Classification of arteriovenous malformations and arteriovenous fistulas
| Pathology | AVM | AVF |
|---|---|---|
| Distinguishing feature | Presence of a nidus | No nidus |
| Grading system | Spetzler-Martin classification | Cognard classification |
| Borden classification | ||
| Classification | Spetzler-Martin AVM grading scale | Cognard classification: |
| Size | Grade I: in sinus wall; normal antegrade venous drainage | |
| Small (<3 cm) = 1 | Grade IIa: in sinus; reflux to sinus, not cortical veins | |
| Medium (3–6 cm) = 2 | Grade IIb: retrograde drainage (reflux) to cortical veins | |
| Large (>6 cm) = 3 | Grade III: direct cortical venous drainage; no venous ectasia | |
| Eloquence of adjacent brain | Grade IV: direct cortical venous drainage and venous ectasia | |
| Noneloquent = 0 | Grade V: Spinal perimedullary venous drainage | |
| Eloquent = 1 | Borden classification: | |
| Venous drainage | Type I: dural arterial supply with antegrade venous drainage | |
| Superficial only = 0 | Type Ia: simple dAVF with single meningeal arterial supply | |
| Deep component = 1 | Type Ib: complex dAVF with multiple meningeal arteries | |
| Type II: retrograde cortical venous drainage | ||
| Type III: dural arteries drain into cortical veins |