Transarterial Onyx Embolization of a Hemorrhagic Tentorial Dural Arteriovenous Fistula via a Tortuous Occipital Artery: Technical Tips for Challenging Vascular Access.

Objective: Tentorial dural arteriovenous fistulas (dAVFs) are rare, accounting for 4%-8% of intracranial dAVFs, and are associated with a high risk of hemorrhage. We report a case of a hemorrhagic tentorial dAVF located at the posterior falcotentorial junction, which was successfully treated by sequential transarterial embolization (TAE) despite severely tortuous feeder anatomy. Case Presentation: A 67-year-old man presented with impaired consciousness due to cerebellar and intraventricular hemorrhage with obstructive hydrocephalus. DSA revealed a tentorial dAVF at the posterior falcotentorial junction (Cognard type IV, Borden type III) with venous ectasia draining into the inferior vermian vein. The fistula was predominantly supplied by the left occipital artery (OA) and the right posterior meningeal artery (PMA), with minor contributions from the right OA and the bilateral tentorial arteries. Sequential TAE was performed: the PMA feeder was first occluded with n-butyl cyanoacrylate, followed by Onyx-18 (Medtronic, Irvine, CA, USA) injection via the left OA. Navigation through the severely tortuous OA and its suboccipital segment required multiple technical innovations, including an S-shaped microguidewire tip (CHIKAI X010; Asahi Intecc, Aichi, Japan) and the use of a compliant balloon catheter (Scepter XC; Terumo, Tokyo, Japan) as an anchor to advance the intermediate catheter (Phenom Plus; Medtronic). Complete obliteration of the fistula was achieved. Conclusion: This case demonstrates that sequential TAE with technical innovations for vascular access can achieve curative treatment of tentorial dAVFs, even when feeder anatomy presents significant navigational challenges. The S-shaped wire technique and balloon-assisted intermediate catheter advancement may be applicable to other cases with tortuous vessel anatomy.