Dural arteriovenous fistulae (DAVF)
DAVF drainage into a dural venous sinus or meningeal vein with normal anterograde flow. Usually benign clinical behaviour.
Anterograde drainage into dural venous sinus and onwards but retrograde flow occurs into cortical veins. May present with haemorrhage.
Direct retrograde flow of blood from the fistula into cortical veins causing venous hypertension with a risk of haemorrhage.