Sleep and breathing in patients with the Prader-Willi syndrome.

The Prader-Willi syndrome is characterized by infantile hypotonia, early childhood obesity, mental deficiency, short stature, small hands and feet, and hypogonadism. Many patients also have hypersomnolence, experience daytime hypoventilation, and subsequently die prematurely of cardiorespiratory failure. Hypersomnolence and daytime hypoventilation are also common occurrences in the sleep apnea syndrome. For a better understanding of the relationship of sleep to the features of the Prader-Willi syndrome, we retrospectively reviewed five patients (two adults, one adolescent, and two children) with this syndrome who underwent polysomnography. All patients were obese; they had hypersomnolence and daytime hypoxemia, and they nored. In all patients, the apnea plus hypopnea index was less than 10 episodes per hour of sleep. During rapid eye movement sleep, nonapneic reductions in oxyhemoglobin saturation were detected in one adult and in one child. Despite the presence of morbid obesity and a history of snoring, patients with Prader-Willi syndrome seem to have only mild sleep-disordered breathing.