and expiratoryphases demonstrate thoracoabdominal dyssyn-chrony in these patients.12 Other earlier studieshave included only older children and adults with avariety of neuromuscular conditions who wereawake; these studies used predominantly invasivemechanical ventilation or low-span bilevel positiveairway pressure (PAP). Perez et al.13 observed par-adoxical breathing in 31 patients with SMA and 19with myopathies with a mean age of 9.7 � 3 yrs byusing the percentage of thoracic contribution totidal volume, a labored breath index, and phaseangles. They also found that nearly full correctionof chest-wall dyssynchrony was reported underthese circumstances during intermittent positivepressure ventilation.13 Diaz et al.14 also observedchest-wall motion asynchrony in five children andyoung adults (mean age 15.6 yrs) with neuromus-cular disease and its correction by noninvasive me-chanical ventilation.

Mechanical ventilation can normalize bloodCO2 levels when hypercapnia is present, improve

growth and development of lung parenchyma andthe chest wall, rest inspiratory muscles, preventpectus excavatum, prolong life, and improve qual-ity of life.15 The aim of this study was to evaluatethe utility of phase angle as a measure of theimprovement of paradoxical chest and abdominalwall movement during sleep using noninvasiveventilation (NIV) delivered by nasal mask in infantpatients with SMA types 1 and 2; these patientswere much younger than those in the previousreports. Our goal was to observe the effects ofvarying bilevel PAP spans on achieve correction ofdyssynchrony high-span nasal bilevel PAP and tostudy its effect on phase angle and other pulmo-nary parameters.

METHODSSample

We studied nine children with DNA deletion–confirmed SMA types 1 or 2, aged 7 mos (range2–33), who had not had any signs of respiratorytract infection for at least 2 wks. Informed consentwas obtained from the parents of each child. Theethics committee of our hospital approved thisstudy.

Instruments and TechniqueSleep studies were performed on a respiratory

ward and supervised by nurses. All studies werecommenced at the patient’s usual bedtime andperformed in a dark, quiet room. No sedation orsleep deprivation was used. All patients were ac-companied by one of their parents throughout thenight. A SomnoStar PT2 (Sensor Medics Corpora-tion) was used to measure heart rate, pulse rate,pulse waveforms, arterial oxyhemoglobin satura-tion (SpO2), calibrated respiratory inductive pleth-ysmography (thoracic, abdominal, and summationchannel), and oronasal airflow (thermistor). Thistechnique has been used previously in children, andtechnical details have been published elsewhere.16,17

Transcutaneous carbon dioxide (tcpCO2) was mea-sured by a noninvasive monitoring system (TCM3,TINA, Radiometer; Copenhagen, Denmark). The in-strument was calibrated before each study. CO2 wasmonitored by transcutaneous methods for nocturnalCO2 baseline and for bilevel PAP titration. No supple-mental oxygen or respiratory stimulants were used.

Thoracoabdominal CoordinationParameters

The rib cage and abdominal waveforms definethe two-compartment model of respiration de-scribed by Konno and Mead.18,19 These two com-ponents can move together or independently.Among the major indices that describe the coordi-nation of movement between the rib cage and

March 2007 Noninvasive Ventilation in SMA 217

abdominal compartments is the phase angle. Aphase angle of 0 degrees indicates perfect in-phasemovements, whereas values of 180 degrees indicatecompletely out-of-phase movements between the ribcage and abdominal compartments. Intermediate val-ues indicate varying degrees of asynchronous andparadoxical motion. The phase angle represents thepercentage agreement between direction of rib-cage and abdominal movements through the entirecycle of a breath. The analysis of thoracoabdominalcoordination was expressed as the mean of theentire sleep monitoring.

Respiratory Parameter DefinitionsThe polysomnogram is programmed to interpret

apneas and hypopneas as being of obstructive or cen-tral origin rather than as a result of inspiratory mus-cle weakness. Because the polysomnogram cannotdiscern between these factors, we did not categorizethe causes of the apneas and hypopneas.

The apnea/hypopnea index (AHI) was definedby the number of apnea/hypopneas per hour ofsleep.20–22 For this study, sleep disordered breath-ing was defined as having an AHI greater than orequal to 1. The oxyhemoglobin desaturation indexwas defined as the number of desaturations ofgreater than or equal to 4% from baseline per hourof sleep. Oximetry artifacts in the pulse waveformtracing were discarded manually after visual in-spection of the traces. Total sleep time was mea-sured, and respiratory parameters were expressedas a percentage of total sleep time.

Protocol TechniqueWe prescribed high-span bilevel PAP (inspira-

tory minus expiratory bilevel PAP greater than 10cm H2O) for SMA patients to promote more normallung growth and chest-wall development.15 Afterthe baseline polysomnogram was done, it was re-peated using nasal bilevel PAP. It was introducedby using it for 20 mins, two or three times a day,before the sleep study. All patients used high-spanbilevel PAP (range 14–20 cm H2O) to obtain goodthoracic and alveolar expansion. Spans less than 10cm H2O were considered low span.

Pressure preset ventilators cycling in pressure-assisted mode (A/C, ACHIEVA PSO2, Puritan Ben-nett-Tyco) were used. Nasal interfaces were se-lected to ensure a comfortable but airtight seal.Ventilator settings were chosen at bedside. To ame-liorate patient–ventilator synchrony in patients un-able to trigger the machine, the assisted/controlledmodality of pressure-cycled machines was usedwith a back-up rate set slightly higher than thespontaneous breathing rate of the infant. As theincrease of the tidal volumes resulted in a decreasein the infant’s spontaneous rate, the machine’sback-up rate was decreased and inspiratory PAP

was augmented. Ventilator settings for bilevel PAPwere initially set to achieve good excursion of chestwall and resolution of tachypnea and hypercapnia.The aim was to increase tidal ventilation, suppresspatient respiratory trigger effort, decrease the pa-tient’s spontaneous breathing rate, and optimizepatient ventilator synchrony. Adjustments weremade during the overnight sleep study to normal-ize gas exchange (mean SpO2 �95% and meantcpCO2 �50 mm Hg) and to eliminate paradox.

Statistical AnalysisStatistical analysis was performed using the

SPSS version 9.0.0 for Windows (SPSS, Inc., Chi-cago, IL). Data were expressed as median andrange, except where otherwise specified. Baselineand bilevel PAP sleep study parameters were com-pared using the Mann–Whitney U test for nonpara-metric data. The threshold for significance was setat 0.05. Statistical applications for nonparametricdata were used because of the small number ofsubjects studied.

RESULTSSubject Characteristics

Subjects’ characteristics are shown in Table 1.

Sleep Study FindingsA summary of baseline sleep study findings is

provided in Table 2. All subjects had mild to severedecreases in SpO2 and increases in thoracoabdomi-nal asynchrony. A second cardiorespiratory sleepstudy was performed during bilevel PAP 10 days(range 5–14) after the baseline study, and the re-sults are shown in Table 2.

There was a statistically significant improve-ment for oxygen desaturation index (P � 0.020),phase angle (P � 0.001), and tcPCO 2 (P � 0.005)with the use of high-span bilevel PAP. No signifi-cant differences were found comparing the otherparameters. Five patients performed an intermedi-ate sleep study using a suboptimal bilevel PAPsetting: inspiratory PAP 14 cm H2O (range 12–16),expiratory PAP 4 cm H2O (range 3–5) for a mean

TABLE 1 Characteristics of children withspinal muscular atrophy (SMA)types 1 and 2

Age, mos 7.0 (2–33)

SMA types 1/SMA types 2 (n) 4/5 (9)Males/females 7/2Weight, kg 9.0 (4.4–16.0)Height, cm 95 (57–125)

Unless otherwise specified, results are given as median(range).

218 Petrone et al. Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

span of 10 cm H2O (range 8–12). With this setting,the AHI was reduced to no more than one event perhour (Table 3); however, the phase-angle improve-ment did not reach statistical significance: 110degrees (range 90–145) vs. 88 degrees (range 54–110); P � 0.080 (NS). The parents noted less night-time perspiration and breathing difficulty duringsleep using bilevel PAP.

DISCUSSIONOvernight sleep studies performed during

high-span bilevel PAP use by SMA type 1 and 2patients showed an overall improvement in thora-coabdominal respiratory movements coordinationas measured by phase angle, in mean tcpCO2, andin SpO2 desaturation rate.

All patients with SMA type 1 have paradoxicalbreathing. SMA type 1 and 2 patients who haveparadoxical breathing develop pectus excavatum ifuntreated. This is caused by the action of the dia-phragm that is not modulated by the intercostalmuscles. In addition, when mechanical limitationsof the ventilatory pump are superimposed on thephysiologic reduction of compensatory inspiratorymechanisms during sleep with an increased upper-airway resistance, there can be serious impairment ina patient’s ability to maintain adequate respiration.23

This probably explains the nocturnal periods of per-spiration and flushing and frequent arousals thathave been reported to be relieved by the use of NIV.15

Bach et al.1 and Mellies et al.24 applied long-term NIV in children and adolescents with a variety

TABLE 2 Comparison between sleep study parameters during spontaneous breathing andnoninvasive ventilation (NIV) in nine children with spinal muscular atrophy types 1 and 2

Baseline Sleep Study High-Span NIV Sleep StudyParameters (n � 9) (n � 9) P Values

TST, hrs 8.2 (7.0–9.4) 8.0 (7.0–8.9) 0.851 (NS)Mean SaO2, % 96 (92–97.9) 97 (95–98) 0.373 (NS)SpO2 �90%, % TST 0.1 (0.0–36.1) 0.0 (0.0–6.7) 0.244 (NS)SpO2 �95%, % TST 3.4 (1.6–46.1) 0.3 (0.0–90.1) 0.184 (NS)ODI, n �4%/hr 3.0 (1.6–46.1) 0.9 (0.0–22.0) �0.020AHI, n/hr 2.1 (0.5–55.8) 0.6 (0.3–8.4) 0.101 (NS)tcpCO2 mean, mm Hg 46 (37–60) 36 (35–38) �0.005Mean phase angle, degrees 127 (72.7–151.7) 44 (38–68) �0.001

Results are given as median (range).The high-span NIV sleep study parameters were obtained using the following settings: inspiratory PAP 18 cm H2O (range

14–20); expiratory PAP 4 cm H2O (range 3–5); bilevel PAP span 14 cm H2O (range 10–15). The baseline sleep study wasperformed during spontaneous breathing. The high-span NIV sleep study was performed using bilevel PAP. TST, total sleeptime; mean SpO2, mean arterial oxyhemoglobin saturation; SpO2 �90% (%TST), percentage of TST spent with an oxyhemoglobinsaturation (SpO2) below 90%; SpO2 �95% (%TST), percentage of TST spent with an oxyhemoglobin saturation (SpO2) below95%; ODI, oxyhemoglobin desaturation index; AHI, apnea/hypopnea index; tcpCO2, transcutaneous CO2.

TABLE 3 Comparison between sleep study parameters during noninvasive ventilation (NIV) usingdifferent bilevel PAP spans in five children with spinal muscular atrophy types 1 and 2

Intermediate NIV Sleep Study High-Span NIV Sleep StudyParameters (n � 5) (n � 5) P Values

Bilevel PAP span, cm H2O 10 (8–12) 14 (10–15) �0.05TST, hrs 8.2 (7.9–8.6) 7.9 (7.0–8.7) 0.341 (NS)Mean SpO2, % 96.7 (95.8–98) 97 (95–97.7) 0.917 (NS)SpO2 �90%, % TST 0.0 (0.0–0.2) 0.0 (0.0–0.0) 0.136 (NS)SpO2 �95%, % TST 0.5 (0.2–4.2) 0.2 (0.0–1.2) 0.115 (NS)ODI, n �4%/hr 2.0 (1.1–2.3) 0.1 (0.0–1.0) 0.101 (NS)AHI, n/hr 0.8 (0.5–1.0) 0.6 (0.3–0.8) 0.242 (NS)Mean tcpCO2, mm Hg 38 (32–40) 36 (35–38) 0.338 (NS)Mean phase angle, degrees 88 (54–110) 48 (38–68) �0.03

Results are given as median (range).The high-span NIV sleep study was performed using high-span bilevel PAP. Bilevel PAP span, inspiratory PAP–expiratory

PAP expressed as centimeters of water. TST, total sleep time; mean SpO2, mean arterial oxyhemoglobin saturation; SpO2

�90% (%TST), percentage of TST spent with an oxyhemoglobin saturation (SpO2) below 90%; SpO2 �95% (%TST),percentage of TST spent with an oxyhemoglobin saturation (SpO2) below 95%; ODI, oxyhemoglobin desaturation index; AHI,apnea/hypopnea index; tcpCO2, transcutaneous CO2.


of congenital neuromuscular disorders (intermedi-ate SMA, congenital muscular dystrophy and my-opathies) who presented with either nocturnal hy-poventilation or diurnal ventilatory failure. Theyreported similar improvements in sleep quality andsymptoms. Eighty-one percent of the neuromuscu-lar patients reported in another study were main-tained on nocturnal ventilation for years. The au-thors postulated that these children remainedstable because the nocturnal ventilation ensuredadequate gas exchange during sleep, reversed atel-ectasis, decreased inspiratory muscle work, andrested the respiratory muscle.25,26 Metabolic ab-normalities caused by chronic hypoventilationwere also ameliorated by the resetting of centralchemoreceptors and/or improving sleep fragmen-tation.23,27 Barois et al.28 advocated undertakingventilator use before the age of 4 yrs in SMA type 2patients to improve rib-cage development and fos-ter lung growth. It has been further suggested thatearlier intervention with respiratory support mayactually allow for greater lung growth and im-proved respiratory outcome.15

Previous studies13,14 have shown improvementin thoracoabdominal asynchrony by measuring re-spiratory inductive plethysmography in older chil-dren and adults using mechanical ventilation.Perez et al.13 studied 31 patients with SMA and 19patients with myopathies, aged 9.7 � 3 yrs. Allpatients were studied in the supine position forseveral minutes, both during spontaneous breath-ing and mechanical ventilation, apparently whileawake. They found that percent thoracic contribu-tion to tidal volume, labored breath index, andphase angle were normalized during intermittentpositive pressure ventilation. Diaz et al.14 studiedfive patients aged 15.6 yrs (range 9–23) with dif-ferent neuromuscular conditions including C-2,C-3, and T-4 transection, congenital myopathy, andSMA in the supine position and apparently awake.Chest-wall motion was recorded for several min-utes in spontaneous breathing and during mechan-ical ventilation. Mechanical ventilation was per-formed using negative pressure ventilation in onesubject, positive pressure nasal ventilation in an-other, and volume-cycled positive pressure ventila-tion via tracheostomy tube in the three remainingsubjects. Diaz et al.14 considered percentage ofthoracic contribution to tidal volume, a laboredbreath index, and phase angles and concluded thatmechanical ventilation improves thoracoabdomialasynchrony and reverses the negative contributionto tidal volume of the paradoxing compartment inchildren and young adults with neuromuscular dis-ease. Neither study correlated changes with venti-lator settings.

Our study concerned only sleeping infantswith SMA types 1 and 2, using only NIV, and

demonstrated improvement in thoracoabdominalcoordination and respiratory movements that cor-related with bilevel PAP spans. Our data suggestthat not only can nocturnal NIV normalize AHI andSpO2 when used at low bilevel PAP spans, but alsothat at higher spans, it can significantly normalizeinspiratory muscle synchrony. This can explain thepreviously reported prevention of pectus excava-tum.29,30 Results of this study indicate that NIV canimprove alveolar ventilation and thoracoabdominalrespiratory movement coordination.

In conclusion, NIV improved sleep breathingparameters and thoracoabdominal coordinationduring sleep in SMA types 1 and 2. Phase-angleimprovement correlated with bilevel PAP pres-sures. Phase angle may be useful for the evaluationand monitoring of therapeutic interventions suchas NIV.

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24. Mellies U, Ragette R, Dohna Schwake C, Boehm H, Voit T,Teschler H: Long-term noninvasive ventilation in childrenand adolescents with neuromuscular disorders. Eur RespirJ 2003;22:631–6

25. Sivan Y, Deakers TW, Newth CJ: Thoracoabdominal asyn-chrony in acute upper airway obstruction in small children.Am Rev Respir Dis 1990;142:540

26. Gilgoff I, Prentice W, Baydur A: Patient and family partici-pation in the management of respiratory failure in Duch-enne’s muscular dystrophy. Chest 1989;95:519–24

27. Annane D, Quera-Salva MA, Lofaso F, et al: Mechanismsunderlying effects of nocturnal ventilation on daytimeblood gases in neuromuscular diseases. Eur Respir J 1999;13:157–62

28. Barois A, Estournet B: Ventilatory support at home inchildren with spinal muscular atrophies (SMA). Eur RespirRev 1992;2:319–22

29. Bach JR, Wang TG: Noninvasive long-term ventilatory sup-port for individuals with spinal muscular atrophy and func-tional bulbar musculature. Arch Phys Med Rehabil 1995;76:213–7

30. Bach JR: Noninvasive Mechanical Ventilation. Philadelphia,Hanley & Belfus, 2002


Authors:John R. Bach, MD

Affiliations:From the Department of PhysicalMedicine and Rehabilitation,University Hospital, Newark, NewJersey.

Correspondence:All correspondence and requests forreprints should be addressed to JohnR. Bach, MD, Department of PhysicalMedicine and Rehabilitation,University Hospital B-403, 150Bergen St., Newark, NJ 07103.


DOI: 10.1097/PHM.0b013e31803216db

Avoiding Respiratory Failure inNeuromuscular DiseaseWhy Is It Not Done?

ABSTRACT

Bach JR: Avoiding respiratory failure in neuromuscular disease: Why is it notdone? Am J Phys Med Rehabil 2007;86:222–224.

Key Words: Noninvasive Mechanical Ventilation, Neuromuscular Disease, Spinal Mus-cular Atrophy, Werdnig–Hoffmann Disease, Duchenne Muscular Dystrophy, AmyotrophicLateral Sclerosis

The severity of spinal muscular atrophy (SMA) type 1 (Werdnig–Hoffmanndisease) can be characterized as severe when the infant definitively requirescontinuous ventilatory support before 5 mos of age, moderate when the childfirst develops acute respiratory failure as the result of an ineffective coughduring an acute respiratory tract infection from 5 to 24 mos of age, and mildwhen the child does not develop respiratory failure and require a gastrostomyfor full nutrition until after the second birthday.1 Considering only the severelyand moderately affected children, death by 2 yrs of age is unavoidable unless theinfant undergoes tracheotomy. In this case, the child remains continuouslyventilator dependent, does not develop functional speech, and most likely diesfrom complications related to the tracheostomy tube.2 However, when thesechildren develop acute respiratory failure and the acute infection has cleared,they can be extubated to noninvasive mechanical ventilation (NIV) regardless ofwhether they have any ability to breathe on their own.1,2 Likewise, it has beendemonstrated that by intermittently applying negative pressure to the airway tosupport expiratory (cough) muscles and by using concomitant abdominalthrusts (mechanically assisted coughing, or MAC), pneumonias and hospital-izations can be avoided in SMA 1 patients using NIV, without need to resort totracheotomy.1,2

In addition to prolonging life by using NIV continuously if necessary, theintroduction of nocturnal NIV for all hypotonic children with paradoxical breathingpromotes lung and chest-wall growth and prevents pectus excavatum.3 Despite this,third-party payers often mandate abnormal polysomnography results before payingfor NIV, even though the issue is not central or obstructive apneas but weakinspiratory muscles that require rest and assistance.

When normal babies cry, their abdomens protrude and their chest wallsexpand. This promotes lung and chest-wall growth. However, the crying of achild with paradoxical breathing only exacerbates paradox, and their lungs andchest walls do not grow normally. The minimum pressure required to provide


COMMENTARY

Pulmonary

a normal tidal volume and expand the chest is18–20 cm H2O for normally compliant lungs andchest walls at any age. Effective inspiratory musclerest also requires NIV at these inspiratory pres-sures. Thus, even if polysomnography is “abnor-mal” and apneas and hypopneas are noted, contin-uous positive airway pressure will not assistinspiratory effort, and titration of bilevel positiveairway pressure (PAP) to reduce hypopneas is sub-optimal. This is because any pressures less than15–20 cm H2O will simply not well rest inspiratorymuscle or reverse paradox to permit expansion toeliminate pectus excavatum.4

This is why the work of Petrone et al.5 isimportant. These investigators have demonstratedthat although low bilevel PAP can titrate awayapneas and hypopneas and maintain more normalSpO2 early on, only high-span bilevel PAP at spansof �15 cm H2O will effectively reverse chest-wallparadox for SMA 1 patients. Thus, polysomogra-phies are irrelevant for treating pediatric neuro-muscular respiratory muscle impairment. Indeed,they interpret all abnormalities as central or ob-structive in nature and cannot distinguish themfrom abnormalities attributable to inadequate in-spiratory muscle force. Once an infant is seen to haveparadoxical breathing secondary to weak chest-wallmuscles, high-span bilevel PAP or NIV at full venti-latory-support volumes and pressures is indicated.

Because it is clear that children with SMA,1,2

muscular dystrophy,6–8 patients with nonbulbaramyotrophic lateral sclerosis,9,10 postpolio,11 high-level traumatic tetraplegia,12,13 and other condi-tions14 can, and prefer15 to, use NIV and MAC ratherthan develop acute respiratory failure and be inva-sively tubed, the big question is: Why this is not beingdone, except in a few centers internationally?7,8,16

The reasons for this include the following:Paradigm paralysis: Physicians are taught to

believe that invasive tubes are required when pa-tients cannot breathe or cough, and they find ithard to explore new paradigms, especially in thislegal climate and with the conservative nature ofphysicians in general. Consider the following ex-amples of paradigm paralysis and the difficulty forthe new to become the convention:

● For the majority of people, the use of tobacco hasa beneficial effect.”—November 18, 1969, Dr. Ian G. MacDonald,Los Angeles surgeon, as quoted in Newsweek

● Everything that can be invented has been in-vented.”—1899, Charles H. Duell, United States commis-sioner of patents

● There is no reason for any individual to have acomputer in their home.”

—Kenneth Olsen, 1977 president and founder ofDigital Equipment Corporation

● [Television] won’t be able to hold on to anymarket it captures after the first six months.People will soon get tired of staring at a plywoodbox every night.”—1946, Darryl F. Zanuck, head of 20th Century-Fox

● The earth is the center of the universe.”—The first-century Ptolemy of Alexandria, andthe Popes of the Roman Catholic Church

To this can now be added:

● Determining the best date for tracheostomy inpatients with (neuromuscular disease) remains achallenge.”—2006, J.-C. Raphael, Garches, France, EuropeanRespiratory Journal, volume 28, pages 468–469

The need for an NIV team: Besides the primarycare physician who needs to introduce NIV andassisted coughing to prevent acute respiratory fail-ure, when such episodes occur despite these ef-forts, the full cooperation of intensive care physi-cians is needed to extubate these patients byspecifically described protocols to NIV and MAC,rather than simply resorting to tracheotomy.1,2

The almost continuous attention to maintain nor-mal SpO2 (�94% in ambient air) by using oximetryas feedback for effective MAC, especially after extu-bation, can necessitate continuous and active partic-ipation of a family member or care provider, becausehospital staff often do not have the time to providethis. Allowing unlicensed care providers to take partin intensive care also requires a new treatment par-adigm, but it is critical for successful extubation,rehabilitation, and transition of care to the home.

In addition, neither the primary care nor inten-sive care physician can manage these patients with-out specifically trained respiratory therapists for bothhome and intensive care. Our Jerry Lewis MuscularDystrophy Association Clinic grant provides funds fora respiratory therapist to evaluate and train patientsin the clinic in these methods. This is preferable tousing the funds for more expensive pulmonary func-tion testing that was neither designed for, nor ade-quate for, patients with muscle impairment ratherthan lung/airways disease.4

Interest: Neurologists have no special interestin reading pulmonary journals any more than pul-monologists are interested in PM&R or neurologyjournals. Indeed, although there are “lung” and“nerve” physicians, the use of inspiratory (NIV) andexpiratory (cough) muscle aids requires a medicaldiscipline concerned with muscle function. Unfor-tunately, only about 20% of neuromuscular diseaseclinics seem to have the involvement of physia-

March 2007 Avoiding Respiratory Failure 223

trists, and few physiatrists are interested in respi-ratory muscle aids.16

“A pulmonologist who considers the airwaysbut who ignores the respiratory muscles is likea cardiologist who considers the blood vesselsbut who ignores the heart.“—Peter Maclem, MD

Money: Physicians are paid more for placinginvasive tubes than for avoiding them. Hospitalsand physicians are compensated for the intensivecare management of patients in respiratory failure,but preventing respiratory failure with appropriatehome care requires time, effort, and letters of ex-planation to third-party payers to provide theneeded training and equipment.

“No matter what you say or how, nothing talkslike money!”—Petronius Arbiter, the Satyricon (time ofNero)

Assistance: Patients who are managed noninva-sively require continuous attention for MAC duringintercurrent respiratory tract infections to avoidpneumonia and acute respiratory failure. This mustbe provided by families or personal care attendants, towhom not all patients have sufficient access.

Inadequate Equipment: In a survey of 88 hos-pitals, it was found that almost none were adequatelyequipped (absence of portable noninvasive ventila-tors, noninvasive interfaces, mechanical in-exsuffla-tors) and that staff were inadequately trained for NIVand assisted coughing.17

Thus, although tracheostomy tubes are avoid-able for ventilator-dependent infants with neuro-muscular disease and are even easier to avoid forolder children and adult ventilator users, untilphysiatrists become actively involved in the newparadigms of evaluation and management, mostpatients will continue to suffer potentially avoid-able episodes of acute respiratory failure and dieprematurely or live with foreign bodies in theirnecks. The latter renders home care more difficult,or even impossible to achieve, and results in an

unnecessarily poorer quality of life and greaterventilator dependence.2,6,14

REFERENCES1. Bach JR, Niranjan V, Weaver B: Spinal muscular atrophy

type 1: a noninvasive respiratory management approach.Chest 2000;117:1100–5

2. Bach JR, Baird JS, Plosky D, Nevado J, Weaver B: Spinalmuscular atrophy type 1: management and outcomes. Pe-diatr Pulmonol 2002;34:16–22

3. Bach JR: Prevention of pectus excavatum for children withspinal muscular atrophy type 1. Am J Phys Med Rehabil2003;82:815–9

4. Bach JR: Respiratory muscle aids: patient evaluation,respiratory aid protocol, and outcomes, in Bach JR(ed): The Management of Patients with NeuromuscularDisease. Philadelphia, Hanley & Belfus, 2004, pp 271–308

5. Petrone A, Pavone M, Testa C, Petreschi F, Bertini E,Cutrera R: Noninvasive ventilation in infants with spinalmuscular atrophy types 1 and 2. Am J Phys Med Rehabil2007;86:000–000

6. Gomez-Merino E, Bach JR: Duchenne muscular dystrophy:prolongation of life by noninvasive respiratory muscle aids.Am J Phys Med Rehabil 2002;81:411–5

7. Toussaint M, Steens M, Wasteels G, Soudon P: Diurnalventilation via mouthpiece: survival in end-stage Duchennepatients. Eur Respir J 2006;28:540–55

8. Benditt JO: Full-time noninvasive ventilation: possible anddesirable. Respir Care 2006;51:1005–15

9. Bach JR: Amyotrophic lateral sclerosis: prolongation of lifeby noninvasive respiratory aids. Chest 2002;122:92–8

10. Bach JR, Bianchi C, Aufiero E: Oximetry and prognosis inamyotrophic lateral sclerosis. Chest 2004;126:1502–7

11. Bach JR, Tilton M: Pulmonary dysfunction and its manage-ment in post-polio patients. NeuroRehabilitation 1997;8:139–53

12. Bach JR, Alba AS: Noninvasive options for ventilatory sup-port of the traumatic high level quadriplegic. Chest 1990;98:613–9

13. Bach JR: New approaches in the rehabilitation of the trau-matic high level quadriplegic. Am J Phys Med Rehabil1991;70:13–20

14. Bach JR: The Management of Patients with NeuromuscularDisease. Philadelphia, Hanley & Belfus

15. Bach JR: A comparison of long-term ventilatory supportalternatives from the perspective of the patient and caregiver. Chest 1993;104:1702–6

16. Bach JR, Chaudhry SS: Management approaches in muscu-lar dystrophy association clinics. Am J Phys Med Rehabil2000;79:193–6

17. Maheshwari V, Paioli D, Rothaar R, Hill NS: Utilization ofnoninvasive ventilation in acute care hospitals: a regionalsurvey. Chest 2006;129:126–33

224 Bach Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

Authors:Assaf T. Gordon, MDGreg E. Lutz, MDMichael L. Boninger, MDRory A. Cooper, PhD

Affiliations:Department of Physical Medicine andRehabilitation, New York University,Rusk Institute, New York, New York(ATG); Department of PhysicalMedicine and Rehabilitation, NewYork–Presbyterian UniversityHospitals of Columbia and Cornell,Hospital for Special Surgery, NewYork, New York (GEL); and Universityof Pittsburgh, Departments of PM&R,Rehabilitation, Science & Technology,and Bioengineering, Pittsburgh,Pennsylvania (RAC, MLB).

Correspondence:All correspondence and requests forreprints should be addressed to AssafT. Gordon, MD, [email protected]


DOI: 10.1097/PHM.0b013e318031ee1a

Introduction to NanotechnologyPotential Applications in Physical Medicine andRehabilitation

ABSTRACT

Gordon AT, Lutz GE, Cooper RA, Boninger ML: Introduction to nanotechnology:potential applications in physical medicine and rehabilitation. Am J Phys MedRehabil 2007;86:225–241.

Nanotechnology is a scientific movement that has the potential to transform thediagnosis and treatment of disease in the 21st century. The area of investigationis defined by the study, design, manipulation, manufacture, and control of mate-rials or devices by physical or chemical means at resolutions on the order of onebillionth of a meter. The potential for a wide range of clinical applications makesa basic understanding of nanotechnology important to physiatrists. This reviewpresents an introduction to nanotechnology and discusses key developments intissue engineering, drug delivery, imaging, diagnostics, surface texturing, andbiointerfaces that could impact the practice of physiatry in the future.

Key Words: Nanotechnology, Rehabilitation, Tissue Engineering, Drug Delivery, Imag-ing, Diagnostic Assays

The broad applications of nanotechnology make it one of the most rapidlygrowing areas of research in contemporary science and medicine. The workingdefinition of nanotechnology involves research on materials and systems whosesizes range between 1 and 100 nanometers (nm)—approximately the scale ofthe basic building blocks of matter and molecules (Fig. 1). The field is not ascientific discipline unto itself but, rather, a confluence of chemistry, physics,engineering, and material science. Much attention has been recently focused bybiomedical scientists, pharmaceutical companies, and investors on the potentialimpact of this rapidly expanding field to medicine. Worldwide public investmentin all uses of nanotechnology was $8.6 billion in 2004, and in 2005 the U.S.government appropriated nearly $1 billion in federal funding among 11 federalagencies.1 Approximately 90 million dollars were appropriated in 2005 forbiomedical research and development to the U.S. National Institutes of Healththrough the National Nanotechnology Initiative. In March 2005, the first volumeof the quarterly journal Nanomedicine was published, an important addition to themultiple technical nanotechnology journals in nonmedical fields.

In both 2004 and 2005, the U.S. National Advisory Board on MedicalRehabilitation Research identified nanotechnology as a research opportunityarea of focus, with an identified shortage of faculty with training in the rehabilitative

March 2007 Introduction to Nanotechnology 225

INVITED REVIEW

Nanotechnology

specialties and a need for clinical trials. Severalpriority areas in nanoscience have been identifiedby the U.S. National Institutes of Health Bioengi-neering Consortium, including tissue engineering,imaging, cell signaling research, implantable biopro-cessors, biocompatible materials, drug delivery agents,and sensor technologies.2

In combination with advancements in bio-chemistry and engineering, nanotechnology hasshown promise for future clinical applicationsacross varied fields. This review of nanotechnologywill focus on the potential applications to rehabil-itation medicine. It is intended to be introductory,not an in-depth critical analysis of the many tech-nical complexities and limitations in this rapidlygrowing field. Given this framework, the goals ofthis review are to (1) introduce nanotechnology tothe rehabilitation community, (2) outline a briefhistory of nanotechnology, (3) focus discussion ofnanotechnology to those specific areas of researchthat will impact the field of physical medicine andrehabilitation, and (4) encourage interest amongphysiatrists in this growing area of scientific inves-tigation. The reader is directed to (Appendix A fordefinitions of possibly unfamiliar nanotechnologyterms (first appearance in italics) in this review.

BRIEF HISTORY OF NANOTECHNOLOGYIn December 1959, Richard Feynman, a theo-

retical physicist well known for his work on theManhattan Project and the development of theatomic bomb, delivered a lecture entitled “There’sPlenty of Room at the Bottom.” This often-quotedspeech has become known as the landmark predic-tion of the potential field of nanotechnology. Dr.Feynman conceived of a time when visualization,manipulation, data storage, and manufacture wouldbe possible in the atomic size range. He asked, “Whycannot we write the entire 24 volumes of the Ency-clopedia Britannica on the head of a pin?”

Many of the specific aspects of the field addressed

in the lecture required 40 yrs of work before theycould indeed be realized or understood. Dr. Feynmananticipated several hurdles to the development of thefield, including increased resistance of circuits on asmall scale and overheating of nanoprocessors. Healso foresaw a nanoworld dominated by differentphysical properties such as van der Waals forces andBrownian motion that would only come to be under-stood after extensive and prolonged study.

The field remained largely theoretical until theearly 1980s, when several key advancements dem-onstrated the successful practical application ofnanotechnology. In 1981, Gerd Binnig and Hein-rich Rohrer (who in 1986 shared the Nobel Prize inPhysics) developed the scanning tunneling micro-scope, which allowed scientists to see substanceson the level of individual atoms.3 Also in the early1980s, Eric Drexler, then a Massachusetts Instituteof Technology graduate student, developed a thesisthat later became a pioneering text entitled “En-gines of Creation: The Coming Era of Nanotech-nology,” published in 1985.4 Drexler foresaw thebottom-up design of proteins that would fabricatecomplex nanodevices with customized specifica-tions. These nanomachines would mimic biologicalprocesses and be capable of self-replication, spe-cialized function, and even self-destruction. Also in1985, Richard Smalley, Robert Curl, and Sir HaroldKroto5 discovered the molecular structures offullerenes (for which they later were awarded theNobel Prize), and a team of IBM scientists manipu-lated 35 xenon molecules on a gold surface to spellout the letters “IBM.” Twenty-six years after Feyn-man’s prediction, nanowriting had become a reality.

NanomedicineAlthough research in nanotechnology has

been broadly expanding in many areas of scienceduring the past 15 yrs, it has been only recentlythat its applications to medicine have undergonerapid development (Fig. 2).

FIGURE 1 The growth of nanotechnology for the last decade in the medical literature, as indicated by thenumber of MEDLINE journal articles per year with the keyword “nanotechnology.”

226 Gordon et al. Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

Appendix A Glossary of nanotechnology definitions related to biosciences

Bottom-up vs.top-down

“Bottom-up” is the term used to describe starting with single atoms and molecules to buildnanostructures. This concept describes technologies enabling the construction of thingsatom by atom to achieve molecular-level structures. The phrase “top-down” refers tomethods and tools to build small components starting from larger regular matter.

Brownianmotion

The physical phenomenon that minute particles immersed in a fluid move around randomly,or the mathematical model used to describe those random movements. It was discoveredby botanist Robert Brown in 1827 while studying pollen particles floating in water underthe microscope.

Buckyball Short for buckminsterfullerene, a molecule of carbon made of 60 atoms and shaped like ageodesic dome. The buckyball was discovered by Richard Smalley and colleagues at RiceUniversity in 1985. Smalley received the Nobel Prize for this discovery. Buckyballs areinert, nontoxic, and infinitely modifiable to form new formulations. The molecule ishollow and has been investigated as a transporter of medicines and contrast. Buckyballsare the third form of pure carbon known to exist naturally, along with graphite anddiamonds. The process of knocking one or more carbon atoms out of the Buckyballstructure and replacing it with metal atoms is known as doping, and the molecule in itsaltered form is referred to as a dopeyball.

Dendrimer A synthetic, tree-shaped macromolecule formed from monomers using a stepwise fabricationprocess. It is the size of a typical protein, but it does not unfold or come apart easilybecause it is held together with stronger chemical bonds. It can be easily attached to avariety of other molecules to transport and release medication/contrast or to transportDNA for gene therapy.

Electrospinning A fabrication process that uses an electric field to control the deposition of polymer fibersonto a target tissue. During the process, a polymer solution is injected with an electricalpotential onto a grounded target. The solvent then evaporates and fibers are formed. Thiscan be used to fabricate fibrous polymer scaffolding for use in tissue engineering.

Fullerines A class of carbon molecules, of which buckyballs are a member. Fullerenes are closed, convexcage molecules containing only hexagonal and pentagonal faces. These molecular forms ofpure carbon are made when vaporized carbon condenses in an atmosphere of inert gas.Although C60 is the most common, there are larger fullerenes containing 70–500 carbonatoms.

Gene chip DNA microarrays used to screen a biological sample for the presence of many geneticsequences with affixed DNA segments known as probes. This technology is being evaluatedas a replacement for the current costly and time-consuming polymerase chain reactionmethods. By spotting thousands of DNA pieces on a small surface (microchip), thousandsof DNA experiments can be completed in a single run, as opposed to one at a time bypolymerase chain reaction.

Lab on a chip A microfluidic device that is a promising analytic tool for analyzing proteins and proteincomplexes. These “laboratories” are fabricated using photolithographic processes developed inthe microelectronics industry to create circuits of tiny chambers and channels in a quartz,silica, or glass chip. They direct the flow of liquid chemical reagents just as semiconductorsdirect the flow of electrons. These microfluidic circuits can be designed to accommodatevirtually any analytic biochemical process and allow for parallel chemical analyses.

Lithography A printing process used in fabrication, often in the electronics industry. There are severaltypes, including a) photolithography, in which an electron beam writes the circuit patternon a microchip; b) soft lithography, in which an elastic stamp produces patterns that holda solidifying polymer; and c) dip-pen lithography, in which an AFM coats a gold surfacewith a self-assembled monolayer of thiol molecules. Several other processes are beinginvestigated that can either adapt existing microtechnology to current electronicproduction or that would require entirely new production techniques and investment forelectronic circuit manufacture.

Nanofibers Structures that do not possess as regular a helical carbon arrangement as carbon nanotubesand, thus, have slightly less impressive mechanical characteristics. They are also farcheaper to produce than nanotubes.

Nanometer(nm)

Unit of measurement: 1 billionth of a meter. 1 nm � 10 angstom units (one angstrom isthe diameter of a hydrogen atom—the smallest element). 1000 nm � one micron. To givea sense of proportion: hydrogen atom � 0.1 nm, protein � 5–50 nm, gene � 2–5 nmwide and 10–100 nm long, virus � 20–450 nm, and red blood cell � 10,000 nm wide.

Nanoparticle A microscopic particle whose size is measured in nanometers. Often, such nanoscaleparticles are used in biomedical applications as drug carriers or imaging agents.Nanoparticles suspended in solution are defined as colloids.

Nanopores Tiny holes that are used in filters, sensors, or tissue scaffolds that enhance function. Forinstance, nanopores allow DNA to pass through one strand at a time, which makes DNAsequencing more efficient. Nanopores can also span cell membranes and allow ionictransport across the otherwise impermeable lipid bilayer.


Some general advances in nanotechnologyhave indirectly impacted biomedicine. For in-stance, new methods for developing computernanocircuits have allowed for smaller and moreeffective medical appliances (e.g., retinal prosthe-

ses,6 implantable microdevices for neural controlof movement7). Although the indirect and “spin-off” technology may be noteworthy, this reviewfocuses on the directly applied nanotechnology inbiomedical research and clinical practice across

Appendix A Continued

Nanoshell A 100-nm bead composed of a spheric shell of metal (often gold) surrounding a core ofsilicon dioxide atoms. Because of their size, nanoshells can easily penetrate severalcentimeters of tissue and can be functionalized by linking to antibodies. They are activelybeing pursued as a treatment for certain cancers because they capture energy at nearinfrared and deform, releasing a chemotherapeutic drug at the tumor site.

Nanotube (NT) Discovered in 1991 by Japanese researcher Sumio Ijyma, a nanotube is a sequence ofnanoscale C60 atoms arranged in a long, thin, cylindrical structure. Carbon nanotubeshave many potential applications because of their specific properties; they are 100 timesstronger than steel (and six times lighter), they are as conductive as copper, and they canresist very high temperatures (up to 1500°C under vacuum). Applications of thenanotubes include resistors, capacitors, inductors, diodes, and transistors. The discovery ofnanotubes has initiated an entirely new field of scientific research. A multiwall carbonnanotube (MWNT) is a cylindrical piling up of single-wall carbon nanotubes (SWNT).

Nanowire A one-dimensional structure with unique electrical or optical properties. Easy to produce,nanowires can be assembled in grids and become the basis of nanoscale logic circuits.They can have very different shapes. Often thin and short “threads,” they can look likecones, carrots, cherries, or comets. Latticed in various combinations, nanowires canfunction as transistors, optoelectronic devices, and biochemical sensors.

National NanotechnologyInitiative(NNI)

Established in 2001, a federal program to support research and development of thenanosciences in the United States. The initiative is designed to develop the necessaryinfrastructure to support education, facilities, instrumentation, and communication inboth the public and private sectors. Its vision is to achieve international leadership innanoengineering and technology to promote sustainable economic benefit and nationalsecurity. Over 20 government agencies are either funded or participate in the NNI. In thefirst year, funding appropriations totaled $464 million. Currently, investment totals arenear $1 billion.

Phaseseparation

A fabrication method to construct synthetic polymer nanofiber matrices in which a polymersolution is separated while in contact with a structured mold. Intrinsic shrinkage duringthe process facilitates the release of the replica from a mold. The unique advantage of thistechnique is the capability of designing three-dimensional nanostructures without usingany special equipment such as clean rooms. Also, the porosity of a polymer scaffold can beeasily modified and controlled.

Quantum dots(QDs)

Nanometer-sized semiconductor crystals that are 5–10 nm in size and that can be dissolvedin water. Their cores contain paired clusters of atoms such as cadmium and selenium thatcombine to create a semiconductor. Ultraviolet light of wide range can be used tostimulate these crystals, but they illuminate at only one specific wavelength, depending onthe size and number of atoms in the core. When biological molecules are attached to thequantum dots, this specificity of illumination allows them to be used as probes to trackantibodies, viruses, proteins, or DNA. The size of the dot also determines its magnetic,electronic, and structural properties.

Scanningtunnelingmicroscope(STM)

An instrument that probes surface contours. It detects small currents between the sharpstylus mounted on a soft spring and the sample, allowing imaging on the scale ofindividual atoms. Critical to the nanotechnology revolution, the STM was invented in1981 by IBM’s Gerd Binnig and Heinrich Rohrer, who, in 1986, shared the Nobel Prize inPhysics for this discovery.

Self-assembly Self-assembly refers to the joining of complementary surfaces, leading molecules to arrangethemselves automatically into higher-order structures. These molecules follow a regularpattern under certain pressure and temperature conditions. Self-assembly allowsproduction of nanostructures or nanopatterns with interesting properties, in largequantities, with low effort and total control of the reaction.

Ultrasmallparticles ofiron oxide(USPIO)

Magnetic nanoparticles used in enhancing magnetic resonance imaging of metastatic tissueand in staining of target cells and molecular processes. Similar entities includesupermagnetic nanoparticles and cross-linked iron oxide nanoparticles.

Van der Waalforces

The electrical intermolecular attractions between one molecule and a neighboring molecule(after botanist Johannes Diderik van der Waals, 1837–1923). Temporary fluctuating dipolesform dispersion forces that attract particles together (also known as London forces). Theseforces become stronger as the atom (or molecule) becomes larger and thinner.


five major areas: (1) tissue engineering, (2) drugand gene delivery, (3) imaging, (4) diagnostic as-says, and (5) texturing/biointerfaces. A brief generalbackground will be provided in each area, followed bya more focused review of research specifically relatedto the field of rehabilitation medicine.

Tissue EngineeringThe basic principles of tissue engineering and

regeneration include in vitro and in vivo genera-tion of tissue. For the in vitro process, the tissueconstruct begins with specialized cells (e.g., stemcells8,9) placed in an environment conducive to cellgrowth, often in an artificial extracellular matrix orscaffolding. The extracellular matrix was oncethought to play largely a structural role. However,it now is recognized to play a major role in cellproliferation, differentiation, and inhibition of ded-ifferentiation.

Nanotechnology has been used largely to in-vestigate improvements in the fabrication tech-niques of synthetic or organic scaffolding. Con-trolled design allows for manipulation of structuralcues, cell attachment, and intercellular signaling.10

Fibrous meshes, porous sponges, or hydrogels canbe modified to mimic natural matrix structure,embedded with growth-specific surface proteins (topromote such factors as angiogenesis11), and de-signed to biodegrade in a controlled fashion (toallow for overgrowth by innate cells). The mostpopular techniques of fabrication of polymer nano-fibers into scaffolding are electrospinning, phaseseparation, and self-assembly.12

The active research in regeneration of dam-

aged brain, spinal cord, skin, cartilage, muscle, andbone tissues is likely to impact the future of reha-bilitation medicine. A compelling and highly pub-licized series of experiments on the potential ben-efits of nanoscaffolding in brain repair and axonalregeneration was conducted by Ellis-Behnke etal.13 In this animal model of brain damage, theoptic tract within the midbrain was completelysevered with a deep knife wound in young andadult hamsters. In one experiment, ten animals inthe treatment group received an injection into thewound of a self-assembling peptide that spontane-ously formed a scaffolding network of nanofibers.The remaining six received injections of isotonicsaline. Both groups were subsequently analyzedhistologically for healing of injury and behaviorallyfor functional restoration of vision.

In all animals that received self-assemblingpeptide, the tissue gap created during injury waseither reduced or completely eliminated at timepoints greater than 24 hrs after injury. All self-assembling peptide–treated animals showed a sig-nificant percentage of axonal reinnervation as mea-sured by fluorescent staining, in contrast to noaxonal regeneration in the control group. Mostimportantly, the self-assembling peptide–treatedhamsters gained an average of 75% recovery ofvisual ability as indicated by the ability to orient toa small object. The control group remained blind.This model was successful in demonstrating thatnanoscaffolding can create an environment condu-cive to functional axonal regrowth in brain tissuewhile reducing scar formation.

FIGURE 2 Relative size of nanoparticles compared with familiar items. The structures in the lower row arebetween 1 and 100 nm in size. Reprinted with permission from McNeil SE: Nanotechnology for thebiologist. J Leukoc Biol 2005;78:1–10.128


Silva et al.14 also explored the potential appli-cation of bioreactive nanoscaffolding in the treat-ment of central nerve regeneration. Their in vitrostudy reports on the encapsulating murine neuralprogenitor cells (NPCs) into a network of nanofi-bers produced by the self-assembly of peptide am-phiphilic molecules (Fig. 3). The scaffolds werecustomized through adjustment in peptide se-quences to have an outer surface that resembledthe basement membrane protein laminin, which isknown to increase neurite differentiation andgrowth. The challenge in neural tissue engineeringis to induce NPCs to differentiate and grow asmature nerve cells. This is complex, because NPCscan also differentiate into astrocytes, oligondenro-cytes, and ependymal cells (glial lineage). Astroctyegrowth is undesirable because it is central to scartissue formation.

In the study, cells in the nanofiber networkresulted in 30–50% NPC promotion of cell differ-entiation into neurons, whereas only 1–5% of NPCdifferentiated into astrocytes (days 1 and 7). Incontrast, control groups without nanoscaffoldinghad 5–15% neuron growth and 15% astrocyte dif-ferentiation. This study was the first to describe ananoengineered material that resulted in a prefer-ential differentiation of a desired cell type. In otherhas also been shown to be a positive cue in nerve stemcell neurite outgrowth12 and functional synapse for-mation,15 both of which are critical aspects to neu-rorepair.

The use of nanofiber scaffolding has also beeninvestigated in the field of wound healing and skinregeneration. Rho et al.16 used electrospun type Icollagen nanofibers to create biomimetic scaffold-ing for the attachment and spread of human kera-tinocytes. In the in vivo component of the study, a1 � 1 cm full-thickness wound was surgically cre-ated in 12 rats. Six rats had a gauze pad appliedwith the collagen nanofibers, and six rats func-tioned as the control with untreated cotton gauzeapplied to the wound. Although late-stage wound

healing were similar between control and experi-mental groups, microscopic examination revealedfaster early-stage healing in the collagen nanofibergroup. At 1 wk, tissue debris in the nanofiber grouphad been cleared, and capillary and fibroblastgrowth was prominent compared with in the con-trol group, in which the wound surface was cov-ered with fibrous debris overlying a dense infiltra-tion of polymorphonuclear leukocytes. Yamaguchiet al.17 also showed that nanostructures stimulatekeratinocyte growth in a skin injury model andincrease inflammatory cytokine response to injury.

Given the extensive orthopedic interest in boneregeneration, much attention has been given todeveloping a scaffold that mirrors the hierarchicalorganization of bone. Bone is a composition ofcollagen fibers aligned in triple helices, uponwhich are layered hydroxyapatite crystals arrangedalong their c axes. Hartgerink et al.18 have devel-oped a self-assembling fibrous scaffold of peptide–amphiphile molecules that resembles bone’s or-ganic template. This scaffolding was designed tohave a repetitive organization of phosphate groupsand a surface-associated protein, fibronectin, tomimic bone’s ultrastructure. When pH is loweredto below 4, it self-assembles, and it can disassemblewhen the pH is brought back to neutral. Surpris-ingly, the scaffolding directed the mineralization ofhydroxyapatite crystals in the c-axis along the longaxis of the fibers, mimicking the organization ofnatural bone. Nanocomposites resembling bonehave been formed through other varied materialsand mechanisms. Investigators have developed hy-droxyapatite/collagen self-organizing matrices,19,20

hydroxyapatite/gelatin preparations,21 nanophaseceramics,22 and even carbon fiber surfaces.23 Im-portantly, these systems have all been tested forbiocompatibility and have demonstrated good os-teoconductivity in vitro.

Similar nanofibrous scaffolds have been usedfor biocompatible and biodegradable matrices forcartilage24,25 and muscle26 tissue engineering. Fur-

FIGURE 3 A, Molecular graphics illustration of an amphiphile molecule and its self-assembly into nanofibers. B,Scanning electron micrograph of a nanofiber network formed by adding cell media to a peptideamphiphile aqueous solution. Reprinted with permission from Silva GA, Czeisler C, Niece KL, et al:Selective differentiation of neural progenitor cells by high-epitope density nanofibers. Science2000;303:1352–5.14 Copyright 2000 AAAS.


thermore, a nanofibrous scaffold has been used topromote selective differentiation in mesenchymalcells, with cellular viability, attachment, and pro-liferation of either adipose, cartilage, or bone, de-pending on the appropriate inductive agents.27

In contrast to the in vitro process, in vivotissue-engineering techniques exploit the nativeenvironment to induce regeneration. Some tissuessuch as cornea (possessing a natural collagen scaf-fold) and bone marrow do not require an artificialscaffold. However, for the majority of tissues, espe-cially when there is a large defect, scaffolding withor without cell seeding is necessary. An importantconsideration for future clinical applications is thatself-assembling scaffolds have the distinct advan-tage of being injectable, with studies already dem-onstrating their assembly, safety, and tolerance inanimal models.14,15,19

Therapeutic application of regenerative modal-ities may become commonplace in the future forphysiatrists working with stroke, spinal cord in-jury, arthritic, or myopathic patients. Physiatrists,for example, may someday inject a partial anteriorcruciate ligament tear, atrophied thenar muscle, ordegenerated intervertebral disc with a regenerativecombination of self-assembling scaffolding andpluripotent cells, and then monitor the complexinteraction between regrowth of these tissues andimprovement in clinical function.

In summary, varied tissue nanobioengineeringmodels, combined with advances in stem cell re-search and an increased understanding of cytokineand protein factors influencing cell growth, arelikely to translate into useful clinical tools to pro-mote regeneration and successful transplantationin the foreseeable future.

Drug and Gene DeliveryNano-based systems are in various stages of

development for the delivery of genes and thera-peutic agents. In conventional drug delivery, for-mulations based on simple physical properties(e.g., solubility) often control drug release. In con-trast, nanosystems are more versatile syntheticchemical formulations that allow tailoring of par-ticle size, with features that mimic biologicalstructure. Nano-based systems offer several impor-tant advantages over conventional therapy. Drugsor genes can be protected in the vascular systemand have controlled release at a chosen site ofaction. The targeted delivery can be achievedthrough interaction with cell receptors, transcrip-tion factors, or signaling proteins. Gene deliveryand antigen display can be realized without induc-ing an immune response and with greater accuracywith respect to the target organ. Finally, the nanosize of the devices allows for penetration of theblood–brain barrier (BBB) and stomach epithe-

lium, and evasion of capture by the reticuloendo-thelial system.

Individualized nanosystems are based on sev-eral modifiable structures, including nanopar-ticles, nanoshells, and dendrimers. The advantageof using these structures is that they are inert,nontoxic, and biocompatible. Their surface andcore are highly modifiable through conjugationwith cellular epitopes and antibodies that bind totargeted cell membranes.28 For example, Thomaset al.29 report on one dendrimer system that wasengineered with three distinct components: a folicacid as the targeting molecule, methotrexate as thechemotherapeutic drug, and fluorescin as the con-trast probe. This dendrimer system permitted en-hanced receptor-mediated exchange of the drug tothe intended tumor cells, and tracking of its ab-sorption and elimination.

Nanostructure surfaces can be engineered tobe cationic or anionic, depending on the desiredoutcome of vascular or cellular penetration. Thestructures are also highly stable and can be used toprotect easily denatured and less stable drug mole-cules. This property potentially allows for an intrave-nous, intramuscular, or subcutaneous drug to bepackaged into an oral form.30 Finally, nanostructurescan be magnetized or bound to a radioopaque dye sothat drug release can be visualized through magneticresonance imaging or computed tomography.31

Polymer therapeutics and nanocarriers showgreat promise in many aspects of medicine, withseveral formulations either approved by the U.S.Food and Drug Administration (FDA) or in clinicaltrials.32,33 These improvements, in combinationwith a greater understanding of genomics, celltransport systems, and molecular basis of pathol-ogy, will result in safer and more direct drugs totreat disease. Targeted drug delivery has been stud-ied most widely for use in chemotherapy agents,with the potential for more specific action anddecreased systemic toxicity. Proof of principal hasbeen demonstrated in animal models of brain tu-mors,34 osteosarcomas,34 and esophageal cancer.35

In January 2005, a nanoformulation of the conven-tional chemotherapeutic agent paclitaxel was FDAapproved. The drug (Abraxane) is approved for usein patients with metastatic breast cancer. By virtueof its molecular size, the drug binds to naturallyoccurring albumin, resulting in better toleranceand fewer side effects. In fact, steroids no longerneed to be administered before and after adminis-tration, as is needed with conventional paclitaxel.

Using the established principles in nanostruc-tured drug delivery, the field of physical medicinewill benefit from the general application of theseengineered drugs for the systemic treatment of ourpatients. However, there also is potential for amore direct application of nanostructured drugs in


rehabilitation medicine. For example, one of themost commonly used drugs in musculoskeletalcare is the localized injection of glucocorticoids,which have intracellular sites of action. Cytoplas-mic concentrations of steroids are maintained onlytransiently when used in solution. Hence, the ther-apeutic effect is seen only for a short duration.Panyam and Labhasetwar36 developed a nanopar-ticle formulation of dexamethasone and tested itsintracellular delivery and effectiveness in inhibit-ing cell proliferation compared with the effective-ness of standard solutions. In cultures of humanvascular smooth muscle, the nanoparticle formu-lation maintained sustained intracellular drug lev-els, whereas the levels dropped rapidly in the cellsthat were treated with the drug in solution. Of thetwo nanoparticle formulations used in the study,the higher-dose formulation demonstrated greater,more sustained intracellular drug levels (35-foldgreater intracellular concentration on day 8 com-pared with the lower dose). Also, the intracellulardrug levels for the two formulations correlatedwith their antiproliferative activity. Significantlyhigher, more sustained (up to 12 days) inhibitionof cell proliferation was obtained with dexametha-sone-loaded nanoparticles compared with the stan-dard solution (up to 5 days). Electromyographyalso showed that nanoparticles were detected in thecytoplasm 14 days after incubation. Importantly,the nanoformulation of dexamethasone accumu-lated in greater concentrations intracellularly andhad a slower and more effective sustained releasethan the conventional solution. Because the doseand duration of a drug’s availability at the intracel-lular site of action determine its therapeutic effi-cacy, a nanoformulation of glucocorticoid may beideally suited to treating chronic conditions. Nano-particles loaded with ibuprofen37 also have beensuccessfully fabricated, with further study requiredto determine their efficacy compared with that ofstandard formulations. Alternative forms of deepheat are achievable through new photothermalcomposites using nanoshells. These optically activenanoparticles consist of a conductive metal layer(usually gold) surrounding a dielectric core andcan be altered to a desired shell thickness andparticle size.38 On absorbing a near-infrared lightat a tunable resonance, the nanoshells emit a doseof heat to a defined tissue volume. Feasibility stud-ies for this technique for thermal tumor ablationhave been conducted in vitro and in vivo, in murinecolon carcinoma39 and human breast epithelialcarcinoma40 models.

Another application of nanostructured drugsin rehabilitation medicine involves chronic degen-erative neurologic diseases. In treatment models ofneurodegenerative disorders such as Alzheimerdisease and amyotrophic lateral sclerosis, fullerines

have been shown to have powerful neuroprotectiveantioxidant qualities.41 As free radicals are col-lected by fullerines, there is a reduction in excito-toxicity and exocytosis occurring with neuronalinjury. Promising animal studies in Parkinson dis-ease models have indicated improved motor per-formance, increased survival, and preserved dopa-mine production.42 It has also been suggested thatfree radicals contribute to multiple cellular injurycascades in stroke, ataxia telangectasia, traumaticbrain injury, and spinal cord injury,43,44 represent-ing a variety of potential areas of fullerene-basedtreatment research.

Gene therapy is another developing field withpotential applications in rehabilitation medicine.For accurate gene delivery, several nanostructuresare being investigated as targeting systems to over-come the limitations and side effects of viral vec-tors. To introduce a nucleic acid into a cell, thechallenge is to design a system that incorporatesthe transfection efficiency of a virus with the easeof manufacture, safety, and targeting capability ofa synthetic system.45 There are several barriersto achieving successful gene delivery, includingtransport of the nucleic acid in the circulation,entry into the cell, dissociation from the vector,transit from cytoplasm to nucleus, entry into nu-cleus, and expression of the transgene.46 Lipo-somes, linear polymers, microbubbles, and nano-particles have been used as platforms for genedelivery, with dendrimers studied most extensively.In contrast to gene delivery through use of viralvectors, these agents can be safely administeredwithout eliciting an immune response in hosts.

Dendrimers are very adaptable, allowing for abroad range of molecules with varying functional-ity. The key attribute of these treelike structures isthe density of terminal groups (or branches), al-lowing for a high surface ratio that offers multipleattachment sites for conjugation of the gene, tar-geting segment, or detection agent. Much of thecurrent research in dendrimer gene delivery in-volves the targeting of solid tumors, with success-ful in vivo delivery and transfection demonstratedin several studies.46,47 In addition to simple nano-structures, more complex multicomponent sys-tems are being constructed. These various forms of“artificial viruses” have a layered assembly of acationic core composed of functional peptides (toaid in nuclear transport), surrounded by an anionicshell of flexible polymers and target ligands (whichcan induce receptor-mediated endocytosis). Al-though the “artificial virus” is in the initial phasesof discovery, these elaborately engineered systemsare being constructed and tested by multiple labo-ratories worldwide.

For physiatrists, these nanotechnologies mayimpact the treatment of patients with genetically


inherited disorders (i.e., muscular dystrophies, spi-nal muscular atrophy, Huntington disease) anddisorders of cellular regulation (i.e., osteosarcoma,astrocytoma).

Drug transport across the BBB is also a majorarea of nanodrug delivery research and may be ofparticular interest to physiatrists working withcentral nervous system disorders. The tight junc-tions of the BBB strictly limit exchange to hydro-philic compounds, small molecules, and chargedmolecules. A major challenge for the treatment ofmost central nervous system disorders is overcom-ing the difficulty of delivering therapeutic agents.The advantage of a nanodrug formulation is that ananoparticle, liposome, or dendrimer can maskBBB limiting qualities (such as surface polarity)while stabilizing the drug for transport. The smallsize allows a nanodrug to also be endocytosed byendothelial cells and, if functionalized, take advan-tage of receptor-mediated endocytocisis, an effec-tive alternative to passive diffusion. In certaincases, peripheral toxicity also can be reduced. Drugpackaging can protect a drug from rapid enzymaticdegradation and elimination in the brain, allowingfor sustained release. Some rehabilitation-relevantexamples of central nervous system drug deliveryusing nanoparticles include amitriptyline,48 tubo-curare,49 and valproic acid.50 A full discussion ofthis developing area of pharmaceutical research isoutside the scope of this paper, and the reader is

referred to several comprehensive review articles ofnanotechnology-based drug delivery across theBBB for a more detailed analysis.51–54

ImagingAdvances in nanotechnology have given rise to

unique possibilities for studying disease in a non-invasive manner. Established imaging techniquessuch as magnetic resonance, radionucleotide (i.e.,positron emission tomography), and optical imag-ing have improved steadily in the past two decades.State-of-the-art nano-based imaging systems haveevolved from these established techniques to pro-vide even greater detail and amplification for invivo imaging of specific target tissues, gene activ-ity, and molecular processes. The technologies arebased largely on the use of quantum dots (QDs)and nanoparticles, which can be conjugated withantibodies and recombinant proteins to target DNA,cell-surface receptors, and intracellular enzymes. Be-cause of their small size, they are also more efficientthan conventional biological stains, contrast agents,or fluorescent probes in traversing cell membranesand diffusing through interstitial spaces.

Semiconductor nanocrystals, also referred toas QDs, have been well studied for their potentialrole in biological imaging. QDs have tunable emis-sion from ultraviolet to infrared. Depending onparticle size (2–8 nm), they will always emit thesame “color” frequency (Fig. 4). This property makes

FIGURE 4 Sensitivity and multicolor capability of quantum dot (QD) imaging in live animals. The righthand imagesshow QD-tagged cancer cells emitting green, yellow, or red light. Approximately 1–2 million beads in eachcolor were injected subcutaneously at three adjacent locations on a host animal. Reprinted with permis-sion from Gao X, Cui Y, Levenson RM, Chung LW, Nie S: In vivo cancer targeting and imaging withsemiconductor quantum dots. Nat Biotechnol 2004;22:969–7659 (www.nature.com).


QDs especially useful as biomolecular probes for usein imaging and diagnostic assays. For QDs to be usedin the study of biological processes, they must bealtered to optimize water solubility. Several strategieshave been employed, including conjugation with wa-ter-soluble ligands,55 silanization,56 and encapsula-tion within micelles.57

Unlike other molecules that fluoresce whenexcited at certain wavelengths, QDs have a broadexcitation spectrum, which makes it possible toexcite many QD “colors” using a single laser wave-length. This enables simultaneous probing formultiple biosensing markers. QDs also show lessphotobleaching than conventional probes, higherluminescence, and longer absorption with minimaldegradation in emission. QDs are so bright that itis possible to detect a cell carrying only one crystal.The extremely high photostability of QDs allows forreal-time monitoring or tracking of intracellularprocesses over long periods of time. Furthermore,QDs have a high surface area:volume ratio, allow-ing for complex nanosystem design and function-alization. To target specific tissues, QDs have beenbound to peptides that recognize various cellularmarkers58 or intracellular processes.56 In previousstudies, QDs have been bioconjugated into probessuitable for imaging and staining of prostate cancercells,59 tumor blood vessels,60 lung tissue,60 andfibroblasts.56 QDs also can be used as fluorescenttracers for uptake studies of dynamic processes suchas embryogensis57 and angiography.61 These tech-niques have shown high in vivo selectivity and greaterpower and detail than conventional methods.

QDs have been studied most extensively incancer cell imaging.62 Of interest to physiatrists,QDs also have been used as probes to study neuro-nal processing.63 For example, Dahan et al.64 usedQDs to selectively track glycine-receptor diffusionin spinal cord neurons (glycine receptors are theprimary inhibitory neurotransmitter receptor inthe spinal cord). The significance of using a QD asa probe is the ultrasensitive measurement it allows.More powerful than larger beads or small fluoro-phores, the QDs used by Dahan et al.64 were able toaccurately record the mobility of individual mole-cules at the neuronal surface. Dahan et al.64 alsowere able to acquire both fluorescence and electro-myographic images using the same probe, a pow-erful way to establish high-resolution localization.QDs also have been used to study neuronal differ-entiation response to nerve growth factor65 andmobility of AMPA receptors.66

Nanoparticles, especially magnetic nanopar-ticles, have also been studied extensively for theirpotential use as improved contrast agents and bi-ological probes. These ultrasmall contrast agentshave unique qualities that allow for enhanced im-aging of occult metastases. Two FDA-approved

agents for detection of occult liver (ferumoxides)and lymph node (ferumoxtran-10) metastasis arecurrently in clinical use. When given intrave-nously, these ultrasmall particles of iron oxide(USPIO) slowly extravasate into the interstitialspace, are internalized by macrophages, and aretaken up into the reticuloendothelial system oflymph nodes. On T2-weighted magnetic resonanceimage sequences, uptake of these results in a loss ofsignal intensity (darkening). Metastatic nodesblock uptake of USPIO, and the difference caneasily be detected visually. Magnetic nanoparticleshave been demonstrated to function as magneticresonance enhancers for lymph node detection ofprostate cancer,67 endometrial cancer,68 cervicalcancer,68 abdominal cancer,69 and brain tumors.70

They also can be delivered into cells to enhance mag-netic resonance imaging of individual cell move-ment,71 gene expression,72 and progenitor cell distri-bution and differentiation.73 Better targeting tospecific tissues is also possible through attachment todendrimers74 or encapsulation within liposomes.75,76

Nanoparticulate contrasts have the unique ad-vantage of enhancing the magnetic resonance sig-nal from the tissue and cell level compared withthe conventional blood-pool agents that enhancesignal from the vascular system. The potential forusing iron oxide–based contrasts for non–cancer-related imaging is being investigated. For example,ferumoxtran-10 (Combidex, Advanced Magnetics,Inc.) has been studied for targeting central nervoussystem inflammatory lesions.77 Twenty-three pa-tients with demyelinating lesions (i.e., multiplesclerosis, acute disseminated enchephalomyelitis),vascular lesions (i.e., stroke), and hematopoieticneoplasms (i.e., lymphoma) received ferumoxt-ran-10 magnetic resonance scans in addition tostandard magnetic resonance imaging as part of adiagnostic workup. Whereas demyelinating lesionsfailed to show superior enhancement, subtle strokelesions showed greater signal intensity on T2-weighted images using ferumoxtran-10 comparedwith gadolinium. Also, one symptomatic cavernousvenous vascular malformation did not enhancewith gadolinium, but it did enhance intensely withferumoxtran-10. Hematopoietic neoplasms all en-hanced with the USPIO, with varied results in sig-nal intensity with each patient compared with gad-olinium. USPIOs also have been used for imaginginflammation in animal models of spinal cordinjury,78 multiple sclerosis,79 and oligodendrocyteremyelination,80 successfully demonstrating invivo USPIO labeling of cellular infiltration.

For physiatrists, the general application ofthese new imaging modalities for diagnosis andtherapeutic interventions may prove useful. In ad-dition to the active research previously mentioned,potential applications include the use of nano-


based imaging to study (a) protein and lipidchanges in the brain after a stroke or traumaticbrain injury, which could then be correlated func-tional status; (b) nociceptive and inflammatory fac-tors in spine and musculoskeletal disorders to ac-curately localize sites of pain generation andinflammation; or (c) nerve root, axon, or myelincomponents to assess degeneration or recovery asan adjunct to electrodiagnostics. New imagingtechniques with nanomaterials represent an ad-vance that may increase accuracy in visualizingpathology and inflammation, labeling large num-bers of cells, and targeting specific tissues anddynamic cellular processes.

Diagnostic AssaysCurrent diagnostic techniques such as West-

ern blots, enzyme-linked immunosorbent assay,cell culture, latex agglutination, and polymerasechain reaction often require purification, separa-tion, and incubation steps that require increasedtime, effort, and cost for processing. Developmentof miniaturized devices using nanotechnology mayprovide faster, more accurate, and, ultimately, lessexpensive technologies for diagnosis of disease andmicrobial pathogens. The main goals of currentnano research are to (a) create high-throughputassays that are rapid and sensitive and that showreal-time processes; (b) develop diagnostic toolsthat do not require additional processes such astarget amplification or use of radioactive labels;and (c) make assays broadly available for use at thebedside, in contrast to current methodologies (e.g.,culture, polymerase chain reaction) that requirededicated technicians in centralized hospital orcommercial laboratories.

Currently, a diverse array of nanotechnologieshave been adapted for potential application as com-mercial diagnostic assays. A gold nanoparticlesandwich assay has been well described in the lit-erature for the ultrasensitive detection of proteins,genes, and nucleic acids (Fig. 5). First reported in1996,81 the technique involves oligonucleotide at-tachment to two sets of nanoparticles (magneticand gold) that sandwich the target. Then, the tar-get compound is isolated with magnetic separationand identified. Nanosphere Inc. (Northbrook, IL)has developed an automated platform based on thistechnology (Verigene System) and has establishedFDA approval for commercial clinical testing ofnucleic acids.82 Bio-bar-code is another sandwichassay supported by the same company and has beenstudied for the detection of proteins and targetDNA. It has been shown to be as sensitive as con-ventional polymerase chain reaction for DNAdetection (even differentiating single base mis-matches), but it does not require the standardenzyme-amplification steps.83,84 The Clear-Readsystem has been developed to target single nucle-otide polymorphisms and can detect DNA se-quences in a single drop of blood or buccal swab.85

It has the advantages of detecting mRNA withoutenzymatic conversion to cRNA or cDNA,86 testingfor pathogens such as methicillin-resistant Staph-ylococcus aureus without media culture or poly-merase chain reaction.87 Several other nano-basedmethods have been used for detection of genes andSNPs, including fluorescent QD assays,88,89 engi-neered nanopores,90,91 and dip-pen nanolithogra-phy for creation of high density gene-chips.92

To analyze non-DNA biomolecules and pro-teins, a wide diversity of diagnostic techniques

FIGURE 5 The bio-barcode amplification assay. The assay uses magnetic nanoparticles (MMP) functionalizedwith antibodies that recognize and bind target DNA. The target DNA is sandwiched between the MMPand a nanoparticle (NP) probe. After repeated washing while using a magnet to immobilize the MMPs,a dehybridization step releases hundreds of barcode DNA strands. Reprinted with permission fromGeorganopoulou DG, Chang L, Nam JM, et al: Nanoparticle-based detection in cerebral spinal fluid of asoluble pathogenic biomarker for Alzheimer’s disease. Proc Natl Acad Sci U S A 2005;102:2273–6.93


has been developed using nanowires, QDs, andnanoshells. Georganopoulou et al.93 describe ananoparticle-based method for detection of the Alz-heimer disease biomarker amyloid-�–derived dif-fusible ligands. By using a nanoparticle assay, theinvestigators were able to quantify the antigen inthe cerebral spinal fluid of test subjects at a con-centration beyond the sensitivity of conventionaltechniques. Wang and colleagues94 recently re-ported their use of silicon nanowire field-effecttransistors to identify and quantify molecular in-hibitors of adenosine triphosphate or substrateproteins to tyrosine kinase. Similar to calorimetryand surface plasmon resonance, the technology ofsilicon nanowire field-effect transistors is a label-free way to detect binding and unbinding of pro-teins to their ligands. The advantage of siliconnanowire field-effect transistors is that it is moresensitive than conventional methods and requires afar smaller sample.95

The highly luminescent properties of QDs alsomake them ideal for large-scale labeling of mole-cules and rapid target identification. Severalgroups have used QDs as biological probes.96 Infact, five differently sized QDs with tunable emis-sion could yield 10,000 codes detectable throughspectroscopic measurement. Each QD can be itsown “chemical lab,” detecting and analyzing aunique compound and resulting in faster and moreflexible high-throughput assays.97 Nanoshell probesshare similar characteristics to QDs and feature highbiocompatibility and near-infrared emission. Nanoshellsare easily conjugated to antibodies and can be fabri-cated to desired optical resonances. This techniqueshows promise for the development of a simple, insitu whole-blood immunoassay comparable with con-ventional enzyme-linked immunosorbent assay andlatex agglutination.98

Nanofluid techniques have also improved con-ventional sampling methods. This has been espe-cially true for improvement in mass spectroscopyand liquid-phase separation techniques. One criti-cal step of mass spectroscopy is the liquid junctioninterface, which involves applying a voltage to thesample as it is injected via an electrospray into theinlet of the spectrometer. Many different designshave been formulated for the electrospray tip,which requires a precise jet and alignment. Gold-coated electronanosprayers are widely available andhave been shown to result in more sensitive andrapid interface of the compound.99 New commer-cial Lab-on-a-Chip technology takes advantage ofnanoflow improvements to create smaller, moreeffective diagnostic tools that require minute sam-ples to run multiple analyses.100 Fluid techniquesalso can isolate individual molecule nanoconcen-trations. The ability to analyze precise samples hasallowed for the detection and quantification of

high-concentration enzymatic processes such assynthesis of double-stranded DNA by DNA polymer-ase.101 Furthermore, advancements in the nanowir-ing of electronic circuits allow for smaller, moreeasily implanted analytic tools.95

For physiatrists, these new systems of DNA,enzyme, protein, and antibody analysis may signif-icantly impact the efficiency and cost of diagnosingdisease. Clinical testing of cytogenetic disorders(e.g., chromosomal variants associated with Charcot–Marie–Tooth Disease), enzyme abnormalities (e.g.,elevated creatine phosphokinase in Duchenne/Beckermuscular dystrophy), protein over/underproduction(e.g., overproduction of M-protein in monoclonalgammopathy), or disease-related antibodies (e.g.,rheumatoid factor in rheumatoid arthritis) are allpossible through currently available nanotechnology-based assays.102,103 In the inpatient setting, nano-inspired tools will allow the physiatrist to gain rapidand accurate data on microbial pathogens causingacute or chronic infections, such as pneumonia andurinary tract infections.104 Proof of principle withdifferent nano-based diagnostics has already been es-tablished for bacteria (E. coli,105 S. aureus87,106) andviruses (influenza, adenovirus,107 herpes simplex108).Furthermore, nanotechnology may allow for theearly detection of emerging antibiotic resistance.87

Importantly, these diagnostic techniques overlapwith those related to drug delivery and imaging anddemonstrate the versatility of nanocompounds intheir application to the biological sciences and clini-cal medicine.

Texturing/BiointerfacesNanotexturing and nanocoating are manufac-

turing techniques applied to inert materials to es-tablish bioactivity and to enhance biocompatibility.The insertion of nonorganic implantable devices mayhave limited efficacy and functional life because of thebody’s intrinsic responses to any object recognized as“foreign.” Problems of tissue ingrowth, inflamma-tion, infection, and thrombogenesis need to beaddressed to optimize biocompatibility.

Nanotexturing is a method to enhance surfacetopography to include nanoscale features such aspits, islands, or ribbons of various depths. Thereare several methods to produce nanotopography onvarious polymer, metal, and ceramic surfaces, in-cluding electron beam nanolithography, self-as-sembling systems, microcontact printing, andinjection molding.109 These processes embed a bi-ological matrix to an otherwise nonbiological sur-face. There is growing evidence that nano featuresstrongly affect surrounding cell growth, prolifera-tion, and differentiation. Human fibroblasts, forexample, were shown to increase cell spread, for-mation of filopodia, and differentiation whengrown on nanoscale island cytoskeleton compared


with fibroblasts grown on a flat surface.110 Osteo-blasts also have been shown in multiple studies toincrease cell adhesion and growth on surfaces thatresemble the nanostructured geometry of hydroxy-apatite,22,111–113 an important consideration for theosseointegration of orthopedic implants.

Nanocoating is the addition of a bioactive com-ponent to a surface, changing the surface chemis-try of the implant to be either more cell attractantor cell resistant. The challenge to researchers is todevelop a physiologically stable biointerface thatcan be modulated to the desired function. Forexample, the ideal nanocoating for an orthopedicimplant would be one that would be resistive tooxidative, hydrolytic, and mechanical forces, yetable to attract osteoblasts directly to the surface ofthe metal to improve osseointegration. Methods ofnanocoating include self-assembly, layer-by-layerassembly, and electrolytic deposition. Various bio-materials have been used in the nanocoatingprocess, including collagen,114 collagen compos-ites,115,116 proteins,117 and inorganic polymers.118

As in texturing, the result is a surface that canincrease desired cell adhesion and growth for im-plants.115 A surface can reduce unwanted biologicalactivities for prosthetic devices in vivo, such as scartissue117 or thrombus formation.118

In addition to orthopedic implants, the areasthat most directly impact rehabilitation medicineare the nanocoating of neural implants and cardio-vascular stents. Ai et al.119 describe a process ofapplying a multilayered nanofilm composed of var-ious biocompatible elements, including lamininand fibronectin, onto silicone rubber tubes. He etal.117 also report on a technique of layered assem-bly of neurointegrative coating for silicon arrays.Currently, silicone tubes are the implant interfacefor ventricular drainage shunts, spinal cord elec-trical stimulators, cochlear implants, and periph-eral nerve–reconstruction scaffolds. Importantly,in both studies above, neurons demonstrated celladhesion, growth, and morphological differentia-tion comparable with that from standard, thickercoatings, without cytotoxicity. These nanocoatingsallow for biocompatibility without changing thesize characteristics of the device. This may be crit-ical in the use of neural implants as prostheticdevices for chronic disease (such as cerebral palsy),where drug delivery or sensory stimulation willrequire long-term integration of the device withsurrounding neural tissue. In addition, these neu-rointegrative coatings may impact those physia-trists working in the areas of direct brain interfac-ing for control of prosthetics and the developmentof biohybrid limbs. For cardiovascular stents, nano-coating has been shown to enhance plaque preven-tion120 and drug delivery121 in animal models ofcarotid and coronary artery injury. Arterial stents

are widely used in the clinical management ofstroke and coronary artery disease, with nanocoat-ings representing a more advanced and versatilesystem than current drug-eluting technology.

The potential impact of nanotexturing andnanocoating to the field of physiatry is significant,given the diversity of implantable devices used inrehabilitation-related fields (orthopedic, neuro-logic, cardiovascular, etc.). In summary, the goal ofthe evolving technologies of nanotexturing andnanocoating is to achieve optimal integration ofliving and synthetic components to restore normaltissue and cell function for skin, vessel, nerve,bone, ligament, and tendon. Wherever an inorgan-ic/organic interaction exists, nanotechnology willbe studied to control this interface.

CAUTIONARY EPILOGUENanotechnology is developing rapidly, with the

applications of the field being examined by an in-creasing number of scientists, venture capitalists,government agencies, and politicians. As the atten-tion has increased, so has the debate. Is nanotech-nology the industrial revolution of the 21st cen-tury? Or have the potential benefits been oversoldby nanotechnology enthusiasts? It remains to beseen whether the initial excitement will result inmeaningful clinical applications and returns onfinancial investment.

As with all new biotechnology fields, seriousconcerns have been raised regarding the environ-mental hazards and health risks regarding nano-structures. The uncertainty is based on the veryaspect of nanotechnology that makes it so appeal-ing: the potential outcomes are unknown andnearly impossible to predict. Concern for wildlifewas publicized in a study of potential water-borneeffects of buckyballs in which it was demonstratedthat the lipophilic uncoated fullerenes selectivelytranslocate into the brain of large-mouth bass andresult in oxidative damage.122 In humans, nanopar-ticles can be rapidly transported into the blood-stream through the lungs, intestines, and even theskin.123 Inhaled nanoparticles have been associatedwith inhibited cellular signaling124 and oxidativestress in the liver.123 Nanotubes also have beenreported to induce granuloma formation in thelungs of rats and mice.125,126

Because the complete toxicity of nanostructuresto humans and the environment are unknown at thepresent time, many argue for rigorous safety testingbefore the initiation of widespread use of nanomate-rials in medicine and industry. This issue has re-ceived federal funding, with several grants distrib-uted by the U.S. Environmental Protection Agencyand the National Toxicology Program to investigatethe effects of nanomaterials on aquatic systems, airpollution, and exposure limits for workers.127 The


National Nanotechnology Initiative alone has bud-geted $106 million to fund the study of the ethical,environmental, and health implications of nano-particles.128 Others have argued for governmentstandardization of assays and characterization ofmaterials to protect the public and to facilitatequality control of manufacturing techniques andreproducible research. Currently, there are no spe-cific regulations pertaining to nanomaterials. Thisreality heightens the fears of those concernedabout the unrestrained and uncontrolled growth ofthe field. The subject of moratoriums on researchhave been introduced at international conferencesto encourage responsible development,129 but, asyet, nothing has curtailed the private and academicpursuit of this emerging field.

Increasingly, private and government-man-dated funds are being poured into the developmentof novel nanoscale products. However, there areseveral obstacles to overcome before theoreticalideas can be translated into biomedical reality.Many products may be complementary to currentmicrotechnology materials, but they may not haveimproved performance. Manufacturing costs maybe prohibitive and may not warrant the investmentneeded for production. In essence, venture capital-ists are avidly courting and supporting many newnanotechnology start-up companies, but the use-fulness and affordability of many nanoproducts hasnot yet been determined.

One aspect of the field that cannot be argued isthat nanotechnology has captured the imaginationof scientists, physicians, and the public. As the fieldcontinues to grow and impact more areas of med-icine, it is important for those in the field of phys-ical medicine and rehabilitation to be familiar withthe potential biomedical benefits and risks ofnanoscale products. Judicious research may eluci-date those aspects of nanotechnology that improvethe lives of patients with disabilities and translateto new methods of clinical practice.

ACKNOWLEDGMENTSWe would like to thank Dr. Nadrian Seeman

(New York University, Department of Chemisty,DNA Nanotechnology Laboratories) and JeffreySchwartz (Princeton University, Department ofChemistry) for kindly reviewing the manuscriptand providing valuable feedback.

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Authors:Sibel Ozbudak Demir, MDCeyda Akın, MDMeltem Aras, MDFusun Koseoglu, MD

Affiliations:From the Ankara Physical Medicineand Rehabilitation Training andResearch Hospital, Ankara, Turkey.

Correspondence:All correspondence should beaddressed to Sibel Ozbudak Demir,Y. Dikmen Mah. Turan GunesBulvarı, 12. Cadde No: 11/6(Aytekinler Apt), 06450 Oran/Ankara,Turkey. Reprints will not be available.

Disclosures:FIM is a trademark of Uniform DataSystem for Medical Rehabilitation, adivision of UB Foundation Activities,Inc.


DOI: 10.1097/PHM.0b013e31802ef5a0

Spinal Cord Injury Associated withThoracic Osteoporotic Fracture

ABSTRACT

Demir SO, Akın C, Aras M, Koseoglu F: Spinal cord injury associated withthoracic osteoporotic fracture. Am J Phys Med Rehabil 2007;86:242–246.

This report details a case of sudden neurologic deficit attributable to acutethoracic fractures associated with senile osteoporosis. A 73-yr-old female patientwith a history of occasional back pain during the past 4 mos had sudden thoracicvertebral fracture with spinal cord injury. The patient, who had a benign pastmedical history, had not been evaluated for osteoporosis.

Thoracic spine radiographs showed a compression fracture at T8. Thoracicmagnetic resonance imaging exposed a compression fracture at T7–T8. Shewas treated operatively. She was found to have spinal cord injury with AmericanSpinal Injury Association classification C (T7), and she had poor sitting balance.She was discharged in a wheelchair and was administered clean intermittentcatheterization every 6 hrs. Six months after discharge, she ambulated with awalker and had spontaneous micturition. Vertebral fractures are a commonpresentation of senile osteoporosis. The risk of neurologic impairment attributableto vertebral fracture is a rare but potentially severe complication. Besides medicaltherapy and suitable rehabilitation programs, surgical treatment is an integral partof the management of patients with osteoporotic vertebral fractures.

Key Words: Osteoporosis, Vertebral Fractures, Spinal Cord Injury

The osteoporotic vertebral fractures that occur spontaneously or after min-imal trauma in the course of daily living can be a major cause of morbidity inelderly people. Twenty percent of women older than age 65 have had one ormore vertebral fractures.1 In many of these cases, the incidence of vertebralfracture increased with rising age in both sexes. Most of these fractures aresubclinical, and the majority are thought to heal without complications.2 Spinalfractures can adversely affect quality of life by causing pain, reducing physicalfunction and mobility, and affecting activities of daily living.3 Despite severespinal deformities, nerve root– and spinal cord compression are rare.4–6 Neu-rologic impairment generally occurs between 1 mo and 1.5 yrs after fracture.Sudden-onset spinal cord injury is extremely rare.7 We present a case of


CASE REPORT

Spinal Cord Injury

immediate spinal cord injury attributable to tho-racic fractures associated with senile osteoporosis.

CASE REPORTA 73-yr-old female patient with a history of

occasional back pain during the past 4 mos wasadmitted to a neurosurgery clinic because of sud-den weakness in the lower extremities and urinaryincontinence. The patient resided with her family,and they denied any history of recent trauma. Thepatient had not attended an outpatient clinic and,therefore, had not been evaluated for osteoporosis.The patient had a benign past medical history,with the exception of diabetes mellitus and hyper-tension. Erythrocyte-sedimentation rate, completeblood count, serum levels of calcium and phos-phate, alkaline phosphatase, protein electrophore-sis, hepatic enzymes, tumor markers, and abdomenultrasonography were all normal. Direct radio-graphic evaluation revealed a compression fractureat T8 (Fig. 1). Magnetic resonance imaging illus-trated a compression fracture at T7–T8 and cordcompression (Fig. 2A). Computed tomographic im-aging showed bony fragments in the spinal canaland spinal cord compression (Fig. 2B). After cor-pectomy, decompression, allografting, and injec-tion of methacrylate at T7–T8, instrumentationwas performed from T6 to T9 (Fig. 3). Postopera-tively, the motor and sensory deficits recoveredpartially. Subsequent histology showed no evi-dence of neoplasia or infection and was consistentwith early new-bone formation. Intraoperative cul-tures also were negative.

The patient was admitted to our clinic postop-eratively with the diagnosis of nontraumatic para-

plegia. She was found to have a poor sitting bal-ance, and there was a stage II pressure sore on thesacrum. She also complained of fecal and urinaryincontinence. Muscle tonus was midly increasedand the deep tendon reflexes were hyperactive. Theupper-extremity motor scores were 25, bilaterally.The lower-extremity motor score was 12 on theright and 0 on the left according to the AmericanSpinal Injury Association (ASIA) classification. Thelight-touch scores were 40 bilaterally, and pinprickscores were 42 bilaterally. The patient was evalu-ated as ASIA C (T7). The motor FIM score was 23and the cognitive FIM score was 35. The pressuresore on the patient’s sacrum was covered with ahydrocolloid wound dressing. She was mobilizedwith a thoracic orthosis. She participated in a mul-tidiciplinary rehabilitation program. A tilting pro-gram was started. She was given range-of-motionexercises, posture exercises, balance and coordina-tion training, progressive resistive exercises, andactive assistive exercises. As exercising precipitatedthe patient’s hypertension, her antihypertensivetherapy was adjusted. When sitting balance wasaccomplished, assisted standing was achieved atthe parallel bars. Standing balance was practicedwith a posterior shell and an assisting dorsiflexor.Duration of the rehabilitation stay was 2.5 mos.Unfortunately, the patient could not achieve anytype of ambulation because of very weak trunkmuscles and upper extremities. The patient’s hy-pertension was also a negative factor. Urodynamicexamination showed a maximum cystometric blad-der capacity of 200 ml and a maximum detrusorpressure of 42 cm H2O with detrusor–sphincterdyssinergia. Oxybutynin hydrochloride was admin-istered twice a day. Bone mineral density evalua-tion by dual-energy x-ray absorptiometry was per-formed. Osteoporosis and fracture risk wasdetected on lumbar (L1–L4: 0.589 g/cm2, T score:�3.99, z score: �1.67) and hip (neck: 0.665 g/cm2,T score: �3.42, z scores: 1.56). For osteoporosis, 70mg/wk of alendronate sodium, 0.25 �g twice a dayof alpha-calcidiol, and 500 mg of elementary cal-cium daily were administered. The lower-extremitymotor score at discharge was 15 on the right and10 on the left. She was still classified as ASIAimpairment scale grade C. The motor FIM score atdischarge was 35. The patient was discharged in awheelchair, clearly in need of assistance duringtransfers and administration of clean intermittentcatheterization every 6 hrs, with a bladder capacityof 250 ml.

Urodynamic examination, which was done at 6mos after discharge, revealed that the patient’smaximum cystometric bladder capacity increasedfrom 200 to 475, and her maximum detrusor pres-sure decreased from 42 to 26 cm H2O. Six monthsafter discharge, the lower-extremity motor score

FIGURE 1 Lateral radiograph of the thoracic spineshows T8 compression fracture.

March 2007 Spinal Cord Injury in Osteoporosis 243

was 19 on the right and 18 on the left. She was nowclassified as ASIA impairment scale grade D, andshe ambulated with a walker. The motor FIM scorewas 52. She had spontaneous micturition and def-ecation.

DISCUSSIONBack pain is a common complaint in the el-

derly age group. Vertebral osteoporosis, which isrelated to compression fractures and mechanicalderangement of the spine, contributes to thispain.2 However, signs and symptoms of vertebralfractures may be mimicked by metabolic diseasessuch as hyperparathyroidism, hyperthyroidism,and multiple myeloma or other malignancies.8

Therefore, vertebral fractures necessitate compre-hensive evaluation to rule out early etiology. Our

patient had an acute paraplegic state after insidiousback pain, with no history of trauma. The diagnosisof osteoporotic fracture was based on normal lab-oratory test results, magnetic resonance imaging,and postoperative histopathologic evaluation.

Compression fractures occur most often at thelower thoracic and upper lumbar spine, followed bythe middle thoracic and lower lumbar spine, and,rarely, in the upper thoracic spine.2,3

The importance of angular deformation andthe shape of the compression fracture are the otherfactors that predispose to neurologic complica-tions. The loss of parallelism between the anteriorand posterior walls of the vertebral body that, intraumatic fractures, implies a major risk of neuro-logic complications, is rarely seen in osteoporoticcollapse. Moreover, when a wedge deformation oc-curs, it is usually located at the anterior part of thevertebral body. This probably explains the usualabsence of neurologic compression.6 Kempinsky9

has reported two cases at the level of T5–T6 inwhich neurologic symptoms occurred a few weeksafter the trauma (i.e., a fall on the buttocks). Sub-sequently, Salomon et al.6 have reported a case inwhich there was a T5 compression fracture withprogressive neurologic impairment followingtrauma. Since then, there have been a few morereports in the literature, but none of these haveshown immediate onset of paralysis.4,5,10,11 Theonly case in which there was acute neurologicimpairment attributable to an osteoporotic frac-ture was reported by O’Connor et al.7 They re-ported a case of complete thoracic spinal cordinjury with acute T5 fractures. The patient hadcontinuous oral corticosteroids for more than 40yrs for both rheumatoid arthritis and restrictivelung disease. The patient, who had not been eval-uated and treated for osteoporosis, was managednonoperatively because of her extremely osteopo-

FIGURE 2 A, Sagittal T2-weighted fast spin-echo image shows compression fracture at T7–T8 and cord com-pression. B, Computed tomographic image shows displacement of bony fragment into the spinalcanal with compression of the spinal cord.

FIGURE 3 Postoperative radiograph demonstratingstabilization extending from T6 to T9.

244 Demir et al. Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

rotic spine and poor medical condition, and shedied 72 hrs after admission. Our patient had asudden-onset spinal cord injury attributable to aspontaneous T7–T8 osteoporotic fracture and wasoperated on. Dommisse12 has shown the spinalcord to have a critical vascular zone between T5and T9 despite the variability of the vascular supplypatterns of the spinal cord. A vascular factor mayaggravate the mechanical compression in this seg-ment, which may have further contributed to pa-ralysis as seen in our patients. The purposes of thetreatment in osteoporotic vertebral fractures are toalleviate pain, provide early mobilization, protectthe sagittal, provide coronal stability, and preventacute and late neurologic complications.2 Treat-ment of spinal osteoporotic fractures should in-clude external orthosis, bed rest, physical modali-ties, analgesics, medications for osteoporosis, andrehabilitation.13 Patients should be instructed toadhere to a diet that is adequate in calories, pro-tein, calcium, and vitamin D.2 The treatment ofvertebral osteoporosis includes the bisphospho-nates (aledronate, risedronate, ibandronate), ralok-sifene, calcitonin, and parathyroid hormone.14 Theselection of appropriate drugs for treatment of ver-tebral osteoporosis will mainly depend on the effi-cacy, tolerability, and safety profile, together withthe patient’s willingness to comply with a long-term treatment.2,14 Early institution of antiosteo-porotic medications can prevent vertebral fracturesand may reduce the possibility of neurologic im-pairment. Performing isometric contractions ofparaspinal muscle can decrease postfracture painand edema. Spinal extensor exercises also shouldbe combined with exercises to reduce the increasedlumbar lordosis that can occur with thoracic hy-perkyphosis. Proprioceptive reduction generatedwithin joints, ligaments, and muscles might con-tribute to an awareness of the relative orientationof functional units of the spine at rest and inmotion.15

The indications for surgery in the osteoporoticspine are not clear. Surgical treatment is currentlyused if neurologic function is at risk or if deformityis substantial.2,16 It is difficult to stabilize thesefractures, which often require cement, metal in-strumentation, and combined anterior–posteriorprocedures.17 Several approaches have been advo-cated, with varying techniques and implants cur-rently defined.2,16–18 The orthopedic literature rec-ommends minimally invasive procedures such asvertebroplasty or kyphoplasty for osteoporotic ver-tebral fractures with pain, whereas decompressionand instrumentation are advocated in patients withneurologic deficits.16 Kyphoplasty reduces pain andalso increases mobility, which restores the pa-tient’s quality of life.19 Posterior approaches aresafe and useful treatments for patients with delayed

osteoporotic vertebral collapse.20 Anterior ap-proaches couple with medical risk in elderly pa-tients. Combined anterior–posterior proceduresare usually recommended in cases of kyphotic de-formities with neurologic deficit secondary to os-teoporosis. However, combined anterior–posteriorsurgery is associated with significant morbidity inelderly patients.17,20 Decompression and instru-mentation were performed on our patient, who hadneurologic deficits. It has been reported that theuse of surgical procedures is very effective in re-lieving pain, decreasing loss of vertebral height andspinal deformity.14–16 Postoperatively, the motorand sensory deficits recovered partially in this case.The patient was classified as ASIA C (T7) aftersurgery. Although our patient’s motor scores in-creased during the rehabilitation program, she stillhad an ASIA C. Six months after discharge, sheambulated with a walker and had spontaneous mic-turition.

Subclinical vertebral fractures attributable toosteoporosis impair quality of life by causing pos-ture distortion and limiting daily activities andsocial life.3 The main objective in management isthe prevention of fractures. Therefore, besides ap-propriate medical therapy, it is necessary to havethe patient undergo periodic vertebral radiography,to arrange suitable rehabilitation programs, and toavoid fractures with the use of appropriate equip-ment and measures that facilitate daily life. Thus,the risk of acute neurologic impairment attribut-able to vertebral fracture, as seen in our patient,can be reduced.

CONCLUSIONSpinal fracture in elderly patients is a typical

manifestation of osteoporosis. Although fracturesare generally associated with pain, it is importantto consider the possibility of vertebral involvementin this population, particularly when there is anobvious progression of kyphotic deformity withoutany discomfort. Despite severe spinal deformities,neurologic injury is generally of a very low inci-dence. Besides appropriate medical therapy and arehabilitation program, surgical treatment is anintegral part of the management of patients withvertebral fractures.

REFERENCES1. Roy DK, O’Neill TW, Finn JD, et al: Determinants of inci-

dent vertebral facture in men and women: results from theEuropean Prospective Osteoporosis Study (EPUS). Osteopo-ros Int 2003;14:19–26

2. Lane JM, Riley EH, Wirganowicz PZ: Osteoporosis: diagno-sis and treatment. J Bone Joint Surg 1996;78A:618–32

3. Adachi JD, Ionnidis G, Berger C, et al: The influence ofosteoporotic fractures on health related quality of life incommunity dwelling men and women across Canada.Osteoporos Int 2001;12:903–8

March 2007 Spinal Cord Injury in Osteoporosis 245

4. Heggeness MH: Spine fracture with neurological deficit inosteoporosis. Osteoporos Int 1993;3:215–21

5. Arciero RA, Leung KYK, Pierce JH: Spontaneus unstableburst fracture of the thoracolumbar spine in osteoporosis.Spine 1989;14:114–7

6. Salomon C, Chopin D, Benoist M: Spinal compression: anexceptional complication of spinal osteoporosis. Spine1988;13:222–4

7. O’Connor PA, Eustace S, O’Byrne JM: Spinal cord injuryfollowing osteoporotic vertebral fracture: case report. Spine2002;27:413–5

8. Bonner FJ, Chestnut CH, Lindsay R: Osteoporosis, in DelisaJA (ed): Physical Medicine and Rehabilitation. Philadelphia,Williams & Wilkins, 2005, pp 699–719

9. Kempinsky WH: Osteoporotic kyphosis with paraplegia.Neurology 1958;8:181–5

10. Baba H, Maezawa Y, Kamitani K, et al: Osteoporotic verte-bral collapse with late neurological complications. Paraple-gia 1995;33:281–9

11. Saita K, Hoskino Y, Kikkawa I, et al: Posterior spinal short-ening for paraplegia after vertebral collapse caused by os-teoporosis. Spine 2000;25:2831–5

12. Dommisse GF: The blood supply of the spinal cord. J BoneJoint Surg Br 1974;56:225–35

13. Huntoon E, Sinaki M: Thoracic osteoporotic fracture with-out upper thoracic pain. Am J Phys Med Rehabil 2004;83:729

14. Close P, Neuprez A, Reginster JY: Developments in phar-macotherapeutic management of osteoporosis. Expert OpinPharmacother 2006;7:1603–15

15. Sinaki M: Critical appraisal of physical rehabilitation mea-sures after osteoporotic vertebral fracture. Osteoporosis Int2003;14:773–9

16. Lane JM, Johnson CE, Khan SN, et al: Minimally invasiveoptions for the treatment of osteoporotic vertebral com-pression fractures. Orthop Clin North Am 2002;33:431–8

17. Hadjipavlou AG, Katonis PG, Tzermiadanos MN, et al: Prin-ciples of management of osteometabolic disorders affectingthe aging spine. Eur Spine J 2003;12(suppl):113–31

18. Lee ST, Chen JF: Closed reduction vertebroplasty for thetreatment of osteoporotic vertebral compression fractures.J Neurosurg 2004;100(4 suppl Spine):392–6

19. Lieberman I, Dudney S, Reinhardt M: Initial outcomeand efficacy of kyphoplasty in the treatment of painfulosteoporotic vertebral compression fractures. Spine 2001;26:1631–15

20. Kim DH, Vacaro AR: Osteoporotic compression fractures ofthe spine: current options and considerations for treatment.Spine 2006;6:479–87

246 Demir et al. Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

LETTERS TO THE EDITOR

RE: RACIAL DISPARITIES IN ACCESS TOCARDIAC REHABILITATION

To the Editor: The article “Racial Disparities in Accessto Cardiac Rehabilitation” by Gregory et al.1 demonstratedthat black patients with heart disease were less likely to bereferred for cardiac rehabilitation than white patients withsimilar clinical presentations. The authors termed thisunderuse of cardiac rehabilitation by black patients a “dis-parity.” This article highlights two important issues: theinterpretation of data showing differential use of health-care services, and the overall low rate of referral for cardiacrehabilitation despite its documented benefits.

The term “disparity” is frequently misused in the med-ical literature. Rathore et al.2 propose five formal criteriathat should be fulfilled before defining a case of differentialuse in services by race as a disparity. These criteria includecomparability between groups in eligibility criteria, clini-cal exclusion criteria, and preferences; lack of confounding(by factors such as demographics and social characteris-tics); and important consequences of not using the servicein question (such as rehospitalization, morbidity, and mor-tality).

Gregory et al.1 provide data and discussion points thatsatisfy several of these suggested requirements. Black andwhite patients seem to be equally eligible for cardiac rehabil-itation, with no systematic differences in exclusions. Litera-ture in the field indicates that cardiac rehabilitation is effec-tive. The authors adjusted for several potential confounders,although the attenuation of the odds ratio for race from 2.5 to1.8 with adjustment indicates that the effect of race mayindeed by mediated by other variables such as insurancestatus and receipt of specialty consultation.

We call particular attention to the role of patientpreferences. Preferences for receiving healthcare servicesmay differ by race and gender.3,4 For instance, minoritiesand women are less likely to choose to undergo jointarthroplasty.5–7 In such circumstances, we should be cau-tious about characterizing underuse as a disparity. In thestudy by Gregory et al.,1 we cannot determine whetherpatients preferred not to undergo cardiac rehabilitation. Ifa patient refused to consider rehabilitation therapy afterbeing offered the option, the differential use would consti-tute an important difference, but not necessarily a dispar-ity. Although Gregory et al. acknowledge the unavailabilityof data on patient preference as a limitation, they call thedifference observed in their study a disparity. We shouldprobe further about the basis of patients’ preferences andacknowledge that preferences themselves may reflect in-ternalized oppression.4 It is essential to distinguish be-tween “difference” and “disparity” because remedies andpolicy implications for each of these are different. None-theless, documenting both differences and disparities isimportant.

The authors report that among those eligible, 11.5%of white patients and 4.7% of black patients were referredfor cardiac rehabilitation. These data suggest that rehabil-itation services are grossly underused. Reasons for under-use may include lack of knowledge about the benefits ofrehabilitation among primary care and other referringphysicians. The rehabilitation academy should consideractive steps to educate referring physicians about the ben-efits of rehabilitation. In addition, it is critical to betterunderstand the reasons for differential use of cardiac re-habilitation by race.

Nitin B. Jain, MD, MSPHDepartment of Medicine

Newton-Wellesley HospitalNewton, Massachusetts

Channing LaboratoryBrigham and Women’s Hospital and Harvard Medical School

Boston, Massachusetts

Jeffrey N. Katz, MD, MSSection of Clinical Sciences and Center for Outcomes Research

Division of Rheumatology, Immunology, and Allergy, andDepartment of Orthopaedic Surgery

Brigham and Women’s HospitalBoston, Massachusetts

REFERENCES1. Gregory PC, Laveist TA, Simpson C: Racial disparities in access to

cardiac rehabilitation. Am J Phys Med Rehabil 2006;85:705–10

2. Rathore SS, Krumholz HM: Differences, disparities, and biases: clari-fying racial variations in health care use. Ann Intern Med 2004;141:635–8

3. Ibrahim SA, Siminoff LA, Burant CJ, Kwoh CK: Understanding ethnicdifferences in the utilization of joint replacement for osteoarthritis:the role of patient-level factors. Med Care 2002;40:I44–51

4. Katz JN: Patient preferences and health disparities. JAMA 2001;286:1506–9

5. Dunlop DD, Song J, Manheim LM, Chang RW: Racial disparities injoint replacement use among older adults. Med Care 2003;41:288–98

6. Skinner J, Weinstein JN, Sporer SM, Wennberg JE: Racial, ethnic, andgeographic disparities in rates of knee arthroplasty among Medicarepatients. N Engl J Med 2003;349:1350–9

7. Suarez-Almazor ME: Unraveling gender and ethnic variation in theutilization of elective procedures: the case of total joint replacement.Med Care 2002;40:447–50

RE: RACIAL DISPARITIES IN ACCESS TOCARDIAC REHABILITATION

The Authors Respond: We thank Drs. Jain and Katz fortheir careful consideration of our article, “Racial Dispari-ties in Access to Cardiac Rehabilitation.”1 Jain and Katz2

use the five formal criteria of Rathore and Krumholz3 tojustify the use of the term “disparity,” arguing that ourstudy has failed to meet at least one of the requirements.Although it has not been established that these criteriahave been widely adopted, we maintain that Drs. Jain andKatz are inaccurate in their critique. In fact, we argue that

March 2007 Letters to the Editor 247

on the basis of these five criteria, our study does define acase of differential use of services by race as a disparity.

Jain and Katz agree that we satisfy criteria 1, 2, 4, and5. We satisfy the first criterion (Patients eligible for the testor procedure are being evaluated) by using the AmericanCollege of Cardiology/American Heart Association guide-lines for candidates for cardiac rehabilitation to define ourstudy population. We satisfy the second criterion (Theanalysis accounts for treatment contraindications) becausethe study population was taken from similar circulatorydiagnoses.

The fourth criterion (There has been risk adjustmentfor patient factors including demographic, clinical, andsocial characteristics) is met because the multivariate anal-yses were adjusted for social and demographic factors aswell as clinical factors such as receipt of cardiac proce-dures. Jain and Katz argue that the attenuation of the oddsratio from 2.5 to 1.8 indicates that the effect of race may bemediated by other variables such as insurance status andreceipt of specialty consultation. We would, however, cau-tion against this overinterpretation of multivariate adjust-ment.4 A person’s race influences insurance before expo-sure to measured social, physiologic, and psychologicalstatus. All of these factors are inherently related to race ina racially stratified society. So, it is not possible to identifyroot cause, because all the variables are interrelated.

We meet the fifth criterion (Racial variations in treat-ment are associated with poorer patient outcomes includ-ing progression of disease) because prior studies haveshown that participation in cardiac rehabilitation reducesthe risk of ventricular arrhythmias and sudden death andreduces mortality by 20% in comparison with nonpartici-pants.5–6

Jain and Katz claim that we do not meet criterion 3(Have patient preferences been considered?) by callingattention to the role of patient preferences. We cite thatthis study evaluated referral for cardiac rehabilitation. Aswe show in Table 1, among patients who were referred forcardiac rehabilitation, 80% of blacks received cardiac re-habilitation and 69% of whites received cardiac rehabilita-tion. There is, therefore, no evidence of disparities inpatient preference for use of cardiac rehabilitation. And, infact, the African American patients in this study seem to bemore likely than whites to adhere to doctor recommenda-tions regarding cardiac rehabilitation. Additionally, inanalyses of these data reported in another article, we foundthat among African American patients who were referredfor other procedures, there was no race difference in ac-ceptance.7

Critics of healthcare-disparities research often sitepatient preferences as a source of disparities; however,there is little research to support this claim. The prob-lem of health disparities, it seems, has more to do withrace differences in obtaining a referral. As the Instituteof Medicine concluded in the 2002 report UnequalTreatment, A small number of studies suggest that ra-

cial and ethnic minority patients are more likely thanwhite patients to refuse treatment. These studies findthat differences in refusal rates are generally small andthat minority patient refusal does not fully explainhealthcare disparities.7 (p 8)

Although we did not specifically assess preferences forcardiac rehabilitation, the available evidence suggests thatpatient preferences are unlikely to be a significant sourceof race differences in use of cardiac rehabilitation in ourstudy. Because all five criteria were met, we have correctlyused the term “disparity.” This study does not show differ-ences in use of services, but it shows differences in referralrates between blacks and whites, with similar use amongthose referred. On the basis of the Rathore and Krumholz3

criteria, this study reflects the differential provision ofappropriate care to black patients after controlling forhealth system factors. We would also argue that this studymeets the criteria for disparity according to the Institute ofMedicine definition in Unequal Treatment, which definesdisparity as racial or ethnic differences in the quality ofhealth care that are not attributable to access-related fac-tors or clinical needs, preferences, or appropriateness ofintervention.8

Most importantly, this study highlights the inequita-ble delivery of health care that leads to poorer outcomesamong the disadvantaged black population.9 Different racegroups have different levels of exposure to health risks thatresult in poorer health outcomes.

Finally, we would echo the fact that cardiac rehabili-tation is grossly underused among those who are eligible,without regard to race. We would further add that there isalso an underlying racial disparity in the referral of pa-tients for cardiac rehabilitation. Efforts should be insti-tuted to educate referring physicians about the benefits ofcardiac rehabilitation and to identify interventions to elim-inate the racial disparity.

Patricia C. Gregory, MDDepartment of Physical Medicine and Rehabilitation

The University of North Carolina–Chapel HillChapel Hill, North Carolina

Thomas A. LaVeist, PhDCenter for Health Disparities Solutions

The Johns Hopkins Medical InstitutionsBaltimore, Maryland

Crystal F. Simpson, MD, MHSDivision of Geriatric Medicine

The Johns Hopkins Medical InstitutionsBaltimore, Maryland

REFERENCES1. Gregory PC, LaVeist TA, Simpson CF: Racial disparities in access to

cardiac rehabilitation. Am J Phys Med Rehabil 2006;85:705–10

2. Jain NB, Katz JN: Re: Racial disparities in access to cardiac rehabili-tation [letter]. Am J Phys Med Rehabil 2007;86:247

3. Rathore SS, Krumholz HM: Differences, disparities, and biases: clari-fying racial variations in health care use. Ann Intern Med 2004;141:635–8

4. Kaufman JS, Cooper RS: Commentary: considerations for use of racial/

248 Letters to the Editor Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

ethnic classification in etiologic research. Am J Epidemiol 2001;154:291–8

5. Kalapura T, Lavie CJ, Jaffrani W, Chilakamarri V, Milani RV: Effects ofcardiac rehabilitation and exercise training on indices of dispersion ofventricular repolarization in patients after acute myocardial infarc-tion. Am J Cardiol 2003;92:292–4

6. Cooper R, Cutler J, Desvigne-Nickens P, et al: Trends and disparities incoronary heart disease, stroke and other cardiovascular diseases in theUnited States. Circulation 2000;102:3137–47

7. Smedley BD, Stith AY, Nelson AR (eds): Unequal Treatment: Confront-ing Racial and Ethnic Disparities in Health Care. Washington, DC,National Academy of Sciences, 2003

8. LaVeist TA: Racial segregation and longevity among African Americans: anindividual level analysis. Health Serv Res 2003;38:1719–33

9. LaVeist TA, Morgan A, Arthur M, Plantholt S, Rubinstein M: Physicianreferral patterns and race differences in receipt of coronary angiogra-phy. Health Serv Res 2002;37:949–62

March 2007 Letters to the Editor 249

A Technique for Ultrasound-GuidedIntrathecal Drug-Delivery System RefillsMark-Friedrich B. Hurdle, MD, Adam J. Locketz, MD,and Jay Smith, MDFrom the Department of Anesthesia Pain Medicine (M-FBH,AJL) and Department of Sports Medicine (JS), PhysicalMedicine and Rehabilitation, Mayo Clinic College of Medicine,Rochester, Minnesota.

0894-9115/07/8603-0250/0American Journal of Physical Medicine & RehabilitationCopyright © 2007 by Lippincott Williams & WilkinsDOI: 10.1097/01.phm.0000248862.98832.9c

Key Words: Ultrasound Guidance, Intrathecal Drug-DeliverySystem

A 41-yr-old woman with kyphoscoliosis received an intra-thecal drug delivery system (ITDDS) for control of pain andmyoclonus. Unfortunately, over the course of several years,her posture worsened and her body mass increased signifi-cantly. Her ITDDS pump reservoir (Medtronic Neurological,Minneapolis, MN) became impossible to consistently accesswithout fluoroscopic guidance. As the result of her kyphosco-liosis and pain with spinal extension, positioning on thefluoroscopic table required the maximal assistance of threepeople for both the transfer and positioning. Consequently,we elected to image and fill the ITDDS using ultrasound (US)guidance via the technique described herein.

The skin is palpated to localize the subcutaneous posi-tion of the pump. Using an US machine (Diagnostic Instru-ments, Inc., Annapolis, MD) and gel, the pump is visualizedwith a 12-MHz linear-array probe. The hyperechoic signal ofthe metallic pump, with posterior acoustic shadowing, can beclearly seen. The optimal imaging angle can then be obtainedby rocking the transducer along both the transverse andlongitudinal axes, until the intensity of the signal is maxi-mized. Next, one can sweep the transducer across the pumpuntil the hypoechoic, centrally located port is visualized (Fig-ure 1). The port is centered in the scan image and then a22-gauge noncoring needle is inserted into the skin perpen-dicular to the long axis of the US transducer (i.e., a short-axisapproach). Once the needle tip enters the imaging field, theoperator can visualize the tip. The operator should repeatedlyangulate and advance the needle until it abuts the port, beingcareful not to allow the needle tip to extend beyond theimaging field. The operator can also appreciate port contactwith the needle tip via tactile feel. Once the port is contacted,the needle is advanced, and the medication delivered. Simul-taneous real-time US during the injection can confirm that

no medication collects superficial to the ITDDS, thus con-firming proper deposition of medication.

Increasingly, patients with refractory pain and spastic-ity are receiving ITDDS. Care providers who refill pumpreservoirs with any intrathecal medication must be knowl-edgeable about the life-threatening consequences associ-ated with refilling errors. The literature contains numer-ous case reports of overdose from ITDDS for a variety ofreasons.1–4 Although not formally studied to date, theincidence of complications will likely increase as the prev-alence of ITDDS increases.

The use of US technology for imaging is becoming morewidespread in the clinical setting. Because of the technicaltraining required to master medical US technology, reluc-tance may exist on the part of operators to use US for guidingan ITDDS refill. However, US-guided ITDDS is both feasibleand practical. We have found a successful and simple tech-nique for properly positioning the needle tip over the refillport to facilitate ITDDS access for any reason. To our knowl-edge, this is the first description of this or any such techniquein the medical literature.

We have successfully refilled multiple hard-to-accesspump reservoirs using this technique. No complications haveoccurred, and both patients and operators have reported auniversally high acceptance of the procedure. US imagingallows both the patient and operator to avoid the ionizingradiation of fluoroscopy and reduces the need for multipleneedle passes in difficult cases, saving time and reducingpatient discomfort. In addition, the soft tissue imaging pro-

All correspondence and requests for reprints should be addressed to Mark-FriedrichB. Hurdle, MD, Mayo Clinic, 200 First Street SW, Rochester, MN 55905.

FIGURE 1 An ITDDS pump under US visualization. AnITDDS magnified x 4.5 is shown. From top to bot-tom, subcutaneous tissue, then the metallic boarderof the pump appearing as a hyperechoic line withthe needle port appearing hypoechoic area in thecenter. All subsequent hyperechoic lines are echoreverberation.

VISUAL VIGNETTE

250 Hurdle et al. Am. J. Phys. Med. Rehabil. ● Vol. 86, No. 3

vided by US can detect potentially clinically significant fluidcollections such as a seroma, hematoma, or abscess. Using USguidance seems to be a safe and effective way to assist withrefilling hard-to-access ITDDS pump reservoirs.

REFERENCES1. Coyne PJ, Hansen LA, Laird J, et al: Massive hydromorphone dose

delivered subcutaneously instead of intrathecally: guidelines for pre-

vention and management of opioid, local anesthetic, and clonidineoverdose. J Pain Symptom Manage 2004;28:273–6

2. Perrot G, Muller A, Laugner B: [Accidental overdose of intrathecalmorphine. Treatment with intravenous naloxone alone]. Ann FrAnesth Reanim 1983;2:412–4

3. Darbari FP, Melvin JJ, Piatt JH Jr, et al: Intrathecal baclofen overdosefollowed by withdrawal: Clinical and EEG features. Pediatr Neurol2005;33:373–7

4. Delhaas EM, Brouwers JR: Intrathecal baclofen overdose: report of 7events in 5 patients and review of the literature. Int J Clin PharmacolTher Toxicol 1991;29:274–80

March 2007 US-Guided ITDDS Refills 251

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