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Neurosurgery. 2018 Apr 1;82(4):491-496. doi: 10.1093/neuros/nyx226.

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

Author information

Department of Neurosurgery, Mount Sinai Medical Center, New York, New York.
Department of Neurology, Mayo Clinic, Rochester, Minnesota.
Department of Epidemiology, University of Iowa, Iowa City, Iowa.
Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL.
Department of Neurosurgery, Wake Forest University, Winston-Salem, North Carolina.
Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa.
Department of Neurosurgery, Mayo Clinic, Rochester, Minnesota.



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.


To use the prospective International Study of Unruptured Intracranial Aneurysms cohort to identify morphological characteristics predictive of unruptured intracranial aneurysm rupture.


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.


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).


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.

Conflict of interest statement

Dr Mocco serves as a consultant to Cerebrotech, Pulsar, TSP Inc, and Rebound Medical. Dr Mocco has investor interests in Blockade Medical and TSP Inc. The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.

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