A case of primary alveolar hypoventilation associated with mild proximal myopathy

A 34-year-old man presented with clinical features of primary alveolar hypoventilation, but was found additionally to have an adult onset myopathy caused by acid maltase deficiency. This was not severe, as judged clinically, and was initially overlooked. His vital capacity and sprint maximal ventilatory volume were only slightly reduced, and the ventilatory response to CO2 was virtually absent. There was, however, a mild impairment in the ability to decrease Pco2 to normal by voluntary hyperventilation. The relation of myopathy and alveolar hypoventilation is discussed, and it is proposed that the primary muscle disease predisposed the patient to the development of the ventilatory abnormality.