Risk factors in carotid artery stenosis and intracranial aneurysms.

Hyperlipoproteinaemia is an important risk factor in extracranial arterial disease and the mean values of serum triglyceride and serum cholesterol were raised in a group of 43 patients with carotid stenosis. The risk factors for carotid stenosis are not unlike those for other types of atherosclerotic disease such as dilating arterial disease. Serum triglyceride and cholesterol levels in a group of 22 patients with intracranial aneurysms are similar to those of age and sex matched control patients and are significantly lower than those of a group of 69 patients with dilating arterial disease. It is suggested that the aetiology of these two aneurysmal diseases may be different. 55% of the patients with intracranial aneurysms were hypertensive and only 50% were heavy smokers. This is a much lower incidence of cigarette smoking than in patients with either carotid stenosis or dilating disease. We conclude that intracranial aneurysms are unlikely to be caused by atherosclerosis.