User:Mr. Ibrahem/High-altitude cerebral edema

High-altitude cerebral edema (HACE) is a medical condition in which the brain swells because of the effects of high altitude. Symptoms often include trouble with coordination and confusion. Often this is preceded by acute mountain sickness with headaches, trouble sleeping, nausea, and loss of appetite. It may be complicated by seizures or high altitude pulmonary edema.

Onset is generally after two days above 4000 m though it can occur as low as 2500 m. Risk factors include rapid accent, strenuous exercise, and prior history of altitude sickness. The underlying mechanism is believed to involve low oxygen resulting in blood vessel dilation, leaky capillaries, and blood–brain barrier disruption. Diagnosis is based on symptoms.

Treatment is by immediate descend to a lower altitude. If descending is not possible oxygen, dexamethasone, or a portable hyperbaric chamber may be used. Prevention is by slowly increasing the elevation at which one sleeps. The medication acetazolamide has also been used for prevention.

HACE is a rare condition, occurring in less than one percent of people who ascend to above 4000 m. Males are more commonly affected than females. Death can occur within 24 hours of onset. The first clear description was in 1913 by Thomas Ravenhill.