Sex-related influences on the frequency and age of onset of primary dystonia

We studied 957 cases of primary (idiopathic) dystonia and found a significa nt excess of female patients for segmental and focal dystonia. A novel obse rvation was a significantly earlier age at onset in males as opposed to fem ales 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, blep harospasm, and laryngeal dystonia. For writer's cramp and focal limb dyston ia, 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, acid sex-linked factors may play a role.