What is it?
High-altitude cerebral edema (HACE) is an emergency in which swelling of the brain occurs because of high altitude. Early recognition is important as it is usually leads to death within 24 hours if left untreated. HACE occurs when people who are not used to being at high altitudes ascend to such places of elevation too quickly.

Symptoms

• Confusion
• Fever
• Fast heart rate (tachycardia)
• Altered mental state
• Worsening coordination
• Severe headache

Sports Medicine Evaluation and Treatment
HACE is generally preceded by acute mountain sickness and high-altitude pulmonary edema (HAPE). HACE rarely occurs at an elevation below 3,000 meters (9,800 feet) above sea level. It usually does not present unless the individual has spent more than 48 hours at 4,000 meters (13,000 feet) above sea level.

• If HACE is suspected, immediate descent to a lower altitude, followed by evacuation to an appropriate medical facility, is necessary.
• Early recognition is important.
• Supplemental oxygen.
• Dexamethasone can improve symptoms.

Injury Prevention

• Gradual ascent – Less than 1,000 meters (3,300 feet) per day
• Avoid sleeping higher than 300 meters (980 feet) for more than one night
• Acetazolamide or dexamethasone can lower the risk of developing HACE

Return to Play
In a few days, athletes who get HACE may fully recover. Some athletes may take a few weeks, though. Going up to the elevation that caused the symptoms may be possible after all symptoms have resolved, although it may have to be done at a much slower pace, and possibly with stops along the way. Acetazolamide may need to be continued upon return to elevation. Dexamethasone, if it was used for treatment, may be stopped.

AMSSM Member Authors: Jon Divine, MD and Justin Mullner, MD

References:
Hackett PH, Roach RC. High-Altitude Illness. N Engl J Med. 2001; 345:107
Luks AM, McIntosh SE, Grissom CK, et al. Wilderness Medical Society Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness. Wilderness Environ Med 2010; 21:146
Madden C, McCarty E, Putukian M, Young C. Netter’s Sports Medicine. Saunders Elsevier; 2010.