Ability of individuals with chronic hemiparetic stroke to locate their forearms during singlearm and between-Arms tasks

According to between-Arms assessments, more than 50% of individuals with stroke have an impaired position sense. Our previous work, which employed a clinical assessment and slightly differing tasks, indicates that individuals who have a deficit on a between-forearms position-localization task do not necessarily have a deficit on a single-forearm position-localization task. Objective Our goal here was to, using robotics tools, determine whether individuals with stroke who have a deficit when matching forearm positions within an arm also have a deficit when mirroring forearm positions between arms, independent of the arm that leads the task. Methods Eighteen participants with chronic hemiparetic stroke and nine controls completed a singlearm position-matching experiment and between-Arms position-mirroring experiment. For each experiment, the reference forearm (left/right) passively rotated about the elbow joint to a reference target location (flexion/extension), and then the participant actively rotated their same/opposite forearm to match/mirror the reference forearm's position. Participants with stroke were classified as having a position-matching/-mirroring deficit based on a quantitative threshold that was derived from the controls' data. Results On our single-Arm task, one participant with stroke was classified as having a positionmatching deficit with a mean magnitude of error greater than 10.7° when referencing their paretic arm. Position-matching ability did not significantly differ for the controls and the remaining seventeen participants with stroke. On our between-Arms task, sevenparticipants with stroke were classified as having a position-mirroring deficit with a mean magnitude of error greater than 10.1°. Position-mirroring accuracy was worse for these participants with stroke, when referencing their paretic arm, than the controls. Concluding remark Findings underscore the need for assessing within-Arm position-matching deficits, in addition to between-Arms position-mirroring deficits when referencing each arm, to comprehensively evaluate an individual's ability to locate their forearm(s).