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Medical Author:

Benjamin Wedro, MD, FACEP, FAAEM

Benjamin Wedro, MD, FACEP, FAAEM

Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

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Medical Editor:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Brain Aneurysm Causes

There are four blood vessels that supply the brain with blood, two carotid arteries and two vertebral arteries. They come together at the base of the brain to form the Circle of Willis and from there smaller blood vessels branch out to send blood to all areas of the brain.

Brain Aneurysm

Weak spots may exist where blood vessels come together or split. These areas are at risk of becoming damaged and, over time, a section of the blood vessel wall can balloon out and form a small sac or bubble just like an inner tube with a weak patch. This weakened area is called an aneurysm. Aneurysms usually do not produce symptoms, except when they leak blood into the subarachnoid space (the area that contains cerebrospinal fluid) or into adjacent brain tissue.

Aneurysms may be caused by a variety of factors. They may be congenital, meaning they were present at birth. They may be hereditary. Poorly controlled hypertension may be a potential cause, with increased blood pressure exerting force on the weakened artery wall. Since aneurysms are often located at blood vessel junctions, it may be that blood flow turbulence -- similar to water turbulence that occurs where rivers come together -- may be a contributing factor. Ultimately, the cause of an aneurysm may be multifactorial.

There are a variety of medical conditions associated with brain aneurysms that may involve abnormalities of blood vessel walls including Marfan syndrome, Ehlers-Danlos syndrome, coarctation of the aorta, and arteriovenous malformations. Systemic lupus erythematosus, collagen vascular diseases, and sickle disease are also associated with an increased risk of brain aneurysms.