Stroke is a form of cerebrovascular disease, meaning it affects the blood vessels in the brain. Stroke was first called “apoplexy,” a Greek word that means “to strike down.” Symptoms may appear slowly or suddenly, but the underlying conditions that lead to stroke are usually present for years.
Stroke is a true medical emergency, and the number three cause of death for Americans but the number one cause of adult disability. Eighty percent of strokes are preventable. The American Heart Association estimates that approximately 700,000 Americans have a new or recurrent stroke each year. Those who survive it may experience paralysis, emotional problems, or trouble with speech, memory, or judgment. The severity of the injury or impairment depends on which artery was blocked and for how long. Although many strokes happen without warning, some physical symptoms may signal the occurrence of a stroke.
What Is A Stroke?
A stroke is to the brain what a heart attack is to the heart. A stroke occurs when blood supply to part of the brain is cut off or when bleeding occurs into or around the brain. Although a stroke is type of brain injury, it also severely affects the rest of the body. The brain is a large, soft tissue mass composed of billions of nerve cells. It is the body’s control center for vision, hearing, taste, smell, speech, movement, thought, emotion, memory, judgment, and awareness. Each of these areas can be affected by a stroke or transient ischemic attack (TIA). The brain’s nerve cells need a constant supply of oxygen and glucose, which are carried in the blood. When blood fails to get through to parts of the brain, the oxygen supply to those areas is cut off. This is called ischemia. Without oxygen, brain cells die. The longer the brain is without blood, the more severe the damage will be. Similar to the heart, the area of tissue death that results from ischemia is known as an infarction.
Blood flow to the brain can be blocked in two ways:
- A blood clot blocks an artery in the brain or neck.
- A weakened brain artery bursts.
Because brain cells control movement, part of the body may also become paralyzed after a stroke. If the right side of the brain is affected, the left side of the body may become paralyzed. If the left side of the brain is affected, the right side of the body may become paralyzed. The effects of a stroke may be mild or severe, short-term or permanent. Some people have strokes and recover within a few days; others may never recover. The severity of a stroke depends on:
- The part of the brain that is affected
- The amount of brain cell damage
- The length of time it takes to restore blood to the injured parts of the brain
- The length of time it takes for the healthy parts of the brain to take over the job of the injured area
What Causes a Stroke?
A blood clot or a blocked artery leading to the brain causes approximately 88% of all strokes. This type of stroke is called an ischemic stroke. There are two kinds of ischemic stroke: cerebral thrombosis and cerebral embolism. The other 12% of strokes are caused by ruptured or leaky blood vessels in or around the brain. This type of stroke is called a hemorrhagic stroke. There are two kinds of hemorrhagic strokes: cerebral and subarachnoid. Hemorrhagic strokes cause more deaths than ischemic strokes, but those who survive a hemorrhagic stroke recover more fully and have fewer disabilities.
Uncontrollable risk factors (highest incidence) include age (over age 55), gender (male), race (African American, Hispanic or Asian/Pacific Islander), and having a family history of stroke or previous stroke or TIA. Medical risk factors include: previous stroke, previous TIA or mini stroke, high cholesterol, high blood pressure, heart disease, atrial fibrillation, and carotid artery disease. These medical risk factors can be controlled with the help of a physician. Lifestyle risk factors include: smoking, being overweight, and drinking too much alcohol. These lifestyle risk factors can also be controlled or decreased.
Learning the symptoms of stroke and acting F.A.S.T. saves lives. Common stroke symptoms include:
- Sudden numbness or weakness of the face, arm, or leg – especially on one side of the body
- Sudden confusion, trouble speaking, or understanding
- Sudden trouble seeing in one or both eyes
- Sudden trouble walking, dizziness, loss of balance, or loss of coordination
- Sudden severe headache with an unknown cause
This simple test helps friends or family members to detect stroke symptoms and Act F.A.S.T.:
F = FACE Ask the person to smile. Does one side of the face droop?
A = ARM Ask the person to raise both arms. Does one arm drift downward?
S = SPEECH Ask the person to repeat a simple sentence. Does the speech sound slurred or strange?
T = TIME If any of these signs are found, call 911 or get to the nearest stroke center or hospital.
Stroke diagnosis includes a complete medical history, a physical and neurological examination, laboratory (blood) tests, tests that show images of the brain (CT scan, MRI), tests that measure the brain’s electrical activity (EEG) and response (evoked response test), and tests that examine blood flow to the brain (carotid duplex scan). These and other diagnostic tests are used to determine the type and severity of the stroke.
Advanced treatments and rehabilitation are helping many stroke patients return to their homes and families. Stroke treatments include anti-clotting drugs, hospital care, rehabilitation, and surgery. Treatment programs are very individualized based on the severity of the stroke and the loss of function. The best therapy for stroke is prevention. By knowing the warning symptoms and controlling risk factors, such as cigarette or tobacco smoking, high blood pressure, diabetes, and heart disease, the risk of stroke can be reduced.
Texas Heart Institute www.texasheartinstitute.com/HIC/Topics/Cond/stroke.cfm
American Heart Association www.americanheart.org/presenter.jhtml?identifier=4755
American Stroke Association www.strokeassociation.org
National Stroke Association www.stroke.org
Medline Plus www.nlm.nih.gov/medlineplus/stroke.html