Background: The middle cerebral artery (MCA) is the most frequent location for unruptured intracranial aneurysms. Controversy remains as to which unruptured MCA aneurysms should be treated prophylactically.
Objective: To identify independent topographical and morphological variables that could predict increased rupture risk of MCA aneurysms.
Methods: A retrospective analysis of CT angiography (CTA) data of 1009 consecutive patients with 1309 MCA aneurysms, referred between 2000 and 2009 to Helsinki University Hospital, was carried out. Morphological and topographical parameters examined for MCA aneurysms comprised aneurysm wall regularity, size, neck width, aspect ratio (AR), bottleneck factor (BNF), height-width ratio, location along MCA, side, distance from internal carotid artery (ICA) bifurcation and dome projection in axial and coronal CTA views. Univariate and multivariate logistic regression analysis were performed to determine independent risk factors for rupture.
Results: Of the 1309 MCA aneurysms, 69% were unruptured and 31% were ruptured. Most unruptured MCA aneurysms had size < 7 mm (78%), smooth wall (80%), height-width ratio = 1 (47%) and were located at the main bifurcation (57%). Ruptured MCA aneurysms, mostly sized 7-14 mm (55%), had irregular wall (78%), height-width ratio > 1 (72%) and were located at the main bifurcation (77%). 38% of MCA bifurcation aneurysms, 74% of large aneurysms, 64% of aneurysms with irregular wall, and 49% of aneurysms with height-width ratio > 1 were ruptured.
Conclusion: Location at the main MCA bifurcation, wall irregularity, and less spherical geometry were independently associated with rupture of MCA aneurysms with correlation to aneurysm size.
From: Anatomic Risk Factors for Middle Cerebral Artery Aneurysm Rupture: Computerized Tomographic Angiography Study of 1009 Consecutive Patients by Elsharkawy et al.