Superior sagittal sinus thrombosis occurring at high altitude associated with protein C deficiency.

A 42-year-old male presented with right-sided weakness, dysphasia and seizures while climbing the French Alps at an approximate altitude of 3,000 m. Imaging studies were consistent with superior sagittal sinus thrombosis with hemorrhage. Laboratory testing for thrombophilic states, 18 days after presentation at our hospital, showed a low protein C level (0.32 U/ml, normal 0.80-1.60 U/ml). A family member was also found to have protein C deficiency without a history of thrombosis. The patient gradually improved and was discharged on warfarin and valproic acid. This is the first reported case of cerebral venous thrombosis in a patient with congenital protein C deficiency who ascended to high altitude. We postulate that the ascent to high altitude represented an additional prothrombotic risk factor to the congenital protein C deficiency leading to cerebral thrombosis.