lumbar spine emg

Introduction to EMG & EMG guided manual therapy of lumbar spine

Satyajit MohantyMSPT,MIAP, MHPC (UK)

Senior Physiotherapist

04/08/23 Recovery Physiotherapy center

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Place of EMG as a investigating Place of EMG as a investigating tooltool

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Classifying MSK presentations

To identify the source of MSK pain, patient's pain pattern is categorized either into

Nonspecific pattern

OR

into one of 4 recognizable pathway patterns

1. Radicular 2. Dorsal ramus 3. Polyneuropathy 4. Sympathetic


How MSK conditions are investigated?

After having roughly identified the origin of Pain, investigations are carried out to confirm the source of pain. Investigative strategies in musculoskeletal sciences takes a comprehensive approach called

THE PHYSIO-ANATOMIC APPROACH

Though function & structure are inseparable aspects of existence, physiological properties & structural integrity of the faulty tissues are separately studied in this approach.


THE PHYSIO-ANATOMIC APPROACH

The physiological approach

Both invasive & non-invasive

Example: EMG, NCV, biothesiometry etc

The anatomical approach

Both invasive & non-invasive Example: X-ray, CTscan, MRI,

Diskography-enhanced

computed tomography


Question 1: Why we are discussing investigative strategies?

Investigative data can provide baseline data

This investigative data can be compared to normative data, which indicate the status of the condition

If these studies are permitted for intermittent assessment, then they provide crucial information on progression of the disease status

Real time information: Many times you can observe what is happening while you are actually performing a therapy. Thus recently real time ultrasound & EMG is used to guide treatment in rehabilitation.


Question 2: Whether it is permitted to employ EMG in the context of studying & guiding manual therapy?

Physicians have been vehemently protesting EMG use by physiotherapists till 2005. One can check the stance of american acedamy of family physicians14. However, the next recommendation by Braddock et al (2007); Manual medicine guidelines for musculoskeletal injuries, National guideline clearinghouse (USA)7 electrodiagnostic studies for the application of manual therapy are indicated under following diagnostic circumstances: 1. Persistent neurological symptoms

2. Conditions non-responsive to conservative care requiring determination of the severity of the deficit

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* This recommendation (Braddock et al, * This recommendation (Braddock et al, 2007) remain silent about those studies 2007) remain silent about those studies involving real time EMG changes of involving real time EMG changes of electrodiagnostic parameters from electrodiagnostic parameters from manual therapy point of view. manual therapy point of view.

* However EMG has been a * However EMG has been a common tool to numerous common tool to numerous researchers for measuring muscle researchers for measuring muscle function before, during & after function before, during & after variety of procedures including variety of procedures including manual therapy procedures. manual therapy procedures.


Performing & interpreting Performing & interpreting Paraspinal EMGParaspinal EMG


Question 3 How the EMG is performed & interpreted?

EMG: An electromyograph detects the electrical potential generated by muscle cell when these cells contract, and also when the cells are at rest.

2 types of EMG are there : Needle electrode guided & surface electrode guided

In needle EMG only a small number of fibers are amenable but in sEMG much more area is exposed to the study


Surface & needle EMGs


EMG studies reveal normal muscle membrane potential is about -70mV with a frequency of discharge 7–20 Hz.

EMG variables changes depending on the size of the muscle (eye muscles versus gluteal muscles), previous axonal damage, muscle damage and various other factors.

The membrane potential in damaged motor units is expected in ranges between 450 and 780 mV13.


Focus of our discussion is surface EMG Focus of our discussion is surface EMG guided manual therapy of lumbar spine. guided manual therapy of lumbar spine.

In surface EMG guided lumbar area manual In surface EMG guided lumbar area manual therapy the target muscles are the lumbar therapy the target muscles are the lumbar paraspinals. Hence the next question is….paraspinals. Hence the next question is….


Question 4 What is the difference between a paraspinal muscle EMG & EMG of other muscles like Tibialis anterior ?

EMG can be done in any skeletal muscle. In most situations (diagnostic situations) muscles innervated by ventral root is investigated (For example in L4-L5 disc prolapse cases the Tibialis anterior are studied who are innervated by ventral roots).

But paraspinals are innervated by the dorsal roots of a corresponding spinal level. Hence the most fundamental difference lies in the anatomic root of stimulation. (see the following diagram)

Second point is Tonic (paraspinal) versus Phasic muscle (tibialis anterior)


Typical spinal nerveTypical spinal nerve


Question 5 Can we study lumbar spine dysfunction via paraspinal EMG?

“Muscle is a informer of joints” - EMG of the muscles where there is intrinsic pathology or defective nerve supply will reveal abnormal picture. More to that we can study different loading patterns, spasms in muscles via an EMG.

Surface electromyography, (sEMG) has been used as a research tool to evaluate the performance of paraspinal muscles in patients with back pain and to further understand the etiology of low back pain11,12.


Example of Paraspinal EMG as an indicator of Lumbar dysfunction

a.Lumbar erector spinae flexion-relaxation phenomenon (FRP)

b.Thoracolumbar myoelectric asymmetry (TMA)


FRPFRP refers to electrical silence as recorded in EMG during trunk flexion.

FRP leads to increased load sharing on passive structures and is a source of low back pain1.

Loss of flexion/relaxation correlates with diminished pressure pain thresholds2.

A number of EMG studies have shown differences in the FRP between patients with chronic low back pain and healthy individuals.


TMA Significant myoelectric differences are

reported in thoracolumbar myoelectric activity of involved & uninvolved sides of the back pain.

sEMG also shows contralateral responsivity i.e. increased myoelectric activity in opposite the side of leg pain.

Hence EMG technique could be used to detect muscle dysfunction related to LBP. However research of sEMG correlations with measures of the manipulability of a lesion is sought.


Comparison of right & left paraspinal Comparison of right & left paraspinal activity with a right sided LBAactivity with a right sided LBA

Following diagram shows prolonged muscle activity pattern Following diagram shows prolonged muscle activity pattern of the upper lumbar paraspinals (the first is right side & the of the upper lumbar paraspinals (the first is right side & the lower one is the left side) in a degenerative PID of L2-L3 lower one is the left side) in a degenerative PID of L2-L3 discs. discs.

The sharp burst of muscle activity corresponded directly to The sharp burst of muscle activity corresponded directly to heel strike of stance phase during ambulation. heel strike of stance phase during ambulation.


Scheme of conducting an EMG for back muscles to assess back muscle impairment

1. The electrodes are strategically placed at specific anatomical locations corresponding to contralateral and ipsilateral paraspinal muscles.

2. Differences in the variable mapped at the beginning

and end of a fatigue-inducing contraction are analyzed to assess impairment.

3. Muscle contractions are submaximal constant-force isometric contractions in which the duration of the contraction is predetermined.


Which EMG parameter (variable) is more indicative?

Recent researchers are more concerned about frequency rather than amplitude of the signal.

Explanation

During sustained contractions, the EMG signal propagates at a slower velocity and undergoes an alteration in shape (De Luca CJ, 1985).

This is called "myoelectric manifestations of fatigue" and are typically measured during a contraction as a decrease in the median or mean frequency (MF) of the EMG signal.


Question 6 How much reliable is the EMG measurements in lumbar paraspinals?

Within-day reliability for control subjects tested in the BAS (back analysis system) result in low (2% -6%) errors.

Between-day variability is low performed 5 days apart. (Thompson and Biedermann)

Which is the more reliable lumbar paraspinal for EMG study?: Thompson and Biedermann reported large & positive correlation coefficients (within a range of .75 to .96) for frequency values recorded from the multifidus and iliocostalis muscles. However, reliability of frequency measurements is consistently higher for the iliocostalis muscle than for the multifidus muscle.


The multifidus & Iliocostalis muscles: Lumbar area muscles for EMG studies


Source of variability of paraspinal surface EMG

According to Roy et al & Thompson DA et al the source of measurement variability are:

1. Electrode placement accuracy: Errors in relocating the electrodes at the same site when repeating a test.

2. Crosstalk: Inability to completely isolate EMG signals from a single muscle. The amount of crosstalk between adjacent erector spinae muscles has been estimated using crosstalk index.

3. Crosstalk index is the ratio between the amplitudes of the EMG signals recorded from the non-stimulated and stimulated muscles. Crosstalk index is in the range of 6% to 7%.


Studies of EMG guiding Studies of EMG guiding Lumbar spine manual therapyLumbar spine manual therapy


The final & the most important question

Question 7 Can EMG be employed to evaluate effectiveness of lumbar spine manual therapy?


Being one the most popular treatment Being one the most popular treatment modality for lower back conditions, manual modality for lower back conditions, manual therapy has not been sufficiently researched therapy has not been sufficiently researched on objective physiological yardsticks like EMG on objective physiological yardsticks like EMG & NCV studies. & NCV studies.

However, recently many researches have However, recently many researches have poured in that validates EMG studies poured in that validates EMG studies especially the real-time EMG, as a manual especially the real-time EMG, as a manual therapy guide. therapy guide.

In the following section we are presenting In the following section we are presenting studies in lumbar spine manual therapy with studies in lumbar spine manual therapy with EMG as a variable. We will be discussing 3 EMG as a variable. We will be discussing 3 studies which has real time EMG monitoring studies which has real time EMG monitoring with lumbar spine manual therapy application. with lumbar spine manual therapy application.


Study 1 (A real time EMG study)

Colloca et al (2001) investigated dynamic stiffness measurements (force/velocity) & concomitant neuromuscular response to extract more information concerning mechanical properties of the low back.

This is the first study that demonstrate neuromuscular reflex responses associated with manually assisted spinal manipulative therapy in patients with low back pain.

Colloca et alColloca et al employed surface EMG recordings employed surface EMG recordings obtained from electrodes (8 leads) located obtained from electrodes (8 leads) located over the L3 and L5 paraspinal musculature to over the L3 and L5 paraspinal musculature to monitor the bilateral neuromuscular activity of monitor the bilateral neuromuscular activity of the erector spinae group during the PA thrusts. the erector spinae group during the PA thrusts.

Results:Results:

1. 1. IncreasedIncreased spinal stiffness index spinal stiffness index and and positivepositive neuromuscular reflex responses in neuromuscular reflex responses in subjects with frequent or constant LBP as subjects with frequent or constant LBP as compared with intermittent or no LBP. compared with intermittent or no LBP.


2. Thrusts applied over the 2. Thrusts applied over the transverse transverse processprocess produce produce more positivemore positive EMG EMG responses in comparison with thrusts applied responses in comparison with thrusts applied over the over the spinous processes.spinous processes.

3. Left side thrusts and right side thrusts over 3. Left side thrusts and right side thrusts over the transverse processes elicit positive the transverse processes elicit positive contralateral EMG responsescontralateral EMG responses..

4. Patients with 4. Patients with frequent to constant low back frequent to constant low back

painpain symptoms tend to have a symptoms tend to have a more markedmore marked EMG response in comparison with patients EMG response in comparison with patients with with occasional to intermittent low back painoccasional to intermittent low back pain. .


Conclusion:Conclusion:

This study concluded identification of This study concluded identification of neuromuscular characteristics, neuromuscular characteristics, together with a comprehensive together with a comprehensive assessment of patient’s clinical assessment of patient’s clinical status, may provide for clarification of status, may provide for clarification of the significance of spinal manipulative the significance of spinal manipulative therapy in eliciting accepted therapy in eliciting accepted conservative therapeutic benefits.conservative therapeutic benefits.


Study 2 (A Real time study)

In clinical situations, many times, posterior spinal exercises are co-prescribed with manual therapy or as maintenance therapy of achieved therapeutic goal.

Investigators studying the effects of back exercise on EMG spectral parameters found these parameters to be sensitive to back muscle adaptations.

However there are no studies that substantiate that spinal manipulative therapy (SMT) may help augmenting the effects of these exercises. It is also less researched what is the appropriate time to implement spinal exercises after SMT.


By an EMG guided study Keller et al (2000) investigated whether lumbar spinal manipulative therapy (SMT) affects it’s paraspinal muscle strength on 40 subjects.

The results of this study demonstrated that SMT results in a significant immediate increase in sEMG erector spinae isometric MVC (maximal voluntary contraction) muscle output.

Hence this altered muscle function may only be a potential short-term therapeutic benefit of SMT. This effect should be exploited in clinical set ups.


Study 3 (A real time study)

Bertolucci LF displayed his work at 1st facsia research congress Howard medical school, Boston, 2007. His work was later on published in journal of body & movement therapy, 2008.

Bertolucci’s original work was on cervical area but currently he has extended his research to lumbar area (ref:http://www.youtube.com/watch?v=HLk_wMK0Ecg ).

His work revolves around recording of EMG signals coming from paraspinals muscles during his self styled myofascial treatments.


Working on a specific mode of manual therapy called Working on a specific mode of manual therapy called muscle repositioning he found post manual therapy muscle repositioning he found post manual therapy paraspinal EMG pattern mimics pandiculation. paraspinal EMG pattern mimics pandiculation.

What is pandiculation?What is pandiculation?We like to stretch our whole body after getting off the We like to stretch our whole body after getting off the bed which usually comes with a bed which usually comes with a yawning.yawning. This This according to modern neuroscientists leads to muscle according to modern neuroscientists leads to muscle realignment which further leads to realignment which further leads to axial & axial & apendicular joint alignment & stability.apendicular joint alignment & stability. According According to Fraser & Walusinski pandiculation has a role in the to Fraser & Walusinski pandiculation has a role in the development and maintenance of the musculoskeletal development and maintenance of the musculoskeletal system. system.


PandiculationPandiculation


What Bertolucci reports while performing What Bertolucci reports while performing muscle repositioning?muscle repositioning?

Real time Paraspinal EMG activity revealsReal time Paraspinal EMG activity reveals a. Progressive a. Progressive isometricisometric activity of the lumbar activity of the lumbar

erectors. erectors. Spreading of EMG Spreading of EMG activity away from activity away from the immediate recipient area which feels like a the immediate recipient area which feels like a bipolar expansionbipolar expansion in the body’s longitudinal in the body’s longitudinal axis. There seems a axis. There seems a segmental integrationsegmental integration of of different body segments mimicking pandiculation. different body segments mimicking pandiculation.

b. Firmer the feel to the clinician’s hand, the b. Firmer the feel to the clinician’s hand, the higher the EMG signals i.e.: the higher the EMG signals i.e.: the degree of degree of firmnessfirmness is possibly related to the intensity of is possibly related to the intensity of the tonic reaction.the tonic reaction.

c. It is also noted that firmer the feeling to the c. It is also noted that firmer the feeling to the touch, the more effective the maneuver.touch, the more effective the maneuver.


Hence it is supposed that clinical Hence it is supposed that clinical efficacy of the maneuvers is related efficacy of the maneuvers is related to the to the tonic reactionstonic reactions (a neural (a neural reflex) during the clinical practice is a reflex) during the clinical practice is a desired clinical effect.desired clinical effect.

Hence Bertolucci considers detecting Hence Bertolucci considers detecting EMG activity EMG activity during during the maneuvers, the maneuvers, brings a high degree of objectivity to brings a high degree of objectivity to the procedure under execution. the procedure under execution.


Conclusion:Conclusion: EMG recording could be used to guide & EMG recording could be used to guide &

monitor appropriateness of manual touch & monitor appropriateness of manual touch & manual therapy procedures so that they manual therapy procedures so that they could be more precise, objective & could be more precise, objective & reproducible. reproducible.

Hence in articular or motion directed Hence in articular or motion directed therapies, muscle function via EMG therapies, muscle function via EMG monitoring becomes essential. monitoring becomes essential.


ReferencesReferences 1. 1. CollocaColloca CJ CJ et al; The biomechanical and clinical significance et al; The biomechanical and clinical significance

of the lumbar erector spinae flexion-relaxation phenomenon: a of the lumbar erector spinae flexion-relaxation phenomenon: a review of literature; J Manipulative Physiol Ther. 2005 review of literature; J Manipulative Physiol Ther. 2005 Oct;28(8):623-31. Oct;28(8):623-31.

2. 2. Leach RALeach RA et al; Correlates of myoelectric asymmetry et al; Correlates of myoelectric asymmetry detected in low back pain patients using hand-held post-style detected in low back pain patients using hand-held post-style surface electromyography; J Manipulative Physiol Ther. 1993 surface electromyography; J Manipulative Physiol Ther. 1993 Mar-Apr;16(3):140-9. Mar-Apr;16(3):140-9.

3. Morningstar MW et al (2006); Improvement of lower 3. Morningstar MW et al (2006); Improvement of lower extremity electrodiagnostic findings following a trial of spinal extremity electrodiagnostic findings following a trial of spinal manipulation and motion-based therapymanipulation and motion-based therapy

4. 4. CollocaColloca CJ CJ et al; J Manipulative Physiol Ther.; Stiffness and et al; J Manipulative Physiol Ther.; Stiffness and neuromuscular reflex response of the human spine to neuromuscular reflex response of the human spine to posteroanterior manipulative thrusts in patients with low back posteroanterior manipulative thrusts in patients with low back pain. 2001 Oct;24(8):489-500. pain. 2001 Oct;24(8):489-500.

5. 5. CollocaColloca CJ CJ et al; Electromyographic reflex responses to et al; Electromyographic reflex responses to mechanical force, manually assisted spinal manipulative mechanical force, manually assisted spinal manipulative therapy, Spine (Phila Pa 1976). 2001 May 15;26(10):1117-24. therapy, Spine (Phila Pa 1976). 2001 May 15;26(10):1117-24.


6. 6. Keller TSKeller TS et al; J Manipulative Physiol Ther. 2000 Nov-Dec;23(9):585-95. et al; J Manipulative Physiol Ther. 2000 Nov-Dec;23(9):585-95. Mechanical force spinal manipulation increases trunk muscle strength Mechanical force spinal manipulation increases trunk muscle strength assessed by electromyography: a comparative clinical trial.assessed by electromyography: a comparative clinical trial.

7. Manual medicine guidelines for musculoskeletal injuries (Reference: 7. Manual medicine guidelines for musculoskeletal injuries (Reference: http://http://www.guideline.gov/summary/summary.aspx?sswww.guideline.gov/summary/summary.aspx?ss=15&doc_id=10798&nbr=5626=15&doc_id=10798&nbr=5626))Braddock E, Greenlee J, Hammer RE, Johnson SF, Martello MJ, O'Connell Braddock E, Greenlee J, Hammer RE, Johnson SF, Martello MJ, O'Connell MR, Rinzler R, Snider M, Swanson MR, Tain L, Walsh G. Manual medicine MR, Rinzler R, Snider M, Swanson MR, Tain L, Walsh G. Manual medicine guidelines for musculoskeletal injuries. California: Academy for guidelines for musculoskeletal injuries. California: Academy for Chiropractic Education; 2007 Apr 1. 33 p.Chiropractic Education; 2007 Apr 1. 33 p.

8. Roy SH et al, Journal of Rehabilitation Research and Development Vol . 8. Roy SH et al, Journal of Rehabilitation Research and Development Vol . 34 No . 4, October 1997 Pages 405-414. Classification of back muscle 34 No . 4, October 1997 Pages 405-414. Classification of back muscle impairment based on the surface electromyographic signal. impairment based on the surface electromyographic signal.

9. Bertolucci LF et al, J Body Mov Ther. 2008 Jul;12(3):213-24. Epub 2008 9. Bertolucci LF et al, J Body Mov Ther. 2008 Jul;12(3):213-24. Epub 2008 Jul 7.Jul 7.

10. 10. OddssonOddsson et al; et al; Physical TherapyPhysical Therapy; An investigation of the reliability and ; An investigation of the reliability and validity of posteroanterior spinal stiffness judgments made using a validity of posteroanterior spinal stiffness judgments made using a reference-based protocol, aug 1998. reference-based protocol, aug 1998.

11. Greenough et al; Assessment of spinal musculature using surface 11. Greenough et al; Assessment of spinal musculature using surface electromyographic spectral color mapping. electromyographic spectral color mapping. SpineSpine 1998;23:768-74 1998;23:768-74

12. DeLuca CJ; Use of the surface EMG signal for performance evaluation 12. DeLuca CJ; Use of the surface EMG signal for performance evaluation of back muscles. of back muscles. Muscle NerveMuscle Nerve 1993;16(2):210-16 1993;16(2):210-16

13. 13. http://encyclopedia.thefreedictionary.com/electrodiagnostichttp://encyclopedia.thefreedictionary.com/electrodiagnostic 14.http://www.aafp.org/online/etc/medialib/aafp_org/documents/policy/14.http://www.aafp.org/online/etc/medialib/aafp_org/documents/policy/

state/emg.Par.0001.File.tmp/stateadvocacy_EMG.pdfstate/emg.Par.0001.File.tmp/stateadvocacy_EMG.pdf

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