Reactive grip force control in persons with cerebellar stroke: effects on ipsilateral and contralateral hand

This study investigates the cerebellar contribution to reactive grip control by examining differences between (22–48 years) subjects with focal cerebellar lesion due to ischaemic stroke (CL) and healthy subjects (HS). The subjects used a pinch grip to grasp and restrain an instrumented handle from moving when it was subject to unpredictable load forces of different rates (2, 4, 8, 32 N/s) or amplitudes (1, 2, 4 N). The hand ipsilateral to the lesion of the cerebellar subjects showed delayed and more variable response latencies, e.g., 278 ± 162 ms for loads delivered at 2 N/s, compared to HS 180 ± 53 ms (P = 0.005). The CL also used a higher pre-load grip force with the ipsilateral hand, 1.6 ± 0.8 N, than the HS, 1.3 ± 0.6 N (P = 0.017). In addition, the contralateral hand in subjects with unilateral cerebellar stroke showed a delayed onset of the grip response compared to HS. Cerebellar lesions thus impair the reactive grip control both in the ipsilateral and contralateral hand.