Curriculum · Toxicology and Emergency Care
Acute mountain sickness and high-altitude cerebral oedema
What it is
Acute mountain sickness is headache in an unacclimated person who recently arrived at an elevation above 2500 m (8200 ft), plus one or more of anorexia, nausea, vomiting, insomnia, dizziness or fatigue.
High-altitude cerebral edema is where it goes if it deteriorates, and it is defined as the onset of ataxia and/or altered consciousness in someone with acute mountain sickness. The two are one line, not two conditions, and ataxia is the point on that line where the name changes.
Causes and risk
The setting is an unacclimated person who has recently arrived at a high elevation. The worked case is a 47-year-old male who lives at sea level and attempts to climb Mt. Rainier: on the first day he ascends to 3400 m (11,000 ft); the next morning he has a headache, nausea, dizziness and fatigue, and as he continues the climb to the summit he becomes ataxic and confused. Those two lines are the whole story: the first is acute mountain sickness, the second is high-altitude cerebral edema.
The other setting is the man who asks before he goes. A 30-year-old taking a motorcycle trip in 6 weeks to Colorado, including a ride to the top of Pikes Peak at 14,100 ft, who has never been above 5000 ft prior to this trip, is generally healthy and takes no medications but smokes 1 pack of cigarettes per day and is allergic to penicillin. The options weighed for him are an intensive aerobic fitness program, varenicline for smoking cessation, prophylaxis with acetazolamide, and prophylaxis with Ginkgo biloba. Which of the four is the right answer is not given on these pages.