Management strategies for posterior cerebral artery aneurysms: a proposed new surgical classification.

In a period of 10 years fifteen patients bearing sixteen aneurysms arising at the posterior cerebral artery were operated at our institution. Based on the approaches selected for each location a division of the posterior cerebral artery into three surgical segments is proposed. The first segment (S1), or anterior extends from the basilar artery bifurcation to the point where the artery reaches the level of the most lateral edge of the cerebral peduncle, the second segment (S2), or middle extends from the posterior limit of S1 to a point located just before the most medial extent of the artery in the quadrigeminal cistern (collicular point), and the third segment (S3), or posterior corresponds to the collicular point and to the portions of the posterior cerebral artery distal to it. Utilizing the concept of surgical segments all aneurysms in our series were satisfactorily exposed. Those arising at the S1 segment (8 cases) were operated either through a pterional or a pretemporal approaches; those from the S2 segment (6 cases) were operated either via the subtemporal or the subtemporal transventricular routes; and that arising from the S3 segment (1 case) was managed through the occipital interhemispheric approach. Among the aneurysms eleven were small, one was large, and four were large or giant. Ten of these aneurysms were surgically clipped, two coagulated, three treated by trapping and in one case the aneurysm was resected and the posterior cerebral artery was reconstructed by a termino-terminal anastomosis. The surgical results were considered good in all cases but one, where the patient died due to clinical complications three months after surgery. It is our belief that the use of this classification can provide the means to best select the most appropriate surgical approach to treat aneurysms arising at the posterior cerebral artery.