Current surgical results with low-grade brain arteriovenous malformations

Abstract

OBJECTIVE Surgical resection is an appealing therapy for brain arteriovenous malformations (AVM) because of its high cure rate, low complication rate, and immediacy, becoming the first-line therapy for many AVMs. To clarify safety, efficacy, and outcomes associated with AVM resection in the aftermath of ARUBA, we reviewed an experience with low-grade AVMs, the most favorable AVMs for surgery and the ones most likely to have been selected for treatment outside of ARUBA’s randomization process. METHODS A prospective AVM registry was searched to identify patients with Spetzler-Martin grade I and II AVMs treated with surgical resection during a 16-year period. RESULTS Of the 232 surgical patients included, 117 (50%) presented with hemorrhage, 33% had Spetzler-Martin grade I, and 67% had grade II AVMs. Overall, 99 patients (43%) underwent preoperative embolization, with unruptured AVMs embolized more often than ruptured AVMs. AVM resection was accomplished in all patients and confirmed angiographically in 218 patients (94%). There were no deaths among patients with unruptured AVMs. Good outcomes (mRS 0–1) were found in 78% of patients with 97% improved or unchanged from their pre-operative mRS scores. Unruptured AVM patients had better functional outcomes (91% good outcome compared to 65% in the ruptured group, p=0.0008), while relative outcomes were equivalent (98% improved/unchanged in ruptured AVM patients versus 96% in unruptured AVM patients). CONCLUSION Surgery should be regarded as the “gold standard” therapy for the majority of low-grade AVMs, utilizing conservative embolization as a preoperative adjunct. High surgical cure rates and excellent functional outcomes in both ruptured and unruptured patients support a dominant surgical posture, with radiosurgery reserved for risky AVMs in deep, inaccessible, and highly eloquent locations. Despite the technological advances in endovascular and radiosurgical therapy, surgery still offers the best cure rate, lowest risk profile, and greatest protection against hemorrhage for low-grade AVMs. ARUBA results are influenced by a low randomization rate, bias toward non-surgical therapies, a shortage of surgical expertise, a lower rate of complete AVM obliteration, a higher rate of delayed hemorrhage, and short study duration. Another randomized trial is needed to reestablish the role of surgery in unruptured AVM management.

Microsurgery for ARUBA Trial (A Randomized Trial of Unruptured Brain Arteriovenous Malformation)–Eligible Unruptured Brain Arteriovenous Malformations

“…Postoperative DSA confirmed complete resection in 98.1% of cases, accounting for the refusal of 1 patient to undergo DSA and thus assuming persistence of AVM in that individual. In contrast, the low-grade ubAVMs (SM1 and SM2) in our series were associated with higher obliteration rates (99.2%) and lower PDD (3.4%), which compares favorably to the overall morbidity (2.2%) and complete obliteration rates (98.5%) presented in a recent systematic review of microsurgery on low-grade AVMs by Potts et al 40 The mean and median duration of follow-up in our series were 36.1 and 18 months, respectively, which is comparable to the mean follow-up in ARUBA (33 months). The short duration of follow-up in this series can be explained by our institutional practice to discharge patients from further clinical follow-up beyond 12 months postoperatively once curative resection is confirmed by DSA.…”

“…15,38,40 In our series, the overall EDD and PDD (mRS≥3) rates were 12.3% and 4.5%, respectively. Postoperative DSA confirmed complete resection in 98.1% of cases, accounting for the refusal of 1 patient to undergo DSA and thus assuming persistence of AVM in that individual.…”

Radiosurgery for Cerebral Arteriovenous Malformations in A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA)-Eligible Patients

“…3,21 Furthermore, 66% of the treated patients in ARUBA had Spetzler-Martin grade I or II AVMs, for which resection can be strongly considered at experienced centers, and radiosurgery provides an excellent risk to benefit profile. [22][23][24][25] Radiosurgery is a minimally invasive modality for the treatment of AVMs, and it is especially favorable, relative to microsurgery, for small-to moderate-sized AVMs in eloquent or deep brain areas. [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] The results of many previous radiosurgery series are confounded by the inclusion of patients who were previously treated with surgical resection, embolization, and fractionated radiation therapy.…”

Responses to ARUBA: a systematic review and critical analysis for the design of future arteriovenous malformation trials

“…Sug gestions included continuing the followup of recruited pa tients over a longer period of time, keeping a registry, 3,4,10 and designing other randomized studies. 6,21,35 …”