E-189 The era of onyx embolization: a systematic and literature review of preoperative embolization before stereotactic radiosurgery for the management of cerebral arteriovenous malformations

Introduction

The current treatment paradigm for intracranial arteriovenous malformations (AVMs) is ultimately aimed at reducing the intracranial hemorrhage risk and is achieved via a multitude of therapeutic means including embolization, stereotactic radiosurgery (SRS), and microsurgical resection. Over time, treatment paradigms have shifted to an increasingly minimally invasive approach with embolization and SRS being trialed to avoid open cranial interventions in patients with AVMs. In an effort to improve AVM obliteration rates with SRS, pre-radiosurgical embolization has been trialed in a number of studies to reduce the volume of the AVM nidus prior to radiosurgery. However, conflicting evidence has been posited regarding the efficacy of pre-radiosurgical embolizations. Herein, the authors conducted a systematic review to evaluate the history and efficacy of pre-radiosurgical embolization for AVMs in the pre-Onyx era and the Onyx era to compare their strengths and weaknesses as they have developed over time.

Methods

A systematic review was performed using PubMed to identify studies with 20 or more AVM patients, embolization material, and obliteration rates for both E+SRS and SRS only groups.

Results

Seventeen articles consisting of 1133 eligible patients were included in this study. 914 (80.7%) patients underwent embolization prior to SRS. Onyx was used as the embolysate in 340 (37.2%) patients in the E+SRS cohorts. Mean obliteration rate for the embolized cohort was 46.9% versus 46.5% in the SRS only cohort. When comparing obliteration rates based on embolysate material, obliteration rates with Onyx+SRS were 42.1% and 50.0% in the non-Onyx embolysate + SRS cohort.

Conclusion

Embolization of AVMs is a nuanced topic that relies heavily on the embolic material used and has evolved significantly over the decades. Previously trialed embolysates have included polyvinyl alcohol (PVA) particles, N-butyl-2-cyanoacrylate (NBCA), and NBCA with adjunctive platinum coils, however, all of these have been associated with conflicting effects on post-embolization radiosurgical outcomes. Recently, Onyx (ethylene vinyl-alcohol (EVOH) copolymer dissolved in dimethyl sulfoxide (DMSO) and suspended in micronized tantalum powder) has been increasingly used for the embolization of intracranial AVMs with increased success in regard to its ease of use from a technical standpoint and has been shown to perform similarly to other embolysate materials.

Disclosures

V. Letchuman: None. H. Gupta: None. L. Ampie: None. D. Raper: None. R. Armonda: None. J. Sheehan: None. R. Kellogg: None. M. Park: None.