Configuration of intracranial arteries and development of aneurysms: a follow-up study

BACKGROUND: The reasons for development of intracranial aneurysms are unknown; hemodynamic factors may play an important role in this process. We performed a cohort study to further elicit the role of intracranial arterial geometry. METHODS: We compared the original CTA/MRA of the circle of Willis of 26 patients who developed an aneurysm during follow-up with those of 78 controls with no aneurysm development who were matched for gender, age, and period of follow-up. We assessed hypoplasia of the arteries of the circle of Willis and measured bifurcation angles within and beyond the circle of Willis on three-dimensional CTA/MRA. Bifurcation angles were classified in tertiles for analysis. We used Student t test for comparison of bifurcation angles and calculated OR with corresponding 95% CI for presence of hypoplasia and bifurcation angles in tertiles. RESULTS: A hypoplastic branch was found in 5 of 7 (71%) sites with aneurysm development and in 6 of 21 corresponding sites (29%) without aneurysm development (OR 6; 95%CI 0.9 to 42). The branch angle was sharp (lowest tertile) in 10 of 14 (71%) sites with aneurysm development and in 8 of 42 (19%) sites without aneurysm development (OR 11.3; 95% CI 2.0 to 64). CONCLUSIONS: Bifurcations with a hypoplastic branch and bifurcations with sharper bifurcation angles are risk factors for development of aneurysms. Analysis of the geometry of intracranial arteries might be helpful in detecting persons with increased risk for developing aneurysm

Clinical, radiological, and flow-related risk factors for growth of untreated, unruptured intracranial aneurysms

BACKGROUND AND PURPOSE: Unruptured intracranial aneurysms are frequently followed to monitor aneurysm growth. We studied the yield of follow-up imaging and analyzed risk factors for aneurysm growth. METHODS: We included patients with untreated, unruptured intracranial aneurysms and ≥6 months of follow-up imaging from 2 large prospectively collected databases. We assessed the proportion of patients with aneurysm growth and performed univariable and multivariable Cox regression analyses to calculate hazard ratios with corresponding 95% confidence intervals (CI) for clinical and radiological risk factors for aneurysm growth. We repeated these analyses for the subset of small ( neck ratio; 2.1 (95% CI, 0.9-4.9) for location in the posterior circulation; and 2.0 (95% CI, 0.8-4.8) for multilobarity. In the subset of aneurysms <7 mm, 37 of 403 (9%) enlarged. In multivariable analysis, hazard ratios for aneurysm growth were 1.1 (95% CI, 0.8-1.5) per each additional mm of initial aneurysm size, 2.2 (95% CI, 1.0-4.8) for smoking, 2.9 (95% CI, 1.0-8.5) for multilobarity, 2.4 (95% CI, 1.0-5.8) for dome/neck ratio, and 2.0 (95% CI, 0.6-7.0) for location in the posterior circulation. CONCLUSIONS: Initial aneurysm size, dome/neck ratio, and multilobarity are risk factors for aneurysm growth. Cessation of smoking is pivotal because smoking is a modifiable risk factor for growth of small aneurysms

Clinical, radiological, and flow-related risk factors for growth of untreated, unruptured intracranial aneurysms

BACKGROUND AND PURPOSE: Unruptured intracranial aneurysms are frequently followed to monitor aneurysm growth. We studied the yield of follow-up imaging and analyzed risk factors for aneurysm growth. METHODS: We included patients with untreated, unruptured intracranial aneurysms and ≥6 months of follow-up imaging from 2 large prospectively collected databases. We assessed the proportion of patients with aneurysm growth and performed univariable and multivariable Cox regression analyses to calculate hazard ratios with corresponding 95% confidence intervals (CI) for clinical and radiological risk factors for aneurysm growth. We repeated these analyses for the subset of small ( neck ratio; 2.1 (95% CI, 0.9-4.9) for location in the posterior circulation; and 2.0 (95% CI, 0.8-4.8) for multilobarity. In the subset of aneurysms <7 mm, 37 of 403 (9%) enlarged. In multivariable analysis, hazard ratios for aneurysm growth were 1.1 (95% CI, 0.8-1.5) per each additional mm of initial aneurysm size, 2.2 (95% CI, 1.0-4.8) for smoking, 2.9 (95% CI, 1.0-8.5) for multilobarity, 2.4 (95% CI, 1.0-5.8) for dome/neck ratio, and 2.0 (95% CI, 0.6-7.0) for location in the posterior circulation. CONCLUSIONS: Initial aneurysm size, dome/neck ratio, and multilobarity are risk factors for aneurysm growth. Cessation of smoking is pivotal because smoking is a modifiable risk factor for growth of small aneurysms

PHASES Score for Prediction of Intracranial Aneurysm Growth

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