The effect of anterior projection of aneurysm dome on the rupture of anterior communicating artery aneurysms compared with posterior projection

Objective: Recent studies have shown that anterior projection aneurysms are associated with increased risk of rupture of anterior communicating artery (ACoA) aneurysms. We aimed to determine differences in patient characteristics and aneurysm morphologies between the anterior projection and posterior projection aneurysm groups and to determine morphological predictors of rupture of the anterior projection aneurysms.

Materials and methods: December 2007 to February 2015, 503 consecutive patients with single ACoA aneurysms were included in this report. The ACoA aneurysms were dichotomized as the anterior and posterior projection groups. Multivariate regression models were used to determine differences in patient and aneurysm characteristics between the 2 groups and to determine predictors of rupture in the anterior projection aneurysms.

Results: 363 (72.2%) patients had anterior projection aneurysms and 140 (27.8%) had posterior projection aneurysms. In univariate analysis, the anterior projection aneurysms were associated with a larger aneurysm size, a higher aneurysm height, a higher perpendicular height, a larger aspect ratio, and a larger size ratio. The multivariate analysis showed that the anterior projection aneurysms were independently associated with a larger size ratio compared with the posterior projection aneurysms. A larger size ratio and a smaller vessel size were independently associated with rupture status in the anterior projection aneurysms.

Conclusions: Compared with posterior projection aneurysms, the anterior projection aneurysms have a higher risk of rupture probably because of significant differences in aneurysm morphologies. A larger size ratio and a smaller vessel size may be helpful to predict the risk of rupture in the anterior projection aneurysms.