Periodic apnea, exercise hypoventilation, and hypothalamic dysfunction.

Periodic apnea and exercise hypoventilation were observed in a 14-year-old boy. Hyperphagia, obesity, serum hyperosmolality without diabetes insipidus or appropriate thirst, and retardation of growth and sexual development indicated a hypothalamic disorder. Neurologic evaluation was normal except for electroencephalographic changes induced by apnea. Pulmonary function tests, resting arterial blood gases in the wakeful state, and ventilatory response to inhaled CO2 were also normal. Acute hypoxemia and respiratory acidosis occurred with apnea during sleep and with insufficient ventilation during exercise. The central origin of sleep apneas was shown by esophageal pressure monitoring. The hypothalamic dysfunction and exercise hypoventilation distinguish this patient from others with obesity and periodic apnea.