The prevalence of focal/segmental dystonia and HFS in Oslo

All patients seeking medical treatment for primary focal and segmental dystonia, and medical or surgical treatment for hemifacial spasm (HFS), in Oslo, Norway were identified in a service-based prevalence study. January 1^st, 2001 was chosen as the prevalence date. Only three hospital departments offered services for Oslo citizens with dystonia, while four departments treated HFS. All together 129 patients with focal and segmental dystonia were treated. The total prevalence was 25.4 per 100,000. An under representation of first generation immigrants was observed. The prevalence for Oslo's ethnical European population was 28.3 per 100,000. This is similar to the highest prevalence previously reported. All together 50 patients with HFS were treated. The total prevalence was 9.8 per 100,000. The prevalence increased with age to 39.7 among those older than 70. Worldwide, only one smaller prevalence study has previously been published. The use of anti-hypertensive drugs was significantly more common in HFS patients (36%) than in Oslo's general population. A possible association between HFS and arterial hypertension has previously been suggested, but not confirmed. Our findings may be taken to indicate, but does not prove, such an association.