Deficits in Cognitive-Motor Control of the Ipsilesional Upper Limb in Subacute Stroke Assessed Using a Robotic Exoskeleton: A Longitudinal Study.

Background/Objectives: This study longitudinally assessed cognitive-motor control deficits in the ipsilesional upper limb following stroke and, secondarily, examined the effect of lesion laterality on these deficits. Methods: Forty-one participants (mean [SD] age: 64.6 [14.4] years; 24 with right-hemisphere lesion; 38 right-handed) were assessed using the KINARM Exoskeleton Lab at approximately 4 weeks (T1), 10 weeks (T2), and 29 weeks (T3) post-stroke. They completed the Visually Guided Reaching (VGR) and Reverse Visually Guided Reaching (RVGR; where the cursor moved in the opposite direction to the subject's hand movement) tasks with their ipsilesional limb to assess motor control and cognitive-motor control, respectively. Global Task-scores and Z-scores for specific variables derived from normative data were used to determine the occurrence of deficits within each task. Linear mixed-effects models examined time and lesion-side effects. Results: About 88% and 56% of participants were impaired on the RVGR global Task-score, at T1 and T3, respectively. In contrast, only 12% and 9% of participants were impaired on the VGR Task-score, at T1 and T3, respectively. Performance on the RVGR task improved over time. Interestingly, deficits were significantly more severe for right-hemisphere lesions on several variables, except for the feedforward variables. Performance on the VGR task remained unchanged with no lesion-side effect. Conclusions: Stroke survivors exhibited significant impairments in cognitive-motor control of the ipsilesional upper limb, independent of pure motor deficits, persisting into the chronic stage. Right-hemisphere lesions were associated with greater impairments, indicating a potential hemispheric specialization for such cognitive-motor control task.