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 admi tted to a regional neurosurgical service for treatment of ruptured cer ebral aneurysm and of 93 control subjects. A further 40 consecutive pa tients admitted in Arhus with ruptured cerebral aneurysm also were stu died. Results The British case-control study showed that smoking was a ssociated with an increased risk of ruptured cerebral aneurysm (odds r atio, 9.1; 95% confidence interval [CI], 3.4 to 23.8; P<.001 for a his tory of >10 pack years). After age and sex adjustment, factors associa ted with ruptured cerebral aneurysm included a cholesterol concentrati on in the highest tertile (greater than or equal to 6.3 mmol/L; odds r atio, 10.2; 95% CI, 3.9 to 26.7; P<.001), an apolipoprotein B concentr ation 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 ch olesterol in the lowest tertile (<1.1 mmol/L; odds ratio, 3.6; 950/0 C I, 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<.00 1) 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 s moking, together with apolipoprotein B levels, in the Danish patients were similar to those in the British patients. In the entire patient g roup, the frequencies of two polymorphic variations in the type III co llagen gene and polymorphisms at the apolipoprotein B, apolipoprotein C-III, and haptoglobin gene loci were not different from control subje cts or the normal population; allele frequencies in British and Danish patients were similar. Conclusions An atherosclerotic profile includi ng increased total cholesterol concentration and a long smoking histor y may contribute to the rupture of cerebral aneurysms. This study prov ides no support for the hypothesis that inherited abnormalities of typ e III collagen are a common cause of cerebral aneurysms.