gms | German Medical Science

Objective: Aneurysm location, size and morphology are well-known risk factors for spontaneous aneurysm rupture causing subarachnoid hemorrhage. In the current study, we aimed to determine the impact of distinct morphological aneurysm features on intraoperative rupture (IOR) during microsurgical clipping of ruptured intracranial aneurysms.

Methods: We retrospectively reviewed consecutive patients that were treated for a ruptured aneurysm by microsurgical clipping at our institution between 2010 and 2017 and underwent preoperative three-dimensional evaluation of aneurysm morphology. The following aneurysm features were evaluated using two- and three-dimensional angiographic images: aneurysm width and height, maximum aneurysm diameter, neck width, dome-to-neck ratio, aspect ratio, width-to-height ratio, mean vessel size, size ratio, inflow angle, aneurysm inclination angle and aneurysm shape. Depending on their shape, the aneurysms were classified into regular aneurysms (single-sac aneurysms with regular margin) and irregular aneurysms (single-sac aneurysms with irregular margin, aneurysms with daughter sacs and lobulated aneurysms). Factors predictive in the univariate analysis (p<0.2) were entered into a step-wise binary logistic regression system to identify independent risk factors of intraoperative rupture.

Results: A total of 138 patients (mean age: 55.1±10.1 years) were enrolled in this study. IOR occurred in a total of 36 cases (26.1%). IOR occurred significantly more often among irregular aneurysms (31%) than among regular aneurysms (9%; p=0.02). Furthermore, there was a tendentially significant association between IOR and increased aneurysm height (7.5±3.5 mm vs. 6.6±3.2 mm, p=0.17) and smaller vessel size (2.0±0.5 mm vs. 2.2±0.6 mm, p=0.07). In the multivariate analysis, irregular aneurysm shape remained the only significant independent risk factor for IOR (OR: 3.9, 95% CI: 1.0–14.6; p=0.047).

Conclusion: Our results revealed that aneurysm shape is an independent risk factor for IOR during microsurgical clipping of ruptured aneurysms. Preoperative assessment of morphological aneurysm features may be helpful for risk stratification and to improve the management of aneurysms with complex shape.