"True" posterior communicating artery aneurysm--report of two cases.

Two cases of true posterior communicating artery (PcomA) aneurysm are described. A 27-year-old female with subarachnoid hemorrhage demonstrated a saccular aneurysm at the branch of the anterior choroidal artery from the PcomA. The aneurysm was successfully clipped. A 23-year-old male involved in an automobile accident suffered from traumatic subarachnoid hemorrhage. Computed tomography 10 weeks after head injury demonstrated a high-density mass in the right parasellar region, diagnosed as a traumatic aneurysm arising from the PcomA. The aneurysm was successfully clipped. Histological examination demonstrated findings consistent with true aneurysm.