Nonparetic arm force does not overinhibit the paretic arm in chronic poststroke hemiparesis

Michael A. Dimyan*, Monica A Perez, Sungyoung Auh, Erick Tarula, Matthew Wilson, Leonardo G. Cohen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Objective To determine whether nonparetic arm force overinhibits the paretic arm in patients with chronic unilateral poststroke hemiparesis. Design Case-control neurophysiological and behavioral study of patients with chronic stroke. Setting Research institution. Participants Eighty-six referred patients were screened to enroll 9 participants (N=9) with a >6 month history of 1 unilateral ischemic infarct that resulted in arm hemiparesis with residual ability to produce 1Nm of wrist flexion torque and without contraindication to transcranial magnetic stimulation. Eight age- and handedness-matched healthy volunteers without neurologic diagnosis were studied for comparison. Interventions Not applicable. Main Outcome Measure Change in interhemispheric inhibition targeting the ipsilesional primary motor cortex (M1) during nonparetic arm force. We hypothesized that interhemispheric inhibition would increase more in healthy controls than in patients with hemiparesis. Results Healthy age-matched controls had significantly greater increases in inhibition from their active to resting M1 than patients with stroke from their active contralesional to resting ipsilesional M1 in the same scenario (20%±7% vs -1%±4%, F1,12=6.61, P=.025). Patients with greater increases in contralesional to ipsilesional inhibition were better performers on the 9-hole peg test of paretic arm function. Conclusions Our findings reveal that producing force with the nonparetic arm does not necessarily overinhibit the paretic arm. Though our study is limited in generalizability by the small sample size, we found that greater active contralesional to resting ipsilesional M1 inhibition was related with better recovery in this subset of patients with chronic poststroke.

Original languageEnglish (US)
Pages (from-to)849-856
Number of pages8
JournalArchives of physical medicine and rehabilitation
Issue number5
StatePublished - May 2014


  • Neurophysiology
  • Paresis
  • Rehabilitation
  • Stroke

ASJC Scopus subject areas

  • Rehabilitation
  • Physical Therapy, Sports Therapy and Rehabilitation


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