A Stump of Occluded Posterior Cerebral Artery Mimicking a Ruptured Aneurysm: Case Report.

We report on a 63-year-old female with subarachnoid hemorrhage who had a stump of occluded posterior cerebral artery (PCA) mimicking a ruptured aneurysm of the basilar bifurcation. Intraoperatively, the aneurysmal opacification on preoperative angiograms proved to be the residual lumen of the occluded right P1 segment. Because of the nodular appearance and upward direction of the stump of the right P1 segment, it was misinterpreted as an aneurysm. During operation, a tiny ruptured aneurysm missed on preoperative angiograms was found in the left A1-A2 junction and was clipped safely.