All laboratory parameters, including a CBC count, serum electrolyte measurements, a biochemical survey, a coagulation profile, and a measurement of serum creatinine phosphokinase levels, were normal. His arterial blood gas analysis results were normal (pH, 7.47; Po2, 85.6 mm Hg; pco2, 33.8 mm Hg). Pulmonary function tests were consistent with a restrictive ventilatory defect (FVC, 2.36 L/min and 59.1% predicted; FEV1, 1.77 L/min and 55.2% predicted). His maximal inspiratory and expiratory pressures were decreased at 35.0 mm Hg (73% predicted) and 45.8 mm Hg (69% predicted), respectively. Electromyography demonstrated the following typical characteristics of type 3 SMA: spontaneous muscle activity with fibrillations and fasciculations, but normal transmission velocity of peripheral sensory nerves.