[P3 portion aneurysm of the posterior cerebral artery; a case report]

A case was reported of surgically treated saccular aneurysm located at the right posterior temporoparietooccipital artery junction (P3 portion of PCA). An aneurysm of this portion is said to be rare, and only 7 cases have been described so far. A 74-year-old female was transferred to our clinic, after 3, 5 months of sustaining aneurysmal rupture, for surgical treatment. The patient had been treated conservatively because of her severe condition in the early stage. She was in nearly apallic state with left hemiparesis at the time of admission to our clinic. During the acute stage of her illness, moderate hematoma in the right ambient cistern without hydrocephalus, and an aneurysm at P3 portion of the right posterior cerebral artery with marked arteriosclerosis were delineated by CT, and by right vertebral angiography respectively. However, in the CT taken 3, 5 months after the onset, moderate hydrocephalus and a low density area in the right internal capsule were detected. Aneurysmal neck clipping was performed using the right posterior subtemporal approach, without any deformity of the parent arteries. Occlusion of the right parietooccipital artery occurred, however, probably on the 2nd postoperative day. Despite the newly developed left homonymous hemianopsia, general condition, including consciousness level, improved postoperatively particularly after the ventriculo-peritoneal shunt was carried out.