A, Preoperative sagittal T1 MR image demonstrates a flow void corresponding to a large vascular compartment and a massive high signal intensity “mucocele.” Compare the black flow void with the lateral angiogram (B).

B, Preoperative lateral catheter arteriogram (left ICA). Early arterial phase shows the carotid artery terminating in an enlarged venous compartment.

C, Preoperative lateral catheter arteriogram (left ICA). Later arterial phase shows rapid arteriovenous shunt surgery into the ophthalmic, petrosal, and cortical veins

D, Frontal arteriogram (right ICA) following proximal balloon occlusion of the left carotid artery shows rapid filling of the fistula by retrograde flow.

E, Frontal arteriogram (right ICA) following coil embolization of the distal (L) carotid artery. The coils were deployed through a microcatheter that had been advanced from the right carotid artery into the left carotid via the anterior communicating artery.

F, Lateral arteriogram (left vertebral artery) following proximal balloon and distal coil trapping of the massive fistula. There is no compromise of the collateral circulation from the posterior circulation. Antegrade flow is restored within the left carotid artery via the posterior communicating artery.

G, Postoperative dynamic (1 frame/s) contrast-enhanced MR image shows isolation of the fistula and complete opacification of the left cerebral hemisphere. Six-month arteriogram (not shown) confirmed complete closure of the fistula.