RESUMEN
Cortical vein thrombosis (CVT) is rare and is most common in the third decade of life. Cerebral venous thrombosis may be due to a variety of pathologic conditions like deficiencies of protein S (PS), antithrombin III, protein C, factor V Leiden, prothrombin gene mutations and hyperhomocysteinemia. Protein S is a vitamin K-dependent anticoagulant present in plasma and prevent thrombosis in association with protein C. Lack of it results in venous thromboembolism (VTE) rarely causing thrombosis of cerebral venous sinuses. Our patient is a 35-year-old male who presented with focal seizures. MRI brain showed venous infarcts, and MR venogram showed extensive thrombosis of superior sagittal sinus. Later work up for hypercoagulable state showed significant Protein S deficiency.