Morphological and Hemodynamic Risk Factors for Middle Cerebral Artery Aneurysm: a Case-Control Study of 190 Patients

This study analyzed morphometric and hemodynamic parameters of aneurysmal and non-aneurysmal middle cerebral artery (MCA) bifurcations and their relationship with optimal values derived from the principle of minimum work (PMW). The study included 96 patients with MCA aneurysm and 94 controls. Aneurysm patients presented with significantly higher values of the radius and cross-sectional area of the MCA trunk, angle between the post-bifurcation branches (alpha angle) and volume flow rate (VFR) and had significantly lower values of junction exponent and pulsatility index than the controls. The Phi (1) and Phi (2) angles (angles between the MCA trunk axis and the larger and smaller branch, respectively) and alpha angle in all groups were significantly larger than the optimal PMW-derived angles. The most important independent predictors of MCA aneurysm were junction exponent (odds ratio, OR=0.42), alpha angle (OR=1.07) and VFR (OR=2.36). Development of cerebral aneurysms might be an independent effect of abnormalities in hemodynamic and morphometric factors. The risk of aneurysm increased proportionally to the deviation of morphometric parameters of the bifurcation from their optimal PMW-derived values. The role of bifurcation angle in aneurysm development needs to be explained in future research as the values of this parameter in both aneurysm patients and non-aneurysmal controls in were scattered considerably around the PMW-derived optimum.