Significance of the open A2 plane in determining the side of approach for microsurgical treatment of anterior communicating artery aneurysms.

[OBJECTIVE] Choosing the side of approach (SoA) in the microsurgical treatment of anterior communicating artery (AComA) aneurysms remains a topic of debate. The aim of this study was to investigate the effectiveness of the open A2 plane as the decisive factor in choosing the SoA.

[METHODS] This retrospective cohort study analyzed data from 59 patients who underwent microsurgical treatment for AComA aneurysms from 2017 to 2024 at a single institution. For 19 patients, the SoA was dictated by an accompanying pathology such as another aneurysm or intracerebral hemorrhage. For 40 patients, the open A2 plane was determined due to the location of the ipsilateral A2 by preoperative 3D CTA or DSA. Every patient was evaluated with DSA postoperatively.

[RESULTS] In superior, anterior, and inferior projecting aneurysms, the posteriorly situated A2 determined the side of the open A2 plane, and in posterior projecting aneurysms, the anteriorly situated A2 directed the approach. Right-sided or left-sided craniotomies were performed for 28 and 12 patients, respectively. The SoA was contralateral to the dominant A1 for 50% of patients, ipsilateral to the dominant A1 for 25%, and there was equal A1 flow for 25% of patients. Two patients, both with inferior orienting aneurysms, experienced early aneurysm rupture. Postoperative DSA showed total neck clipping in 37 of 40 patients.

[CONCLUSIONS] Choosing the SoA based on the open A2 plane facilitated exposure of the aneurysm neck, with high rates of aneurysm closure via a less complicated clip construction.