Evaluating the Role of Onyx Embolization in the Management of Spinal Dural Arteriovenous Fistulas: A 20-Year Single-Center Experience

Abstract

Background: Open surgery is widely regarded as the standard treatment for spinal dural arteriovenous fistulas (SDAVFs). However, endovascular treatment (EVT) with liquid embolic agents has emerged as an alternative. While N-butyl cyanoacrylate is often preferred for its superior penetration into draining vein, this study aims to assess the effectiveness of an embolization-first strategy using Onyx, drawing on 20 years of clinical experience.

Methods: A retrospective analysis included 50 patients treated between 2004 and 2024. Only patients undergoing EVT as the first-line therapy for SDAVF were included.

Results: Overall, EVT achieved complete occlusion in 38 (76%) cases, with an additional 6 (12%) requiring adjuvant surgery resulting in definitive cure. In the remaining 6 (12%) patients, embolization of the feeding artery and fistula nidus led to permanent clinical improvement (n = 4, 66%) or stability (n = 2, 33%), supported by indirect fistula signs regression on follow-up magnetic resonance imaging. Onyx was solely used in 84% of EVTs, achieving a complete occlusion rate of 83%. Clinical improvement or stabilization was observed in 46 (92%) patients, with no recurrences in successfully treated patients. There was no EVT-related complication. Follow-up magnetic resonance imagings showed regression of perimedullary varices and regression or stability of myelopathy in all cases (n = 50, 100%).

Conclusions: The embolization-first strategy, with adjuvant surgery when necessary, can achieve outcomes nearing those of purely surgical approaches. Based on our long-term experience, EVT with Onyx can result in complete and permanent cure of SDAVF in more than 80% of cases.

Keywords: Endovascular treatment; Onyx; Spinal dural arteriovenous fistula.