Ruptured High-Grade Tentorial Dural Arteriovenous Fistula Masquerading as Aneurysmal Sylvian Subarachnoid Hemorrhage: A Diagnostic Pitfall

Abstract

Dural arteriovenous fistulas (DAVFs) are rare intracranial vascular shunts (10–15% of intracranial AV malformations) whose clinical impact depends on venous drainage. Lesions with cortical venous drainage (Cognard III–V) are at high risk of hemorrhage. We report a case of Cognard type IV DAVF presenting with left Sylvian subarachnoid hemorrhage (SAH) and temporal lobe hematoma.

A previously healthy 54-year-old male presented to the emergency department with a sudden severe headache, confusion, expressive aphasia, and right hemiparesis. Initial computed tomography (CT) showed an acute SAH in the left Sylvian fissure and a left temporal intraparenchymal hematoma. Vascular imaging (CT angiography) suggested a dural fistula, and digital subtraction angiography (DSA) confirmed a left tentorial DAVF with multiple feeders from the left external carotid (internal maxillary and middle meningeal arteries) and an ectatic draining cortical vein (Cognard type IV anatomy). The patient underwent an urgent left frontotemporal craniotomy and microsurgical disconnection of the fistula. The feeding arteries were coagulated and the ectatic vein was excised. Postoperative DSA revealed complete obliteration of the fistula. The patient's neurological status steadily improved and the aphasia resolved over weeks.

This case highlights that DAVFs, especially those with cortical venous reflux and venous ectasia (Cognard IV), can present with nonaneurysmal SAH and intracerebral hematoma. These “high-grade” fistulas have a substantial risk of rebleeding (historical series reported up to ∼35% within 2 weeks) and demand prompt treatment. Diagnosis requires a high index of suspicion, and DSA is the gold standard. Treatment of aggressive DAVFs often includes endovascular embolization, microsurgical disconnection, or a combination of these. In this case, direct surgery achieved a definitive cure.