Abstract
The cerebellum is known to play an important role in the coordination and timing of limb movements. The present study focused on how reach kinematics are affected by cerebellar lesions to quantify both the presence of motor impairment, and recovery of motor function over time. In the current study, 13 patients with isolated cerebellar stroke completed clinical measures of cognitive and motor function, as well as a visually guided reaching (VGR) task using the KINARM exoskeleton at baseline (~2 weeks), as well as 6, 12, and 24-weeks post-stroke. During the VGR task, patients made unassisted reaches with visual feedback from a central ‘start’ position to one of eight targets arranged in a circle at a distance of 10cm. At baseline, 7/13 patients were impaired across several parameters of the VGR task compared to a Kinarm normative sample (n=307), revealing deficits in both feed-forward and feedback control. The only clinical measures that consistently demonstrated impairment were the Purdue Pegboard Task (PPT) and the Montreal Cognitive Assessment. Overall, patients who were impaired at baseline showed significant recovery by the 24-week follow-up for both VGR and the PPT. A lesion overlap analysis indicated that the regions mostly commonly damaged in 5/13 patients (38% overlap) were lobule HIX and Crus II of the right cerebellum. Our results are consistent with previous work indicating that the cerebellum is involved in both feedforward and feedback control during reaching, and that cerebellar patients tend to recover relatively quickly overall. Notably, baseline PPT scores predicted only 33% of the variance in VGR task performance. This suggests that objective kinematic measures may provide a more complete picture of overall motor impairment than clinical measures alone. These additional kinematic data could be helpful in monitoring the assessment and recovery of motor function in patients with cerebellar stroke with greater precision.