Sex-related influences on the frequency and age of onset of primary dystonia. Epidemiologic Study of Dystonia in Europe (ESDE) Collaborative Group.

We studied 957 cases of primary (idiopathic) dystonia and found a significant excess of female patients for segmental and focal dystonia. A novel observation was a significantly earlier age at onset in males as opposed to females for primary segmental (mean age, 44.6 versus 53.3) and focal dystonia (43.8 versus 47.8). This trend was also apparent in cervical dystonia, blepharospasm, and laryngeal dystonia. For writer's cramp and focal limb dystonia, this trend was reversed with an earlier age at onset in females. These results suggest that focal dystonia should not be treated as an homogenous group, and sex-linked factors may play a role.