Background: Aneurysms originating from the A3 segment of anterior cerebral artery (A3A) form about 5% of all IAs. They are the most common among distal anterior cerebral artery aneurysms. There are relatively few reports on management of A3As. In this article, we review the practical anatomy, preoperative planning, and avoidance of complications in the microsurgical dissection and clipping of A3As.
Methods: This review, and the whole series on IAs, is mainly based on the personal microneurosurgical experience of the senior author (JH) in 2 Finnish centers (Helsinki and Kuopio), which serve, without patient selection, the catchment area in Southern and Eastern Finland.
Results: These 2 centers have treated more than 10000 patients with IAs since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients and 4253 IAs, there were 163 patients carrying 174 A3As, forming 5% of all patients with IAs, 4% of all IAs, and 15% of all ACA aneurysms. Ninety-seven (60%) patients presented with ruptured A3As with ICH in 27 (28%) and IVH in 26 (27%). Ninety-four (58%) patients had multiple aneurysms.
Conclusions: Aneurysms of A3 segment of ACA are often small, even when ruptured, with relatively wide base, and they are frequently associated with ICHs of IVHs. Our data suggest that A3As rupture at smaller size than IAs in general. The challenge is to select appropriate approach, to locate the aneurysm deep inside the interhemispheric fissure, and to clip the neck adequately without obstructing branching arteries at the base. Unruptured A3As also need microneurosurgical clipping even when they are small.