Anticholinergics in Adult-Onset Focal Dystonia

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Abstract
Anticholinergics are one of the most common treatments used in adult-onset focal dystonias although their general efficacy has not been proven. We have investigated the effects of intravenous administration of atropine, benztropine and chlorpheniramine, in comparison to normal saline, in 20 patients with adult-onset focal dystonias (spasmodic torticollis (9), cranial dystonia (6), writer’s cramp (5)), and have retrospectively reviewed the notes of 78 patients (spasmodic torticollis (38), cranial dystonia (25), writer’s cramp (15)), who had received chronic oral anticholinergic therapy in varying doses at some time in the past. Patients with spasmodic torticollis and writer’s cramp showed no consistent change with any of the intravenous drugs, while the few with cranial dystonia who improved usually did so at the expense of drug-induced sedation. The natural variability of these disorders was evident in the response to normal saline, which caused changes in the scores for severity of the involuntary movements of 20% or more in some patients. Only 8 of the patients who had received chronic oral therapy obtained more than mild benefit, and in 3 of them this improvement was transient. We conclude that cholinergic mechanisms are not of general or prime importance in the pathogenesis of adult-onset focal dystonias. However, each new patient warrants a trial of chronic oral anticholinergic therapy in view of the occasional useful responses obtained with these drugs.