Dural arteriovenous fistula (DAVF)

DAVF Classification

The two most common classifications for dural AVFs are the Borden and the Cognard classification shown below:

Borden Classification

Type	Features
I	DAVF drainage into a dural venous sinus or meningeal veins, with normal anterograde flow. Usually clinically benign.
II	DAVF draining anterograde into dural venous sinus, but with retrograde flow into cortical veins.
III	DAVF with direct retrograde flow from fistula into cortical veins, causing venous hypertension.

Cognard Classification

1. I Venous drainage into dural venous sinus with antegrade flow
2. IIa Venous drainage into dural venous sinus with retrograde flow
3. IIb Venous drainage Into dural venous sinus with antegrade flow and CVR
4. IIa+b Venous drainage into dural venous sinus with retrograde now and CVR
5. IV Type III With venous ectasias of the draining subarachnoid venis
6. V Direct drainage Into spinal perimedullary veins (CVR indicates cortical venous reflux)

Presence of cortical venous drainage is the most important determinant of rupture nsk from dural arteriovenous fistula. The other factors listed have not been convincingly linked to risk of hemorrhage.