Abstract
A 64-year-old male presenting with subarachnoid hemorrhage had a saccular aneurysm arising from the anomalous anterior cerebral artery. The aneurysm was located on the curved mid-portion of the anomalous artery and extended underneath the right optic nerve. The aneurysm was clipped without unroofing the right optic canal. Postoperatively, he suffered from temporary mild deterioration of the right visual acuity. Hemodynamic stress may be important in the development of such aneurysms.