A stroke is the interruption of the flow of blood to any part of the brain, which causes damage to brain tissue. Today, some call a stroke a "brain attack" to illustrate its seriousness and its relationship to heart attack (the interruption of blood flow to the heart). Stroke causes one out every fifteen deaths in the U.S., is the third leading cause of death in most developed countries, and the leading cause of disability in adults. The damage to brain tissue can lead to various problems, such as impaired speech and mobility, changes in vision, reflexes, and eye movements, decreased sensation, and weakness or even paralysis in one side of the body.
In most cases, the blood flow is interrupted by a blood clot blocking an artery in the brain or leading to the brain. There are four main arteries leading to the brain: two carotid arteries in the front of the neck and two vertebral arteries in the back of the neck. Blockage in these arteries, especially in the carotid arteries, is often caused by atherosclerosis, an accumulation of "plaque" (deposits of fat) on the inside wall of the arteries; this is the same condition that can lead to heart attack. The type of stroke caused by blockage in an artery is called an ischemic stroke. There is a second, less common type, called a hemorrhagic stroke, in which the blood flow is interrupted by bleeding in the brain, caused by a ruptured blood vessel.
The risk factors (things that increase your chance of getting a disease) for stroke include:
- High blood pressure: This is the leading modifiable risk factor for stroke.
- Age: The chance of having a stroke goes up with age and doubles for every decade after 55.
- Family history: The chance of having a stroke goes up (is higher than average) if your family members had one.
- High cholesterol: This can cause fat to build up in the arteries, leading to blockage and stroke (as well as heart attack).
- Diabetes: This disease can cause high blood pressure, blocked arteries (atherosclerosis), and inability to break down blood clots.
- Heart disease: This disease can result from atherosclerosis and doubles your risk of stroke.
- Smoking: Cigarette smoke damages the cardiovascular system, which can lead to heart disease and stroke.
- Previous stroke: Having a stroke places you at higher risk of having another one, compared to people who have not had a stroke.
- Race: The chance of getting the disease is higher for African-Americans because they have a higher rate of diabetes and high blood pressure.
- Certain medications: Among the drugs that promote clot formation are birth control pills, especially if you're over 35 and a smoker. But newer, low dose pills create a much lower risk.
- Gender: Generally, men are more likely to have a stroke, women are more likely to die of one, and women have a higher than normal risk during pregnancy and the weeks immediately after it.
- Life style: Among life style risk factors are smoking, alcohol abuse, illicit drugs such as cocaine, and uncontrolled stress.
There are preventative measures (things that decrease your risk of getting a disease) you can take against stroke. For information about them, go to Key Point 3.
- A stroke is not a death sentence, nor does it necessarily mean you must live with diminished capabilities. Preventative measures, such as taking medicines and making some lifestyle changes, can prevent a first or second stroke; today's rehabilitation facilities and techniques can help stroke patients greatly improve their physical and mental abilities.
- Most of the steps you can take to prevent a stroke will also help prevent heart attack. So you get "double benefits" when you:
- keep your blood pressure under control
- keep your cholesterol under control
- eat a "head-healthy" and heart-healthy low fat diet
- get more physical exercise
- stop smoking
- stop drinking alcohol heavily
- The body manufactures more cholesterol at night than during the day. Therefore, cholesterol lowering medicines are most effective when taken during the evening, at dinner or before bed.
- A transient ischemic attack or TIA is a temporary disturbance in brain function that creates stroke-like symptoms, such as dizziness, loss of ability to speak or walk, mental confusion, weakness, etc. But these symptoms usually last for less than 24 hours and possibly as short as a few minutes.
- A TIA may not be serious in itself, but it's a warning sign that a person may be a potential stroke victim.
- Angioplasty is the process of opening or widening a narrowed blood vessel. First used in the 1970s to treat coronary artery disease, it is now used to open the carotid arteries that carry blood to the brain, to prevent stroke. Recently, the procedure has included the placement of a stent.
- A stent is an object put inside a blood vessel to keep it open and unblocked. It's usually a tiny tube made of a metallic mesh and looks something like a wire cage or spring.
- Ignore television commercials for prescription drugs. The "pill" advertised may not be appropriate for your problem, and probably will have side effects. Get your medical treatment from your doctor, not your television.
*Quick Facts have been reviewed by Medical Advisors and are current as of October 2005.
Ask Your Doctor
This list of questions is a good starting point for discussion with your doctor. However, it is not a comprehensive list.
- What life-style changes (such as diet, exercise, etc.) should I make to prevent a stroke?
- What medications can I take to make to prevent a stroke?
- What kind of services are available to people who have had a stroke?
- What kind of services are available to those taking care of people who have had a stroke?
- What are the treatment options, and what are their benefits, risks, and side effects?
- What follow-up care will I need?
- If I have pain, how will it be managed?
- Am I a good candidate for a clinical trial?
- What will the recovery period be like?
Key Point 1
Time is essential. You have a very limited period of time to restore blood flow to the brain before the injury is irreversible. You must know what a stroke looks like and get to a hospital.
The sudden occurrence of one or more of the following may be symptoms of a stroke:
- Numbness, weakness, or tingling in the face, arm or leg (especially on one side of the body)
- Changes in vision, double vision, blurriness, loss of vision in one or both eyes
- Confusion or problems with judgment, memory, spatial orientation, or perception
- Difficulty with or inability to walk, loss of balance, and dizziness
- Difficulty with or inability to speak or understand
- Difficulty with swallowing
- Dizziness, loss of balance, coordination or consciousness
- Drowsiness or lethargy
- Mood changes (sudden depression or apathy)
- Severe, sudden headache, possibly along with pain between the eyes, in the face, or a stiff neck, and vomiting or altered consciousness
Note that the key words for all symptoms are sudden onset. Slowly developing problems in any of these areas are probably not symptoms of a stroke. Furthermore, a condition called a transient ischemic attack or TIA creates symptoms that mimic a stroke, but they usually last for less than 24 hours (possibly as short as a few minutes). A TIA is a temporary loss of or disturbance in brain function. In itself it may not be serious, but it is a warning sign that you could have stroke in the future.
A number of tests can be used to decide the type and cause of a stroke, and the specific areas of the brain that have been affected. Most of these tests create images of the brain and the arteries that feed it. They could also be used before a stroke to look for blockages in the carotid arteries. Among the imaging techniques used are arteriography, computerized tomographic angiography (a form of CT scanning with a dye injected into the vein), MRI, and ultrasound. For information about them, go to Key Point #2.
One of the most effective ways to limit the effects of a stroke is to begin treatment as quickly as possible. A stroke is the interruption of the flow of blood to any part of the brain, which damages brain tissue. The longer the delay before treatment begins, the more damage to the brain tissue. The interruption in blood flow is caused either by a blood clot or other particles blocking the arteries that carry blood to the brain (an ischemic stroke) or by bleeding in the brain, caused by a ruptured blood vessel or an injury (a hemorrhagic stroke). So the goal of emergency treatment is to find out what kind of stroke the person is having and then take appropriate measures to stop it by dissolving the blood clot or stopping the bleeding.
Ischemic strokes can be stopped by using a class of drugs known as thrombolytics or clot busting medicines. Injected directly into a vein, they can break up or dissolve blood clots, thus removing the blockage and restoring blood flow to the brain. The most widely used is called TPA (for tissue plasminogen activator). However, TPA must be given within three hours of the start of symptoms. After three hours, the benefits of dissolving the clot no longer outweigh the risk of hemorrhage (N.B. There really is no debate about IV TPA after 3 hours-it is contraindicated. )
Further, because of potential side effects and risks, some people who have had an ischemic stroke are not ideal candidates for thrombolytics even within three hours. Doctors must understand the details of each individual case before giving the drugs. For example, if your blood pressure is uncontrollable when they're being considered, your doctor may not use them. Finally, before any thrombolytics can be given, it must be certain that the person is having an ischemic stroke. If the stroke is caused by bleeding, the drugs could make things worse.
Other possible drugs to treat ischemic strokes include blood thinners, such as heparin and coumadin, and aspirin and other anti-platelet agents.
Hemorrhagic strokes are caused by bleeding. One of the most common types of hemorrhagic stroke is due to high blood pressure. Tiny blood vessels deep in the brain can rupture, causing bleeding into the brain tissue. This type of bleeding is often called "intracerebral hemorrhage". Another type of bleeding may be caused by a ruptured.(broken), badly formed blood vessel. This type of blood vessel is called an AVM, for "arteriovenous malformation." Some AVMs can be removed by surgery, and that may be a way of preventing a possible stroke. But if an AVM is too large or found deep within the brain, surgery may not be possible. There are other possible treatments for AVMs, including procedures that shrink them by blocking the arteries that supply them with blood.
Another possible cause of a hemorrhagic stroke is an aneurysm, a localized, blood-filled dilatation (swelling) of a blood vessel caused by a disease or the weakening of the vessel's wall. Again, there are a number of surgical treatments for aneurysms, including aneurysm clipping (the aneurysm is clamped shut, preventing it from getting blood from the artery it's attached to) and aneurysm embolization (a tiny coil is put into the aneurysm which makes it clot, preventing blood from nearby arteries getting into it).
A hemorrhagic stroke may also require surgery to remove blood that has pooled in the brain during the stroke.
After a stroke, the emphasis should be on preventing a second stroke (about 25 % of people who recover from a first stroke will have a second within 5 years) and rehabilitation. Rehabilitation obviously depends on the type of disability the person has, and can include speech, occupational, and physical therapy. About 10% of those who have had a stroke recover most or all of their abilities; 50% can remain at home with medical assistance; 40% move to long-term care facilities. Unquestionably, however,
a supportive family, friends and environment can help stroke patients in their recovery.
For links to information about long-term recovery go to Resources.
Key Point 2
Treatment of an ischemic stroke is the restoration of blood flow to the brain to prevent and minimize damage.
A blockage is usually caused by atherosclerosis, an accumulation of "plaque" (deposits of fat) in the arteries that narrows them, reducing blood flow, or by blood clots in the arteries. The plaque not only blocks the blood flow itself, it can also help create a clot because it forces the blood to flow abnormally. A clot that stays in one place (usually the place it was formed) is called a thrombus. A clot that breaks loose, travels to another spot, and wedges itself into a narrower blood vessel, is called an embolism.
The first indication that an artery may be blocked can be an abnormally loud, harsh noise coming from it, heard through a stethoscope during a physical examination. This noise is called a bruit (pronounced "bru-we"). The next step can be one or more tests to look at the arteries that feed the brain and measure the amount and type of blockage in them. They're the same type of diagnostic imaging tests now used to diagnose a wide range of conditions, including heart problems. They include:
- Carotid arteriogram (also called carotid angiogram): This is an x-ray of the carotid arteries to look for blockages. A catheter (a small tube) is inserted through a small incision into a blood vessel and threaded up into the carotid arteries. A contrast dye is then injected into the catheter to make blockages more visible on the x-ray.
- Carotid ultrasound: Many people are familiar with ultrasound imaging used with pregnant women to produce images of fetuses. Similarly, carotid ultrasound produces pictures of the carotid arteries. High-frequency sound waves are sent into the neck, pass through the tissue, and then bounce back. The results are images that show any narrowing or clotting in the carotid arteries.
- Computerized tomography angiography (CTA): Many people are also familiar with CT scanning (often called "CAT scanning") which produces detailed images of organs and tissues. CTA is a form of CT scanning that uses dyes injected into the bloodstream to make blockages and other problems more visible.
- Magnetic resonance imaging (MRI): This technique uses a strong magnetic field to create a three-dimensional view of the brain to look for the areas damaged by a stroke.
- Magnetic resonance angiography (MRA) combines an MRI with an injected dye to better see the arteries in the neck and brain. It is used to determine if the stroke was caused by bleeding (hemorrhage) or other lesions and to define the location and extent of the stroke.
If these tests show that either of the two carotid arteries are narrowed, a physical intervention to remove the blockage may be needed. When an individual has symptoms of a stroke or TIA from a carotid artery that is over 70% blocked, evidence suggests that those individuals should strongly consider undergoing an operation to remove the blockage. If the individual has not had any symptoms from the severe blockage, or if the amount of blockage is less severe (50-70%), decisions about surgery should be individualized, depending on unique patient characteristics and preferences.
The process of removing the blockage is called carotid revascularization. Currently, one of two approaches is generally followed.
One approach is an operation called a carotid endarterectomy (CEA). The surgeon opens the affected artery and physically removes the blockage – the plaque, clot, etc. Studies show that this procedure reduces the risk of stroke and is especially helpful to people with severe blockages, even if they have no symptoms at all. Although all surgery has general and specific risks (the specific risks for carotid endarterectomy is that the surgery itself might cause a stroke or heart attack), the risks for CEA are not great.
The second approach is known as carotid artery stenting or carotid angioplasty-stent (CAS) and may be more appropriate than surgery in some patients. Angioplasty is the process of opening or widening a narrowed blood vessel. The procedure was first used in the 1970s to treat coronary artery disease; now it has been extended to other arteries, including the carotid artery. A catheter is threaded up into the arteries. A tiny balloon at the end of the catheter is inflated to open the narrowed blood vessel. The process may also involve using a tiny umbrella-like filter (called a "distal protection device") at the end of the catheter to catch any particles that break free from the artery and prevent them from traveling to and blocking some other blood vessel.
A stent is an object put inside a blood vessel to keep it open and unblocked. Today a stent is usually a tiny tube made of a metallic mesh that looks something like a wire cage or spring. After a blocked blood vessel has been opened, a stent can be slid along the catheter and put in place to keep the vessel open. Some stents are coated with medicines to help prevent further blockages.
While carotid stenting is a newer technique and still under investigation, current research has shown it to be as effective as carotid endarterectomy in some cases and a less invasive form of surgery. Meanwhile, other new techniques to remove clots, such as catheter embolectomy (using a catheter threaded into one of the carotid arteries to remove clots) are being explored.
Key Point 3
You may not have to have a stroke. You've heard it before – control your blood pressure, control your cholesterol, stop smoking and keep your body to a healthy weight. You can dramatically reduce the risk of having a stroke, along with preventing a heart attack, Type 2 diabetes and many other diseases.
In general, to prevent stroke you shold:
- Know your risk factors and develop a plan, with your doctor, to reduce them;
- Learn more about the risk factors for stroke.
- Control high blood pressure, high cholesterol, diabetes, and heart disease with lifestyle changes and medicines prescribed by your doctor.
High blood pressure is the leading risk factor for stroke. But you can reduce your blood pressure by making some simple lifestyle changes.
- Stop smoking.
- Don't abuse alcohol (no more than 1 to 2 drinks per day).
- Eat a low-fat diet.
- Minimize the amount of sodium in your diet.
- Sodium is found in table salt (chemical name, sodium chloride), so minimize the amount of salt you eat; avoid salty snacks.
- Exercise often, on a regular schedule.
- Lose weight if you're overweight.
- Reduce and manage stress by changing your lifestyle and simplifying your life, exercising and using relaxation techniques.
There are also prescription medicines that help reduce blood pressure, such as:
- ACE (angiotensin-converting enzyme) inhibitors
- Angiotensin receptor blockers
- Calcium channel blockers
You should discuss these medicines with your doctor, who will prescribe what's appropriate for you. You can get more information about them at Medline Plus, an on-line service of the National Library of Medicine, the National Institutes of Health, and other government agencies and health-related organizations.
Most strokes are caused by a blood clot or atherosclerosis (fatty build-up) blocking the flow of blood through arteries leading to the brain. Atherosclerosis is the same condition that can also cause a heart attack. High levels of LDL-cholesterol (commonly called "bad cholesterol") are a major cause of atherosclerosis. Therefore, two other types of stroke preventing medicines are those that:
- reduce blood clotting
- reduce LDL-cholesterol, plaque and atherosclerosis
The first type, prescription anti-clotting medicines, include anticoagulants, antiplatelet agents, and thrombolytics. Like all prescription medicines, they must be used properly, following all of your doctor's recommendations and precautions.
- Anticoagulants decrease the blood's ability to form clots. They're often called "blood thinners," though they don't actually thin the blood, nor do they dissolve clots already present.
- Antiplatelets stop blood platelets (substances in blood that promote clotting) from clumping together to form clots.
- Thrombolytics are often called "clot busters" because they break up or dissolve already existing blood clots. For information about them, go to Key Point 1.
Aspirin is a non-prescription antiplatelet medicine. But even though it is available over-the-counter, it may not be appropriate because it increases the risk of bleeding. Do not "self-medicate" yourself with aspirin. Instead, talk to your doctor about its risks and benefits.
The second type of medicine, prescription LDL-cholesterol reducing drugs, include statins, bile acid sequestrants, and fibrates.
- Statins are currently considered the most important and effective group of LDL-cholesterol reducing medicines. They slow cholesterol production and increase the liver's ability to remove the LDL-cholesterol already there. Because the body makes more cholesterol at night, these drugs are usually taken in the evening, at dinner or before bed. Side effects appear to be minimal and studies show that people using statins have reported 20 to 60 percent lower LDL-cholesterol levels. As of this writing, five statin drugs are available in the U. S.:
- Bile acid sequestrants bind with bile acids in the intestines that contain cholesterol. Then they are eliminated during defecation, reducing the amount of cholesterol in the blood. Often, these drugs are prescribed in combination with statins. As of this writing, three main bile acid sequestrants are available here:
- Fibrates lower the level of triglycerides (the main component of fat and therefore another major cause of atherosclerosis) in the blood.
Nicotinic acid is a non-prescription cholesterol lowering substance. It's a form of niacin, the water-soluble B vitamin. When taken in high doses, well above the suggested daily amount, it can be effective in lowering LDL-cholesterol and triglyceride levels. Note that there's another form of niacin, nicotinamide, that doesn't lower cholesterol and shouldn't be used instead of nicotinic acid. Further, high doses of nicotinic acid can have side effects. Do not "self-medicate" yourself with Vitamin B. Instead, talk to your doctor about its risks and benefits.
In addition to all these preventative measures, there are also physical ways to unblock an artery, including surgery and a procedure called "stenting." For information about them, go to Key Point 2.
Conduct an off-site search for Stroke information from MedlinePlus. These up-to-date search results are based on search terms specific to Second Opinion Key Points.