Balloon-assisted Onyx Embolization in the Management of Complicated Dural Arterioevenous Fistula

OBJECTIVE: Dural arteriovenous fistula (dAVF) is an abnormal vascular communication between the meningeal artery and vein at the dura mater, with frequent recruitment of collateral arterial pedicles. In recent years, Onyx embolization has become the mainstay intervention for dAVF at various locations, although an unfavorable vascular anatomy often limits effective obliteration of the lesion. Balloon assistance may facilitate curable occlusion of the abnormal shunt with Onyx while preserving the patency of the affected sinus, even in complicated dAVFs. METHODS: We retrospectively reviewed the clinical and angiographic findings of patients with dAVF treated endovascularly in our institution between September 2018 and August 2019. Based on the detailed analysis of individual angioarchitecture, we defined complicated dAVF as lesions for which a complete cure is considered difficult to achieve with simple transarterial Onyx embolization alone, primarily due to a high flow and/or diffuse shunt with or without drainage to the functioning but compromised sinus. We evaluated the preoperative symptoms, anatomical classification, endovascular procedure, radiologic results, and clinical outcomes of these patients. RESULTS: Five patients met our criteria, all of whom were treated with balloon-assisted Onyx embolization (two superior sagittal sinus dAVF, two transverse–sigmoid sinus dAVF, and one torcular dAVF). In four cases, Onyx was injected from a tiny branch of the middle meningeal artery under balloon occlusion of the collateral arteries or balloon devascularization of the competitive inflow. In three cases, balloon sinus protection was performed to prevent the inadvertent occlusion of the vital venous outflow with Onyx. In one case, for the complementary occlusion of the remnant shunt through the previously coiled but recanalized occipital artery, Onyx was injected from the wire lumen of a dual-lumen balloon catheter to avoid undesirable reflux. The angiographic results were an anatomical cure in four cases and near-complete occlusion in one case. No procedural complications were observed in any cases. The clinical outcome was a complete cure in four cases and improvement in one case. CONCLUSION: Our cases suggest that balloon devascularization can improve the unfavorable flow environment and simplify the vascular anatomy. Balloon sinus protection can support not only securing the patency of the normal venous outflow but also encourage aggressive intervention. Onyx injection via a dual-lumen balloon catheter can augment the controllability of embolization while preventing reflux. Each of these techniques can facilitate safe and effective Onyx embolization in the treatment of complicated dAVFs, and their combination may further expand the therapeutic horizon.