Spasticity,weakness, force variability,and sustained spontaneous motor unit discharges of resting spastic–paretic biceps brachii muscles in chronic stroke |
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| Authors: | Shuo‐Hsiu Chang PT PhD Gerard e Francisco MD Ping Zhou PhD W Zev Rymer MD PhD Sheng Li MD PhD |
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| Institution: | 1. Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston (UTHealth), , Houston, Texas, USA;2. UTHealth Motor Recovery Laboratory at TIRR Memorial Hermann Hospital, , 1333 Moursund Street, B‐107, Houston, Texas 77030, USA;3. Sensory Motor Performance Program, Rehabilitation Institute of Chicago, , Chicago, Illinois, USA;4. Department of Physical Medicine and Rehabilitation, Northwestern University, , Chicago, Illinois, USA;5. Institute of Biomedical Engineering, University of Science and Technology of China, , Hefei, China |
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| Abstract: | Introduction: The purpose of our study was to examine relations among spasticity, weakness, force variability, and sustained spontaneous motor unit discharges in spastic–paretic biceps brachii muscles in chronic stroke. Methods: Ten chronic stroke subjects produced submaximal isometric elbow flexion force on impaired and non‐impaired sides. Intramuscular EMG (iEMG) was recorded from biceps and triceps brachii muscles. Results: We observed sustained spontaneous motor unit discharges in resting biceps on iEMG. Spontaneous discharges increased after voluntary activation only on the impaired side. The impaired side had greater matching errors and greater fluctuations in isometric force. Spontaneous discharges were not related functionally to spasticity, force variability, or weakness. However, greater strength on the impaired side correlated with less force variability. Conclusion: Weakness rather than spasticity is a main factor interfering with voluntary force control in paretic–spastic biceps brachii muscles in chronic stroke. Muscle Nerve, 2013 |
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| Keywords: | electromyography (EMG) force hemiparesis spasticity spontaneous discharges stroke sustained motor unit variability |
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