A Damp-and-Push Technique for the Copolymer (Onyx) Embolization of Dural Arteriovenous Fistula

Background: Copolymer (Onyx) embolization is an effective treatment for dural arteriovenous fistula (dAVF), however, some dAVFs have multiple, high-flow feeding vessels, resulting in insufficient embolization. For the treatment of such patients, we have developed a novel flow-control technique, the 'damp-and-push technique'. The purpose of this study was to evaluate the technical efficiency and safety of this technique. Methods: Seven patients who had been diagnosed with intracranial dAVF were treated by transarterial Onyx embolization using the damp-and-push technique between 2016 and 2019. This technique was designed to reduce blood flow to the shunt site using a balloon catheter in the major feeding vessel other than the one injected with Onyx, leading to better Onyx penetration and enabling more controlled embolization of complex dAVFs. Retrospectively collected data were reviewed to assess the occlusion rates and clinical outcomes. Results: The dAVF was at a transverse sinus-sigmoid sinus junction in four patients, in the superior sagittal sinus in two, and in the tentorium in one. Five cases were Cognard type IIb and two cases were Cognard type IV. All the patients were treated by transarterial Onyx injection via the main feeding vessel, combined with flow reduction in the other main feeding vessel using a balloon catheter. Complete occlusion was achieved in six patients and elimination of cerebral venous reflux was achieved in all the patients. There were no immediate or delayed post-interventional complications. Conclusions: Transarterial Onyx embolization of dAVF using the damp-and push technique is safe and yields a high complete occlusion rate.