Classification of arteriovenous malformations and arteriovenous fistulas

Distinguishing featurePresence of a nidusNo nidus
Grading systemSpetzler-Martin classificationCognard classification
Borden classification
ClassificationSpetzler-Martin AVM grading scaleCognard 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 = 1Borden 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