Aneurysm Morphology and Prediction of Rupture: An International Study of Unruptured Intracranial Aneurysms Analysis

• Published in: Neurosurgery Vol. 82; no. 4; pp. 491 - 496
• Main Authors: Mocco, J, Brown, Robert D, Torner, James C, Capuano, Ana W, Fargen, Kyle M, Raghavan, Madhavan L, Piepgras, David G, Meissner, Irene, III, John Huston
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 01-04-2018; Copyright by the Congress of Neurological Surgeons; Wolters Kluwer Health, Inc
• Subjects: Adult; Aged; Aneurysm, Ruptured - epidemiology; Aneurysm, Ruptured - etiology; Aneurysms; Case-Control Studies; Cohort Studies; Female; Humans; Intracranial Aneurysm - complications; Intracranial Aneurysm - pathology; Middle Aged; Morphology; Multivariate Analysis; Neurosurgery; Research—Human—Clinical Studies; Risk Factors; Stroke; Cerebrovascular circulation; Cerebral aneurysm; Subarachnoid hemorrhage; Morphology; Hemorrhagic stroke; Aneurysm; Unruptured; Natural history
• ISSN: 0148-396X; 1524-4040
• DOI: 10.1093/neuros/nyx226

Abstract
BACKGROUND
There are conflicting data between natural history studies suggesting a very low risk of rupture for small, unruptured intracranial aneurysms and retrospective studies that have identified a much higher frequency of small, ruptured aneurysms than expected.
OBJECTIVE
To use the prospective International Study of Unruptured Intracranial Aneurysms cohort to identify morphological characteristics predictive of unruptured intracranial aneurysm rupture.
METHODS
A case-control design was used to analyze morphological characteristics associated with aneurysm rupture in the International Study of Unruptured Intracranial Aneurysms database. Fifty-seven patients with ruptured aneurysms during follow-up were matched (by size and location) with 198 patients with unruptured intracranial aneurysms without rupture during follow-up. Twelve morphological metrics were measured from cerebral angiograms in a blinded fashion.
RESULTS
Perpendicular height (P = .008) and size ratio (ratio of maximum diameter to the parent vessel diameter; P = .01) were predictors of aneurysm rupture on univariate analysis. Aspect ratio, daughter sacs, multiple lobes, aneurysm angle, neck diameter, parent vessel diameter, and calculated aneurysm volume were not statistically significant predictors of rupture. On multivariate analysis, perpendicular height was the only significant predictor of rupture (Chi-square 7.1, P-value .008).
CONCLUSION
This study underscores the importance of other morphological factors, such as perpendicular height and size ratio, that may influence unruptured intracranial aneurysm rupture risk in addition to greatest diameter and anterior vs posterior location.