[Amyotrophic lateral sclerosis. Occurrence and prognosis].

The epidemiology of amyotrophic lateral sclerosis in Hordaland county, western Norway, was studied during the period 1979 through 1988. Average annual incidence was 1.60 per 100,000 habitants and the male/female ratio was 1:26. The maximal age-adjusted annual incidence was 8.12 and occurred in the age-group 61-65 years. The mean age at start of symptoms was 60.9 years. The prevalence of amyotrophic lateral sclerosis in Hordaland as per 1 January 1989 was 3.67 per 100,000. The mean survival from onset of disease was 28 months, distributed as 24 months in patients with bulbar onset of symptoms and 40 months in patients with spinal onset symptoms.