Stereotactic radiosurgery for arteriovenous malformations after Onyx embolization: a case-control study

Abstract

E mbolization of intracranial arteriovenous malformations (AVMs) was first introduced by Luessenhop and Spence in 1960. 32 Over the next few decades, advances in embolization materials and techniques, including the introduction of transfemoral embolization, detachable or calibrated-leak balloons, particle or liquid embolization, and superselective angiography, made embolization a valuable tool for the management of intracranial AVM. Several reports demonstrated 0%-94% cure rate, 5%-35% morbidity rate, and 0%-5% mortality rate. 1,8,18,23,29,34,37,44,52 Following the introduction of radiosurgical technique in the early 1960s, Steiner et al. successfully treated a brain AVM with stereotactic radiosurgery (SRS) in 1970. 62Since then, SRS has been established as an effective treatment alternative for intracranial AVMs, particularly for those with small-or medium-sized nidi located in eloquent or deep regions. In previously reported series, intracranial AVMs treated with 20-25 Gy have 3-year obliteration rates between 55% and 81% and complication rates ranging from 2.5% to 9.3%. 16,22,49,67,68 Endovascular embolization and radiosurgery each have specific advantages, and either may be used as a standaBBreViatiONS ARE = adverse radiation effect; AVM = arteriovenous malformation; DSA = digital subtraction angiography; EVOH = ethylene-vinyl alcohol; GKS = Gamma Knife surgery; LINAC = linear accelerator; MRA = MR angiography; nBCA = n-butyl-2-cyanacrylate; PVA = polyvinyl alcohol; RBAS = radiosurgery-based AVM score; SRS = stereotactic radiosurgery. OBJect Onyx, an ethylene-vinyl alcohol copolymer mixed in a dimethyl sulfoxide solvent, is currently one of the most widely used liquid materials for embolization of intracranial arteriovenous malformations (AVMs). The goal of this study was to define the risks and benefits of stereotactic radiosurgery (SRS) for patients who have previously undergone partial AVM embolization with Onyx. methOdS Among a consecutive series of 199 patients who underwent SRS between January 2007 and December 2012 at the University of Virginia, 25 patients had Onyx embolization prior to SRS (the embolization group). To analyze the obliteration rates and complications, 50 patients who underwent SRS without prior embolization (the no-embolization group) were matched by propensity score method. The matched variables included age, sex, nidus volume before SRS, margin dose, Spetzler-Martin grade, Virginia Radiosurgery AVM Scale score, and median imaging follow-up period. reSultS After Onyx embolization, 18 AVMs were reduced in size. Total obliteration was achieved in 6 cases (24%) at a median of 27.5 months after SRS. In the no-embolization group, total obliteration was achieved in 20 patients (40%) at a median of 22.4 months after SRS. Kaplan-Meier analysis demonstrated obliteration rates of 17.7% and 34.1% in the embolization group at 2 and 4 years, respectively. In the no-embolization group, the corresponding obliteration rates were 27.0% and 55.9%. The between-groups difference in obliteration rate...

Highlights on Cerebral Arteriovenous Malformation Treatment Using Combined Embolization and Stereotactic Radiosurgery: Why Outcomes are Controversial?

“…Similarly, several groups have shown a parallel trend of results [37-39]. Sirin, et al [38] in 2006, studied outcomes in 28 patients with gigantic AVM sizes (SM IV-VI), after embo/SRS treatment and obtained obliteration rates as worse as 20%-29% over three years follow-up period.…”

“…Therefore, Dalyai and co-workers concluded that this combined approach is very useful for the treatment of large and complex AVMs [14]. Several investigators have also obtained improved obliteration outcomes with combined treatment, ranging between 50%-78% with minimal SAEs [17,25,37-39], as displayed in Table 4.…”

“…Sirin, et al [38] in 2006, studied outcomes in 28 patients with gigantic AVM sizes (SM IV-VI), after embo/SRS treatment and obtained obliteration rates as worse as 20%-29% over three years follow-up period. Lee, et al in 2015 [39], studied 199 AVM patients with a subsequent four-year follow-up. The obliteration rate with combined (Onyx/SRS) treatment was 24%, and the single SRS was 40%.…”

Stereotactic radiosurgery as a feasible treatment for intramedullary spinal arteriovenous malformations: a single-center observation

“…New advances in stereotactic radiosurgical techniques definitely facilitate the application of CyberKnife™ to spinal AVMs [13][14][15]. In this report, we summarize the clinical and radiographic outcomes of five patients with spinal AVM who were treated with CyberKnife™.…”

Onyx embolization prior to stereotactic radiosurgery for brain arteriovenous malformations: a single-center treatment algorithm

“…Lee et al published the first study comparing outcomes between Onyx embolized and non-embolized groups: 25 patients who underwent pre-SRS embolization with matched patients who underwent SRS alone 26. Radiographic obliteration occurred in 6 (24%) embolized patients and in 20 (40%) non-embolized patients.…”