Effects of High Altitude on Neurological and Pulmonary Function: The Effect of High Altitude on Visual Evoked Potentials in Humans on Mt. Everest

摘要

The goal of the Ultima Thule Everest Expedition was to investigate the effects of high altitude on cerebral function. We were interested in noninvasive methods of assessing cerebral function at altitude and thus used electrophysiological tests involving cortical evoked potential studies and a drug study using Dilantin and placebo in a double blind randomized fashion. The subjects were climbers and support members of the expedition. Our hypothesis was that acute mountain sickness was a form of cerebral edema and could be objectively assessed with visual evoked potential measurements. Visual evoked potentials were chosen since it has been shown that these wave forms are directly altered by raised intracranial pressure. Dilantin was chosen as a drug that works in the CNS and stabilizes brain function. We hypothesized that Dilantin might prevent some of the symptoms of acute mountain sickness. Our studies revealed that exposure to high altitude, both with and without the symptoms of acute mountain sickness, altered the evoked potential patterns in a significant fashion. With comparison of baseline measurements to high altitude measurements it was seen that certain individuals had objective evidence of transient raised intracranial pressure. The Dilantin study was minimally conclusive based on lack of symptoms of altitude sickness, thus making comparison of the effects of Dilantin to placebo very difficult. However, it was seen that the subjects taking Dilantin had fewer and less severe headaches than the placebo group.