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.