Headache, usually bilateral and aggravated by exertion, caused by ascent above 2,500 metres. It resolves spontaneously within 24 hours after descent.
- Headache fulfilling criterion C
- Ascent to altitude above 2,500 metres has occurred
- Evidence of causation demonstrated by at least two of the following:
- headache has developed in temporal relation to the ascent
- either or both of the following:
- a) headache has significantly worsened in parallel with continuing ascent
- b) headache has resolved within 24 hours after descent to below 2,500 metres
- headache has at least two of the following three characteristics:
- a) bilateral location
- b) mild or moderate intensity
- c) aggravated by exertion, movement, straining, coughing and/or bending
- Not better accounted for by another ICHD-3 diagnosis.
10.1.1 High-altitude headache is a frequent complication of ascent to altitude, occurring in more than 30% of mountaineers. Risk factors include a history of 1. Migraine, low arterial oxygen saturation, high perceived degree of exertion, restrictions in venous outflow and low fluid intake (<2 litres in 24 hours).
Most cases of 10.1.1 High-altitude headache respond to simple analgesics such as paracetamol (acetaminophen) or ibuprofen. However, acute mountain sickness (AMS) consists of at least moderate headache combined with one or more of nausea, anorexia, fatigue, photophobia, dizziness and sleep disturbances. Acetazolamide (125 mg, 2-3 times daily) and steroids may reduce susceptibility to AMS. Other preventative strategies include 2 days of acclimatization prior to engaging in strenuous exercise at high altitudes, liberal fluid intake and avoidance of alcohol.
Dwelling at altitudes above 1,000 metres increases not only prevalence but also the severity of the symptoms of 1. Migraine. The mechanisms are unknown, and probably unrelated to those of 10.1.1 High-altitude headache.