Abstract
Objective: To assess corticomotor (CM) excitability of the antagonist biceps brachii (BB) post-stroke in preparation for pronator contraction. In healthy subjects, we previously demonstrated that prior to pronator contraction CM excitability of the antagonist BB was suppressed. Methods: Transcranial magnetic stimulation (TMS) was used to assess pre-contraction changes in motor evoked potential (MEP) amplitude of the BB, when BB was acting either as an antagonist or an agonist. TMS was applied 100-200 ms prior to rhythmic isometric BB or pronator contractions in chronic stroke survivors and age/gender matched healthy control subjects. Results: Prior to pronator contraction, MEPs in BB were elicited in the stroke group but were absent in healthy controls indicating that CM excitability of the antagonist BB was increased post-stroke. The extent of the abnormal increase in excitability positively correlated with the extent of upper limb motor impairment. Conclusions: Our results suggest that an alteration of cortical control mechanisms regulating motor excitability of the antagonist BB may contribute to the impairment of upper limb motor coordination post-stroke. Significance: This study offers a unique approach to study the potential for a cortical origin of post-stroke motor discoordination.
Original language | English (US) |
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Pages (from-to) | 683-692 |
Number of pages | 10 |
Journal | Clinical Neurophysiology |
Volume | 119 |
Issue number | 3 |
DOIs | |
State | Published - Mar 2008 |
Funding
We are grateful to Tobey DeMott, MS PT for assessment of stroke patients and to Mary Ellen Stoykov MS OTR/L, Carol Mottram, PT PhD and Michelle Prior MS for their help in recruitment of subjects. We are also grateful to subjects who volunteered for this study. Financial support was provided through a T32 grant from NIH (PI, WZR). Additional financial support was provided by the AHA (JWS).
Keywords
- Abnormal flexor synergy
- Motor preparation
- Stroke
- Transcranial magnetic stimulation
ASJC Scopus subject areas
- Clinical Neurology
- Neurology
- Sensory Systems
- Physiology (medical)