Amyotrophic lateral sclerosis in Palermo, Italy: an epidemiological study.

The incidence, prevalence and natural course of ALS were determined in the population of the province of Palmero, Italy. The average annual incidence calculated for the years 1973 through 1984, was 044./100.000 inhabitants. The prevalence rate on prevalence day December 31, 1984, was 1.67/100.000 population. The male/female ratio was 1.38. The mean age at onset was 54.3 +/- 11.02. The most common clinical form was the conventional one (61.4%); the bulbar form was more frequent among females than males. The mean duration of the disease was 33.7 +/- 35.8 months. The longest duration belongs to the pseudopolyneuritic form. The median survival was 36 months: 16 months for the bulbar, 36 months for the conventional and 51 months for the pseudopolyneuritic form.