Interpretation
| Result | Meaning |
|---|---|
| I–II | Spetzler-Ponce A: low surgical risk |
| III | Spetzler-Ponce B: intermediate |
| IV–V | Spetzler-Ponce C: high surgical risk |
| VI | Inoperable (not computed) |
Formula
Size: <3 cm 1 · 3–6 cm 2 · >6 cm 3. Eloquent location: 1. Deep venous drainage: 1. Grade = sum (I–V).
Clinical pearls
- Eloquent areas: sensorimotor, language and visual cortex; hypothalamus and thalamus; internal capsule; brainstem; cerebellar peduncles; deep cerebellar nuclei.
- Deep drainage = any drainage through deep veins (internal cerebral, basal vein of Rosenthal, precentral cerebellar vein); for posterior fossa AVMs only cerebellar hemispheric veins draining to straight sinus or transverse sinus count as superficial.
- Grade VI (inoperable) is assigned clinically and is not produced by this calculator. The Lawton-Young supplementary grade adds age, rupture status and nidus diffuseness.
Examples
spetzler martin 2.5 cm avm in motor cortex with deep drainageAVM grade: 7 cm nidus, non-eloquent, superficial drainage
FAQ
What is a grade III AVM?
Spetzler-Martin grade III (e.g. small, eloquent, deep drainage or medium, eloquent, superficial drainage) is heterogeneous; Spetzler-Ponce class B suggests multimodality treatment.
Is a 3 cm AVM small or medium?
Medium: small is <3 cm, medium 3–6 cm, large >6 cm.