Disintegration and reorganization of cortical motor processing in two patients with cerebellar stroke

Cerebello-cerebral interaction plays a fundamental role in movement processing. Extensively studied in monkeys, cerebello-thalamo-cerebral information processing is less clear in humans. Taking advantage of the tight linkage between cerebellum and cerebral motor cortex, the objective of this experiment was to gain information on cerebellar function, dysfunction and recovery by analyzing movement-related cortical potentials (MRCPs). MRCPs were recorded prior to voluntary repetitive finger movements from two cerebellar stroke patients, in the acute phase of cerebellar stroke and after clinical recovery. Ten normal subjects served as controls. The main result was a significant depression of late MRCP components over the contralateral motor cortex when patients performed index finger movements of the affected side in the acute phase, and improvement of depressed components after clinical recovery, 8-10 months later. Topographic maps of late MRCP components showed diffusely enlarged potential fields with ataxic movements in the acute phase, and re-focused fields on follow-up. We conclude that (1) late MRCP components are particularly sensitive to cerebellar input in humans and can reflect different functional states of the cerebellum, (2) disturbance of motor cortex function after cerebellar stroke (diaschisis) can occur as a temporary phenomenon that reverses with good clinical recovery.