Mexiletine in the treatment of torticollis and generalized dystonia.

Mexiletine is an antiarrhythmic drug that has been reported to exert antidystonic properties. We performed an open-label study to collect further evidence of the antidystonic effect of mexiletine in spasmodic torticollis (ST) and to evaluate its possible use in generalized dystonia. We administered mexiletine to six patients with dystonia (three with generalized dystonia and three with ST) who had failed to respond to previous pharmacotherapy. The drug was started at a dose of 200 mg/d by mouth and increased up to a maximum dose of 800 mg/d. Patients were evaluated at regular intervals over a 6-week period with use of the Fahn & Marsden Dystonia Scale and the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) and videotaped. At the end of the trial, the videotapes were reviewed and scored by a blind observer. Patients were then followed for at least 1 year and evaluated every 3 months at the dose reached during the study period. No adverse effects were reported in five patients; in one patient, dizziness developed at the dosage of 800 mg/d, requiring a reduction of the dose. At the end of a 6-week period, a significant improvement in the rating scale for dystonia and in videotape ratings was observed after mexiletine treatment (p < 0.01). Our data indicate that mexiletine is a useful drug in dystonia treatment.