title: Trigger factors for rupture of intracranial aneurysms in relation to patient and aneurysm characteristics.
abstract: Female gender, age above 60 years, and an aneurysm larger than 5 mm or location on the posterior circulation are associated with a higher rupture risk of intracranial aneurysms. We hypothesized that this association is explained by a higher susceptibility to (one of) the eight trigger factors that were recently identified. We included 250 patients with aneurysmal subarachnoid hemorrhage. We calculated relative risks (RR) with 95% confidence intervals (95% CI) of aneurysmal rupture for trigger factors according to sex, age, site, and size of the aneurysms by means of the case-crossover design. None of the triggers except for physical exercise differed according to patient and aneurysm characteristics. In the hour after exposure to physical exercise: (1) patients over the age of 60 have a six-times-higher risk of rupture (RR 13; 95% CI 6.3-26) than those of 60 years of age and under (RR 2.3; 1.3-4.1); (2) aneurysms at the internal carotid artery have a higher risk than those at other locations (RR 17; 7.8-37), but this was only statistically significant when compared to anterior communicating artery aneurysms (RR 3.2; 1.6-6.1); (3) aneurysms 5 mm or smaller had a higher risk of rupture (RR 9.5; 4.6-19) than larger aneurysms (RR 2.4; 1.3-4.3); and (4) women and men had similar risks. A higher susceptibility to exercise might explain part of the higher risk of rupture in older patients. Why women and patients with aneurysms larger than 5 mm or posterior circulation aneurysms have a higher risk of rupture remains to be settled.
authors.affiliation: Department of Neurology and Neurosurgery, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Monique H M
authors.initials: MH
authors.lastname: Vlak
authors.forename: Gabriel J E
authors.initials: GJ
authors.lastname: Rinkel
authors.forename: Paut
authors.initials: P
authors.lastname: Greebe
authors.forename: Johanna G
authors.initials: JG
authors.lastname: van der Bom
authors.forename: Ale
authors.initials: A
authors.lastname: Algra
mesh_terms: D000367:Age Factors; D017542:Aneurysm, Ruptured / Q000150:complications / Q000453:epidemiology* / Q000473:pathology; D016001:Confidence Intervals; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications / Q000453:epidemiology*; D008875:Middle Aged; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D013345:Subarachnoid Hemorrhage / Q000453:epidemiology* / Q000209:etiology