Abstract 190: Hemorrhage of Cerebral Arteriovenous Malformations Significantly Alters Stereotactic Radiosurgery Outcomes

Abstract

Introduction: Intracranial hemorrhage is simultaneously the most frequent and most debilitating manifestation of cerebral arteriovenous malformations (AVM), but its impact on success and complications of radiosurgery has not been rigorously assessed. In this case-control study, we define the effect of prior hemorrhage on AVM radiosurgery outcomes. Methods: From a prospective, institutional database of 1400 AVM patients treated with Gamma Knife radiosurgery, unruptured and ruptured AVMs were matched in a 1:1 fashion, blinded to outcome, based on patient demographics, prior embolization, AVM size (mean volume of unruptured AVMs 3.7 cm3 versus ruptured AVMs 3.5 cm3, P=0.195), Spetzler-Martin grade and radiosurgical treatment parameters (mean prescription dose for unruptured AVMs 20.9 Gy versus ruptured AVMs 21.0 Gy, P=0.837). There were 270 patients in each cohort. Matched statistical analyses were used to compare the baseline characteristics, obliteration rates, post-radiosurgery latency period hemorrhage risks, and incidences of radiation-induced changes (RIC) between the two cohorts. Results: The actuarial obliteration rates of the two cohorts were similar (unruptured AVMs: 38%, 58%, 76% at 3, 5, 10 years, respectively; ruptured AVMs: 40%, 60%, 73% at 3, 5, 10 years, respectively; P=0.592). However, for embolized AVMs, complete obliteration was more likely to be achieved in unruptured lesions (unruptured AVMs: 25%, 32%, 54% at 3, 5, 10 years, respectively; ruptured AVMs: 18%, 27%, 42% at 3, 5, 10 years, respectively; P=0.038). Prior AVM rupture resulted in a higher annual risk of post-radiosurgery latency period hemorrhage (ruptured AVMs 2.3% versus unruptured AVMs 1.1%, P=0.025) but a lower rate of cumulative and symptomatic RIC (cumulative RIC: ruptured AVMs 30.4% versus unruptured AVMs 48.9%, P<0.0001; symptomatic RIC: ruptured AVMs 7.0% versus unruptured AVMs 12.2%, P=0.041, respectively). The rates of permanent RIC were similar between the unruptured (2.2%) and ruptured (1.9%) AVM cohorts (P=0.761). Conclusion: Prior AVM rupture significantly alters the risk of latency period hemorrhage and RIC following radiosurgery. These effects should be taken into consideration with the multidisciplinary management of AVM patients.