HIGH ALTITUDE NEUROLOGICAL SYNDROMES PART 1

Induction to high altitude exposes the individual to increasingly severe hypoxia resulting in high altitude illnesses. Neurological symptoms constitute an important aspect of these illnesses. The high altitude headache is the commonest and is reported in as high as 83% of the members of an expedition over 7000 feet. Among various studies incidence of acute mountain sickness varied from 8.3% to 67%. While incidence of life threatening high altitude cerebral edema is reported as less than 0.001% in people traveling to 2500 meters to 1% for those traveling to 4000-5000 meters, the incidence of high altitude pulmonary edema varied from 0.4 to 15.5%. While 20-8% of acute mountain sickness case develop cerebral edema, 50% cases of high altitude pulmonary edema have acute mountain sickness another 14% have high altitude cerebral edema. High altitude pulmonary edema and high altitude cerebral edema, if unrecognized or left untreated, are associated with a high mortality rate of 44% and 60% respectively. Early recognition, prompt treatment and evacuation to low altitude result in complete recovery. Strict adherence to acclimatization schedule and physical checkup before induction to high altitude can prevent these complications. The areas where high altitude activities are common should have a well equipped hospital with trained staff and an evacuation plan.There is a need of evolving a method of predicting the illness before induction to high altitude. This article summarizes the present knowledge regarding clinical manifestations, pathogenesis and management of neurological syndrome and high altitude with reference to high altitude illnesses.