Abstract
Study design:
Prospective cohort study.
Objective:
This study was designed to neurophysiologically characterize motor control recovery after spinal cord injury (SCI).
Setting:
University of Louisville, Louisville, Kentucky, USA.
Material:
Eleven acute SCI admissions and five non-injured subjects were recruited for this study.
Methods:
The American Spinal Injury Association Impairment Scale (AIS) was used to categorize injury level and severity at onset. Multimuscle surface electromyography (sEMG) recording protocol of reflex and volitional motor tasks was initially performed between the day of injury and 11 days post onset (6.4±3.6, mean±s.d. days). Follow-up data were recorded for up to 17 months after injury. Initial AIS distribution was as follows: 4 AIS-A; 2 AIS-C; 5 AIS-D. Multimuscle activation patterns were quantified from the sEMG amplitudes of selected muscles using a vector-based calculation that produces separate values for the magnitude and similarity of SCI test-subject patterns to those of non-injured subjects for each task.
Results:
In SCI subjects, overall sEMG amplitudes were lower after SCI. Prime mover muscle voluntary recruitment was slower and multimuscle patterns were disrupted by SCI. Recovery occurred in 9 of the 11 subjects, showing an increase in sEMG amplitudes, more rapid prime mover muscle recruitment rates and the progressive normalization of the multimuscle activation patterns. The rate of increase was highly individualized, differing over time by limb and proximal or distal joint within each subject and across the SCI group.
Conclusions:
Recovery of voluntary motor function can be quantitatively tracked using neurophysiological methods in the domains of time and multimuscle motor unit activation.
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Acknowledgements
The authors express their appreciation to the subjects who participated in this study, to Anne Watson, RN, for project management support and Renee Ford for obtaining informed consent and coordination of study scheduling. We are also grateful to Yangsheng Chen for data conversion and Dongchul Lee, and Matthew Nitzken for their preparation of tools used in the calculation of the voluntary response index. In addition, we would like to acknowledge the neurosurgery residents at the University of Louisville Hospital for providing the clinical assessments reported in this study. This study was supported by NIH NINDS funded project #NS049954-01.
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McKay, W., Ovechkin, A., Vitaz, T. et al. Neurophysiological characterization of motor recovery in acute spinal cord injury. Spinal Cord 49, 421–429 (2011). https://doi.org/10.1038/sc.2010.145
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DOI: https://doi.org/10.1038/sc.2010.145
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