Objective: 

The aim of this study was to analyse the contribution of the cerebellum to movement efficiency in a precision grip task.

Methods: 

Grip force and pull force were analysed in an isometric prehension task. Pull force had to be increased in a smooth and linear fashion. Movement efficiency was derived by stochastic frontier analysis in healthy subjects (CTRL, N=11) and cerebellar patients (CBL, N=11). This technique allows covariation of grip force and the resulting pull force to be analysed with the variation of the grip force being taken into account. For each trial an efficiency score (range: 0–1) is calculated describing the performance differences in grip-force/pull-force coupling.

Results: 

In contrast to CTRL, CBL tended to decompose the pull-force movement into two phases: after an initial sharp and brief increase (1st phase) pull force remained constant (2nd phase). During the first phase CBL and CTRL showed no difference in movement efficiency. In contrast, during the second phase the values of movement efficiency were reduced in CBL compared with CTRL. Results of individual subjects were summarized and the median group score was calculated. CBL had a median score of 0.23, which was significantly lower (p<0.01) than the value of CTRL (movement efficiency score = 0.53).

Conclusion: 

Cerebellar patients have more difficulty in generating smooth isometric movements. In addition, they have difficulties coupling grip force and pull force efficiently. Supported by the "Else-Kröner-Fresenius Stiftung" (A12/07)