The Role of A1 Variations on the Outcomes of Anterior Communicating Artery Aneurysm Treatment.

Anterior communicating artery (ACoA) aneurysms are common and complex. This study investigated the effect of A1 artery variations (hypoplasia/aplasia) on treatment outcomes.We retrospectively reviewed 104 patients with ACoA aneurysms treated either microsurgically or endovascularly.Ruptured aneurysms were present in 58.7% of patients. A1 variations occurred in 45.2% of cases, more frequently in unruptured aneurysms (69.8%,  < 0.01). The neck width of ruptured aneurysms was significantly smaller than that of unruptured ones. Variations reduced the risk of rupture (odds ratio = 0.16, 95% confidence interval = 0.06-0.41;  = 0.001). Microsurgery was the primary treatment (74%), and the rate of A1 variations was significantly lower in these cases ( < 0.05). Second interventions were required in 11.5% of patients, with no significant association to variation or treatment type. Vasospasm occurred in 41% of the ruptured aneurysm cases. Functional outcomes (modified Rankin Scale) were better in patients with A1 variations ( < 0.05). Mortality was 11.5% and unrelated to A1 variation. A higher bottleneck ratio increased mortality risk, whereas a higher height/width ratio decreased it.A1 variations were more common in unruptured ACoA aneurysms. They did not significantly influence retreatment or mortality. These findings may guide management strategies as the detection of unruptured aneurysms increases.