True posterior-communicating artery (PcoA) aneurysms are rare, and usually have no association with the internal carotid artery (ICA) or the posterior cerebral artery. Here we report the case of an 82-year-old woman with severe subarachnoid hemorrhage due to true PCoA aneurysm rupture. Cerebral angiography revealed an aneurysm of the left PCoA itself with superomedial projection. The patient underwent left pterional craniotomy and neck clipping of the aneurysm. Intra-operatively, the aneurysm was not observed on the lateral side of the ICA, although its origin could be seen on the posterolateral wall of the ICA. The aneurysm was approached via the opticocarotid space after removing the anterior clinoid process and opening the carotid dural ring. The aneurysm was completely obliterated and the PCoA was preserved.
True PCoA aneurysms can have a variety of projecting directions, which must be considered when choosing the surgical approach to their treatment.
