Deficits in movements of the wrist ipsilateral to a stroke in hemiparetic subjects.

We examined step-tracking movements of the wrist and associated EMG activity in seven patients (age range, 27-73 yr) and in seven normal subjects that were matched to patients in age, sex, and handedness. All patients exhibited a hemiparesis that resulted from a unilateral cerebrovascular accident (CVA) that included motor areas in the frontal lobe or their efferents. The lesion in three patients was in their dominant hemisphere. The patients were tested 1-48 mo following their CVA. They had great difficulty in performing or were unable to perform step-tracking movements with the contralesional wrist. In addition, the patients displayed striking deficits in wrist movements and muscle activity of the ipsilesional wrist. These movements were >50% slower than those of controls. The initial movement step routinely undershot the target and was only 63% as large as that of controls. The patients made wrist movements with marked directional errors requiring corrective responses. These errors were due largely to inappropriate temporal sequencing of muscle activity. The deficits in movement and muscle activity in the wrist ipsilesional to a CVA were marked, regardless of whether the lesion was in the dominant or nondominant hemisphere. These observations indicate that unilateral lesions can have significant bilateral effects on the generation and control of distal limb movements.