Wire perforation of the missed tiny aneurysm originating from the fenestrated A1 segment during the endovascular approach.

Vascular anomaly and aneurysmal formation of an anterior communicating artery (ACOM) complex has often been reported. Because of such a complicated relationship between the vascular structure and aneurysms, ACOM aneurysm is one of the most difficult aneurysms to treat among other common anterior circulation aneurysms. We herein report a case of wire perforation of a missed tiny aneurysm arising from the fenestrated A1 segment during the endovascular approach to ACOM aneurysm. Although the fenestration of A1 segment is a rare vascular anomaly, it is likely to accompany saccular type aneurysms in the vicinity of the vascular anomaly. Endovascular treatment for ACOM aneurysm requires more detailed evaluations of the accompanying vascular anomaly and hemodynamics around ACOM to avoid complications.