Upper-extremity interlimb coupling in persons with left hemiplegia due to stroke

Objective: To investigate interlimb coupling in an adult population with left hemiplegia and an age-matched control group to better understand the unique motor control issues in stroke rehabilitation. Design: A chi-square analysis was performed to compare the distribution of participants adopting a given movement pattern ratio during 2 different bimanual movement tasks for both groups. The task involved oscillating the upper limbs at the elbow in asymmetric patterns, with I limb oscillating at twice the frequency of the other. Setting: Testing was done in the subjects' residences or in an outpatient clinic. Participants: Participants were between the ages of 45 and 75 years (mean +/- standard deviation, 63 +/- 9.4y), right handed, and included 18 left hemiparetic and 18 control subjects. Selection criteria for the hemiparetic group included status after nonhemorrhagric stroke within the distribution area of the right middle cerebral artery (RMCA). Interventions: Not applicable. Main Outcome Measure: Relative phase of the upper extremities. Results: The hemiplegic group produced predominantly an in-phase 1-to-1 movement pattern, whereas the control group exhibited antiphase. 2-to-1 movement harmonics and, to a lesser extent, in-phase movement patterns. Conclusions: This study suggests that brain damage caused by stroke in the RMCA distribution area results in the reduction of selectable interlimb movement patterns. Specifically, bimanual upper extremity movement tended to be highly coupled in an in-phase movement pattern. Research is needed to examine the ability of stroke survivors to learn bilateral upper-extremity tasks at less stable levels of interlimb coupling.