Adult intracranial pial arteriovenous fistulas: a case report and literature review.

Intracranial pial arteriovenous fistula (PAVF) is a rare high-flow cerebrovascular lesion defined by a direct shunt between pial/cortical arteries and a single draining vein or venous pouch without a nidus, adult cases are particularly uncommon. A 56-year-old woman presented with sudden severe headache after yoga. CT/MRI revealed a right frontal intracerebral hemorrhage associated with a giant venous pouch, and angiography demonstrated a single-channel PAVF fed by an MCA M2 branch with venous drainage to the superior sagittal and sphenoparietal sinuses. The patient underwent craniotomy for hematoma evacuation, microsurgical fistula disconnection, and venous pouch resection under indocyanine green angiography and FLOW800 guidance. Postoperative CT confirmed complete hematoma removal, and follow-up DSA on day 4 showed total obliteration of the fistula with no residual abnormal drainage. Pathology revealed a vascular malformation with focal calcification. She was discharged neurologically intact and remained symptom-free without recurrence on CTA at 3 months. Adult PAVF is extremely rare but carries a high risk of hemorrhage; early angiographic diagnosis and definitive flow disconnection yield excellent outcomes.