Clinical Neurophysiological Assessment of Residual Motor Control in Post-Spinal Cord Injury Paralysis

McKay, William; Lim, Hyun Chul; Priebe, Michael M.; Stokić, Dobrivoje S.; Sherwood, Arthur M.

doi:10.1177/0888439004267674

Cited by 109 publications

(92 citation statements)

References 26 publications

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“…This was discussed in another publication of our group. 2 Previous work using sEMG has shown that as motor control deteriorates during a fatiguing voluntary motor task in healthy subjects, muscles not involved in the task begin to coactivate, and coactivation continues to increase during the period of the exercise. 28 Also, using sEMG as an objective measure of coactivation, Thomas et al 29 noted that muscles 'weakened by SCI' require near-maximal effort and activation that is accompanied by synergistic activation of other antagonistic muscles that further exacerbates the weakness of the movement.…”

Section: Discussionmentioning

confidence: 99%

“…However, lesions clinically judged as complete often retain residual supraspinal connectivity not clinically recognizable. 1,2 For motor incomplete spinal cord injured (iSCI) subjects, partially disrupted voluntary control of lower-limb muscles determines many aspects of their recovery following the acute phase post injury.…”

Section: Introductionmentioning

confidence: 99%

“…24 Further, the VRI has been used to characterize trace voluntary control in complete SCI subjects. 2 The purpose of this study was to evaluate the VRI for its criterion validity as an objective, quantitative measure of SCI lesion severity as it impacts voluntary motor control severity.…”

Section: Introductionmentioning

confidence: 99%

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Neurophysiological assessment of lower-limb voluntary control in incomplete spinal cord injury

et al. 2005

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Study design: Cross-sectional retrospective study of a neurophysiological method of voluntary motor control characterization. Objectives: This study was undertaken to validate the surface electromyography (sEMG)-based voluntary response index (VRI) as an objective, quantitative, laboratory measure of spinal cord injury severity in terms of voluntary motor control disruption. Setting: VA Medical Centers in Houston and Dallas Texas, USA. Methods: A total of 67 subjects with incomplete spinal cord injury (iSCI), American Spinal Injury Association Impairment Scale (AIS)-C (n ¼ 32) and -D (n ¼ 35) were studied. sEMG recorded during a standardized protocol including eight lower-limb voluntary motor tasks was analyzed using the VRI method that relates multi-muscle activation patterns of SCI persons to those of healthy-subject prototypes (n ¼ 15). The VRI is composed of a measure of the amount of the sEMG activity (magnitude) and the distribution of activity across muscle groups compared to that of healthy subjects for each motor task (similarity index, SI). These resulting VRI components, normalized magnitude and SI, were compared to AIS clinical findings in this study. Receiver operating characteristic analysis was performed to determine the SI values best separating AIS-C and AIS-D subjects. Results: Magnitude and SI for AIS-C subjects had mean values of 0.2770.32 and 0.6570.21, respectively. Both parameters were significantly larger in the AIS-D subjects (0.7870.43 and 0.9370.06), respectively (Po0.01). An SI value of 0.85 was found to separate AIS-C and AIS-D groups with a sensitivity of 0.89 and a specificity of 0.81. Further, the VRI of each leg strongly correlated with the respective AIS motor score (0.80, ro0.01). Conclusions: In the domains of voluntary motor control, the sEMG-based VRI demonstrated adequate face validity and sensitivity to injury severity as currently measured by the AIS.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Neurophysiological assessment of lower-limb voluntary control in incomplete spinal cord injury

et al. 2005

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“…Even in individuals with severe SCIs, some spared trans-lesional systems, descending long-tract fibers or propriospinal fibers, are nearly always present. 15,16 It has been shown that the remaining altered spinal cord circuits below the injury can be activated and modified by transcutaneous spinal cord stimulation. 17 We suppose that in patients in whom the vestibulospinal pathways remained preserved, the altered spinal cord circuits below the injury could be conditioned by activation of the vestibulospinal pathways.…”

Section: Introductionmentioning

confidence: 99%

A paradigm of galvanic vestibular stimulation diminishes the soleus muscle H-reflex in healthy volunteers

Cobeljic¹,

Miljković

Ribarič-Jankes

et al. 2015

Spinal Cord

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Study design: In this study, we explored how galvanic vestibular stimulation can modify the soleus H-reflex (Hoffman reflex), that is, the excitability of the spinal cord circuits, in healthy humans. Objectives: Our aim was to demonstrate H-reflex amplitude modulation caused by changing the duration and the intensity of the anodal galvanic vestibular stimulation. Therefore, we measured H-reflex before and after applied vestibular stimulation. Settings: This study was conducted in Rehabilitation Clinic, Belgrade, Serbia. Methods: The measurements were performed on 5 male volunteers aged 22-30 years. Anodal galvanic stimulation was applied on the right mastoid in prone position. H-reflex was elicited by nervus tibialis stimulation and measured from the right soleus muscle. In three subjects, trains of weak and strong galvanic stimuli (1, 5 and 9) were applied. In two subjects, only a train of 9 strong stimuli was applied. Results: A statistically significant decrease of the H-reflex amplitude after anodal galvanic stimulation was demonstrated in all subjects. The percentage of H-reflex amplitude diminution was between 6 and 18 in subjects with weak and strong stimuli and 5 and 6 in subjects with only 9 strong stimuli. Conclusion: We intend to use this paradigm of stimulation to explore whether the vestibulospinal function exists after spinal cord injury (SCI). If it exists, it can be used to influence the preserved spinal cord circuits after SCI. INTRODUCTIONIt has been long known that a small direct current, also called galvanic current, applied between mastoids produces an inclination of the standing person. 1 Several researchers have studied the electromyographic (EMG) responses occurring in response to galvanic stimulation of postural muscles in healthy subjects. They used a 1-or 4-to 6 -s duration, 1-4-mA intensity stimulus. 2,3 If averaging of the EMG activity was necessary, they used stimuli of shorter duration. [4][5][6] There is general agreement that anodal stimulation causes hypotonia and cathodal stimulation causes hypertonia of the ipsilateral postural muscles. The effect of galvanic current is also influenced by head and body posture, 7 as well as postural task. 8 In squirrel monkeys, it was demonstrated that the galvanic stimulation acted directly on the vestibular afferents (from semicircular canals, as well as otoliths): cathodal current increased the firing rate (causing hypertonia) and anodal current decreased the firing rate (causing hypotonia of the muscles). 9 More recently, 10-13 the electrical-induced analog of the monosynaptic reflex called the H-reflex has been used in assessment of the modulation of the monosynaptic activity at the spinal cord level.If a short-lasting electrical stimulus is applied to the tibial nerve within the popliteal fossa, motor and sensory fibers are stimulated simultaneously. The stimulation of motor fibers results in a muscle twitch of the soleus muscle, which can be demonstrated by means of bipolar superficial electrodes placed over the corresponding muscle be...

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“…14,22 While the Ashworth and modified Ashworth scales 14,15,23 are commonly used to assess the severity of spasticity, there is some question about their validity in the lower limbs of persons with SCI. 24 As spasticity outcomes vary between clinical patient groups and depend on a variety of factors within each individual, a battery of assessment tools is recommended, incorporating clinical, electrophysiologic, neurophysiological, 25 and/or biomechanical techniques. 14,26,27 It is important to note that there are generally poor correlations among clinical scales and, further, reductions in spasticity are not necessarily correlated with improvement in function.…”

Section: Introductionmentioning

confidence: 99%

Spasticity after spinal cord injury

2005

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Symptoms of spasticity are often experienced by individuals with spinal cord injury (SCI) following a period of spinal shock and, in many cases, these symptoms negatively affect quality of life. Despite its prevalence, spasticity as a syndrome in the SCI population is not always managed effectively. This is likely due to the fact that the syndrome can have various presentations, each with their own specific etiology. This overview summarizes the symptoms and pathophysiology of the various presentations of spasticity in the SCI population and discusses the currently accepted management techniques. There is a need for a better understanding of the syndrome of spasticity as well as the development of a valid and reliable assessment tool.

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Clinical Neurophysiological Assessment of Residual Motor Control in Post-Spinal Cord Injury Paralysis

Cited by 109 publications

References 26 publications

Neurophysiological assessment of lower-limb voluntary control in incomplete spinal cord injury

Neurophysiological assessment of lower-limb voluntary control in incomplete spinal cord injury

A paradigm of galvanic vestibular stimulation diminishes the soleus muscle H-reflex in healthy volunteers

Spasticity after spinal cord injury

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