
| Size | Small (>3 cm) Medium (3–6 cm) Large (>6 cm) |
| Location | Noneloquent Eloquent |
| Pattern of Venous Drainage | Superficial only Deep |

Classically, risk of operative morbidity has been related to the SpetzlerMartin (SM) scale which scores AVM on 3 features for a grading score of 1 to 5 .