<unk>  occurs in 0.5% to 1% of people who climb or trek between and . In some unusual cases, up to 30% of members of expeditions have suffered from the condition. The condition is seldom seen below , but in some rare cases it has developed as low as . The condition generally does not occur until an individual has spent 48 hours at an altitude of .
High-altitude cerebral edema
High-altitude pulmonary edema
Decompression sickness
Chronic mountain sickness
Intracranial hypertension syndrome
Idiopathic intracranial hypertension
Viral meningitis
Cerebral edema