Double trouble: Ruptured venous aneurysm in dural arteriovenous fistula caused by focal venous hypertension - a rare cerebrovascular case.

Dural arteriovenous fistulas (dAVFs) are uncommon intracranial vascular shunts that typically cause hemorrhage when retrograde cortical venous drainage and diffuse venous hypertension are present. Venous aneurysms are usually considered a sequela of sustained venous hypertension; however, localized focal hemodynamic stress may also contribute to aneurysm formation and rupture. We report a rare case of a 51-year-old woman who presented with acute expressive aphasia and dense right hemiparesis. Imaging revealed a large left temporoparietal intracerebral hemorrhage with subarachnoid extension. Digital subtraction angiography demonstrated a left temporal dAVF supplied by the middle meningeal artery and draining via the veins of Trolard and Labbé into the superior sagittal sinus. A discrete saccular venous aneurysm was identified at a sharply angulated and stenotic draining segment, suggesting localized venous hypertension without diffuse angiographic congestion. Transarterial embolization using Onyx-18 achieved complete obliteration of the fistula and aneurysm. At one-month follow-up, the patient showed complete recovery of aphasia and marked motor improvement. This case illustrates that focal venous hypertension, even without diffuse angiographic congestion, can result in aneurysm formation and rupture. Early angiographic assessment and endovascular intervention remain critical for favorable outcomes.