ARE CEREBRAL ANEURYSMS ATHEROSCLEROTIC

Background and Purpose The aim of our study was to investigate plasma and genetic risk factors for rupture of cerebral aneurysms. Methods In London, a case-control study was made of 56 consecutive patients admitted to a regional neurosurgical service for treatment of ruptured cerebral aneurysm and of 93 control subjects. A further 40 consecutive patients admitted in Arhus with ruptured cerebral aneurysm also were studied. Results The British case-control study showed that smoking was associated with an increased risk of ruptured cerebral aneurysm (odds ratio, 9.1; 95% confidence interval [CI], 3.4 to 23.8; P<.001 for a history of >10 pack years). After age and sex adjustment, factors associated with ruptured cerebral aneurysm included a cholesterol concentration in the highest tertile (greater than or equal to 6.3 mmol/L; odds ratio, 10.2; 95% CI, 3.9 to 26.7; P<.001), an apolipoprotein B concentration in the highest tertile (greater than or equal to 0.84 g/L; odds ratio, 6.4; 95% CI, 2.5 to 16.3; P<.001), and concentrations of HDL cholesterol in the lowest tertile (<1.1 mmol/L; odds ratio, 3.6; 950/0 CI, 1.4 to 8.2; P<.01). History of hypertension was of less importance (odds ratio, 4.0; 95% CI, 1.41 to 11.7; P<.01). Smoking history (P<.001) and increased concentrations of cholesterol (P<.0001) were the most important independent risk factors associated with ruptured cerebral aneurysm on multivariate analysis. The histories of hypertension and smoking, together with apolipoprotein B levels, in the Danish patients were similar to those in the British patients. In the entire patient group, the frequencies of two polymorphic variations in the type III collagen gene and polymorphisms at the apolipoprotein B, apolipoprotein C-III, and haptoglobin gene loci were not different from control subjects or the normal population; allele frequencies in British and Danish patients were similar. Conclusions An atherosclerotic profile including increased total cholesterol concentration and a long smoking history may contribute to the rupture of cerebral aneurysms. This study provides no support for the hypothesis that inherited abnormalities of type III collagen are a common cause of cerebral aneurysms.