Evidence for changes in segmental motoneurone pools by chronic cerebellar stimulation and its clinical significance.

Electrophysiological studies in eight patients with severe motor system abnormalities are described both before and after the start of chronic electrical stimulation of the anterior cerebellum. With stimulation, at least one of following changes was found in seven of these eight patients: reversal of abdominal F amplitude ratios (flexor/extensor muscles), decreased prominence of F responses, and loss of H reflexes in at least one muscle other than the soleus. These changes indicate that cerebellar stimulation can affect the excitability of segmental motoneurone pools. Although clinical changes, particularly decrease in tone, were observed in all the patients with stimulation, the complexity of trying to relate the physiological findings to functional improvement is emphasised.