Multimodality Management of Spetzler-Martin Grade 3 Brain Arteriovenous Malformations with Subgroup Analysis

Abstract Introduction Spetzler-Martin grade 3 (SM3) lesions entail 4 distinct subtypes described based on size, eloquence, and deep venous drainage (DVD) (3A-3D). The ideal management of each is contentious, and the results of A Randomized Trial of Unruptured Brain AVMs (ARUBA) introduced additional controversy and attention towards management strategies of unruptured bAVMs. Methods We retrospectively reviewed 114 patients with treated SM3 bAVMs, including both ruptured and unruptured lesions. Primary outcomes included modified Rankin score (mRS) at most recent follow-up, angiographic cure, and permanent treatment related complications (morbidity). Other outcomes included mortality, bAVM recurrence or rebleed, and transient treatment related complications. We used uni and multivariate modeling to determine if any specific features were predictive of outcomes. For unruptured bAVMs, an “ARUBA-eligible” subgroup analysis was performed. We also reviewed the literature on management of ruptured and unruptured SM3 bAVMs. Results Of the 114 identified SM3 bAVMs, 40% were unruptured. Most (43.5%) lesions in the unruptured group were type 3C, whereas most ruptured bAVMs (66.2%) were 3A. Unruptured lesions were mostly managed with radiosurgery (47.8%) and ruptured ones with preoperative embolization and surgery (36.7%). Surgical intervention was predictive of angiographic cure in multivariate modeling, even after controlling for at least 2 years of follow up, though associated with a slightly higher rate of morbidity. Focal neurological deficit (FND) was the only predictor of a worse (mRS > 2) functional outcome in follow-up for unruptured bAVMs. For ruptured bAVMs, superficial and cerebellar location were predictive of better outcomes in multivariate models, in the absence of a focal neurological deficit at presentation and new post-surgical deficit. ARUBA SM3 bAVMs specifically underwent more embolization as a monotherapy and less microsurgical resection than the present series. Conclusions In spite of a heterogeneous array of angioarchitectural and anatomical features, SM3 bAVMs can be treated safely and effectively with surgery and radiosurgery either without or with pretreatment embolization. Ruptured lesions are more often type 3A, with smaller nidus, deep brain location, and deep venous drainage. FND predicts worse clinical outcomes. Contemporary multimodality management of SM3 bAVMs is not adequately represented in the results of ARUBA, likely due to differe