Definition

An aneurysm is an outpouching of a blood vessel wall. This can occur anywhere there are blood vessels, including in the brain. The bulging, blood-filled pocket can put pressure on parts of the brain. In addition, the blood vessel can rupture (hemorrhage). Early detection and diagnosis may help prevent severe or fatal complications in some patients. Many aneurysms go unnoticed for a lifetime and cause no symptoms.

Causes

Aneurysms form in areas where the artery wall becomes thin or weak. Thinning artery walls and resulting aneurysms can be caused by a number of factors. Common causes include:

• Congenital (present at birth) weakness in artery wall
• High blood pressure
• Infection
• Trauma or injury to the brain
• Tumor
• Plaque build-up on artery walls

Risk Factors

These factors increase your chance of developing a brain aneurysm. These risk factors also increase your chance of a rupture. Older adults are more likely to develop an aneurysm than children. Females are at slightly higher risk. Tell your doctor if you have any of these risk factors:

• Genetic diseases—circulatory, connective tissue, or polycystic kidney disease
• Family history of aneurysms
• Smoking
• Heavy alcohol use
• Drug abuse
• High blood pressure
• Tumors
• Traumatic head injury
• Arteriovenous malformations

Symptoms

Symptoms may include:

• Pain behind the eye
• Numbness, sometimes on one side of the face or body
• Weakness on one side of the body or face
• Vision changes
• Drooping eyelid
• Differences between the size of the pupils
• Speech impairment

Most aneurysms do not cause symptoms until they leak or rupture. A leaking or ruptured aneurysm may cause:

• Headache
• Nausea
• Vomiting
• Stiff neck
• Confusion or sleepiness
• Loss of consciousness
• Seizures

Diagnosis

You will be asked about your symptoms and medical history. A physical exam will be done. Tests may include the following:

• Brain imaging, such as CT scan or MRI scan
• Catheter, MRI, or CT angiography (dye contrast test to view the arteries and veins)
• Spinal fluid analysis

Treatment

Talk with your doctor about the best treatment plan for you. Other medical conditions; lifestyle factors; as well as the type, size, and location of the aneurysm will direct treatment. For a known aneurysm that is not leaking or ruptured, treatment options include the following:

Prevention

In many cases, there is no known way to prevent an aneurysm from forming. To help reduce your chances of getting a brain aneurysm or having it burst, take the following steps:

• Control high blood pressure.
• If you smoke, talk to your doctor about ways to quit.
• Do not use illegal drugs.
• Discuss with your doctor:
  • Benefits and risks of oral contraceptives
  • Whether it is safe to use daily aspirin or other pain medications that may thin the blood

National Institute of Neurological Disorders and Stroke http://www.ninds.nih.gov

Heart and Stroke Foundation Canada http://www.heartandstroke.ca

Vlak M, Rinkel, Gabriel J, et al. Trigger factors and their attributable risk for rupture of intracranial aneurysms: a case-crossover study. Stroke. 2011 May 5.