Morphological Predictors of Middle Cerebral Artery Bifurcation Aneurysm Rupture

Abstract Objective Middle cerebral artery (MCA) bifurcation aneurysms are more likely to be associated with severe hemorrhage or hematoma in a clinical setting. We aimed to investigate the morphologic predictors of MCA bifurcation aneurysm rupture. Patients and Methods We conducted a retrospective analysis of 317 patients with MCA aneurysms between January 2009 and October 2016. Aneurysm status was grouped into ruptured and unruptured groups. The MCA bifurcation was defined as the bifurcation of the main trunk (the origin of the M2 trunks). Aneurysm morphologies were determined using CT angiography. We performed univariate and multivariable regression analyses to investigate the association of morphological characteristics with ruptured MCA bifurcation aneurysms. Results A total of 268 (84.5%) patients with 280 MCA bifurcation aneurysms were included. 207 (73.9%) aneurysms had ruptured. In the univariate analysis, a larger aneurysm (p = 0.042), a larger size ratio (p = 0.001), a larger aspect ratio (p = 0.017), a greater bottleneck ratio (p = 0.047), an irregular aneurysm (p = 0.004) and the presence of a daughter dome (p = 0.002) were associated with aneurysm rupture. The multivariate analysis showed that a larger size ratio (OR 1.324, 95% CI, 1.062-1.651; p = 0.013) and the presence of daughter dome (OR 2.462, 95% CI, 1.123-5.398; p = 0.024) were independently associated with ruptured aneurysms. The threshold of the size ratio for discriminating ruptured and unruptured aneurysms was 2.53 (p  Conclusions The size ratio and the presence of a daughter dome were independent predictors of the rupture of MCA bifurcation aneurysms. These parameters may contribute to the evaluation of the risk of rupture of aneurysms.