Obstructive sleep apnea presenting as acute delirium.

Obstructive sleep apnea syndrome (OSA) has not been previously reported as a cause of acute delirium. A patient who presented to the emergency department with acute delirium according to DSM-IIIR criteria was noted to have an abnormal respiratory pattern with periods of apnea associated with oxygen desaturation. The observation that the patient had episodes of apnea while sleeping led to the suspicion that this patient had OSA, and formal polysomnography confirmed the diagnosis. Other causes for acute delirium were ruled out. The delirium resolved after the OSA was treated.