Abstract
Two routes in the pterional approach to the distal basilar artery aneurysms have been known: one is via the space between the optic nerve and the internal carotid artery (opticcarotid triangle: OCT), and the other is lateral to the ICA (retrocarotid approach: RCA). Although the approach via the OCT has several advantages of its own, it had been considered applicable to very limited cases. We successfully clipped such aneurysms via OCT in four cases out of 12 cases (33%), and the neuroradiological findings observed in these cases are analyzed and reported.
Measurements were made on the following items on the carotid angiogram of the cases operated via the OCT (OCT group) and the RCA (RCA group): the distance of ICA bifurcation from the midline (D) and the height of ICA bifurcation from the baseline between the anterior and posterior clinoid processes (H). Although these two values seemed to be higher in the OCT than in the RCA group, no significant difference was found. The product of D and H (D×H) was observed to be significantly higher in the OCT than in the RCA group. The value of D×H is considered one of the indicate of the size of the OCT and has proved to be useful in judging whether the approach via the OCT is applicable or not.
The approach via the OCT has several advantages, such as no injury to the oculomotor nerve, less retraction to the ICA and easy visualization of the P1 segment of the opposite side. The space of the OCT can be used not only for clipping itself but also as a line of sight to the deep structures as well as clips applied from other routes.
