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 seizu res while climbing the French Alps at an approximate altitude of 3,000 m. I maging studies were consistent with superior sagittal sinus thrombosis with hemorrhage. Laboratory testing for thrombophilic states, 18 days after pre sentation 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 deficienc y without a history of thrombosis, The patient gradually improved and was d ischarged on warfarin and valproic acid. This is the first reported case of cerebral venous thrombosis in a patient with congenital protein C deficien cy who ascended to high altitude. We postulate that the ascent to high alti tude represented an additional prothrombotic risk factor to the congenital protein C deficiency leading to cerebral thrombosis.