Stroke
What is stroke?
A stroke, or brain attack, occurs when the blood supply to a part of the brain is disrupted. Those functions controlled by the part of the brain denied blood will be affected. For example, a stroke in the parietal lobe may affect one's ability to speak or understand language; a stroke in the occipital lobe may affect sight and a stroke in the motor cortex may affect your ability to move.
There are two main types of stroke, ischemic and hemorrhagic.
- Ischemic Stroke. In everyday life, blood clotting is beneficial. When a person bleeds from a wound, blood clots work to slow and eventually stop the bleeding. In the case of stroke, however, blood clots are dangerous because they can block arteries, cut off blood flow and cause brain injury, a process called ischemia.
Ischemic stroke is categorized as either "embolic" and "thrombolytic." In an embolic stroke, a blood clot forms somewhere in the body (usually the heart) and travels through the bloodstream to the brain. Once in the brain, the clot eventually travels to a blood vessel small enough to block its passage. With the blood vessel blocked, blood is denied to a part of the brain, causing a stroke.
In thrombolytic strokes, blood flow stops because of a blockage to one or more of the arteries supplying blood to the brain. The process leading to this blockage is known as thrombosis. - Hemorrhagic stroke, on the other hand, is caused by bleeding into the brain (commonly caused by the breakage or "blowout" of a blood vessel in the brain). Hemorrhages may be caused by a number of disorders which affect the blood vessels, including long-standing high blood pressure and cerebral aneurysms.
Like ischemic stroke, there are two types of hemorrhagic stroke, "subarachnoid" and "intracerebral". In an intracerebral hemorrhage, bleeding occurs from vessels within the brain itself. Hypertension (high blood pressure) is the primary cause of this type of hemorrhage. In a subarachnoid hemorrhage, an aneurysm bursts in a large artery on or near the thin, delicate membrane surrounding the brain. Blood spills into the area around the brain that is filled with a protective fluid.
In addition to the two major types of stroke, many individuals may experience a pre-stroke or mini-stroke known as a transient ischemic attack or TIA. A TIA occurs when a clot temporarily blocks a vessel carrying blood to the brain. In TIA, the clot dissolves before the brain experiences any permanent damage.
How often do strokes occur?
Stroke is the third leading cause of death in the United States. It is the leading cause of disability. The overall death rate from stroke is 60 people per 100,000 each year. However, it is more common in the elderly and causes approximately 400 deaths per 100,000 individuals over age 65 each year.
If you have had a TIA, your risk for stroke increases dramatically. Between 4-8% of patients with a TIA will experience a major stroke within a month; 12%-13% will experience a major stroke within a year; and 24-29% will experience a major stroke within five years. If you have had, or believe you may have had, a TIA, it is very important that you seek medical attention immediately.
What are the risk factors for stroke?
There are a number of risk factors for stroke. (See Virtual Stroke Screening)
- Incidence of stroke rises sharply after age 65
- African Americans have a higher incidence of stroke
- Males have a higher incidence of stroke overall but a slightly lower incidence of stroke after age 65
- Diabetes
- Hypertension or high-blood pressure (Diastolic blood pressure > 90)
- Family history
- Prior stroke or TIA.
- Smoking
- Asymptomatic carotid bruit, that is, a abnormal finding by stethoscope on the carotid artery, the principle artery carrying blood to the brain, indicating stenosis or narrowing of that artery.
Can stroke be prevented?
Stroke is a symptom of vascular disease. Most, though certainly not all, strokes are caused by the build up of damaging plaque in the blood vessels. You can take steps to reduce the build-up of plaque. They include:
- If you are diabetic, tightly controlling blood glucose levels
- If you suffer from high blood pressure, treating the high blood pressure
- If you smoke, quit
- If you suffer high cholesterol levels, lowering those levels
- Exercising
- If you are overweight, losing weight
How is stroke detected and diagnosed?
The five most common stroke symptoms include:
- Sudden numbness or weakness of 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 coordination
- Sudden severe headache with no known cause
Less common symptoms of stroke include sudden nausea and vomiting, a brief loss of consciousness or a period of decreased consciousness that might include fainting, confusion, convulsions or even coma.
What should I do if I believe I or a family member
may be experiencing a stroke or is at high risk for stroke?
If you believe you may be experiencing a stroke, call 911 immediately and get to an emergency room as quickly as possible. It is very important to remember the exact time you may have first experienced stroke symptoms.
If you have had a stroke, or have had stroke warning signs (TIA) or have risk factors for stroke, it is very important to seek prompt medical attention. Your doctor will work with you to find the cause of your problem and determine the best treatment. Even if your symptoms go away without treatment, you should discuss them with your doctor. Don't assume that a problem is unimportant if it goes away on its own. Never try to make a diagnosis by yourself.
What is the treatment for stroke?
At the hospital, your doctor or health care provider will obtain a medical history. If you can't communicate, a family member or friend will be asked for this information. Your doctor will ask about the symptoms you are having and have had in the past, previous medical problems or operations and any illnesses that run in your family. Be sure to bring a current list of all the medicines you take (prescription and non-prescription). If your symptoms were temporary, your doctor might also want to talk with someone who was with you at the time.
The next step is a thorough physical examination. Your doctor will check your pulse and blood pressure, and examine the rest of your body (heart, lungs, etc). The neurologic examination includes detailed tests of your muscles and nerves. The doctor will check your strength, sensation, coordination and reflexes. In addition, you will be asked questions to check your memory, speech and thinking.
Depending on the results of your evaluation, your doctor may need additional tests to fully understand your problem. You may also be referred to a medical specialist in brain disorders (neurologist), brain surgery (neurosurgeon) or another area. If the doctor believes you have suffered a stroke, he may order imaging studies to confirm a stroke and to determine what kind of stroke you may have suffered. Imaging studies may include CT scan or MRI.
The treatment of stroke has changed dramatically over the past five years. In 1996, the Food and Drug Administration approved the use of a clot-busting agent known as tissue Plasminogen Activitor, or tPA, for use in stroke patients. Hospitals with stroke teams, such as Sacred Heart Medical Center, may use tPA intravenously (IV) for patients with ischemic stroke if it is given within three hours of the onset of stroke symptoms. At Sacred Heart Hospital, it is being used intra-arterially (IA) up to six hours after the onset of stroke symptoms.
What are the risks associated with treatment?
Brain cells denied blood for a long period of time will die with or without a tPA. There is a high risk of hemorrhage associated with the use of any clot busting agent. More than three hours after stroke, it has been determined that the risk of hemorrhage outweighs the possible benefits of clot busting therapy.
Time is brain. Recognize the symptoms of stroke and contact emergency medical personnel immediately if you believe you or a loved one may be experiencing stroke symptoms.