Analysis of Nonmodifiable Risk Factors for Intracranial Aneurysm Rupture in a Large, Retrospective Cohort

Abstract

Abstract Background: The risk factors predictive of intracranial aneurysm rupture remain incompletely defined. Objective: To examine the association between various nonmodifiable risk factors and aneurysm rupture in a large cohort of patients evaluated at a single institution. Methods: A retrospective analysis of patients admitted to a cerebrovascular facility between January 2006 and 2010 with a primary diagnosis of cerebral aneurysm. Aneurysms were divided into 2 groups: unruptured or ruptured. The dome diameter, aspect ratio (AR), location, sidedness, neck morphology, and multiplicity were entered into a central database. A full model was constructed, and a systematic removal of the least significant variables was performed in a sequential fashion until only those variables reaching significance remained. Results: We identified 2347 patients harboring 5134 individual aneurysms, of which 34.90% were ruptured and 65.09% were unruptured. On admission, 25.89% of aneurysms with a dome diameter <10 mm and 58.33% of aneurysms with a dome >10 mm were ruptured (P < .001). Of aneurysms with an AR >1.6, 52.44% presented following a rupture (P < .001). The highest incidence of rupture (69.21%) was observed in aneurysms with an AR >1.6, dome diameter <10 mm, and a deviated neck. Deviated neck-type aneurysms had a significantly greater incidence of rupture than classical necktype aneurysms (P < .001). Conclusion: An AR >1.6, dome diameter >10 mm, a deviated neck, and right-sidedness are independently associated with aneurysm rupture.