Intracranial Venous Thrombosis (Cerebral Venous Sinus Thrombosis) is an uncommon neurological condition where a blood clot blocks normal drainage of blood from the veins/venous sinuses of the brain. This can increase the pressure inside the skull resulting in brain swelling, a stroke, or bleeding. Possible causes include clotting disorders, infections, dehydration, pregnancy, drugs, and chronic medical conditions. Symptoms vary and may include a severe headache, seizures, visual disturbances, weakness, confusion, and difficulty speaking.