Combined Open Surgical and Endovascular Embolization of Complex Skull Base Dural Arteriovenous Fistulas

Introduction: Dural arteriovenous fistulas (DAVFs) are abnormal communications, within the dural leaflets, between meningeal arteries and dural venous sinuses and/or subarachnoid veins. The goal of treatment is either surgical or endovascular disconnection of the feeding vessels and the draining veins. Successful endovascular embolization requires occlusion of the venous outflow. Although, this can usually be achieved via a transarterial or transvenous route, occasionally endovascular access to the fistula is not possible. In those circumstances skull base approaches can be utilized to expose the draining venous outflow and subsequently directly embolize the fistula with coils. We present two cases of complex skull base DAVFs that could not be treated via primary endovascular means due to inadequate vascular access. The surgical/endovascular techniques with intraoperative video illustrations will be discussed in depth.

Case: A 62-year-old female patient presented with headaches and a left sixth cranial nerve palsy was diagnosed with an indirect carotid-cavernous fistula (CCF). The patient underwent an initial attempt of transvenous embolization. The ipsilateral left inferior petrosal sinus (IPS) was hypoplastic and could not be catheterized. Access to cavernous sinus (CS) via the superior ophthalmic vein (SOV) was not feasible as it did not communicate with the facial vein. The CS was subsequently coiled via the contralateral IPS. Final angiogram revealed near occlusion of the fistula with delayed filling of the SOV and absence of cortical venous reflux. Unfortunately, 1-month follow-up angiogram revealed persistence of the fistula and reappearance of cortical venous drainage. Another attempt at embolization via the superior petrosal sinus failed due to inability to access the CS. The SOV cut-down was not feasible as the SOV did not reach the eyelid. A direct transorbital puncture of the CS was attempted but access was prevented due to the previously placed coils. Finally, the CS was surgically exposed and the lateral wall of the CS punctured directly and catheterized with a micro-sheath. Intraoperative coil embolization was performed through a microcatheter. Complete obliteration of the CCF was confirmed with an intraoperative angiography. On 10-month follow-up, the patient’s symptoms had completely resolved and one-year angiogram revealed complete obliteration of the left CCF.

Case 2: A 28-year-old male patient presented with several month of pulsating headaches, right retro-orbital pain, and tinnitus. The patient was found to have a right temporal skull base complex DAVF. The patient initially underwent an attempt at both transarterial and transvenous embolization but was unsuccessful due to the tortuosity and small caliber size of the vessels. He subsequently underwent a craniotomy with exposure of the anterior temporal skull base fistula. Intraoperative coil embolization was then performed via direct puncture of the venous outflow. The patient’s symptoms resolved immediately after surgery and he was discharged home two days after. At 6-month follow-up, the patient remained asymptomatic and the angiogram demonstrated persisted occlusion of the fistula.

Conclusion: Interdisciplinary assessment of complex skull base DAVFs is important to identify unconventional treatment options in case of endovascular inaccessibility. In those situations, combined treatment with surgical exposure and direct endovascular access to treat the fistula is the ideal solution for cure.