Why does a dural arteriovenous fistula (DAVF) develop?
Unlike AVMs, which are thought to be present from birth, cranial DAVF most often develop later in life following blockage or thrombosis of a cranial dural venous sinus. Cranial dural venous sinuses are relatively large-caliber blood-containing structures that exist in-between the leaflets of the brain’s dural covering. These sinuses usually move large volumes of venous blood from the brain, back towards the base of the brain where they form the internal jugular vein on each side of the head/neck junction. When a venous sinus blocks off for whatever reason, the brain can try to compensate by moving venous blood across other parallel or collateral pathways. In this process, however, a fistula may form, representing an abnormal collateral pathway to drain blood away from the brain. Why would a venous sinus block off or thrombose? Reasons include chronic central nervous system infection, brain trauma, or a patient with some form of hypercoagulability state (tendency to experience thrombosi
