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

23 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

Keywords

  • Abnormal flexor synergy
  • Motor preparation
  • Stroke
  • Transcranial magnetic stimulation

ASJC Scopus subject areas

  • Sensory Systems
  • Neurology
  • Clinical Neurology
  • Physiology (medical)

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