The Yasargil classification is one of the two common systems for classifying vein of Galen malformations that is currently in use at the time of writing (mid 2016).
Classification
type I: small pure cisternal fistula between the vein of Galen (voG) and either the pericallosal arteries (anterior or posterior) or posterior cerebral artery
type II: multiple fistulous communications between the vein of Galen and the thalamoperforating vessels
type III: high flow mixed type I and II
type IV: parenchymal arteriovenous malformation (AVM) with drainage into the vein of Galen