Methazolamide for essential voice tremor.

We studied the safety and efficacy of methazolamide (average dose 168 mg/day) in a placebo-controlled blinded investigation in nine patients with essential voice tremor. There were no significant differences for physician or patient clinical rating scores. Digital audio tape recordings showed no difference for amplitude modulation, but frequency modulation was significantly altered by methazolamide. Side effects were common with the drug. We conclude that methazolamide has limited usefulness in the treatment of essential voice tremor.