Vocal tremor reduction with deep brain stimulation.

We present a case illustration of the significant effect that deep brain stimulation (DBS) of the thalamus can have on vocal tremor. A 72-year-old female with a history of essential tremor was noted preoperatively to have a moderate vocal tremor (3 on a scale of 1-5). Following bilateral DBS of the thalamus, the vocal tremor rating improved to 1. Acoustic analysis demonstrated her vocal tremor to be affecting the amplitude of her voice at 5.58 Hz preoperatively, at 1. 93 Hz postoperatively with both leads on and at 1.54 Hz with only the left lead on. A videotaped endoscopic view of the patient's vocal cords (presented at the 1999 ASSFN meeting) clearly illustrated the dramatic changes apparent in the vocal tremor when the stimulators were turned on and off.