Posterior fossa AVMs: Increased risk of bleeding and worse outcome compared to supratentorial AVMs

Outcome was poor in 10.8% of the patients with stAVM and in 28.3% of patients with itAVM (p < .001). The risk of a new hemorrhage-associated deficit was significantly higher in itAVMs (p < .001). Most posterior fossa AVMs are associated with an increased hemorrhage rate. Thus they are a predictor for poor outcome and should be treated even if unruptured to maintain good neurological function.