Background and Purpose-Prediction of the risk of rupture of unruptured intracranial aneurysms is mainly based on aneurysm size and location. Previous studies identified features of aneurysm shape and flow angles as additional risk factors for aneurysm rupture, but these studies were at risk for confounding by patient-specific risk factors such as hypertension and age. In this study, we avoided this risk by comparing characteristics of ruptured and unruptured aneurysms in patients with both aneurysmal subarachnoid hemorrhage and multiple intracranial aneurysms. Methods-We included patients with aneurysmal subarachnoid hemorrhage and multiple aneurysms who presented to our hospital between 2003 and 2013. We identified the ruptured aneurysm based on bleeding pattern on head computed tomography or surgical findings. Aneurysm characteristics (size, location, shape, aspect ratio [neck-to-dome length / neck-width], flow angles, sidewall or bifurcation type, and contact with bone) were evaluated on computed tomographic angiograms. We calculated odds ratios with 95% confidence intervals with conditional univariable logistic regression analysis. Analyses were repeated after adjustment for aneurysm size and location. Key Words: anatomy and histology ◼ intracranial aneurysm ◼ multidetector computed tomography ◼ subarachnoid hemorrhage

Background and Purpose-Growth of an intracranial aneurysm occurs in around 10% of patients at 2-year follow-up imaging and may be associated with aneurysm rupture. We investigated whether PHASES, a score providing absolute risks of aneurysm rupture based on 6 easily retrievable risk factors, also predicts aneurysm growth. Methods-In a multicenter cohort of patients with unruptured intracranial aneurysms and follow-up imaging with computed tomography angiography or magnetic resonance angiography, we performed univariable and multivariable Cox regression analyses for the predictors of the PHASES score at baseline, with aneurysm growth as outcome. We calculated hazard ratios and corresponding 95% confidence intervals (CI), with the PHASES score as continuous variable and after division into quartiles. Results-We included 557 patients with 734 unruptured aneurysms. Eighty-nine (12%) aneurysms in 87 patients showed growth during a median follow-up of 2.7 patient-years (range 0.5-10.8). Per point increase in PHASES score, hazard ratio for aneurysm growth was 1.32 (95% CI, 1.22-1.43). With the lowest quartile of the PHASES score (0-1) as reference, hazard ratios were for the second (PHASES 2-3) 1.07 (95% CI, 0.49-2.32), the third (PHASES 4) 2.29 (95% CI, 1.05-4.95), and the fourth quartile (PHASES 5-14) 2.85 (95% CI, 1.43-5.67). Conclusions-Higher PHASES scores were associated with an increased risk of aneurysm growth. Because higher PHASES scores also predict aneurysm rupture, our findings suggest that aneurysm growth can be used as surrogate outcome measure of aneurysm rupture in follow-up studies on risk prediction or interventions aimed to reduce the risk of rupture.

Relatives of patients with aneurysmal subarachnoid haemorrhage (SAH) have an increased risk of this type of stroke. In a population-based study, we analysed individualized risks of SAH according to the number of affected first-degree relatives. We retrieved all patients diagnosed with SAH in 2001-05 from the Swedish Inpatient Register. For each of the 5,282 patients, we identified five controls (n = 26,402) through the nationwide Register of Total Population. Through the Multi-generation Register, we retrieved all first-degree relatives for patients and controls and checked whether these 130,373 relatives had been diagnosed with SAH. By means of conditional logistic regression, we calculated odds ratios with corresponding 95% confidence intervals (95% CI) for the risk of SAH according to the number of affected relatives, and to the gender, age and type of kinship of the patient and affected relative. The odds ratio of SAH for individuals with one affected first-degree relative was 2.15 (95% CI 1.77-2.59). For individuals with two affected first-degree relatives, the odds ratio was 51.0 (95% CI 8.56-1117). Gender, age and type of kinship did not influence the risk for individuals with one or more affected relatives. The risk of SAH is slightly increased in the cases with one, but strongly increased in cases with two or more affected first-degree relatives. The latter strongly increased risk corresponds to a considerable absolute life-time risk of SAH and underscores the need to consider screening for aneurysms in these individuals.

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