Abstract 1122‐000117: Transcranial Arterial Embolization of an dAVF: A Case Report
Authors: Suryadevara Neil , Hoffman Haydn , Jalal Muhammad S , Koutsouras George , Gould Grahame 
Published: December 2021

Introduction
: We detail the management of a woman with a posterior fossa dAVF (dural arteriovenous fistula) that was unable to be treated by standard transarterial or transvenous embolization or microsurgical ligation. She underwent craniotomy for surgical exposure and direct access of her left middle meningeal artery followed by microcatheter embolization with favorable results.

Methods
: This is a case report, which describes a case of a difficult to access dAVF.

Results
: A 72 year‐old woman presented with vertigo, nausea, and vomiting one week following a fall. CT head disclosed cerebellar vermis intraparenchymal hematoma and CT head angiography was suspicious for underlying vascular malformation. Diagnostic cerebral angiogram demonstrated extensive tentorial and suboccipital dural arteriovenous fistula (dAVF) fed by branches of both middle meningeal and occipital arteries with direct cortical venous drainage and venous aneurysmal ectasia directly adjacent to the vermian hemorrhage (ruptured Cognard grade 4). Left vertebral artery angiogram demonstrated excessive tortuosity of vertebral enlarged posterior meningeal artery, which was unable to be catheterized sufficiently beyond its origin despite different microwires and microcatheters due to tortuosity. Transfemoral venous approach was also attempted, however, this was also unsuccessful and decision was made to proceed with microsurgical treatment.

The following day a suboccipital craniotomy was performed, but was ultimately aborted due to nearly uncontrollable bleeding from bony exposure and dural access secondary to severe venous hypertension. The next day percutaneous endovascular treatment was attempted a second time. A small right middle meningeal artery (MMA) contribution to the fistula was embolized with liquid embolic but, again because of excessive tortuosity and insufficient microcatheter access, right MMA occlusion occurred without embolic agent reaching the fistula. Similar access related difficulties due to tortuosity were encountered in accessing the left middle meningeal and occipital arteries contributing to the fistula. Repeat transvenous access was also attempted from the occipital and right transverse sinuses, but microcatheter access to the fistula was unable to be established beyond the venous outflow from the aneurysm, and, given the risks of hemorrhage related to embolization of the venous outflow without occluding arterial inflow into the ruptured aneurysm, transvenous embolization was not performed.
A few days later, after the patient was given time to recover from the prior procedures, the patient underwent left temporal craniotomy in a hybrid operating room/interventional radiology suite for direct cannulation of the left MMA. Localization of the craniotomy site over the left MMA access point was planned by transfemoral cerebral angiogram and a transcarotid/peripheral access kit was used to catheterize the left MMA directly following surgical exposure. An .017 microcatheter was advanced close to the fistula point using standard biplanar roadmap fluoroscopy, and Onyx embolization of the fistula was performed to complete occlusion, without complication.

Conclusions
: For cerebrovascular disorders that are inaccessible by traditional endovascular and surgical means, a hybrid approach should be considered.