Impairments of prehension kinematics and grasping forces in patients with cerebellar degeneration and the relationship to cerebellar atrophy

Objective This study established the relationship between kinematic and grip force parameters in prehension tasks, disease severity and cerebellar atrophy in patients with cerebellar degeneration. Methods Prehension was tested in a condition during which the hand reached out, grasped, and lifted an object. Task complexity was modified by limiting the transport component to a single-joint movement, and introducing a bimanual condition. Results Compared to controls the cerebellar patients showed disturbances in hand transport, in hand shaping and the most pronounced in time to peak grip force and the grip/load force coupling. Task-dependent changes did not differ between groups. Ataxia scores revealed significant correlations with hand transport and shaping measures only. Ataxia subscores correlated with volume reduction of appropriate longitudinal cerebellar zones. Volume reduction of the intermediate zone was associated with grip force coordination deficits. Conclusions Results indicate that the cerebellum may have a more general role in motor control of grasping independent of task complexity. Temporal and coordinative measures of grip force appear to be most useful to assess the severity of grasping deficits in patients with cerebellar degeneration not detectable by clinical ataxia scales. Significance To assess the severity and course of cerebellar disease grip force control in a standard prehension task is a sensitive quantitative measure.