OBJECTIVE: ARUBA (A Randomized Trial of Unruptured Brain Arteriovenous Malformations) found better short-term outcomes after conservative management compared with intervention for unruptured arteriovenous malformations (AVMs). However, because Spetzler-Martin (SM) grade I–II AVMs have the lowest treatment morbidity, sufficient follow-up of these lesions may show a long-term benefit from intervention. The aim of this multicenter, retrospective cohort study is to assess the outcomes after stereotactic radiosurgery (SRS) for ARUBA-eligible SM grade I–II AVMs.
METHODS: We pooled SRS data for patients with AVM from 7 institutions and selected ARUBA-eligible SM grade I–II AVMs with ≥12 months follow-up for analysis. Favorable outcome was defined as AVM obliteration, no post-SRS hemorrhage, and no permanently symptomatic radiation-induced changes.
RESULTS: The ARUBA-eligible SM grade I–II AVM cohort comprised 232 patients (mean age, 42 years). The mean nidus volume, SRS margin dose, and follow-up duration were 2.1 cm3, 22.5 Gy, and 90.5 months, respectively. The actuarial obliteration rates at 5 and 10 years were 72% and 87%, respectively; annual post-SRS hemorrhage rate was 1.0%; symptomatic and permanent radiation-induced changes occurred in 8% and 1%, respectively; and favorable outcome was achieved in 76%. Favorable outcome was significantly more likely in patients treated with a margin dose >20 Gy (83%) versus ≤20 Gy (62%; P < 0.001). Stroke or death occurred in 10% after SRS.
CONCLUSIONS: For ARUBA-eligible SM grade I–II AVMs, long-term SRS outcomes compare favorably with the natural history. SRS should be considered for adult patients harboring unruptured, previously untreated low-grade AVMs with a minimum life expectancy of a decade.