Recurrent sagittal sinus thrombosis occurring at high altitude during expeditions to Cho Oyu.

We report the case of a previously healthy 32-year-old man presenting with severe headache on 2 separate expeditions to Cho Oyu (8201 m). No brain imaging was performed after the first expedition. On the second expedition, thrombosis of the superior sagittal sinus was detected. Investigations for hypercoagulable states, including polycythemia, were negative. He had no neurological symptoms except headache, vomiting, and slight drowsiness. In retrospect, there are strong indications that cerebral thrombosis caused his headache on the first expedition as well. Severe headache occurring at high altitude that persists despite adequate treatment for high-altitude cerebral edema should raise suspicion of a cerebrovascular disorder.