Depressed ventilatory response in oculocraniosomatic neuromuscular disease.

Four patients with ptosis, external ophthalmoplegia, and ragged-red fibers on muscle biopsy were found to have decreased ventilatory responses to hypoxia and hypercapnia. Respiratory muscle weakness was not responsible for these findings since these responses were normal in muscle disease control patients. An altered metabolic state also can cause diminished ventilatory response, but overall oxygen consumption data in the ragged-red fiber patients were normal. The decreased ventilatory responses may be clinically significant because two of the ragged-red fiber patients had episodes suspicious of hypoventilation with poor response to hypoxia.