Topic Overview
What is a brain aneurysm?
A brain (cerebral) aneurysm is a bulging, weak
area in the wall of an artery that supplies blood to the brain. In most cases,
a brain aneurysm causes no symptoms and goes unnoticed. In rare cases, the
brain aneurysm ruptures, releasing blood into the skull and causing a
stroke.
When a brain aneurysm ruptures,
the result is called a
subarachnoid hemorrhage. Depending on the severity of
the hemorrhage, brain damage or death may result.
The most common
location for brain aneurysms is in the network of blood vessels at the base of
the brain called the circle of Willis.
What causes a brain aneurysm?
A person may inherit the tendency
to form aneurysms, or aneurysms may develop because of hardening of the
arteries (atherosclerosis) and aging. Some risk factors that can
lead to brain aneurysms can be controlled, and others can't. The following risk
factors may increase your risk for an aneurysm or, if you already
have an aneurysm, may increase your risk of it rupturing:
- Family history. People
who have a family history of brain aneurysms are more likely to have an
aneurysm than those who don't.
- Previous aneurysm. People who have had a brain aneurysm are more likely to have another.
- Gender. Women are more likely to
develop a brain aneurysm or to suffer a
subarachnoid hemorrhage.
- Race. African Americans are more likely than whites to have a subarachnoid
hemorrhage.
- High blood pressure. The
risk of subarachnoid hemorrhage is greater in people who have a history of
high blood pressure.
- Smoking. In addition to being a cause of high blood pressure, the use
of cigarettes may greatly increase the chances of a brain aneurysm rupturing.
What are the symptoms?
Most brain aneurysms cause no symptoms and may only be discovered during
tests for another, usually unrelated, condition. In other cases, an unruptured
aneurysm will cause problems by pressing on areas in the brain. When this
happens, the person may suffer from severe headaches, blurred vision, changes
in speech, and neck pain, depending on what areas of the brain are affected
and how bad the aneurysm is.
Symptoms of a ruptured brain aneurysm often
come on suddenly. If you have any of the following symptoms or
notice them in someone you know, call 911 or other emergency services right away:
- A sudden, severe headache that is
different from past headaches.
- Neck pain.
- Nausea and
vomiting.
- Sensitivity to light.
- Fainting or loss of
consciousness.
- Seizures.
How is a brain aneurysm diagnosed?
Because unruptured brain aneurysms often do not
cause any symptoms, many are discovered in people who are being treated for a
different condition.
If your doctor believes that you
have a brain aneurysm, you may have the following tests:
- Computed tomography (CT) scan. A CT scan
can help identify bleeding in the brain. Sometimes a
lumbar puncture may be used if your doctor suspects that you have a ruptured cerebral aneurysm with a
subarachnoid hemorrhage.
- Computed tomography angiogram (CTA) scan. CTA is a more precise method of
evaluating blood vessels than a standard
CT scan. CTA uses a combination of CT scanning,
special computer techniques, and
contrast material (dye) injected into the blood to
produce images of blood vessels.
- Magnetic resonance angiography (MRA). Similar to a CTA,
MRA uses a magnetic field and pulses of radio wave
energy to provide pictures of blood vessels inside the body. As with CTA and
cerebral angiography, a dye is often used during MRA to make blood vessels show
up more clearly.
- Cerebral angiogram. During
this X-ray test, a catheter is inserted through a blood vessel in the groin or
arm and moved up through the vessel into the brain. A dye is then injected into
the cerebral artery. As with the above tests, the dye allows any problems in
the artery, including aneurysms, to be seen on the X-ray. Although this test is
more invasive and carries more risk than the above tests, it is the best way to
locate small (less than 5 mm) brain aneurysms.
How is it treated?
Your doctor will think about several things before
deciding the best treatment for you. Things that will determine the type of
treatment you receive include your age, size of the aneurysm, any additional
risk factors, and your overall health.
Because the risk of a
small (less than 10 mm) aneurysm rupturing is low and surgery for a brain
aneurysm is often risky, your doctor may want to continue to
observe your condition rather than do surgery. Your doctor may suggest ways to keep your blood vessels as healthy as possible, such as managing high blood pressure and not smoking. If your aneurysm
is large or causing pain or other symptoms, though, or if you have had a previous
ruptured aneurysm, your doctor may recommend surgery.
The following procedures are used to treat both ruptured and unruptured
brain aneurysms:
- Endovascular embolization.
During this procedure, a small tube is inserted into the affected artery and positioned near the aneurysm. For coil embolization, soft metal coils are then moved through the tube into the aneurysm, filling the aneurysm and making it less likely to rupture. In mesh embolization, mesh is placed in the aneurysm, reducing blood flow to the aneurysm and making it less likely to rupture. These procedures are less invasive than surgery. But they involve risks, including rupture of the aneurysm.
- Surgical clipping. This surgery involves placing a small metal clip around the
base of the aneurysm to isolate it from normal blood circulation. This
decreases the pressure on the aneurysm and prevents it from rupturing. Whether
this surgery can be done depends on the location of the aneurysm, its size, and
your general health.
Both of these procedures should be done in a hospital where many procedures like these are done.
Some aneurysms bulge in such a way that the aneurysm has to
be cut out and the ends of the blood vessel stitched together, but this is very
rare. Sometimes the artery is not long enough to stitch together, and a
piece of another artery has to be used.
Aneurysms that have bled
are very serious. In many cases, they lead to death or disability. Management
includes hospitalization, intensive care to relieve pressure in the brain
and maintain breathing and vital functions (such as blood pressure), and
treatment to prevent rebleeding.