A Novel Robotic Task for Assessing Impairments in Bimanual Coordination Post-Stroke

Abstract

Background: Bimanual tasks are integral to the performance of many activities of daily living, but impairments in bimanual coordination following stroke are not well quantified with existing clinical tools. Objective: The current study outlines a novel robotic task for the objective and quantitative assessment of bimanual impairment following stroke. Methods: We developed a robotic, bimanual assessment task using the KINARM robot. The task involved moving a virtual ball on a bar linking the two hands, to targets displayed using a virtual reality system. Seventy-five healthy control participants and 23 participants with sub-acute stroke were assessed using the task. Task performance of participants with stroke was compared with the healthy control group, as well as to standard clinical tests (Chedoke- McMaster Stroke Assessment (CMSA) arm and hand, Functional Independence Measure (FIM), Montreal Cognitive Assessment (MoCA) and Behavioural Inattention Test (BIT)). Results: A range of impairments in bimanual task performance was found for participants with stroke. As a group, 85% of participants with stroke had impairments on more task parameters than 95% of healthy controls. Participants with stroke commonly displayed impairments in task success (fewer targets hit); movement metrics (slower movement speed) and bimanual coordination (larger difference in reaction time between hands, greater number of speed peaks with unaffected versus affected limb and greater absolute tilt of the bar). Overall performance of the robotic task (total number of parameters ‘failed’) was significantly correlated with motor performance scores (CMSA, r=-0.6) and strongly correlated with measures of functional ability (FIM motor, r=-0.8). Conclusions: A robotic bimanual task can identify impairments in a population of stroke participants and provides a quantitative measure of bimanual coordination.