1Grenoble Institut of Neurosciences, INSERM, Grenoble, France; 2Laboratoire HP2, INSERM, Echirolles, France; 3Ecole Nationale de Ski et dAlpinisme, Chamonix, France; 4SFR1, Universit Joseph Fourier, Grenoble, France; 5ESRF, Grenoble, France; 6Clinique universitaire de neuroradiologie et d'IRM, CHU Grenoble, Grenoble, France
We assess the effects of a sojourn of 6 days at 4,350m on cerebral perfusion and on cerebrovascular reactivity to CO2 using ASL at sea level and transcranial Doppler ultrasound at altitude. We demonstrate that high altitude exposure significantly decreases vasoreactivity to CO2. The increase in CBF observed after several days at high altitude is not only the consequence of the vasodilating effect of hypoxia but probably involves other mechanisms such as changes in cerebral autoregulation and angiogenesis. This study is the first to measure cerebral perfusion and vasoreactivity with ASL after a prolonged stay at high altitude.