Transpetrosal Translabyrinthine Approach for Obliteration of Large Perimesencephalic Dural Arteriovenous Fistula

Introduction: Intracranial dural arteriovenous fistulas (dAVFs) are a rare cause of intracranial hemorrhage, thought to be idiopathic lesions though can be associated with trauma or previous craniotomies. Due to technical advances in endovascular techniques, the vast majority are adequately treated with embolization. The aim of this case report is to describe the surgical approach to a large perimesencephalic dAVF not amenable to endovascular therapy.

Description: This is a 47-year-old who presented with diffuse subarachnoid hemorrhage, complicated by cardiac arrest and seizures, requiring emergent external ventricular drain placement. Cerebral angiogram demonstrated a large dAVF to the basal venous plexus with arterial supply from the meningohypophyseal artery and right middle meningeal artery with multiple venous aneurysms. After multiple attempts, endovascular catherization was unable to secure a safe transarterial route for embolization and transvenous embolization was aborted due to difficulty navigating the tortuous basilar plexus. Partial embolization of the right middle meningeal artery feeders through external carotid artery was completed, and a decision was made to proceed with surgical intervention through a right orbitozygomatic craniotomy approach. This provided adequate exposure to the superior portions of the dAVF but the venous complex just posterior to the clivus was unable to be visualized. Several small arterialized veins were coagulated and divided. An intra-op angiogram demonstrated significant reduction in blood flow to the complex structure with residual patency. Two weeks after surgery, there was a clinical decline associated with re-rupture of his dAVF. A decision was made to extend the prior right orbitozygomatic craniotomy posteriorly including transpetrosal translabyrinthine approach to provide better exposure to middle cranial fossa and more basal structures. Dura was opened lateral to the sigmoid sinus and the superior petrosal sinus coagulated allowing further extension medially along the tentorium. The fourth nerve and PCA were visualized and adequately protected. Microdissection along the middle fossa identified the prior vascular clip placed and then the cerebellopontine angle was followed, identifying 5, 7, 8 nerves as well as multiple venous aneurysms with abnormal small arterial feeding vessels superior, inferior, and intertwined within the trigeminal nerve. Dissection was continued inferior to this nerve. The transpetrosal approach allowed for visualization of many feeding vessels lateral and anterior to the brainstem that otherwise would have been hidden by the multiple venous aneurysms. While attempting to coagulate and remove feeding dural/tentorial feeders, significant venous bleeding was encountered and hemostasis was obtained. At this point the remainder of feeders were divided and there was complete obliteration of dAVF. Postoperative angiogram at one month confirmed absence of residual dAVF. At last follow up patient was living at home and clinically improving.

Discussion: This case demonstrates a presigmoid transpetrosal translabyrinthine approach for obliteration of a complex dAVF nonamenable to standard endovascular treatment. Importance of preoperative planning and adequate exposure was vital to complete obliteration of the dAVF.