Role of peripheral inputs in cerebellar tremor

Tremors reflected in the handwriting in nine right-handed male patients with right-sided cerebellar lesions were studied by reversibly blocking peripheral inputs from the hand. Blocking was achieved by applying a sphygmomanometer cuff over the mid-arm and increasing the pressure up to 200 mm Hg. Evoked potentials from the ulnar nerve and handwriting were monitored in each subject at periodic intervals. Improvement in writing was noticed in 3-5 min in different subjects that coincided with partial reduction of the amplitude of the neurograms. This reduction is consistent with dissociate conduction in a small population of large medullated fibers. On releasing the cuff, the neurograms returned to their normal height within the same time frame of 3-5 min, and the handwriting deteriorated with return of tremor. No change in the handwriting of the volunteers was observed at any stage. The ages of the volunteers ranged from 25 to 48 years and those of the patients from 28 to 56 years. The duration of illness of the patients ranged from 1 to 8 years.