The morphological characteristics and risk of rupture of ruptured and unruptured internal carotid siphon aneurysms: a preliminary study

Objective To compare morphological features between ruptured and unruptured internal carotid artery siphon aneurysms (ICSA) and identify predictors associated with rupture risk.Methods We retrospectively analyzd 156 patients with ICSA—49 with ruptured aneurysms (51 aneurysms) and 107 with unruptured aneurysms (120 aneurysms) – evaluated using volume computed tomographic digital subtraction angiography (VCTDSA). Twenty-one morphological and clinical indices, including aneurysm size, inclination angle and aspect ratio, were compared. Statistical analyses comprised univariate testing, receiver operating characteristic (ROC) curve analysis, and multivariate logistic regression.Results Univariate analysis revealed significant differences in aneurysm size, morphology, dimensions, angulation parameters, shape indices, maximal diameter, multiplicity and patient age between ruptured and unruptured ICSA (all p < 0.05). ROC curve analysis identified the inclination angle (AUC = 0.730), the inflow angle (AUC = 0.763) and aneurysm size (AUC = 0.755) as strong discriminators of rupture risk. Multivariate logistic regression identified three independent predictors of rupture: aneurysm size (OR = 12.607, 95% CI: 4.400–36.124; p < 0.001), inclination angle (OR = 4.062, 95% CI: 1.570–10.513; p = 0.004), and multiplicity (OR = 4.274, 95% CI: 1.620–11.272; p = 0.003).Conclusions Inclination angle, aneurysm size, and multiplicity are key morphological predictors of rupture in ICSA. These findings provide a valuable reference for morphologic assessing aneurysm rupture risk, enhancing clinical risk stratification.