Abnormal corticomotor excitability assessed in biceps brachii preceding pronator contraction post-stroke

Tatyana Gerachshenko, W. Zev Rymer, James W. Stinear*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

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 languageEnglish (US)
Pages (from-to)683-692
Number of pages10
JournalClinical Neurophysiology
Volume119
Issue number3
DOIs
StatePublished - 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)

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