Treatment of involuntary movement disorders with tetrabenazine.

Seventeen patients with choreiform, athetoid, or ballistic involuntary movements, or with spasmodic torticollis, were treated with tetrabenazine in doses of 25 to 200 mg daily for periods varying from two weeks to more than six months. Randomized ciné film of the patients' involuntary movements, taken before, during, and after treatment was assessed individually by seven `blind' observers. Eight patients were judged improved; two had Huntington's chorea, two athetosis, two dystonia musculorum deformans, one hemiballismus, and one spasmodic torticollis. Four of the eight improved patients have continued taking the drug for longer than six months. In a second study seven patients with Huntington's chorea were treated for two weeks each with tetrabenazine (50 mg t.d.s.) and with amantadine (100 mg t.d.s.) and the results assessed by the same method. The choreiform movements of six of these patients were strikingly improved with tetrabenazine therapy, but amantadine had no effect. Tetrabenazine is an effective agent for the suppression of choreiform and ballistic involuntary movements. It is only slightly effective in the treatment of athetosis and spasmodic torticollis. Drowsiness, insomnia, and depression were the most conspicuous unwanted effects, and these may limit the clinical usefulness of the drug.