A clinical epidemiological study of 251 cases of amyotrophic lateral sclerosis in the south of Brazil

Objective: To study the clinical forms of amyotrophic lateral sclerosis (ALS) and the possible presence of risk factors in order to verify if there is any difference between cases in Parana, Brazil. Method. We studied 251 cases, all of which fulfilled the diagnosis criteria proposed in El Escorial (WFN). Between 1977 and 2004, 157 male and 94 female patients were examined. Results: 220 cases were classified as ALS-Spinal Onset (ALS-SO), 24 as ALS-Bulbar Onset (ALS-BO),and 7 as Familial ALS. The mean age at time of evaluation was 54.4 +/- 12.3 years, and symptoms had started 17.9 +/- 15.7months previously. In the group studied, statistical relationships were found between heavy occupations and males; previous surgeries and females; ALS-BO and dysphagia and dysarthria in females; and ALS-SO and males, cramps, weakness, muscle atrophy, hypertonia, increased deep tendon reflex and abnormal gait. Conclusion: The average age at time of evaluation was lower than that registered in the literature but similar to the Brazilian series. Domestic work and heavy occupations appear to be related to precocious perception of the symptoms by interference with daily functions. The socioeconomically higher classes seek medical care early. There was no relationship with exposure to toxic agents or trauma.