The Berlin Bimanual Test for Stroke Survivors (BeBiT-S): Evaluating exoskeleton-assisted bimanual motor function after stroke

Background. Brain/neural hand exoskeletons (B/NHEs) can restore motor function after severe stroke, enabling bimanual tasks critical for various activities of daily living (ADL). Yet, reliable clinical tests for assessing bimanual function compatible with B/NHEs are lacking. Here, we introduce the Berlin Bimanual Test for Stroke (BeBiT-S), comprising 10 relevant bimanual tasks, and evaluate its psychometric properties as well as sensitivity to change related to B/NHE application. Methods. 24 stroke survivors (mean age 56.5 years, 9 female) with upper-limb hemiparesis after stroke underwent the BeBiT-S assessment (baseline). Psychometric properties were evaluated via interrater reliability (ICC) and construct validity (as measured by the correlation with the Chedoke Arm and Hand Activity Inventory, CAHAI). Sensitivity to change related to B/NHE application (intervention) was assessed across 15 stroke survivors (mean age 50.3 years, 5 female). Order of conditions (baseline vs. intervention) was randomized across participants. Results. BeBiT-S showed excellent interrater reliability at baseline (ICC = 0.985, P < .001) and good reliability at the intervention condition (ICC = 0.862, P < .001). Baseline BeBiT-S strongly correlated with CAHAI-8 scores (r(22) = 0.95, P < .001), demonstrating construct validity. The BeBiT-S score improved significantly between baseline (Mdn = 38) and intervention (Mdn = 60, P < .05), evidencing the test’s sensitivity to change following the application of a B/NHE. Conclusions. The BeBiT-S is a reliable and valid test for evaluating bimanual task performance in stroke survivors, and sensitive to assess B/NHE-related improvements in bimanual task performance. Trial registration: NCT04440709, submitted June 18 ^th , 2020