Vascular geometry associated with anterior communicating artery aneurysm formation.

Abstract Objective We aimed to identify clinical and morphological risk factors that are correlated with anterior communicating artery (ACoA) aneurysm formation. Methods Three-dimensional morphological parameters obtained from CT-angiography (CTA) or digital subtraction angiography (DSA) from 504 patients with ACoA aneurysms and 201 patients with aneurysms elsewhere, diagnosed at the Brigham and Women’s Hospital and Massachusetts General Hospital between 1990 and 2016 were evaluated. We examined the presence of hypoplastic and aplastic A1 segments, and diameters and angles of surrounding parent and daughter vessels. Univariable and multivariable statistical analyses were performed to determine statistical significance. Sensitivity analyses with small (≤ 3mm) aneurysms only was also performed. Results Aplastic and hypoplastic A1s were more common in the ACoA group (38.9% vs 6.5% hypoplastic, and 22.2% vs 0.5% aplastic). In multivariable analysis, the presence of an hypoplastic A1 segment was associated with ACoA aneurysms. A2-ACoA (daughter-daughter) angle was also significantly associated with ACoA aneurysms in multivariable analysis, however, since Pearson’s correlation test between aneurysm width and daughter-daughter angle was significant, daughter-daughter angle was most likely not independently associated with aneurysm presence, but may be a result of the presence of an aneurysm. Subgroup analyses of small aneurysms (≤3mm) and of unruptured aneurysms only showed similar results. Conclusions Our results demonstrate that of all the morphological parameters, the presence of a hypoplastic A1 segment was the only parameter independently associated with the presence of ACoA aneurysms that was uncorrelated with aneurysm size, and could aid as a simple screening parameter.