Anterior Choroidal Artery Aneurysm Clipping: Angiographic Diagnostics and Surgical Tactics Focused on Visualizing the Anterior Choroidal Artery Behind the Aneurysm

Objective: This study describes our experiences with anterior choroidal artery (AChA) aneurysm clipping with a focus on visualizing the AChA just behind the aneurysm to identify the risk factors for adhesion of the AChA or its branches to the posterior wall of the AChA aneurysm. Methods: The initial segment of the AChA just behind the aneurysm was evaluated preoperatively using three-dimensional (3D) rotational angiography, and its course was designated as posteromedial, posterior, or posterolateral. The posterior aspect of the AChA aneurysm was inspected intraoperatively using an endoscope or micromirror. Results: Based on 3D rotational angiography, the main trunk of the AChA showed a posteromedial (n = 47, 57.3%), posterior (n = 18, 22.0%), or posterolateral (n = 17, 20.7%) course just behind the aneurysm. Intraoperatively, 14.6% (12 of 82) of the clipped AChA aneurysms revealed an AChA branch adhered to the posterior wall of the aneurysm. A multivariate analysis revealed that the posterior or posterolateral course of the initial segment of the AChA was a statistically significant risk factor for adhesion of an AChA branch to the posterior wall of the aneurysm (odds ratio [OR] 21.083, 95% confidence interval [CI] 2.567–173.166, P = 0.005). Conclusions: The initial course of the AChA just behind an AChA aneurysm can be evaluated using 3D rotational angiography. In contrast to a posteromedial course, a posterior or posterolateral course of the AChA just behind an AChA aneurysm can be a significant risk factor for adhesion of an AChA branch to the posterior wall of an AChA aneurysm.