Risk of rupture of an intracranial aneurysm based on patient characteristics: a case-control study.

BACKGROUND AND PURPOSE Knowledge about risk factors contributes to understanding the pathophysiological mechanisms that cause intracranial aneurysm rupture and helps to develop possible treatment strategies. We aimed to study lifestyle and personal characteristics as risk factors for the rupture of intracranial aneurysms. METHODS We performed a case-control study with 250 patients with an aneurysmal subarachnoid hemorrhage and 206 patients with an unruptured intracranial aneurysm. All patients with an aneurysmal subarachnoid hemorrhage and patients with a unruptured intracranial aneurysm were asked to fill in a structured questionnaire about their lifestyle and medical history. For patients with an unruptured intracranial aneurysm, we also collected data on the indication for imaging. With logistic regression analysis, we identified independent risk factors for aneurysmal rupture. RESULTS Reasons for imaging in patients with an unruptured intracranial aneurysm were atherosclerotic disease (23%), positive family history (18%), headache (8%), preventive screening (3%), and other (46%). Factors that increased risk for aneurysmal rupture were smoking (odds ratio, 1.9; 95% confidence interval, 1.2-3.0) and migraine (2.4; 1.1-5.1); hypercholesterolemia decreased this risk (0.4; 0.2-1.0), whereas a history of hypertension did not independently influence the risk. CONCLUSIONS Smoking, migraine and, inversely, hypercholesterolemia are independent risk factors for aneurysmal rupture. Data from the questionnaire are insufficient to conclude whether hypercholesterolemia or its treatment with statins exerts a risk-reducing effect. The pathophysiological mechanisms through which smoking and migraine increase the risk of aneurysmal rupture should be investigated in further studies. Although a history of hypertension does not increase risk of rupture, a sudden rise in blood pressure might still trigger aneurysmal rupture.