PROS1 and Rare hereditary thrombophilia: However, in almost all cases, when LP plays a role in CVT, there is 1 or more susceptible factors such as the use of high-dose steroid, inherited thrombophilia, malignancy, the postpartum state, oral contra-ceptives and reduced activity of Protein C and Protein S.[4,6] Studies have shown that CVT occurs after high-dose steroid therapy in the absence of LP history and other risk factors.[7] These results suggest that high-dose steroid therapy may be an independent risk factor for CVT.