Cerebral venous infarction during a high altitude expedition.

Bilateral venous infarction of the brain due to thrombosis of the deep cerebral venous system is relatively rare, accounting for approximately 3-8 percent of all cases of cerebral venous thrombosis (CVT). Known risk factors include the use of oral contraceptives, pregnancy, puerperium, malignancy and thrombophilic states. CVT, in the setting of acute mountain sickness (AMS), has rarely been reported. We present an unusual occurrence of bilateral deep subcortical venous infarction in a previously-well, 39-year-old woman, who developed AMS during a high altitude expedition in Nepal. The possible mechanisms responsible for this unfortunate event include dehydration with resultant relative polycythaemia and raised intracranial pressure at high altitudes. CVT should be considered in mountain climbers presenting with progressive neurological deterioration that is not solely attributable to AMS.