Reduction in voice tremor under thalamic stimulation.

We studied the effect of deep brain stimulation (DBS) of the ventral intermediate thalamic nucleus on voice symptoms in seven patients with essential tremor. All had undergone DBS for management of hand tremor. Five of the patients had received unilateral implants; two were treated bilaterally. Each reported improvement in hand tremor with thalamic stimulation (a 1-to-3-point change on a 5-point severity scale). Voice tremor was evaluated with and without stimulation using patient and clinician severity ratings, and acoustic measures (rate and amplitude). Four of the seven patients showed reductions in voice symptoms in at least two of these measures, although degree of change differed (e.g., from 1 to 3 points on the 5-point severity scale). Voice gains typically were restricted to those patients with the more severe symptoms and did not parallel improvements in the upper extremities. It appears that reduced voice tremor may be an additional benefit of DBS for some individuals.