Cognard Classification (dAVF)

Antegrade drainage into sinus only (No cortical reflux).

Antegrade drainage into sinus with sinus reflux present.

Drainage into sinus with retrograde cortical venous reflux (CVR).

Drainage into sinus with BOTH sinus and cortical reflux.

Direct drainage into cortical veins only (No sinus ectasia).

Direct drainage into cortical veins with venous Ectasia (>5mm).

Drainage into spinal perimedullary veins.