Aneurysm geometry predicts rupture in very small (<4mm) intracranial aneurysms
Jefferey Katz, David Chalif, David Bonda, David Langer, Amir Dehdashti, Claire Carrazco, Pina Sanelli
Introduction: Prediction of rupture risk for intracranial aneurysms remains inconsistent. Our ability to identify patients at risk for subarachnoid hemorrhage relies on an imprecise set of "predictive" factors, such as aneurysm size.
Objective: We use a geometric approach to explore the risk factors associated with rupture of very small aneurysms(< 4mm), which are routinely observed when found incidentally.
Methods: Patients with ruptured or unruptured intracranial aneurysms treated from 2010 to 2013 were identified. Aneurysms measuring less than 4mm from neck to dome were analyzed with a focus on aneurysm dimensions, incident angle, and parent vessel geometry. Measurements were conducted using DSA, CTA, or MRA, and parameters were analyzed for significance using two-sided student’s t-test for continuous variables and odds ratios with 95% confidence intervals for discrete variables.
Results: A total of 113 aneurysms in 86 patients were analyzed, with 57 of them ruptured (50.4%). Average age was 55 in both groups. 68% of patients with ruptured aneurysms and 86% of unruptured aneurysms were female. Acom and Pcom aneurysms were most likely to rupture(OR 7.1 and 4.3, p=0.01 and 0.003, respectively). Statistically significant differences in dome-to-neck ratio (DNR)(1.4/1.1 p=0.007) and aspect ratio (AR)(1.3/1.1 p=0.041) were found; all other variables did not reach statistical significance.
Conclusions: Measurement of aneurysm geometry represents a promising method for better characterizing intracranial aneurysms and stratifying risk of rupture. This approach may be particularly useful for very small(<4mm) aneurysms, which have historically eluded reliable risk stratification. Younger patients who present with aneurysms <4mm with high DNR and AR could be considered for prophylactic intervention.