Acute respiratory failure and sleep-disordered breathing in Arnold-Chiari malformation.

We report on the case of a 32-year-old man who was admitted after an episode of acute respiratory failure. Clinical and laboratory investigations revealed nocturnal hypoventilation with predominately obstructive sleep apneas accompanied by lower cranial nerve palsies, cerebellar and mild pyramidal signs. Magnetic resonance imaging disclosed Arnold-Chiari type I malformation with syringomyelia. Transcranial magnetic stimulation demonstrated the integrity of the corticodiaphragmatic pathway and it was postulated that the respiratory disorder was mainly due to the severe and irreversible lower cranial nerve palsies. Two years after decompressive craniectomy, sleep disordered-breathing persisted despite no radiological evidence of brain stem compression. Nevertheless, non-invasive positive pressure ventilation (NIPPV) during sleep proved to be quite effective in the management of the patient's refractory respiratory insufficiency. In conclusion, Arnold-Chiari type I may rarely present with acute respiratory failure and sleep apneas. An electrophysiological investigation into the mechanism of the respiratory dysfunction is presented.