Epidemiology of primary dystonias in Japan: comparison with Western countries.

We performed epidemiological studies of primary dystonia in the city of Kyoto. The prevalence was at least 10.1 per 100,000 persons, which was similar to that in Western countries. Facial dystonia was more common than other types, which contrasts with that reported in Europe. Age of onset for both genders was in agreement with that in other countries.