Understanding Stroke
What is a stroke?
A stroke is damage to part of the brain tissue as a result of a loss of
blood and oxygen. A stroke can also be called a "brain attack."
What happens during a stroke?
Brain tissue needs a constant supply of oxygen and nutrients to keep nerve
cells and other parts of the tissue alive and functioning. The brain cannot
store oxygen, so it relies on a network of blood vessels to provide it with
blood that is rich in oxygen.
A stroke occurs when one of these blood vessels becomes damaged or blocked,
preventing blood from reaching a part of the brain tissue. When the tissue is
cut off from its supply of oxygen for more than three to four minutes, it begins
to die.
Types of stroke
Hemorrhagic stroke -- occurs when a weakened blood vessel in the brain
ruptures. This type of stroke is the most serious. A hemorrhage, or bleeding
from the blood vessel, happens suddenly. The force of blood that escapes from
the blood vessel can also damage surrounding brain tissue.
(See illustrations above.)
Ischemic stroke -- occurs when a blood vessel in the brain develops a
clot and cuts off the blood supply to the brain. A blood clot that forms in a
blood vessel in the brain is called a "thrombus." A blood clot that
forms in another part of the body, such as the neck or lining of the heart, and
travels to the brain is called an "embolus." Blood clots often result
from a condition called "atherosclerosis," the build-up of fatty
deposits within the blood vessel walls.
Transient ischemic attack (TIA) or "mini stroke" -- occurs
when blood flow to a certain part of the brain is cut off for a short period of
time, usually 15 minutes or less. A TIA is a painless episode but is a warning
sign that something is wrong, and it should be treated as seriously as a stroke.
What causes a blood vessel to burst in the brain?
- High blood pressure that, over time, weakens the blood vessel wall,
causing it to balloon and burst
- A birth defect that makes the blood vessel weak and more likely to burst
Seventy percent of all strokes that are caused by a bleeding blood vessel
occur in people who have high blood pressure. High blood pressure puts added
stress on the blood vessel walls, which can weaken them and make them more
likely to burst. High blood pressure can also speed up the build-up of fatty
deposits in blood vessels throughout the body.
What are the warning signs of stroke?
If you experience any of the major stroke warning signs listed below, call
9-1-1. You must get to the hospital immediately.
- Sudden numbness or weakness in the face, arm or leg (especially on one
side of the body)
- Sudden nausea, fever and vomiting
- Difficulty speaking or understanding words or simple sentences
- Sudden blurred vision or decreased vision in one or both eyes
- Difficulty swallowing
- Dizziness, loss of balance or uncoordination
- Brief loss of consciousness
- Sudden inability to move part of the body (paralysis)
- Sudden, unexplainable and intense headache
A stroke is a medical emergency
It is important to realize that stroke warning symptoms are the signs of an
emergency. For every minute that brain cells are deprived of oxygen during a
stroke, brain damage increases. Also, the chances for survival and recovery are
much better when the right treatment begins within the first few hours of
noticing stroke symptoms.
How to help a stroke victim
While you are waiting for an emergency vehicle to arrive, you (or the person
with the stroke symptoms) should lie down. Watch the person suspected of having
a stroke and lift the chin to open the airway. Check for breathing and pulse. If
necessary, perform cardiopulmonary resuscitation (CPR).
If the person is breathing but unconscious, roll him or her onto his or her
side. (Do not move the person if you suspect a head, neck or back injury.)
If the person is conscious, try to reassure and comfort him or her. Loosen
constricting clothing or jewelry. If the person is having difficulty swallowing,
try to turn him or her onto the side. Do not give the person anything to eat or
drink.
Stroke risk factors
About half a million Americans suffer from stroke each year. Often these
strokes are preventable by making lifestyle changes.
Risk factor facts
- High blood pressure makes you 4 to 6 times more likely to have a stroke.
- High cholesterol can double your risk.
- Heart disease makes you 6 times more likely to have a stroke.
- If you have already had a stroke or transient ischemia attack (TIA), you
are at risk for having another stroke.
- Smoking doubles your risk of stroke.
- Heavy drinking is associated with stroke.
- Being overweight makes you more likely to have other stroke risk factors
such as high cholesterol, high blood pressure and diabetes.
How can I reduce my risk?
- Don't smoke. If you need help quitting smoking, call the Cleveland
Clinic Smoking Cessation Program at (216) 444-5819 or call the Health
Information Library at (216) 444-3771 for smoking cessation resources in
your community.
- Have your cholesterol level checked and control your cholesterol level, if
necessary, by limiting the amount of fat and cholesterol you eat. Your
health care provider can give you specific recommendations.
- Limit the amount of alcohol you drink.
- Have your blood pressure checked and control your blood pressure, if
necessary. Your health care provider can give you specific
recommendations about how to control your blood pressure.
- Follow your health care provider's instructions for changing your diet.
- If you have diabetes, follow your health care provider's instructions for
managing the disease.
- Follow your health care provider's instructions for preventive
medications.
What lasting damage can a stroke cause?
The effects of a stroke depend on the extent and the location of damage in
the brain.
Among the many types of damage that can result from a stroke are:
- Inability to move part of the body (paralysis)
- Weakness in part of the body
- Memory loss
- Inability to speak or understand words
- Change in personality
- Confusion or poor judgement
- Difficulty swallowing
Why does a stroke affect different parts of the body?
Nerve cells in the brain tissue communicate with other cells to control such
functions as memory,
speech and movement. When a stroke happens, nerve cells in the brain tissue
become injured. As a result, they cannot communicate with other cells, and
functions are impaired. If a stroke occurs on the right side of the brain, the
left side of the body is affected, and vice versa.
How is a stroke treated?
The only FDA approved treatment for acute ischemic (sudden onset) stroke is
a thrombolytic agent (TPA) or "clot buster" medication. TPA must be
given within the first 3 hours of the onset of stroke symptoms.
Also, there are several new and experimental drugs that may stop -- and even
reverse -- the brain damage if administered immediately after a stroke.
There are many different types of diagnostic tests your physician can use to
help him or her prevent or treat stroke. Each test is designed to provide a
specific piece of information from which your physician can draw a clear picture
of the type of stroke present or the type or stroke that is most likely to
occur.
Atherosclerosis (the build-up of fatty deposits within the blood vessel
walls) can be treated with changes in diet and lifestyle, as well as with
medications.
For some patients, the surgical removal of the plaque within the carotid
artery (the artery that supplies blood to the brain) may be recommended. This
procedure is called a carotid endarterectomy. The carotid angioplasty and
stenting procedure is the newest, less invasive treatment appropriate for some
patients who have blockages within the carotid arteries of the brain.
Angioplasty is a non-surgical procedure in which a carotid angiography is first
performed. In angiography, a long, slender tube called a catheter is inserted
through a blood vessel in the groin and guided into the carotid arteries. Once
the catheter is in place, balloon angioplasty and stenting are performed.
Balloon angioplasty is a procedure in which a small balloon at the tip of the
catheter is inflated to stretch the artery open and increase blood flow to the
brain. A stent is a small, metal mesh cylinder that is inserted into the artery
with a catheter. When the stent is released from the catheter, it expands to the
size of the artery and holds it open.
Where can I learn more?
We understand that if you or a loved one has suffered a stroke, you may be
experiencing a difficult time and have a lot of questions. Please talk to your
your health care providers about your concerns, or contact:
- Cleveland Clinic Health Information Library (216) 444-3771 or (800)
223-2273 ext. 43771
- National Stroke Association 8480 East Orchard Road, Suite 1000 Englewood,
Colorado 80111 (303) 771-1700
- The American Heart Association (800) 242-8721
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