Interlimb coordination deficits during cyclic movements in cerebellar hemiataxia.

The authors report a 35-year-old man whose unilateral cerebellar lesion resulted in marked deficits in coordinating simultaneous cyclic movements of the arm and leg on his ipsilesional side. He exhibited no such deficits when making simultaneous movements of the contralesional limbs or when moving paired left and right limbs. Thus, the cerebellum, which is already known to underlie within-limb interjoint coordination, also contributes to coordination between limbs.