Dominant Orbitofrontal Pial Supply in Anterior Cranial Fossa Dural Arteriovenous Fistula: Angiographic Differentiation from Mixed Pial-Dural Arteriovenous Malformation and Anatomy-Based Treatment Selection

Background: Anterior cranial fossa dural arteriovenous fistulas (ACF DAVFs) usually receive ethmoidal dural supply. Pial arterial supply has been described in intracranial DAVFs, including ACF DAVFs, but a dominant orbitofrontal pial feeder can create diagnostic overlap with mixed pial-dural arteriovenous malformation and make endovascular treatment hazardous. Case Presentation: A 75-year-old man with atrial fibrillation presented with right middle cerebral artery occlusion and underwent intravenous thrombolysis followed by mechanical thrombectomy. During right internal carotid angiography, transient arterial-phase opacification of a contralateral frontal draining vein through the anterior communicating artery prompted post-recanalization angiography. A high-grade left ACF DAVF was diagnosed, with dominant supply from the left orbitofrontal artery, minor anterior ethmoidal supply, two venous drainage routes, cortical venous reflux, and a varix. Although the DAVF was incidental to the ischemic presentation, it was considered to require treatment because of high-risk angioarchitecture, including Borden type III/Cognard type IV drainage, cortical venous reflux, and venous ectasia. No intraparenchymal nidus or normal venous-phase use of the refluxing veins was identified. Because pial transarterial access and complete transvenous closure were considered unsafe or uncertain, microsurgical draining-vein disconnection was performed. Postoperative angiography confirmed complete obliteration. Conclusions: In this case, microsurgical disconnection achieved angiographic cure, and the patient was transferred for rehabilitation with a modified Rankin Scale score of 1. The central diagnostic and therapeutic issue in pial-feeder-dominant ACF DAVF is not rarity alone, but angiographic differentiation from mixed pial-dural arteriovenous malformation and assessment of whether the shunt can be closed without compromising normal pial arteries or venous outflow. The thrombectomy angiogram provided the route to diagnosis, whereas pial arterial dominance and divided venous drainage determined the curative strategy.