Primary writing tremor treated by stereotactic selective thalamotomy.

Three cases with primary writing tremor were treated successfully by stereotactic selective thalamotomy centred mainly on the ventralis intermedius nucleus. They exhibited progressive coarse tremor of 5-7 Hz during writing, and Westphal's phenomenon on stretch, as the only neurological manifestations. Within the thalamus, a very high incidence of irregular burst discharges was recorded. These findings suggest that the writing tremor is an organic disorder.