RESUMO
Amyotrophic Lateral Sclerosis (ALS) is a fast progressing neuromuscular disease that affects all but the extrinsic muscles of the eye and sphincters. The main cause of morbidity and mortality are the respiratory complications that usually start in a late stage of the diseases natural history. In a small number of cases acute respiratory failure is the initial manifestation of the disease. The authors present 2 case studies admitted to a pulmonary department, without previously known neuromuscular disease, with the diagnosis of acute respiratory failure of unknown etiology and that were later shown to be cases of ALS. Analysis of the cases presented here, and those already published in the literature, suggests that the occurrence of acute respiratory failure in patients without a previous history of pulmonary and/or heart disease, especially in the 5th and 6th decade of life, should alert to ALS as a possible diagnosis.
