Onyx as an adjunctive embolic material for transvenous embolization of cavernous sinus dural arteriovenous fistula after coiling.

Background: Transvenous coil embolization (TVCE) is a common and effective treatment for cavernous sinus dural arteriovenous fistulas (CSDAVFs). However, some patients may experience residual fistulas or worsening visual symptoms after the procedure. This study aimed to compare the effectiveness of transvenous coil and Onyx embolization (TVCOE) with TVCE in treating CSDAVFs.

Methods: The study included 207 patients with 222 CSDAVFs referred for TVCE, all of whom had complete angiographic follow-up over 9 years. Ninety patients (mean age, 65.3 years) with 97 CSDAVFs underwent TVCOE after coiling. Clinical data, angioarchitecture, and outcomes were retrospectively assessed and compared to 125 CSDAVFs treated with TVCE.

Results: Key reasons for selecting TVCOE included improvement in immediate complete obliteration (CO) of CSDAVFs (n = 47, 48.5%), presence of cranial nerve palsy (n = 26, 26.8%), residual fistula with persistent pial venous reflux (PVR, n = 22, 22.7%), and redirection of fistula flow to PVR (n = 2, 2.1%). The average volume of Onyx used in TVCOE was 1.7 ml per CSDAVF. The mean coil lengths for TVCOE and TVCE were 143 cm and 228 cm, respectively, with a statistically significant difference (p < 0.05). Immediate digital subtraction angiography showed CO or nearly CO of CSDAVFs in TVCOE and TVCE at rates of 97.9% and 76.8%, respectively, indicating statistical significance in immediate CO (p < 0.05). Transient hemodynamic instability occurred in 81 (90.0%) patients due to Onyx toxicity, and 1 patient (1.1%) experienced hemorrhagic complications during TVCOE.

Conclusion: The use of a small volume of Onyx as an adjunctive embolic material in TVCOE resulted in reduced coil use and improved immediate CO. This technique is viable for patients with PVR. Aside from the transient hemodynamic instability, periprocedural complications and follow-up angiographic outcomes did not show significant differences between the two groups.