Stroke

Definition
A stroke, sometimes referred to as a "brain attack," occurs when blood fails to circulate within the brain, causing a lack of oxygen to the brain tissue. Without adequate oxygen, brain tissue cannot survive.

Causes/associated factors
Most strokes are caused by a blockage of blood flow to the brain, leading to the death of brain cells due to the lack of blood flow. These are called ischemic strokes. A condition known as atherosclerosis, in which fatty deposits collect on blood vessel walls, is responsible for most blockages. Clots that form in the blood vessels of the brain or neck (thrombosis) or those that move to the brain from another part of the body (embolism) may also be responsible. Sometimes, blockages are related to the narrowing of a blood vessel in the brain (stenosis).
A less common, but more serious cause of stroke is called a hemorrhagic stroke. This occurs when an artery in or near the brain bursts and blood floods into the brain tissue. The pressure caused by the bleeding interferes with the brain's normal functioning. A combination of blood vessel disease and high blood pressure is often behind a cerebral hemorrhage. An aneurysm, which may also cause a stroke, develops when part of a weak blood vessel bursts or bleeds into the brain.

Strokes can cause permanent brain damage and varying degrees of disability, depending on what part and how much of the brain was damaged. In some cases, strokes are fatal.

Stroke remains the third leading cause of death in developed countries. The more risk factors you have, the higher your risk of having a stroke. Some risk factors for stroke cannot be controlled, such as:

age, especially after age 65
gender (Men have a higher risk of stroke.)
race (Statistically, African Americans -- especially those living in the southeastern United States -- have the highest risk.)
a family history of strokes
diabetes
Risk factors that may be in your control include:

high blood pressure
heart disease
smoking
heavy alcohol intake
high blood cholesterol
illicit drug use
obesity
About 25 percent of people who recover from their first stroke will have another one within five years. A transient ischemic attack (TIA) can also increase the risk for stroke. A TIA is sometimes referred to as a mini-stroke. It is caused by reduced or blocked blood flow to the brain, typically caused by a buildup of plaque in the arteries, an arterial spasm, a blood clot or an embolism (a blockage of a blood vessel by a blood clot, air bubble, fat deposit or other foreign substance). By definition, a TIA lasts less than 24 hours and results in complete recovery of previous neurological function.

Women over age 35 who take birth control pills and have other combined risk factors, such as migraines, smoking or high blood pressure, also may face a higher risk of stroke.


Signs/symptoms
The key to recognizing stroke symptoms is their sudden onset.
Common symptoms include:

weakness, tingling or numbness on one side of the body
vision loss, typically in one eye
dizziness or lightheadedness
difficulty speaking or loss of speech
loss of balance and/or coordination
headache, usually sudden and severe
confusion

Diagnosis
The rapid development of one or more of the above symptoms is a main factor in diagnosis. In addition to routine blood studies, imaging studies of the arteries and/or brain can help the doctor pinpoint where the damage has occurred, as well as the extent of the damage. Computed tomography (CT scan), for example, creates a computer-generated, cross-sectional picture of internal body parts. Magnetic resonance imaging (MRI), another imaging technique, is based on computer analysis of the body's response to a magnetic field. An electrocardiogram (a recording of the electrical activity of the heart) can provide helpful information when a stroke or TIA is suspected, particularly if an abnormal rhythm is thought to be a contributing factor. Also, an echocardiogram (using sound waves to look at the heart without penetrating the skin) may be done if a clot from the heart is suspected to be the cause of the stroke. Doppler ultrasonography (using sound waves to look at tissues, vessels or organs) may be used to check the circulation of the carotid arteries (arteries that supply blood to the brain) or other arteries that provide blood to the brain.
If you have a condition that may require surgery, such as an aneurysm, a cerebral angiography may be done. This procedure is an imaging technique that allows the study of blood vessels through the injection of a contrast dye (a substance used with various imaging techniques that will create a different density on an X-ray film to help the medical team study tissues or organs better).


Treatment
Prompt medical intervention (within three hours) can significantly decrease the effects of a stroke. Seek immediate medical attention when symptoms begin because some brain cells can survive if blood flow is restored quickly enough. Medications to break up blood clots, such as alteplase (brand name Activase), may be prescribed but must be given soon after symptoms appear. Before treatment begins, however, the doctor will determine the type of stroke you've had, its severity, the area involved and the associated disability, and any contraindications you may have to the clot-dissolving medications.
Early on, hospitalization is necessary and blood pressure management is critical. You may be given medication to help prevent blood clotting, such as aspirin. Researchers are currently studying other medications with brain protective properties to potentially treat stroke.

Carotid endarterectomy (the surgical removal of plaque from inside a blood vessel) with or without a stent may be recommended if you have symptoms and more than 50-percent narrowing of the arteries. This procedure is not recommended for everyone, however, especially if you have coronary artery atherosclerosis (hardening of the arteries that carry blood to the heart caused by a buildup of cholesterol). Your doctor will determine if you're an appropriate candidate for surgery.

A hemorrhagic stroke may require surgery to remove the bleeding that has collected in the brain. Medications may be prescribed to control blood pressure and pressure within the brain.

Long-term treatment usually includes physical, speech and occupational therapy.


Complications
Complications of a stroke may include:
heart attack
permanent disability (such as weakness, paralysis or speech impediment)
pneumonia
depression
malnutrition
blood clots in the legs or lungs
stomach ulcers
constipation
muscle contractions or spasms
skin breakdown
shoulder pain
permanent memory loss
seizures
incontinence
In some cases, a stroke may be fatal.


Pregnancy-specific information
Strokes are uncommon during pregnancy. A stroke is more likely to happen if you smoke or have high blood pressure, sickle cell anemia, rheumatic heart disease, diabetes or abnormal blood vessels in the brain. Sometimes, a blood-clotting disorder or a complication of pregnancy may lead to a stroke. Discuss any specific concerns with your doctor.

Senior-specific information
Again, the risk of stroke increases with age. Make sure you know the symptoms of a stroke, and seek emergency care if you think you're having a stroke.

Prevention
Many of the risk factors for stroke and TIA are treatable and controllable. The National Stroke Association has established the following guidelines for controlling risk factors:
Know your blood pressure. If it's elevated, work with your doctor to keep it under control.
Find out if you have atrial fibrillation (AF), which is an irregular heartbeat rhythm. If you have AF, work with your doctor to manage it.
If you smoke, quit.
If you drink alcohol, do so in moderation.
Know your cholesterol numbers. Work with your doctor to control your cholesterol.
If you have diabetes, follow your doctor's recommendations carefully to control your diabetes.
Include exercise in the activities you enjoy in your daily routine.
Follow a lower-sodium (salt), lower-fat diet.
Ask your doctor if you have circulation problems that increase your risk for stroke.
If you have any stroke symptoms, seek immediate medical attention.