motor learning in children with hemiplegic cerebral palsy and the role of sensation in short-term...

DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY ORIGINAL ARTICLE

Motor learning in children with hemiplegic cerebral palsy andthe role of sensation in short-term motor training of goal-directedreaching

MAXIME T ROBERT1,2 | RHONA GUBEREK2 | HEIDI SVEISTRUP3 | MINDY F LEVIN1,2,4

1 Integrated Program of Neuroscience, McGill University, Montreal, QC; 2 Center for Interdisciplinary Research in Rehabilitation (CRIR), Montreal, QC; 3 Faculty ofHealth Sciences, University of Ottawa, Ottawa, ON; 4 School of Physical and Occupational Therapy, McGill University, Montreal, QC, Canada.

Correspondence to Dr Mindy F Levin, School of Physical and Occupational Therapy, McGill University, 3630 Promenade Sir-William-Osler, Montreal, H3G 1Y5, Canada.

E-mail: [email protected]

PUBLICATION DATA

Accepted for publication 2nd May 2013.

Published online 30th July 2013.

AIM Our aim was to determine if improved upper limb kinematics in children with cerebral

palsy (CP) during a reach-to-grasp task could be retained and transferred to a similar task.

We also characterized the relationship between sensation and motor learning.

METHOD We used a prospective, single-participant research design with 16 children (seven

males, nine females; mean/median age 8.6/9y; age range 6–11y) with spastic hemiparesis

(Manual Ability Classification System levels II–IV). Children were randomly allocated to one

of two groups: (1) task-oriented training with or (2) without trunk restraint. The intervention

consisted of three 1-hour sessions per week for 5 weeks (total 15h). Evaluations consisted of

sensory modalities (tactile threshold, touch, proprioception, stereognosis) and upper limb

kinematics during reach-to-grasp of an object located near and far from the body (five

assessments: three pre-intervention, immediately post-intervention and 3mo post-

intervention).

RESULTS Motor improvements could be retained 3 months after the intervention and

transferred to a similar task in children with CP. Proprioception and tactile thresholds were

associated with retention of improvements in endpoint velocity (F2,13=4.832, p=0.027).

INTERPRETATION Practice of activities aimed at improving upper limb kinematics led to better

learning and retention of movement patterns in children with CP. Our results underline the

importance of sensation for motor learning in children with CP.

Motor skill acquisition continues throughout the lifespan.In typically developing children and adolescents, improve-ments in upper limb motor skills during the first two dec-ades of life are attributable to maturation in bothsensorimotor and cognitive systems.1,2 We define upperlimb motor skill improvements as occurring in both motorperformance (endpoint velocity, trajectory straightness,and/or precision) and in movement quality (active jointranges, and temporal and spatial interjoint coordination).3

The ability to improve and acquire new motor skillsdepends on motor learning, defined as internal neural andcognitive processes concerning practice or experience lead-ing to a relatively permanent change in performance.4 Thedemonstration of motor learning implies that changes inmotor behavior are retained after the period of skill acqui-sition. Another feature of learning is that newly acquiredskills transfer to other similar tasks. Despite differences insome aspects of learning (e.g. learning rate, feedback fre-quency)5 motor learning principles are similar for mosttasks in adults and children and include elements such asintensive and meaningful practice involving active learner

participation.6 Practice-induced improvements in upperlimb movements have been described in typically develop-ing children. For example, children (mean age 10.7y) whopracticed horizontal elbow movements using a lightweightlever improved performance accuracy over four 50-trialsessions.7 Children who received a higher feedback fre-quency during practice of an upper limb discrete and coor-dinated movement using a lightweight vertical lever hadfewer errors in retention than those who received less fre-quent feedback.7

Children with cerebral palsy (CP) whose upper limbmovements are limited by changes in range of motion(ROM), impaired motor control, tone, and sensation, maynot have opportunities to develop typical reaching andgrasping patterns,8 resulting in feeding and self-care prob-lems.9 In the few studies evaluating upper limb motor skillacquisition in children with CP, findings on learningability are mixed. Children aged 7 to 14 years had morevariable directional errors and more difficulty adapting planararm movements to changes in an external viscous force-fieldcompared to typically developing children.10 Conversely,

© 2013 Mac Keith Press DOI: 10.1111/dmcn.12219 1121

similarly aged children with CP (6–12y) were able toincorporate verbal and non-verbal feedback to improvemotor performance and retain and transfer some grossmotor functions described in the GMFM-66.11

Sensory feedback is important for learning motor skillsin adults12 and it is increasingly recognized that childrenwith CP have sensory deficits13 that can affect movementproduction.14,15 For example, there was a moderate-to-strong relationship between tactile threshold of the fingers(Semmes–Weinstein monofilaments) and upper limb motorperformance (Melbourne Assessment) in 52 children withhemiplegic CP.14 Furthermore, children with hemiplegicCP had more difficulty than typically developing childrenreplicating different target arm positions with bothimpaired and less-impaired arms, especially for large move-ment amplitudes.15 A decrease of proprioception in chil-dren with CP could have accounted for the difficulty ofreproducing different target arm positions. However, therole of specific sensory deficits in motor learning remainsunclear.12

While different treatment approaches have been used toimprove upper limb function (e.g. constraint-inducedmovement therapy,16 bimanual intensive therapy17), fewstudies have identified improvements in movement qualityaccompanying functional gains and their relationship tosensory deficits. In a recent study of restriction of compen-satory trunk movement on improvements in goal-directedreaching in children with CP, Schneiberg et al.1 found thattrunk restraint promoted greater improvement in upperlimb movement quality for reaches to targets closelylocated, including less compensatory trunk use. However,practice-induced learning and transfer as well as the effectof altered sensation on motor learning, have not beenevaluated.

Our goal was to determine whether upper limb kine-matic improvements after reaching training in childrenwith CP were retained and transferred to another similartask. Our second goal was to describe the role of alteredsensation in motor learning.

METHODParticipantsOut of 28 children contacted between 2006 and 2010, 16children aged 6 to 11 years (mean/median age 8.6/9y) withspastic hemiparetic CP from five Quebec pediatric centersparticipated in the study. Reasons for non-participationincluded scheduling problems and non-compliance withinclusion criteria. The convenience sample included 11 outof 16 children who participated in the previous study1 aswell as five additional children. Parents signed informedconsent forms approved by the Centre for InterdisciplinaryResearch in Rehabilitation (CRIR) ethics committee. Chil-dren aged 11 years signed child-assent forms. Childrenwere included if they had impaired motor control in atleast one arm, could sit unsupported, understood instruc-tions, had less than 10° elbow or shoulder contracture, hadfunctional vision, and were cooperative. Children were

excluded if they had athetosis, chorea or ataxia, traumaticbrain injury, pain, medical or surgical procedures in the6 months leading up to or planned during the study per-iod, or were receiving upper limb occupational or physicaltherapy.

Study designIn this prospective single-participant research, childrenwere closely paired by age and Manual Ability ClassificationSystem (MACS) level (Table I) and randomly allocated toone of two upper limb training groups by an individualuninvolved with recruitment, evaluation or training. Onegroup practiced upper limb tasks while trunk movementswere restricted by two-three-inch wide straps placed acrossthe chest and attached to the chair, the ‘with trunkrestraint’ (WTR) group. The straps limited forward trunkdisplacement and rotation without constraining scapularmovement. Age-appropriate trunk movement was allowed,based on norms in typically developing children.18 The sec-ond group practiced the same tasks without trunk restraint,the ‘no trunk restraint’ (NTR) group. This group also worestraps but these were not attached to the chair.

Evaluations were conducted before (three pre-tests),immediately after (post-test) and 3 months after (follow-up) a 5-week intervention consisting of 15 60-minute ses-sions performed three times per week. Interventions wereperformed by an occupational or physical therapist, una-ware of clinical and kinematic evaluation results. A singleevaluator, blinded to group assignment, completed all out-come assessments.

InterventionEquipment and training protocols were identical in alltreatment centers.1 For each session, children sat on apediatric chair in front of a custom-made upper limbworkstation consisting of horizontal and vertical surfaces(Fig. 1c). Chair and table height were adjusted so that thehorizontal surface was at elbow height and feet were fullysupported. The vertical surface extended from the trunk tothe limit of the child’s arm length and was divided intoupper and lower sections by a shelf placed at shoulderlevel.

Each 60-minute training session consisted of 3 minutesof stretching, 20 minutes of activities performed in each ofa physical and a virtual (Fig. 1b) environment (order ran-domized), 7 minutes’ rest, and 10 minutes’ practice of achild/family-selected functional activity. Therapists keptwork-logs of training sessions. Trunk restraints (Fig. 1a)were only used during the 40-minute activity period.

In the physical environment, table workspaces weredivided into four horizontal and four vertical quadrants in

What this paper adds• Evidence for motor learning and transfer of improvements in upper limb

motor skills to a similar task in children with CP.

• Support for the importance of sensation, particularly proprioception and tac-tile threshold, for motor learning in children with CP.

1122 Developmental Medicine & Child Neurology 2013, 55: 1121–1128

which children practiced task-oriented activities commonlyincluded in therapy. Training was impairment-based,client-centered and consisted of playing with toys or boardgames with one or both arms. Activities were progressedtaking into account child/therapist preferences and clinical

goals. Children received verbal feedback about movementquality from the therapist.

For training in the virtual environment, the verticalworkspace was replaced by a computer monitor displayinginteractive games controlled by arm and hand movements

Table I: Demographic and clinical parameters of children with cerebral palsy

ChildAge

(y)/side Gender MACS S–WaStereo

(% recognized)Touch/20

Propr/8

ROM/24

MELB/122

With trunk restraint (WTR) group1 9-L F 4 R=3.6 L=2.8 100 17 8 22 712 8-L F 4 R=2.8 L=4.1 0 19 0 16 563 7-L F 3 R=3.2 L=3.2 83 20 6 24 894 9-R F 3 R=1.7 L=2.8 100 20 5 22 745 8-R M 2 R=3.2 L=3.2 100 20 8 22 N/A6 11-L M 3 R=2.8 L=2.4 80 14 8 24 917 9-R M 2 R=2.8 L=2.8 50 10 6 23 N/A8 9-L F 2 R=2.8 L=2.4 100 13 8 23 91

No trunk restraint (NTR) group9 9-R M 4 R=4.7 L=2.4 20 20 6 24 5810 10-L M 3 R=2.8 L=2.4 80 19 6 24 9011 9-R F 4 R=3.2 L=3.2 83 16 6 24 7712 11-R F 3 R=3.4 L=3.1 57 14 6 23 8213 8-L M 2 R=2.8 L=2.4 50 10 7 21 N/A14 9-R F 2 R=2.8 L=2.8 80 18 8 23 9015 6-L M 2 L=5.5 – 50 13 2 24 N/A16 6-L F 2 R=2.8 L=4.3 50 10 7 23 N/A

aFor S–W, the normal age appropriate range is 2.83 to 3.61.19 M, male; F, female; L, left; R, right; MACS, Manual Ability Classification Sys-tem; S–W, Semmes–Weinstein; Stereo, Stereognosis; Propr, proprioception; ROM, range of motion; MELB, Melbourne assessment of uni-lateral arm function; N/A, Not Available.

i ii

iviiiiii

i ii

iv

(c)

FT CT

(d)

(b)(a)

Figure 1: Upper limb motor training (a, b, c) and experimental (d) set-up for kinematic assessment. (a) Trunk restraint system for upper limb training.(b). Example of a virtual game used during upper limb training in which the child’s hand interacts with objects on a computer screen. (c) Horizontaland vertical planes showing zones for reaching training in the near (i and ii) and the far (iii and iv) workspaces of the most affected arm. (d) Forkinematic data acquisition of the reaching task, children were seated and performed a reach-to-grasp task to a close target (CT) and a far target (FT).In both set-ups, chair and table height were adjusted so that the horizontal surface was at elbow height. Both feet were fully supported. For kinematicassessment, close target was placed at the child’s arm length. Far target was placed at 1 + 2/3 arm length.

Motor Learning in Children with CP Maxime T Robert et al. 1123

(IREX, GestureTek, Toronto, ON, Canada). Movementsthroughout the arm workspace were recorded with a web-cam and projected into the game scene. Children receivedfeedback about task success through sounds, game scores,and therapist interaction. All training activities in bothenvironments were done in an arm workspace defined bythe child’s arm length, measured from medial axilla towrist crease.

EvaluationsClinical testing included sensation–hand dorsum tactilethresholds (stereognosis, touch, proprioception) via Semmes–Weinstein filaments (S-W; Lafayette Instruments, Lafayette,IN, USA) – and upper limb passive ROM. S-W values intypically developing children aged 5 to 9 years range from2.83 to 3.61mm.19 For stereognosis, the number of objectsplaced in the affected hand successfully identified with eyesclosed was expressed as a percentage of the total. Lighttouch (touch) and proprioception were measuredon numeric scales20 with maximum scores of 20 and 8respectively, indicating no impairment. Upper limb ROMof five arm joints was measured on three-point scaleswhere 24 points represented full, painless ROM. Upperlimb impairment and function was measured with the validand reliable Melbourne assessment of unilateral arm function(Melbourne) test.21 The Melbourne, which was videotapedand independently analyzed, assesses 16 arm and hand move-ments for ROM, accuracy, fluency, quality, accomplishment,and/or speed on four- or five-point scales for a maximumscore of 122 points.

Laboratory testing evaluated arm and trunk movementsduring two standardized reach-to-grasp tasks. Movementswere recorded (Optotrak 3020, 100Hz; Northern Digital,Waterloo, ON, Canada) from 10 infrared-emitting diodes(IREDs) positioned on the arm and trunk, as previouslydescribed.1 Seated children reached to grasp a 2cm3 blockplaced at two distances proportional to the child’s armlength (close target = arm length, far target = 1+2/3 armlength) in the body midline (Fig. 1d). Seven to 12 trialsper target were recorded in randomized blocks. Closetarget location corresponded to the distance at which mosttraining occurred. The far target tested the ability of thechild to reach beyond the arm workspace, a movement thatwas not practiced during the training in either environ-ment.

Data analysisKinematic outcomes were restricted to those shown to bereliable for describing arm movements in similarly agedchildren with CP:22 two performance (trajectory straight-ness, endpoint [hand] velocity) and two movement quality(shoulder flexion ROM, elbow extension ROM) measures.Endpoint tangential velocity data were low-pass filtered(cut-off 10Hz) and used to define arm movement start andend times as when the endpoint tangential velocity roseabove/fell below 5% peak velocity for at least 50ms. Peakvelocity (mm/s) was determined from the endpoint tangen-

tial velocity trace. The index of curvature measured trajec-tory straightness as the ratio of actual endpoint path lengthto the length of a straight line joining initial and final posi-tions. Elbow angle was calculated using vectors formed byradius and lateral epicondyle IREDs and lateral epicondyleand ipsilateral acromion IREDs where full extensionequaled 180°. Shoulder angle was calculated from vectorsbetween IREDs on the lateral epicondyle and ipsilateralshoulder and lateral iliac spine, with full shoulder flexionbeing 180°.

Statistical analysisA single-participant research design was used because ofsmall sample size and participant heterogeneity. To deter-mine whether changes occurred in each parameter for eachchild at post-test and follow-up for each target, we usedregression with visual trend analysis and computed effectsizes using standard mean differences. A linear regressionline was fit through all three pre-test (baseline) data pointsand a horizontal straight line was extended from the end ofthe regression through post-test and follow-up data. Thenumber of data points above or below the line was countedfor each phase. Between-mean differences of post-test andpre-test values were divided by the pre-test standard devia-tion to determine effect size. The same was carried out tocalculate effect sizes at follow-up, with post-test replacedby follow-up. Effect sizes of 0.20, 0.50, and 0.80 were con-sidered small, moderate and large respectively.23 Effectsizes greater than 0.50 identified motor learning and trans-fer based on previous studies.7,24 ‘Motor learning’ wasdefined by retention at follow-up of improvements in per-formance and/or movement quality variables for the closetarget reach-to-grasp task. ‘Transfer’ was defined asimprovements in performance and/or movement qualityvariables at post-test for the far target reach-to-grasp task.

In this mixed-design analysis, v2 tests determinedwhether the number of children showing improvements ineach variable was different between WTR and NTRgroups. We also described learning and transfer of kine-matic improvements in the whole group of children.

For the second goal, relationships between sensory andkinematic variables were assessed using multiple regres-sions at post-test (close target), follow-up close target(learning), and post-test far target (transfer). Minimal sig-nificance levels of p<0.05 were used.

RESULTSAll children (seven males, nine females; mean/median age8.6/9y; age range 6–11y) with spastic hemiparesis (ManualAbility Classification System levels II–IV) completed allstudy phases and complied with the treatment and testingsessions.

Sensory evaluationsThe profile of sensory deficits in the children in eachgroup was mixed (Table I) with deficits ranging from mildto severe.


Performance outcomesEndpoint velocityFor the close target, five children in the WTR and four inthe NTR group increased endpoint velocity after the inter-vention. Improvements were maintained at follow-up intwo children in WTR and one in the NTR. Among thenine children who improved endpoint velocity, three WTRchildren and one in the NTR group showed transfer ofimprovement to the far target at post-test (Table II).

Index of curvatureFive children in the WTR and four in the NTR groupimproved trajectory straightness for close target after train-ing. Improvements were maintained at follow-up in threechildren in each group. Among the nine children whoimproved trajectory straightness for the close target at postintervention five children in WTR and two in NTRshowed a transfer of improvement to far target post-inter-vention (see Table SI, online supporting information).

Movement quality outcomesElbow extensionFor close target, six children in WTR and three children inNTR improved elbow extension range after the interven-tion. Improvements were maintained at follow-up in onechild in WTR and two children in NTR and transfer ofimprovement to far target at post-test occurred in five chil-dren in WTR and two in NTR (see Table SII, online sup-porting information).

Shoulder flexionFour children in WTR and two in NTR improved shoul-der flexion range for close target after training. Improve-

ments were maintained for close target at follow-up inthree children in WTR and one in NTR. Improvementstransferred to far target at post-test for three children inWTR and one in NTR (see Table SIII, online supportinginformation).

Overall learning and transfer of improvement effectsThere were no differences between groups (WTR, NTR)in the number of children who learned or transferredimprovements for any of the four kinematic variables(v2, p>0.05). Therefore, the data were combined for allchildren. Figure 2 illustrates how many children (1)improved motor performance or movement quality vari-ables for close target at post-test based on effect sizes(large pie charts in each panel); (2) retained improvementfor close target at follow-up (left small pie charts); and (3)transferred improvements for far target at post-test (rightsmall pie charts). Approximately two-thirds of the childrenshowed evidence of motor learning and transfer of improve-ments for each of the four kinematic variables.

Melbourne scores were correlated with the index of curva-ture post-test (r=�0.63, p=0.02) and at follow-up (r=�0.60,p=0.03) for close target and at post-test (r=�0.75, p=0.004)for far target.

Correlations between motor learning, kinematic, andsensory variablesFor the group, improvements (post-test) in shoulder flex-ion ROM correlated with improvements in endpoint veloc-ity (r=0.48, p=0.029) and index of curvature (r=�0.56,p=0.015) for close target. For motor learning (follow-up),endpoint velocity was correlated with index of curvature

Table II: Improvement in endpoint velocity indicated by the number of points above the baseline trendline, and mean differences and effect sizes (ES)for reaches to the target at arm’s length (close target [CT]) and the target at arm’s length plus 2/3 (far target [FT])

VelocityCT post-Intervention CT follow-up FT post-Intervention

Child

Points abovebase-linetrend line

Post minusbaselinedifference ES


Follow-up minusbaselinedifference ES


Post minusbaselinedifference ES

WTR1 5/11 182.6 1.108 3/10 178.5 1.084 4/11 109.8 0.5512 5/10 173.6 0.655 1/9 103.3 0.390 4/10 149.1 0.8363 8/11 203.5 0.858 6/11 86.4 0.364 3/9 281.1 0.7844 5/10 229.2 0.688 6/9 459.6 1.380 3/11 131.8 0.3725 10/10 33.1 0.104 11/11 �247.5 �0.774 7/9 62.1 0.2236 1/10 �281.9 �1.095 5/10 14.5 0.056 8/10 233.6 0.8077 9/9 340.8 0.835 7/10 8.6 0.021 6/10 �67.9 �0.1628 6/9 75.2 0.447 0/11 �387.3 �2.303 3/8 6.7 0.016

NTR9 4/11 132.0 0.603 0/12 �300.9 �1.374 1/10 �43.0 �0.13010 6/11 240.2 0.894 1/10 139.3 0.518 4/10 232.4 �0.00811 7/9 230.0 1.112 3/9 23.2 0.112 7/9 344.2 2.12612 11/11 �12.7 �0.032 10/10 �166.7 �0.423 7/10 �180.5 �0.45313 3/7 �149.0 �0.276 5/11 �178.0 �0.330 8/11 365.7 0.75214 1/10 �341.9 �1.414 7/13 54.8 0.214 0/11 �180.7 �0.61915 5/10 �66.8 �0.210 0/9 �456.9 �1.438 2/11 �220.8 �0.56816 6/11 173.6 0.940 0/10 �414.3 �1.303 3/12 �243.2 �0.883

Data are shown for two groups of children practicing task-oriented reaching with (WTR) or without (NTR) trunk restraint. Differences areshown for post-intervention minus baseline and for follow-up data minus baseline. Moderate to large ES indicating improvement areshown in bold and those indicating deterioration are indicated in grey shading.


(r=�0.33, p=0.021) for close target. However, correlationsbetween changes in kinematic variables were not evidentfor transfer of learning (far target post-test).

There was a significant association between propriocep-tion, tactile threshold and retention of the improvement inendpoint velocity for close target (R2=0.34, F2,13=4.832,p=0.027). However, there was no relationship betweenindex of curvature, shoulder and elbow ROM, and sensa-tion for motor learning.

DISCUSSIONLearning occurred in some children in both groups butlearning was not affected by the type of practice. Improve-ments were documented in both movement performanceand quality. Specifically, movements were faster andstraighter and accomplished with greater elbow extensionand shoulder flexion. We also found that decreased sensa-tion affected motor learning.

Children in both groups improved kinematics, but therewas no difference between groups in terms of retention or

transfer. Although a larger number of children in theWTR group showed evidence of learning to make move-ments faster and with more shoulder flexion, group differ-ences could not be identified because of the small numberof participants. It is possible that the use of a trunkrestraint is not an important element for learning move-ment kinematics. However, results are inconclusive andshould be interpreted with caution.

Motor learningMotor pattern improvements following the 5-week upperlimb training program in children with CP were retainedfor at least 3 months in some children. Although comparableresults for motor learning were found in a similar groupof children with CP,1 this may be the first evidence oftransfer of kinematic improvements in children with CP.Motor learning is influenced by many factors, includinggenetics, somatosensory function,12 prior experience, andgender.4 Indeed, learning to make faster reaching trajecto-ries was related to better sensation (proprioception andtactile sensation) in our group of children. This supportsprevious studies on children with CP about the linkbetween these two sensory modalities and motor learn-ing.14,15 Indeed, there is ample evidence from animal stud-ies about the dependence of motor and sensory systems formotor production and motor learning.25,26 When a childwith CP has decreased sensory information, different sys-tems can be used to guide motor learning. Izawa and Shad-mehr27 demonstrated that sensory feedback is not solelyresponsible for motor learning. When reaching during vi-suomotor perturbations, both sensory and reward predic-tion errors promoted motor learning, though only theformer affected sensory maps. Consequently, using a rele-vant reward system may improve results during training.Indeed, differences in learning and retention of other kine-matic variables were not accounted for by sensory statusalone. These differences could be explained by other fac-tors mentioned above as well as by differences in brainpathologies among the children. Nevertheless, our resultssupport the notion that practice of skilled upper limbmovements leads to effective change in kinematics in chil-dren with CP.28

Transfer of improvementsUpper limb performance and movement quality can beimproved and changes can transfer to similar tasks follow-ing a specific upper limb training intervention. Two-thirdsof the participants could transfer improvements to a similartask for each of the four kinematic variables. The transferof improvements could be explained by the level of motorimpairment of the children. Indeed, having less physicalimpairment may facilitate the ability to improve upperlimb performance and movement quality and transferimprovements to a similar task.11 Furthermore, the transferof improvements may be due to the similarity of the trans-fer task.4 Improvements in and transfer of learning can alsobe related to practice intensity or schedule. For example,

IC Endpoint velocity

Shoulder flexion Elbow extension

Learning Learning

Learning Learning

Transfer Transfer

Transfer Transfer

Deterioration No change Improvement

Figure 2: Pie charts illustrating the number of children (n=16) whoimproved (white sections), deteriorated (black sections), or did notchange (grey sections) on each of the kinematic variables based oneffect sizes. The bigger pie chart for each variable represents the resultsof reaches to the close target post-test. Of those children who improved(white sections in larger pie chart), the lower two pie charts illustrate theproportion of children who showed evidence of motor learning (retentionof improvements for reaches to close target at follow-up) and the propor-tion who showed evidence of transfer of motor learning (reaches to thefar target at follow-up). IC, index of curvature.


Bar-Haim et al.11 showed that intensive variable practiceled to transfer of motor improvements, measured by theGross Motor Function Measure-66, in children with CP.

CONCLUSIONChildren with CP can learn to use new motor patterns andretain improvements after practice. Motor skills learnedthrough practice may be transferred to similar movementsin children with CP, and those children with better sensorystatus are likely to be better learners. Future studies shouldidentify how practice elements should be adapted to opti-mize motor learning in a larger group of children withgreater symptom variability. How kinematic improvementsmay transfer to more functional reaching and graspingtasks should also be addressed.

ACKNOWLEDGEMENTS

Thanks are extended to Sheila Schneiberg for some of the data

collection. This research was supported by the Canadian Institutes

of Health Research. MTR is supported by a Vanier Canada Grad-

uate Scholarship. MFL holds a Tier 1 Canada Research Chair in

Motor Recovery and Rehabilitation. The authors thank the chil-

dren who participated in this study and their parents.

SUPPORTING INFORMATION

Additional supporting information may be found in the online

version of this article.

Table SI: Improvement in trajectory path straightness (index

of curvature [IC]) indicated by the number of points below the

baseline trendline, and mean differences and effect sizes (ES) for

reaches to the target at arm’s length (close target) and the target

at arm’s length plus 2/3 (far target). Data are shown for two

groups of children practicing task-oriented reaching with (WTR)

or without (NTR) trunk restraint. Differences are shown for post-

intervention minus baseline and for follow-up data minus base-

line. Moderate to large effect sizes indicating improvement are

shown in bold and those indicating deterioration are indicated in

grey shading.

Table SII: Improvement in elbow extension indicated by the

number of points above the baseline trendline, and mean differ-

ences and effect sizes (ES) for reaches to the target at arm’s

length (close target) and the target at arm’s length plus 2/3 (far

target). Data are shown for two groups of children practicing

task-oriented reaching with (WTR) or without (NTR) trunk

restraint. Differences are shown for post-intervention minus base-

line and for follow-up data minus baseline. Moderate to large

effect sizes indicating improvement are shown in bold font and

those indicating deterioration are indicated in grey shading.

Table SIII: Improvement in shoulder flexion indicated by the

number of points above the baseline trendline, and mean differ-

ences and effect sizes (ES) for reaches to the target at arm’s

length (close target) and the target at arm’s length plus 2/3 (far

target). Data are shown for two groups of participants practicing

task-oriented reaching with (WTR) or without (NTR) trunk

restraint. Differences are shown for post-intervention minus base-

line and for follow-up data minus baseline. Moderate to large

effect sizes indicating improvement are shown in bold and those

indicating deterioration are indicated in grey shading.

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