Definition A cerebral aneurysm is an abnormal swelling of the wall of a blood vessel inside the brain.
What is going on in the body? Cerebral aneurysms are areas where a blood vessel in the brain weakens and "balloons". They are the result of defects in the elastic layer of the blood vessel wall. Aneurysms usually develop where arteries branch. The fork formed where arteries branch may be weaker than other areas. When pulsating blood pushes this area of weakness outward, an aneurysm results. Eventually, the aneurysm may balloon and thin the wall to the point that it ruptures.
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 generally produces a sudden, severe headache. Headache is usually followed by neck pain and neck stiffness that occur when blood causes an irritation of the meninges.
The meninges are the protective layers covering 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. A large blood clot can also press on surrounding brain tissue. When this happens, the person may show progressive drowsiness. Other symptoms, such as paralysis and visual impairment, can also develop.
What are the causes and risks of the condition? Aneurysms may be congenital, which means they are present at birth. They can get larger with age and high blood pressure. Arteriosclerosis, or hardening of the arteries, can also weaken the vessel wall. This may lead to an aneurysm, particularly in elderly individuals. Rarely, 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, death, or permanent disability. Re-occurring bleeding and blood vessel spasm may also lead to death.
What can be done to prevent the condition? The best prevention is the proper medical management of high blood pressure. Lower blood pressure puts less stress on the damaged blood vessel wall. Careful management of clotting problems can reduce the risk of bleeding from aneurysms. Blood thinners should not be taken by a person with a diagnosed aneurysm.
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. A spinal tap involves the insertion of a special needle into the spinal column to collect a sample of cerebrospinal fluid. A special X-ray test can also be used to locate the aneurysm.
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 to carry the excess fluid down into the abdominal cavity.
What are the risks to others? A cerebral aneurysm is not contagious and poses no risk to others.
What are the treatments for the condition? Appropriate treatment of an aneurysm is decided on an individual basis. While an untreated aneurysm can rupture and cause a stroke, surgery to repair the aneurysm is also quite risky.
The size of the aneurysm, as well as the person's age and life expectancy and general health is usually taken into consideration when surgery is considered.
Surgery to repair an aneurysm involves a craniotomy, or brain surgery. The most common technique involves a metal clip that closes off the aneurysm at its base. Medications may be used to control high blood pressure, or to treat blood clotting problems.
What are the side effects of the treatments? Side effects vary, depending on the treatment chosen. Medications can cause allergic reactions and blood clotting problems. Surgery carries a risk of bleeding, infection, and allergic reaction to the anaesthesia.
Even successful surgery can result in permanent disabilities, including personality problems, weakness, or fatigue.
What happens after treatment for the condition? A person with significant disabilities may need rehabilitation therapy on a long-term basis. This may include speech therapy, occupational therapy, and physiotherapy.
How is the condition monitored? After successful surgery, a person may require no further monitoring. However, someone who develops significant disabilities may need frequent visits to the doctor. Any new or worsening symptoms should be reported to the doctor.
Author: James Warson, MD Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
