Impact of the Intracranial Course of Internal Carotid Artery on Optimal Surgical Approach for Posterior Communicating Artery Aneurysms

Abstract

The anterior temporal approach (ATA) has been reported as suitable for surgical clipping of posteriorly projecting internal carotid artery (ICA) aneurysms. As the ICA follows a variable course, tortuosity of the ICA may affect visualization of the aneurysm. The aim of this study was to investigate the impact of the intracranial course of the ICA and aneurysm projection on surgical approach. Consecutive patients with posterior communicating artery aneurysms treated with clipping at our hospital between May 2015 and April 2018 were retrospectively reviewed. When the transsylvian approach (TSA) could not achieve adequate exposure of the aneurysm, the ATA was subsequently performed. Distance between the ICA and the anterior and posterior clinoid line, angle between the midline and the C1 segment of the ICA, and aneurysm projection were compared between ATA and TSA groups. Of 52 patients (40 ruptured, 12 unruptured), 12 were in the ATA group, and 40 were in the TSA group. Mean ICA-anterior and posterior clinoid distance was significantly shorter in the ATA group than in the TSA group (P= 0.002), and mean midline-C1 angle was significantly larger in the ATA group than in the TSA group (P < 0.0001). The ATA group was associated with a greater frequency of posteriorly projecting aneurysms (12 of 12; 100%) than the TSA group (9 of 40; 22.5%) (P < 0.00001). A low-lying, laterally projecting intracranial ICA and posteriorly projecting aneurysm are predictors of the necessity for the ATA in the surgical clipping of posterior communicating artery aneurysms.