Brain Aneurysm - Cerebral Aneurysm

A cerebral aneurysm is an abnormal swelling of a blood vessel wall inside the brain.

What is going on in the body?

A cerebral aneurysm is an area where a blood vessel in the brain weakens. As a result, the vessel wall balloons out. This results from defects in the elastic layer of the blood vessel wall. Aneurysms usually form where arteries branch. The vessel wall is sometimes weaker at this branch. When pulsating blood pushes this area of weakness outward, an aneurysm forms. Over time, the aneurysm may balloon and thin the wall so much that it ruptures.

What are the causes and risks of the condition?

Aneurysms are often congenital. That means a person is born with them. As the person gets older, the aneurysm may get larger. High blood pressure and atherosclerosis, also known as hardening of the arteries, can further weaken the blood vessel walls. This may lead to an aneurysm, particularly in the elderly. Although rare, sometimes an aneurysm can be caused by an infection in the blood. The infection can lodge in the vessel wall and weaken it.

The first rupture of an aneurysm may lead to stroke, permanent disability, or death. Recurring bleeding and blood vessel spasm may also lead to death.

What are the signs and symptoms of the condition?

Many aneurysms cause no symptoms until they get quite large or rupture. Bleeding from a ruptured aneurysm irritates the meninges. The meninges are layers that cover and protect the brain and spinal cord. If the amount of blood in the space under the meninges is large, other blood vessels may go into spasm. This can cause a sudden, severe headache. Headache is usually followed by neck pain and neck stiffness.

A large blood clot can also press on brain tissue around the meninges. When this happens, the person may show progressive drowsiness. Other symptoms, such as paralysis and visual impairment, can also develop.

How is the condition diagnosed?

A cranial CT scan or cranial MRI can show blood in the brain from a ruptured aneurysm. There will also be large amounts of blood in the fluid collected by a spinal tap. To do a spinal tap, the doctor inserts a special needle into the spinal column. Through this needle, the doctor collects a sample of cerebrospinal fluid. A special X-ray test can also be used to locate the aneurysm.

What can be done to prevent the condition?

The best prevention is to manage high blood pressure. Lower blood pressure puts less stress on a damaged blood vessel wall. Treating clotting problems can reduce the risk of bleeding from aneurysms. A person with a diagnosed aneurysm should not take medicines that thin the blood.

What are the long-term effects of the condition?

The blood from a ruptured aneurysm dissolves and gets absorbed within a few days. Sometimes the breakdown of red blood cells produces excess protein. The excess protein draws fluid into the space around the brain. Repeated spinal taps can be done to remove excess protein and prevent fluid buildup. In some cases, a ventriculoperitoneal shunt is inserted in the brain. This tube carries the excess fluid from the brain down into the abdominal cavity.

What are the risks to others?

A cerebral aneurysm poses no risk to others.

What are the treatments for the condition?

The best treatment for an aneurysm varies from person to person. Surgery to repair the aneurysm is quite risky. The American Heart Association, called the AHA, has issued guidelines for treatment of unruptured aneurysms.

The AHA guidelines advise the doctor to look at three factors when choosing the treatment plan:

Younger people are usually good candidates for surgery. For older persons with an unruptured aneurysm, the AHA guidelines recommend to wait and watch. The aneurysm can be monitored with regular cranial CT scans or cranial MRIs.

A craniotomy is a type of brain surgery that is used to repair an aneurysm. With the most common type, a metal clip is used to close off the aneurysm at its base. Medicines may be used to control high blood pressure or to treat problems with blood clotting.

What are the side effects of the treatments?

Side effects vary, depending on the treatment chosen. Medicines can cause allergic reactions and problems with blood clotting. Surgery carries a risk of bleeding, infection, and allergic reaction to the anesthesia.

Even if the person survives surgery, he or she can be left with permanent disabilities, including personality problems, weakness, or fatigue.

What happens after treatment for the condition?

A person with significant disabilities may need rehab therapy on a long-term basis. This may include speech therapy, occupational therapy, and physical therapy.

How is the condition monitored?

If surgery resolves the aneurysm, a person may not need any more monitoring. However, someone who has major disabilities may need frequent visits to the doctor. Any new or worsening symptoms should be reported to the doctor.

Author:James Warson, MD
Date Written:
Editor:Crist, Gayle P., MS, BA
Edit Date:10/17/02
Reviewer:Kathleen A. MacNaughton, RN, BSN
Date Reviewed:10/17/02