title: Role of contralesional hemisphere in paretic arm reaching in patients with severe arm paresis due to stroke: A preliminary report.
abstract: Stroke is highly prevalent and a leading cause of serious, long-term disability among American adults. Impaired movement (i.e. paresis) of the stroke-affected arm is a major contributor to post-stroke disability, yet the mechanisms of upper extremity motor recovery are poorly understood, particularly in severely impaired patients who lack hand function. To address this problem, we examined the functional relevance of the contralesional hemisphere in paretic arm motor performance in individuals with severe arm paresis. Twelve individuals with severe stroke-induced arm paresis (Upper Extremity Fugl-Meyer Assessment=17.1 ± 8.5; maximum score=66) participated in the study. Participants performed a reaching response time task with their paretic arm. At varying time intervals following a 'Go' cue, a pair of transcranial magnetic stimulation (TMS) pulses were delivered to contralesional hemisphere primary motor (M1) or dorsal pre-motor cortex (PMd) to momentarily disrupt the pattern of neural firing. Response time components and hand-path characteristics were compared across the 2 sites for trials with and without TMS disruption. There was no significant effect of TMS disruption on overall Response time or Reaction time, but Movement time was significantly longer (i.e. slower) with disruption of the contralesional hemisphere (p=0.015), regardless of which area was stimulated. Peak hand-path velocity and hand-path smoothness were also significantly lower (p=0.005 and p<0.0001, respectively) with TMS disruption of the contralesional hemisphere. The data from this study provide evidence supporting a functionally relevant role of contralesional hemisphere motor areas in paretic arm reaching movements in individuals with severe post-stroke arm impairment.
authors.affiliation: University of Montana, Missoula, MT, USA.
authors.forename: Sambit
authors.initials: S
authors.lastname: Mohapatra
authors.affiliation: MedStar National Rehabilitation Hospital, Washington DC, USA; Georgetown University Medical Center, Washington DC, USA.
authors.forename: Rachael
authors.initials: R
authors.lastname: Harrington
authors.affiliation: MedStar National Rehabilitation Hospital, Washington DC, USA; MedStar Health Research Institute, Columbia, MD, USA.
authors.forename: Evan
authors.initials: E
authors.lastname: Chan
authors.affiliation: MedStar National Rehabilitation Hospital, Washington DC, USA; Georgetown University Medical Center, Washington DC, USA; Washington DC VA Medical Center, Washington, DC, USA.
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Dromerick
authors.affiliation: MedStar National Rehabilitation Hospital, Washington DC, USA; MedStar Health Research Institute, Columbia, MD, USA; Washington DC VA Medical Center, Washington, DC, USA.
authors.forename: Erika Y
authors.initials: EY
authors.lastname: Breceda
authors.affiliation: MedStar National Rehabilitation Hospital, Washington DC, USA; Georgetown University Medical Center, Washington DC, USA; George Mason University, Fairfax, VA, USA. Electronic address: michelle.l.harris-love@medstar.net.
authors.forename: Michelle
authors.initials: M
authors.lastname: Harris-Love
mesh_terms: D000328:Adult; D000368:Aged; D001132:Arm / Q000503:physiopathology*; D002908:Chronic Disease; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009068:Movement; D010291:Paresis / Q000209:etiology / Q000503:physiopathology*; D011930:Reaction Time; D020521:Stroke / Q000150:complications / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation
keywords: Paresis; Reaching; Stroke; TMS