Disturbance of motor imagery after cerebellar stroke.

The authors studied the possible involvement of the cerebellum in nonexecutive motor functions needed for a normal performance of complex motor patterns by analyzing (using chronometric evaluation) finger movement sequences and their respective motor imagery (a mental simulation of motor patterns). Patients suffering from a cerebellar stroke (n=11) were compared with aged-matched control volunteers (n=11). Patients that had apparently recovered from a unilateral cerebellar stroke showed a marked slowing of motor performance in both hands (ipsi- and contralateral to lesion). This effect was accompanied by a similar slowing of motor imagery, suggesting that the cerebellum, traditionally implicated in the control of motor execution, is also involved in nonexecutive motor functions such as the planning and internal simulation of movements.