From The MayoClinic
April 20, 2007
Introduction
A brain aneurysm is a bulge in an artery in your brain. Also known as a cerebral aneurysm, the bulge may pose little risk to your health — as long as it’s small and it doesn’t rupture. An aneurysm may go undetected indefinitely and produce no signs or symptoms.
However, some brain aneurysms are large enough to put pressure on surrounding brain tissue. Others may rupture at a weak spot in the artery wall, flooding an area of your brain with blood (hemorrhage).
People of all ages can have a brain aneurysm, but most develop as a result of aging. Most are discovered in people ages 35 to 60. Women are slightly more likely to develop an aneurysm than men are.
How serious an aneurysm is depends on its size and location and on your age and health. Small aneurysms are often best left alone, though treatments are available for larger aneurysms. A ruptured aneurysm may quickly become life-threatening and requires prompt medical attention.
Signs and symptoms
An unruptured brain aneurysm may produce no symptoms, particularly if it’s small. However, a large aneurysm may press on brain tissues and nerves, possibly causing a droopy eyelid or double vision.
Once an aneurysm ruptures, signs and symptoms may include:
* Sudden, severe headache
* Nausea and vomiting
* Stiff neck
Less common signs and symptoms of a ruptured aneurysm include:
* Sensitivity to light
* Seizure
* Loss of consciousness
Causes
Most brain aneurysms develop as a result of the wear and tear on arteries that comes with aging. Recent research indicates that brain aneurysms aren’t present at birth (congenital), as once was commonly believed. However, some people may have a predisposition to developing an aneurysm.
Rarely, a blow to your head or an infection in an artery can weaken an artery wall and result in an aneurysm.
Risk factors
If one or more family members had a brain aneurysm, you’re at increased risk. Other factors that may contribute to developing a brain aneurysm or increase the risk of rupture include:
* Smoking. Among other effects, smoking may constrict your blood vessels.
* Use of stimulant drugs and medications. Drugs such as cocaine can cause a sudden increase in blood pressure. Some over-the-counter medications, such as cold medicines, also contain stimulants.
* Sudden increase in blood pressure. Certain activities, such as lifting heavy weights, and some health conditions can cause a sudden increase in blood pressure.
In addition, several genetic or inherited conditions have been associated with the development of aneurysms because they involve congenital defects in the structure of the arteries. They include:
* Polycystic kidney disease, in which the kidneys and possibly other organs develop multiple cysts
* Arteriovenous malformation (AVM), a condition in which an abnormal connection exists between arteries and veins in the brain
* A narrowing of the aorta at birth (coarctation)
* Connective tissue disorders, such as Marfan syndrome and Ehlers-Danlos syndrome
When to seek medical advice
Because a ruptured brain aneurysm can be life-threatening, seek immediate medical attention if you develop a sudden, extremely severe headache, particularly if it’s accompanied by other signs or symptoms, such as stiff neck and nausea and vomiting.
If you’re with someone who complains of a sudden, severe headache or who loses consciousness or has a seizure, call 911 or other emergency number or get the person to a doctor or emergency room immediately.
Screening and diagnosis
An aneurysm is likely to go undetected until it either ruptures or shows up on a brain imaging test that you might undergo for another condition. However, after an aneurysm has ruptured, there are a number of ways to confirm diagnosis. Your doctor is likely to begin with a physical exam and a neurological exam. A neurological exam includes checking your memory and concentration, vision, hearing, balance, coordination and reflexes. Then, your doctor may conduct other tests, including:
* Computerized tomography (CT). A CT scan of your head can reveal the presence of a suspected aneurysm and, if it has burst, show whether blood has leaked into your brain. Similar to an X-ray, a CT scan shows a more detailed image of your brain than a conventional X-ray can. Some scans involve use of a contrast dye injected into your vein. Known as CT angiography, this test produces an even more detailed image.
* Magnetic resonance imaging (MRI). This type of imaging uses a magnetic field and radio waves to create detailed, cross-sectional images of your brain. When his test involves use of a contrast dye, it’s known as magnetic resonance angiography.
* Cerebral arteriogram. This is a more invasive X-ray test. During this procedure, your doctor inserts a thin, flexible tube (catheter) into a large artery — usually in your groin — and threads it past your heart into the cerebral arteries in your brain. A special dye injected into the catheter fills your arteries so that they show up better on the X-rays. A cerebral arteriogram provides a clear picture of the arterial blood flow in your head.
* Cerebrospinal fluid analysis. This procedure, also known as a spinal tap, involves the use of a needle to extract a small amount of the fluid that protects your brain and spinal cord. Analysis of the fluid can detect brain hemorrhage.
Complications
Results of ongoing research known as the International Study of Unruptured Intracranial Aneurysms indicate that small unruptured aneurysms have a low risk of rupture. However, some brain aneurysms are large enough to put pressure on surrounding brain tissue, and some may rupture.
A brain aneurysm that bursts can cause stroke, permanent nerve damage or death. A ruptured aneurysm on the surface of the brain causes a subarachnoid hemorrhage, bleeding into the space between your brain and your skull. When an artery in the brain bursts and bleeds into the surrounding brain tissue, it’s called a cerebral hemorrhage. Other possible complications include:
* Fluid buildup in the brain (hydrocephalus)
* Narrowing of the arteries (vasospasm), which can lead to lack of blood flow to part of the brain (ischemic stroke)
Treatment
The decision to treat an unruptured aneurysm depends on a number of factors, including the type, location and size of the aneurysm, your age and general health and risks of treatment. Small, unruptured aneurysms appear to pose little risk of rupture, whereas the risk of treating aneurysms may be significant. So if you have a small aneurysm that hasn’t burst, check with your doctor. Many are best left untreated. If you have a large aneurysm that hasn’t burst, especially if it’s pressing against brain tissue and causing signs and symptoms, such as headaches or impaired vision, you’re more likely to need treatment.
Treatment options for ruptured and unruptured brain aneurysms include:
* Microvascular clipping. This surgical procedure is performed with general anesthesia. The neurosurgeon removes a section of your skull (craniotomy) to access the aneurysm. The surgeon locates the blood vessel that feeds the aneurysm, then places a tiny metal clip on the neck of the aneurysm to stop the flow to it. Then the surgeon replaces the portion of skull and closes the wound. If the artery that leads to the aneurysm is damaged, the surgeon may clamp off (occlude) all of it. The surgeon also may perform a bypass, grafting a small blood vessel to the damaged artery to reroute the blood flow.
* Endovascular embolization. This is a less invasive alternative to surgical clipping. You’re given general anesthesia or sedation. The doctor then inserts a hollow plastic tube (catheter) into an artery, usually in your groin, and threads it through your body to the aneurysm. He or she then uses a guide wire to pass either tiny platinum coils or a small latex balloon through the catheter to the aneurysm. The coils or the balloon destroy the aneurysm by blocking the blood flow and causing the blood to clot.
Both procedures pose risks, including post-surgical stroke and damage to other blood vessels. Also, with both procedures, there’s a possibility the aneurysm may recur and bleed again.
A large, randomized clinical trial compared microvascular clipping to endovascular coiling. The results, published in 2002, indicated that for people with a ruptured aneurysm who were equally suited to either treatment option, endovascular coiling produced a 22 percent lower relative risk of significant disability or death after one year than did microvascular clipping. Also, people treated with endovascular coiling tended to have a shorter hospital stay and faster recovery. However, more study is needed to determine the long-term outcomes of both procedures.
Other treatments for ruptured brain aneurysms are aimed at relieving signs and symptoms. They may include:
* Medications. Anticonvulsant medications can prevent seizures, analgesics may relieve headache symptoms, and calcium channel blockers can help widen narrowed blood vessels.
* Ventriculoperitoneal shunt. If necessary, your surgeon may surgically insert a shunt system that drains fluid from your brain to relieve harmful buildup of cerebrospinal fluid. This system consists of a flexible silicone rubber tube (shunt) and a valve. This artificial channel allows the fluid to flow away from the brain. One end of the channel begins inside one of the ventricles in the brain. At the other end of the channel, the fluid may drain into the abdominal cavity or into a chamber of the heart, where the fluid can be absorbed.
Prevention
To try to prevent the development of a brain aneurysm or lessen the risk of rupture:
* Don’t smoke or use stimulant drugs. Both can cause a sudden increase in blood pressure and damage arteries.
* Limit caffeine intake. Caffeine is a stimulant that can cause a sudden increase in blood pressure.
* Avoid straining. Extreme activities that make you strain, such as lifting heavy weights, can cause a sudden increase in blood pressure.
* Be cautious of aspirin use. If you have an aneurysm, talk to your doctor before taking aspirin or other drugs that inhibit blood clotting because they may increase blood loss if you hemorrhage.
Coping skills
Many people have small brain aneurysms that pose little risk of rupture. If you’ve had a ruptured brain aneurysm, you’ll need to recover from the effects of the damage the bleeding causes. Learn all you can about your condition. Talking about your concerns to a loved one or professional therapist may help relieve some of your anxiety. It may also help to talk to others with conditions similar to yours.
By Mayo Clinic Staff