Familial paroxysmal dystonic choreoathetosis: a family study.

We interviewed and examined 12 members of a single family affected by paroxysmal dystonic choreoathetosis. Three subjects experienced characteristic painful dystonic spasms, often precipitated by cold and prolonged physical activity. Three other family members suffered painful cramping of their limbs, without involuntary movement, following physical exertion. Based on the clinical features of affected subjects, we suggest that exertional cramping may represent a "forme fruste" of paroxysmal dystonia.