Microsurgical management of complex anterior communicating artery and proximal A2 anterior cerebral artery aneurysms by the bifrontal interhemispheric approach.

[OBJECTIVE] Large, giant, and complex anterior communicating artery (ACoA) and A2 anterior cerebral artery (ACA) aneurysms may require a bifrontal interhemispheric approach for better exposure of the aneurysm and bilateral A2-ACA branches and the ability to perform a bypass if needed. The authors sought to investigate the operative techniques and long-term outcomes of ACoA and proximal A2-ACA aneurysms treated with the bifrontal interhemispheric approach.

[METHODS] The authors reviewed ACoA and proximal A2-ACA aneurysms treated by microsurgical clipping with or without a bypass via the bifrontal interhemispheric approach from 2005 to 2024 as a subset of all ACoA aneurysms surgically treated at their institution. The indications for this approach were 1) a complex neck requiring exposure of bilateral A1 and A2 vessel segments, and/or 2) need for bypass. Demographic, clinical, and radiographic data were collected and reviewed. Aneurysm occlusion, bypass patency, functional outcomes (modified Rankin Scale [mRS] score), and complications were assessed at the 3-month and long-term (> 12 months) follow-up.

[RESULTS] Of 383 patients with ACoA or proximal A2-ACA aneurysms treated with microsurgery at the authors' institution, 30 patients met the inclusion criteria. The mean radiographic follow-up was 3.1 years. Sixty percent of patients (18/30) had a subarachnoid hemorrhage. Twenty-five (83.3%) aneurysms were ACoA and 5 (16.7%) were proximal A2-ACA. Bypasses were performed for 16 (53%) aneurysms. Direct side-to-side bypasses were the most common, accounting for 81% (13/16) of all bypasses. Complete aneurysm occlusion was achieved in 90% of aneurysms at the last follow-up. Immediate postoperative patency of the bypass was 100% (16/16). Long-term bypass patency was 87.5% (7/8). Postoperative stroke occurred in 2 patients (6.7%), both of whom recovered with mRS scores < 2 at the 3-month follow-up.

[CONCLUSIONS] The bifrontal interhemispheric approach offers the ability to expose large and giant ACoA aneurysms and bilateral A2 vessel aneurysms, which allows an operative corridor for possible bypass revascularization. The results of this approach were excellent, with a low rate of aneurysm recurrence and complications.