[Usefulness of polysomnography at an early stage of amyotrophic lateral sclerosis].

A 47-year-old man who presented moderate muscle weakness in the neck and all the extremities was diagnosed as having early stage of amyotrophic lateral sclerosis (ALS). He did not have bulbar dysfunction and respiratory distress. His pulmonary function tests and arterial blood gas analysis showed no abnormalities, but polysomnography (PSG) revealed sleep-disordered breathing requiring mechanical support ventilation. Bi-level positive airway pressure treatment was started only at night, which improved both sleep-disordered breathing and daytime activity. PSG should be considered in ALS patients at an early clinical stage in order to predict mild respiratory dysfunction.