Stroke

A stroke occurs when part of the brain is deprived of blood for too long a time. That part of the brain dies because the brain cannot survive for long without oxygen and nutrients, which are supplied by blood. A stroke causes permanent brain damage.

A stroke can strike with the suddenness and devastation of a lightning bolt, sometimes permanently disabling a person. Thus, stroke is one of the most feared disorders, particularly by older people.

Stroke is a leading cause of disability and death worldwide. For people over 55, the risk of stroke more than doubles every 10 years. Most people who die of a stroke are over 65. Stroke affects women and men, and more than half of people who die of a stroke are women.

Even though a stroke causes permanent brain damage, most people recover. How well they recover varies, depending largely on how severe the stroke was. People may recover fully or be disabled slightly, severely, or anywhere in between. Early treatment may result in less brain damage and a better recovery. Consequently, knowing the early symptoms of stroke is important. Then people can seek treatment right away.

There are two types of strokes: ischemic and hemorrhagic. In ischemic stroke, something prevents blood from reaching part of the brain. The most common cause is blockage of an artery. About 85% of strokes are ischemic strokes.

In hemorrhagic stroke, a blood vessel bursts. As a result, blood escapes into or around brain tissue. This blood can irritate brain tissue and can rapidly accumulate. The accumulating blood causes swelling, putting pressure on and damaging brain tissue. The accumulating blood also interferes with the blood supply to brain tissue. Hemorrhagic strokes usually involve bleeding within the brain (intracerebral hemorrhage) or bleeding between two of the layers of tissue covering the brain (subarachnoid hemorrhage). Among people over 60, intracerebral hemorrhage is more common than subarachnoid hemorrhage.

Causes

Certain conditions (called risk factors) make a person more likely to have a stroke. They include abnormal cholesterol levels, atherosclerosis (sometimes called hardening of the arteries), some heart disorders (such as abnormal heart rhythms, heart valve disorders, and heart attacks), high blood pressure, and diabetes. Smoking cigarettes, being physically inactive, being overweight, and drinking large amounts of alcohol also increase the risk of stroke.

People who have had a transient ischemic attack (TIA) are more likely to have a stroke—most commonly within the next month and often within 2 days. In a TIA, something temporarily interrupts the blood supply to the brain. The risk factors for a TIA are the same as those for stroke.

See the figure Clogs and Clots: Causes of Ischemic Strokes.

Other conditions may increase the risk of stroke, but the connection is less clear. They include inflammation (such as that in periodontal disease or rheumatoid arthritis), a tendency for blood to clot too easily, and a high level of homocysteine in the blood (hyperhomocysteinemia). A high level of homocysteine, an amino acid, may increase the risk of stroke by increasing the risk of atherosclerosis and by making blood more likely to clot. As people age, the homocysteine level increases.

See the figure Bursts and Breaks: Causes of Hemorrhagic Strokes.

The risk factors for ischemic and some types of hemorrhagic strokes can overlap.

For additional detail on this topic, see Causes of Stroke.

See the sidebar What Is a Transient Ischemic Attack?

Symptoms

Symptoms of a stroke occur suddenly, sometimes instantaneously. They may worsen over a period of hours or sometimes days.

Symptoms of a stroke last for at least 24 hours. If symptoms do not last that long and if bleeding is not the cause, the disorder is considered a transient ischemic attack, not a stroke. Most transient ischemic attacks last less than 90 minutes.

Everyone should know what the common early symptoms of a stroke are. Most strokes, whether ischemic or hemorrhagic, cause one or more of the following early symptoms:

• Sudden difficulty moving or sudden abnormal sensations on one side of the body. The affected part may feel weak or be unable to move (paralyzed). Or it may tingle, feel prickly, or be numb. One arm or leg, half of the face, or all of one side of the body may be affected.
• Sudden difficulty speaking or understanding speech. Speech may be slurred, or a person may suddenly become confused.
• Sudden changes in vision, particularly in one eye. Vision may be dim, blurred, double, or lost.
• Sudden loss of balance and coordination or sudden dizziness. Dizziness may involve unsteadiness or a sensation of spinning (vertigo). Falls may result.
• Sudden, severe headache with no apparent cause. A hemorrhagic stroke due to a subarachnoid hemorrhage typically begins with a sudden, severe headache.

Other symptoms may occur early or later. They include difficulty swallowing, difficulty walking, partial loss of hearing, uncontrollable leakage of urine (urinary incontinence), and loss of control of bowel movements (fecal incontinence). Remembering, perceiving, understanding, and learning things may be difficult. People may have difficulty remembering where they are, what time it is, and who other people are (orientation problems). They may be unable to pay attention and concentrate. Their thoughts may be disorganized. Some people cannot recognize parts of their body. They may be unaware of the stroke's effects.

Many people have problems with speech and language. For example, they may have difficulty expressing themselves or understanding other people (aphasia) or difficulty physically forming words (dysarthria). A stroke can cause depression or aninability to control emotions. People may cry or laugh at inappropriate times. Some people continue to have these symptoms, even after treatment and rehabilitation.

Strokes, particularly hemorrhagic strokes, can cause nausea, vomiting, and drowsiness. Sometimes a stroke results in a coma. People may suddenly go into a coma. Or they may become progressively drowsy and unresponsive until they cannot be aroused. Some strokes cause blood pressure to go up and down erratically and cause breathing and heart rate to become irregular.

See the figure Why Strokes Affect Only One Side of the Body.

Which symptoms occur and how serious they are depend not only on how much of the brain is affected but also on which part of the brain is affected. Some small strokes cause more devastating symptoms than some large strokes. How many strokes occur also affects symptoms. People who have one stroke may have problems with memory or thinking. If they continue to have strokes, dementia may result.

With some strokes, symptoms are most severe immediately after the stroke occurs. With other strokes, symptoms become progressively worse, causing the greatest loss of function after a few hours up to a day or two. This type of stroke is called an evolving stroke, a progressing stroke, or a stroke in evolution.

Sometimes a stroke leads to other problems. For example, immediately after a stroke, an arm may be weak, numb, or paralyzed and thus be more easily injured. If swallowing is difficult (whether a person notices it or not), food or saliva may be inhaled into the windpipe and reach the lungs. Aspiration pneumonia may result. Being unable to move can result in blood clots forming in the deep veins of the legs and groin (a disorder called deep vein thrombosis). Part of a clot can break off, travel through the bloodstream, and block an artery that supplies the lungs (a disorder called pulmonary embolism). Pulmonary embolism can cause difficulty breathing, chest pain, and, if severe, very low blood pressure or death. Being unable to get out of bed or having urinary incontinence can make urinary tract infections more likely. Not being able to move joints for a long time can result in permanently stiff joints (contractures). Muscles may become tight and stiff (spastic), making movement awkward. Being in one position too long can result in bedsores (pressure sores).

Diagnosis

Often, doctors can diagnose a stroke based on symptoms and the results of a physical examination. They ask the person, if able, to describe the symptoms. A stethoscope is used to listen to blood flow in arteries in the neck, particularly the carotid arteries. Blood flow through partially blocked arteries is noisy. Doctors also check pulse and blood pressure and listen to the heart.

Computed tomography (CT) or magnetic resonance imaging (MRI) of the head is usually promptly done. CT and MRI help doctors determine whether symptoms are caused by a stroke or another brain disorder, such as a brain tumor or traumatic injury. These tests also help doctors distinguish a hemorrhagic stroke from an ischemic stroke. They can show how much and which part of the brain is affected.

Blood tests can also help doctors determine whether symptoms are caused by a stroke or another disorder. For example, the level of sugar is measured, because a low blood sugar level can cause symptoms similar to those of a stroke. Blood tests are also useful in identifying the cause of the stroke. For example, cholesterol levels are measured because abnormal levels can lead to a stroke. To determine whether the blood clots more easily than normal, doctors measure how long blood takes to clot.

Other tests are often done to identify the cause of the stroke, usually within the first few days. Identifying (and treating) the disorder that caused the stroke can help prevent later strokes. Which tests are done depends on the area of the brain affected, the type of stroke, and the person's medical history.

If an ischemic stroke is suspected, tests are done to check for blockages in arteries. Doctors often use Doppler ultrasonography first because it is painless and safe. Other tests, such as magnetic resonance angiography (MRA) and computed tomography angiography (CTA) may also be done. Magnetic resonance angiography uses radiofrequency waves produced in a magnetic field, and computed tomography angiography uses x-rays. Both tests can provide images of the arteries. In both tests, a substance may be injected into a blood vessel to outline the arteries.

Angiography with a catheter is the most accurate way to detect blockages. However, angiography is an invasive test and is usually unnecessary. (Invasive tests involve cutting into or inserting instruments into the body.) Consequently, particularly for older people, angiography is done only when other tests have not provided enough information for a diagnosis or to help doctors decide on treatment. People with atherosclerosis are more likely to have problems after angiography. For this test, a thin, flexible tube (catheter) is inserted into an artery and threaded into the arteries that supply blood to the brain.

Rarely, a spinal tap (lumbar puncture) is needed to help diagnose a subarachnoid hemorrhage. A spinal tap can detect blood in the spinal fluid, which surrounds the spinal cord. If a subarachnoid hemorrhage occurs, blood almost always appears in the spinal fluid. For this test, a needle is inserted in the lower back to withdraw a sample of spinal fluid, and the fluid is analyzed.

Electrocardiography (ECG) may be done to check for abnormal heart rhythms and evidence of a recent heart attack. A person may be asked to wear a portable ECG device that records heart rhythms continuously (Holter monitor). The monitor is usually worn for 24 hours or more.

Echocardiography (ultrasonography of the heart) may be done to check for blood clots, a heart valve disorder, or other structural abnormalities of the heart. For this test, a handheld device that emits and records ultrasound waves is placed on the chest. Sometimes, to get a better view of the heart, doctors pass the device down the person's throat into the esophagus and behind the heart. This method is called transesophageal echocardiography. This test is generally safe but can cause gagging and anxiety. Therefore, doctors usually give the person a sedative beforehand.

Prevention

For strokes, an ounce of prevention is worth a pound of cure. Modifying—eliminating or controlling—risk factors for stroke can often help prevent strokes from occurring and from recurring.

Changes in lifestyle can modify many risk factors. For example, people who smoke cigarettes can stop. After people stop smoking, their risk of having a stroke decreases to that of nonsmokers in about 2 to 5 years. People can increase their physical activity and, after checking with their doctor, start a regular exercise program. People who are overweight can lose weight. For people who drink alcoholic beverages, drinking in moderation (no more than 1 or 2 drinks a day for men and 1 drink a day for women) is recommended.

Sometimes modifying one risk factor modifies another. Stopping smoking, exercising, and losing weight help lower high blood pressure and high cholesterol levels as well as help control diabetes.

Eating a healthy, low-fat diet, including lots of fruits and vegetables, can help reduce the risk of stroke in several ways. It helps people control their weight and keep their cholesterol levels in a healthy range. It also helps prevent or control diabetes. Limiting the amount of salt in the diet can help prevent or lower high blood pressure.

Having regular checkups is important. Doctors can then identify disorders that may lead to a stroke so that treatment can be started early. People should have their blood pressure checked at least twice a year.

If needed, disorders that can lead to a stroke are treated. High blood pressure can be lowered with antihypertensive drugs. Diabetes can be controlled well with diet, drugs that are taken by mouth to lower blood sugar levels, and, if necessary, insulin injections. High cholesterol levels can be lowered with cholesterol-lowering drugs, such as statins. For people with coronary artery disease, taking a statin may reduce their risk of stroke.

For most people who are at risk of having a stroke or who have had a TIA or stroke, doctors recommend taking an antiplatelet drug such as aspirin to help prevent strokes. Platelets are particles in the blood that help blood clot when an injury occurs. Antiplatelet drugs make platelets less likely to clump and blood clots less likely to form. Other antiplatelet drugs, such as dipyridamole, clopidogrel, or ticlopidine, are sometimes used instead of or in addition to aspirin.

Warfarin (an anticoagulant) can help some people who have a heart disorder that can lead to a stroke, particularly atrial fibrillation. Anticoagulants (commonly called blood thinners) make blood less likely to clot. However, people who take warfarin must have blood tests periodically to check on how the anticoagulant, other drugs, diet, and other conditions are affecting the blood's ability to clot. If blood is taking too long to clot, excessive bleeding can occur.

If a blockage is detected in an artery in the neck (usually a carotid artery), surgery to remove the blockage may be done. This procedure, called an endarterectomy, may reduce the risk of ischemic stroke. However, the effectiveness and safety of the surgery depend on the skill of the surgeon and the resources of the hospital. Furthermore, any major surgery has risks. Angioplasty may be done instead. In angioplasty, a catheter with a balloon at its tip is threaded into the blocked artery. The balloon is then inflated to open the artery. To keep the artery open, doctors often insert a tube made of wire mesh (a stent) into the artery. Angioplasty with a stent is still considered experimental as a treatment of blocked carotid arteries.

Treatment

A person with any symptom suggesting a stroke should go to a hospital immediately, even if the symptom goes away quickly or does not cause pain. An ambulance should be called because the person may need emergency care as soon as possible. A person having a stroke may not know a stroke is occurring or may be unable to communicate. So anyone who suspects another person is having a stroke should call an emergency telephone number (usually 911) for help. Treatment is most likely to be effective when given soon after symptoms begin.

When a person who has had a stroke arrives at the hospital, the person's breathing, heart rate, and temperature are restored to normal if necessary. An intravenous line is inserted so that fluids and drugs can be given as needed. If the person has difficulty breathing, supplemental oxygen can be given. Sometimes a breathing tube is needed to help with breathing. If the person has a fever, it may be lowered using drugs (such as acetaminophen) or a cooling blanket. Tests are done to identify the cause of the stroke.

Specific treatment varies depending on the type of stroke.

Ischemic strokes: A drug called tissue plasminogen activator (tPA, or alteplase), which breaks up clots, is sometimes used. This drug must be given intravenously within 3 hours of the first symptoms. Because tPA helps restore blood flow, it may help limit the amount of brain damage. However, tPA can increase the risk of bleeding in or around the brain. Most people who have had an ischemic stroke cannot be given tPA, usually because they arrive at the emergency department too late or because they have a condition that makes tPA too risky. Risky conditions include very high blood pressure, a severe stroke, swelling in or around the brain, a head injury, recent surgery, and bleeding in the digestive tract.

If a stroke is worsening, heparin (an anticoagulant) is sometimes given to reduce the risk of blood clots. However, there is no evidence that heparin is beneficial in this situation.

In some specially equipped hospitals, other treatments for ischemic strokes are being tried. For example, if people arrive at the hospital too late to be given tPA intravenously, they may be given this or a similar drug in another way. The drug is applied directly to the clot through a flexible tube (called a catheter) that is inserted in an artery and threaded to the clot.

Hemorrhagic strokes: After a hemorrhagic stroke, controlling blood pressure—preventing it from becoming too high or too low—is important. Drugs such as mannitol may be given to decrease swelling in the brain and thus decrease pressure there. Occasionally, a drainage tube is placed in the brain to decrease pressure. Some people benefit from using a machine that helps them breathe (mechanical ventilation). For subarachnoid hemorrhage, surgery or another procedure (with a catheter) may be done to repair an aneurysm or another abnormality and thus prevent bleeding from continuing or recurring.

Control of problems after a stroke: People who have had a stroke usually stay in the hospital for at least a few days. They are closely monitored. Tests such as x-rays may be done to check whether swallowing and certain other body functions are impaired. The disorder that caused or contributed to the stroke is treated as needed.

Some hospitals have specialized units that provide stroke care (stroke units). In stroke units, care is focused on prevention of the problems stroke can lead to and on rehabilitation.

Measures to prevent problems are started early. For example, a person is not given food or drink until doctors make sure the person can swallow well enough. This precaution helps prevent aspiration pneumonia. If a person has had an ischemic stroke, heparin or a similar drug may be injected under the skin to prevent blood clots from forming in the veins of the legs. Pneumatic stockings may also be used to help prevent clots, particularly in people who have had a hemorrhagic stroke or who have a problem with blood clotting. Usually made of plastic, pneumatic stockings are automatically pumped up and emptied by an electric pump. They repeatedly squeeze the calves and empty the veins. Thus, they help keep blood moving. They are worn as long as the person must remain in bed. If a person cannot turn over in bed, staff members turn the person frequently, and mattresses designed to minimize pressure on the skin are used. These measures help prevent pressure sores.

Rehabilitation, including physical therapy, is started in the hospital as soon as a person is physically able—usually within 1 or 2 days of admission. Staying in bed for a long time can cause many problems, so the person is encouraged to get up as soon as possible.

Because a stroke often causes mood changes (especially depression), staff members, family members, and friends should be on the lookout for signs of depression. They should tell the doctor if the person seems depressed. Depression can and should be treated.

Long-term treatment: After the person is discharged from the hospital, rehabilitation can be continued in a rehabilitation center, at the hospital, in a nursing home, or at home. Rehabilitation can help many people regain some of their lost abilities. Rehabilitation helps people maintain and improve physical condition as well as relearn old skills and learn new ones.

Specific therapy is available for people who have difficulty walking, paralysis of one side, spastic muscles, lack of coordination, vision problems, problems with thinking (cognitive problems), and speech or language problems. Speech therapists can help people with language problems communicate more effectively. They may also help people who have problems swallowing learn to eat more safely.

Occupational and physical therapists can suggest ways to make life easier and the home safer. For example, they may suggest certain helpful devices. There are devices to help with walking (such as canes, walkers, or braces), to help with daily activities (such as utensils with built-up grips and electric can openers), and to help with communication (such as picture boards or electronic communication devices).

Getting back to daily activities as much as possible helps people recover. Living on the first floor and having access to a car or a driver can help. The home may need to be modified to help a person function better. For example, grab bars may be installed in the bathroom, or a chair lift or glide may be attached to a rail that runs the length of the stairs. Having support from other people and being active can help prevent or lessen depression. Depression can make people less interested in trying to regain lost abilities, doing daily activities, and spending time with people. Exercise helps preserve gains achieved during rehabilitation.

Adjusting to life after a stroke is challenging for family members, other caregivers, and friends as well as for the person who had the stroke. Learning what effects the stroke has had (emotionally and physically) can help family members determine what kind of help is needed. For example, a person who has had a stroke may become angry or upset more easily. Knowing that strokes have this effect can help family members be patient and calm. People who have had a stroke, their family members, and other caregivers can also get help from support groups.

For people whose quality of life remains very poor despite treatment, care focuses on controlling pain, keeping the person comfortable, and providing fluids and nourishment. Many people with severe disabilities need care in a nursing home because their care is so demanding. However, some can remain at home if home health care or hospice care can be arranged.

Outlook

A stroke may result in disability that is slight, severe, or anywhere in between. Some people need help at home. A few need care at a nursing home or another facility. Some people are never able to move, speak, or eat normally again. Some eventually recover completely. However, others die immediately or within days or weeks.

People recover most rapidly during the first 30 days after the stroke. Over the next 2 months, many people continue to recover, although somewhat less rapidly. Some people continue to recover for longer periods after the stroke.

Hemorrhagic strokes, particularly intracerebral hemorrhages, result in death more often than ischemic strokes. Intracerebral hemorrhages due to high blood pressure can be extensive and devastating. However, people who survive a hemorrhagic stroke may also recover. If the hemorrhage is small, people can recover to a remarkable degree. If a subarachnoid hemorrhage is treated before much brain damage occurs (that is, when the only symptom is a headache), complete recovery may be possible. People who have had a hemorrhagic stroke may continue to improve for months, even years.

How well a person who has had a stroke can eventually function depends partly on the location and extent of brain damage and on the type of stroke. Rehabilitation is also important.

People who have had a stroke are at risk of having more strokes. Because strokes recur and progress unpredictably, people who have had a stroke should prepare advance directives as soon as possible. People at risk of having a stroke should also do so. Advance directives help a health care practitioner determine what kind of medical care people want if they become unable to make these decisions. For example, whether to use treatments that sustain life artificially may have to be decided.