Objectives: Posterior fossa brain arteriovenous malformations (PFbAVMs) are rare lesions. Management is complicated by eloquence of adjacent neurological structures, multimodality treatment is often necessary and obliteration not always possible. We describe our 15-year experience in the management of posterior fossa brain AVMs with focus on clinical outcome.
Methods: From 1989 to 2004, prospectively collected information on 106 patients with diagnosis of a PFbAVMs was obtained. Clinical and angioarchitectural characteristics, management options and complications are described and reviewed to evaluate their impact on final outcome as measured by mRS (modified Rankin Score).
Results: Ninety-eight patients were followed for an average of 3.3 years (1-14.6). Male to female ratio was 1:1. Ninety-five out of 98 patients (96.9%) were symptomatic at presentation, with 61 (62.2%) intracranial hemorrhages. Sixty-two patients were treated (46 cerebellar, 16 brainstem). Ten hemorrhages occurred in follow up (4.1%/year). Modified Rankin Score was obtained in 62 patients and was classified as low (good, mRS ≤ 2) or high (poor, mRS ≥ 3). Hemorrhage was the only predictor of poor mRS at presentation (p=0.0229). A poor clinical outcome was correlated with the presence of AA (p=0.0276), a poor initial mRS (p<0.0001) and the number of treatments needed (p=0.0434). Patients were significantly more likely to improve than to deteriorate over time (p=0.0201).
Conclusion: The final clinical outcome in PFbAVMs relates directly with the presence of associated aneurysms, number of treatments needed to occlude the AVM and mRS at presentation. Overall, patients are more likely to improve than to deteriorate with management, and expedite, more definitive treatment is probable a better choice in patients with good mRS after hemorrhage.