Unchanged incidence and prevalence of amyotrophic lateral sclerosis in the canton of Zürich.

The incidence and prevalence of amyotrophic lateral sclerosis (ALS) was determined for the canton of Zürich over the ten year period 1981-1990. The annual incidence rate was found to be 0.92 per 100,000 population, while the prevalence rate was 3.88 per 100,000 population, with a preponderance for males. Strong yearly fluctuations in the number of newly detected cases average out over the whole period with no trends of increased incidence. Data are within the range as reported from other industrialized countries.