PROS1 and Rare hereditary thrombophilia: There is increasing evidence associating underlying thrombophilic disorders to CVT [20–22], so we studied the hereditary thrombophilias and found that AT III deficiency was found in 11.25% of the patients presenting with CVT this result conforms with Khealani et al. [23], who found that 7% of their patients had AT III deficiency, we found that 5% of patients have protein S and C deficiency which is consistent with Pai et al. [24], and Martinelli et al. [25], respectively.