Radiosurgery for Cerebellar Arteriovenous Malformations: Does Infratentorial Location Affect Outcome?

OBJECTIVE: The cerebellum is an uncommon location for arteriovenous malformations (AVM) with unique angioarchitecture compared to the cerebrum. We evaluate the outcomes of radiosurgery in a cohort of cerebellar AVMs and assess the effect of infratentorial location by comparing them to a matched cohort of supratentorial AVMs. METHODS: From a prospective AVM radiosurgery database of 1400 patients, we identified 60 cerebellar AVM patients with at least 2 years of radiologic follow-up or obliteration. The median volume and prescription dose were 2.3 mL and 22 Gy, respectively. The median radiologic follow-up was 39 months. The cerebellar AVM patients were matched (3:1) to a cohort of supratentorial, lobar AVM patients based on AVM size and patient age. Univariate and multivariate Cox proportional hazards regression analyses were used to identify factors associated with obliteration and favorable outcome. RESULTS: Cerebellar and supratentorial AVMs were similar in baseline characteristics except for an increased incidence of ruptured lesions in the cerebellar AVM cohort (P < .001). Obliteration was achieved in 72% of cerebellar AVMs. Younger age (P = .019), no preradiosurgery embolization (P < .001), and decreased volume (P = .034) were independent predictors of obliteration. The annual risk of postradiosurgery hemorrhage in cerebellar AVMs was 1.3%. The rates of symptomatic and permanent radiation-induced changes were 7% and 3%, respectively. Compared with the matched supratentorial AVM cohort, there was no difference in the rates of obliteration, postradiosurgery hemorrhage, or symptomatic radiation-induced changes. CONCLUSIONS: Radiosurgery is an effective treatment modality for cerebellar AVMs with relatively limited adverse events. Infratentorial location did not affect radiosurgery outcomes.