High altitude cerebral edema

High altitude cerebral edema (HACE) is a severe form of acute mountain sickness (AMS) characterized by the same symptoms, headache, malaise and fatigue which can progress to ataxia, altered consciousness, hallucinations, coma and death. Signs include papilledema, extensor plantar responses and other neurological signs. There may be mild fever, cyanosis (which may be secondary to concomitant high altitude pulmonary edema (HAPE)), increased pulse and respiratory rates. Computed tomography (CT) and post-mortem appearance indicate cerebral edema, and magnetic resonance imaging (MRI) scans show lesions in the splenium and corpus callosum. In untreated cases remaining at altitude, death can occur in a few hours or days.