The Cognard classification, along with the Borden classification, is used to categorize dural AV fistulas. Based on the Cognard classification, dural AV fistulas are divided into 5 different types[^1].
Classification
Cognard type | Description |
Type I | Normal antegrade flow in dural sinuses |
Type IIa | Retrograde flow in sinus |
Type IIb | Retrograde filling of cortical veins |
Type IIc | Retrograde drainage into sinus and cortical veins |
Type III | Direct drainage into cortical veins with retrograde flow |
Type IV | Direct drainage into cortical veins with venous ectasia > 5 mm and 3 times larger than draining vein |
Type V | Drainage into spinal perimedullary veins |