Motor learning in essential tremor.

Classical conditioning is abnormal in patients with cerebellar degeneration. Pathological studies have recently demonstrated the finding of Purkinje cell loss in a subset of essential tremor (ET). We studied 10 subjects with long duration ET using a blink reflex conditioning paradigm and compared them with nine controls. A 55.6% reduction in motor learning was seen in the first block of stimulation and this finding persisted across all subsequent trials. We conclude that motor learning is significantly abnormal in subjects with advanced ET and likely reflects pathological involvement of the cerebellum.