High-attitude headache: Epidemiology, pathophysiology, therapy and prophylaxis

Headache is known to be the predominant symptom in acute mountain sickness which is also frequently accompanied by nausea, vomiting and insomnia. Nowa days, every year millions of skiers and mountaineers are attracted to mount ains all over the world. At altitudes between 2500 m and 5000 m about 20% t o 90% of those who are not adapted to high altitude will experience high al titude headache (HAH). It is well documented that HAH can be best prevented by observance of the golden rule: not to go too high too fast. Although ma ny mountaineers are aware of this rule, its observance is complicated by un known individual susceptibility, the location of mountain huts, the use of cable cars, limited holiday time, unfavorable weather or avalanche conditio ns. Therefore, there is a widespread use of drugs for the treatment and pre vention of HAH. In the past, the increase in cerebral blood flow during acute hypoxia was t hought to be the main cause of HAH. More recent findings, however, have cau sed this hypothesis to be reduced in importance and have supported the path ogenetic consequence of sensitization of intracranial pain-sensitive struct ures. The effectiveness of cyclooxygenase inhibition for the treatment and prevention of HAH suggests that especially prostaglandins may be an importa nt mediator between hypoxia and HAH. Besides oxygen, acetazolamide, dexamethasone and especially inhibitors of p rostaglandin synthesis such as ibuprofen and naproxen are approved for the treatment of HAH. Acetazolamide, dexamethasone, and aspirin were also found to prevent HAH. The most beneficial effects however, may be achieved by th e combined application of acetazolamide and aspirin. This combination incre ases oxygenation and reduces prostaglandin synthesis.