Skip to Content

Ischemic Stroke


Ji Y. Chong

, MD, Weill Cornell Medical College

Last full review/revision Jul 2020| Content last modified Jul 2020

An ischemic stroke is death of an area of brain tissue (cerebral infarction) resulting from an inadequate supply of blood and oxygen to the brain due to blockage of an artery.

  • Ischemic stroke usually results when an artery to the brain is blocked, often by a blood clot and/or a fatty deposit due to atherosclerosis.
  • Symptoms occur suddenly and may include muscle weakness, paralysis, lost or abnormal sensation on one side of the body, difficulty speaking, confusion, problems with vision, dizziness, and loss of balance and coordination.
  • Diagnosis is usually based on symptoms and results of a physical examination and brain imaging.
  • Other imaging tests (computed tomography and magnetic resonance imaging) and blood tests are done to identify the cause of the stroke.
  • Treatment may include drugs to break up blood clots or to make blood less likely to clot and procedures to physically remove blood clots, followed by rehabilitation.
  • Preventive measures include control of risk factors, drugs to make blood less likely to clot, and sometimes surgery or angioplasty to open blocked arteries.
  • About one third of people recover all or most of normal function after an ischemic stroke.

(See also Overview of Stroke.)

Causes of Ischemic Stroke

An ischemic stroke typically results from blockage of an artery that supplies blood to the brain, most commonly a branch of one of the internal carotid arteries. As a result, brain cells are deprived of blood. Most brain cells die if they are deprived of blood for 4.5 hours.

Supplying the Brain With Blood

Blood is supplied to the brain through two pairs of large arteries:

  • Internal carotid arteries, which carry blood from the heart along the front of the neck
  • Vertebral arteries, which carry blood from the heart along the back of the neck

In the skull, the vertebral arteries unite to form the basilar artery (at the back of the head). The internal carotid arteries and the basilar artery divide into several branches, including the cerebral arteries. Some branches join to form a circle of arteries (circle of Willis) that connect the vertebral and internal carotid arteries. Other arteries branch off from the circle of Willis like roads from a traffic circle. The branches carry blood to all parts of the brain.

When the large arteries that supply the brain are blocked, some people have no symptoms or have only a small stroke. But others with the same sort of blockage have a massive ischemic stroke. Why? Part of the explanation is collateral arteries. Collateral arteries run between other arteries, providing extra connections. These arteries include the circle of Willis and connections between the arteries that branch off from the circle. Some people are born with large collateral arteries, which can protect them from strokes. Then when one artery is blocked, blood flow continues through a collateral artery, sometimes preventing a stroke. Other people are born with small collateral arteries. Small collateral arteries may be unable to pass enough blood to the affected area, so a stroke results.

The body can also protect itself against strokes by growing new arteries. When blockages develop slowly and gradually (as occurs in atherosclerosis), new arteries may grow in time to keep the affected area of the brain supplied with blood and thus prevent a stroke. If a stroke has already occurred, growing new arteries can help prevent a second stroke (but cannot reverse damage that has been done).

Supplying the Brain With Blood

Common causes

Commonly, blockages are blood clots (thrombi) or pieces of fatty deposits (atheromas, or plaques) due to atherosclerosis. Such blockages often occur in the following ways:

  • By forming in and blocking an artery: An atheroma in the wall of an artery may continue to accumulate fatty material and become large enough to block the artery. Even if the artery is not completely blocked, the atheroma narrows the artery and slows blood flow through it, like a clogged pipe slows the flow of water. Slow-moving blood is more likely to clot. A large clot can block enough blood flowing through the narrowed artery that brain cells supplied by that artery die. Or if an atheroma splits open (ruptures), the material in it can trigger formation of a blood clot that can block the artery (see figure How Atherosclerosis Develops).
  • By traveling from another artery to an artery in the brain: A piece of an atheroma or a blood clot in the wall of an artery can break off and travel through the bloodstream (becoming an embolus). The embolus may then lodge in an artery that supplies the brain and block blood flow there. (Embolism refers to blockage of arteries by materials that travel through the bloodstream to another part of the body.) Such blockages are more likely to occur where arteries are already narrowed by fatty deposits.
  • By traveling from the heart to the brain: Blood clots may form in the heart or on a heart valve, particularly artificial valves and valves that have been damaged by infection of the heart's lining (endocarditis). These clots may break off and travel as emboli and block an artery to the brain. Strokes due to such blood clots are most common among people who have recently had heart surgery, who have had a heart attack, or who have a heart valve disorder or an abnormal heart rhythm (arrhythmia), especially a fast, irregular heart rhythm called atrial fibrillation.

Clogs and Clots: Causes of Ischemic Stroke

When an artery that carries blood to the brain becomes clogged or blocked, an ischemic stroke can occur. Arteries may be blocked by fatty deposits (atheromas, or plaques) due to atherosclerosis. Arteries in the neck, particularly the internal carotid arteries, are a common site for atheromas.

Arteries may also be blocked by a blood clot (thrombus). Blood clots may form on an atheroma in an artery. Clots may also form in the heart of people with a heart disorder. Part of a clot may break off and travel through the bloodstream (becoming an embolus). It may then block an artery that supplies blood to the brain, such as one of the cerebral arteries.

Clogs and Clots: Causes of Ischemic Stroke

Blood clots in a brain artery do not always cause a stroke. If the clot breaks up spontaneously within less than 15 to 30 minutes, brain cells do not die and people's symptoms resolve. Such events are called transient ischemic attacks (TIAs).

If an artery narrows very gradually, other arteries (called collateral arteries—see figure Supplying the Brain With Blood) sometimes enlarge to supply blood to the parts of the brain normally supplied by the clogged artery. Thus, if a clot occurs in an artery that has developed collateral arteries, people may not have symptoms.

Lacunar infarction

Lacunar infarction refers to tiny ischemic strokes, typically no larger than about a third of an inch (1 centimeter). In lacunar infarction, one of the small arteries deep in the brain becomes blocked when part of its wall deteriorates and is replaced by a mixture of fat and connective tissue—a disorder called lipohyalinosis. Lipohyalinosis is different from atherosclerosis, but both disorders can cause arteries to be blocked.

Lacunar infarction tends to occur in older people with diabetes or poorly controlled high blood pressure. Only a small part of the brain is damaged in lacunar infarction, and the prognosis is usually good. However, over time, many small lacunar infarcts may develop and cause problems, including problems with thinking and other mental functions (cognitive impairment).

Other causes

Several conditions besides rupture of an atheroma can trigger or promote the formation of blood clots, increasing the risk of blockage by a blood clot. They include the following:

  • Blood disorders: Some disorders, such as an excess of red blood cells (polycythemia), antiphospholipid syndrome, and a high homocysteine level in the blood (hyperhomocysteinemia), make blood more likely to clot. In children, sickle cell disease can cause ischemic stroke.
  • Oral contraceptives: Taking oral contraceptives, particularly those with a high estrogen dose, increases the risk of blood clots.

An ischemic stroke can also result from any disorder that reduces the amount of blood supplied to the brain. For example,

  • An ischemic stroke can occur if inflammation of blood vessels (vasculitis) or infection (such as herpes simplex) narrows blood vessels that supply the brain.
  • In atrial fibrillation, the heart does not contract normally, and blood can stagnate and clot. A clot may break loose, then travel to an artery in the brain, and block it.
  • Sometimes the layers of the walls of an artery that carries blood to the brain (such as arteries in the neck) separate from each other (called dissection) and interfere with blood flow to the brain.
  • Migraine headaches or drugs such as cocaine and amphetamines can cause spasm of the arteries, which can narrow the arteries supplying the brain long enough to cause a stroke.

Rarely, a stroke results from a general decrease in blood flow, as occurs when people lose a lot of blood, become severely dehydrated, or have very low blood pressure. This type of stroke often occurs when narrowed arteries supplying the brain are narrowed but had not previously caused any symptoms and had not been detected.

Occasionally, an ischemic stroke occurs when blood flow to the brain is normal but the blood does not contain enough oxygen. Disorders that reduce the oxygen content of blood include a severe deficiency of red blood cells (anemia), suffocation, and carbon monoxide poisoning. Usually, brain damage in such cases is widespread (diffuse), and coma results.

Sometimes a blood clot in a leg vein (deep venous thrombosis) or, rarely, small pieces of fat from the marrow of a broken leg bone move into the bloodstream. Usually, these blood clots and pieces of fat travel to the heart and block an artery in the lungs (called pulmonary embolism). However, some people have an abnormal opening between the right and left upper chambers of the heart (called a patent foramen ovale). In such people, the blood clots and pieces of fat may go through the opening and thus bypass the lungs and enter the aorta (the largest artery in the body). If they travel to arteries in the brain, a stroke can result.

Risk factors

Some risk factors for ischemic stroke can be controlled or modified to some extent—for example, by treating the disorder that increases risk.

The major modifiable risk factors for ischemic stroke are

Risk factors that cannot be modified include

  • Having had a stroke previously
  • Being male
  • Being older
  • Having relatives who have had a stroke

Symptoms of Ischemic Stroke

Usually, symptoms of an ischemic stroke occur suddenly and are often most severe a few minutes after they start because most ischemic strokes begin suddenly, develop rapidly, and cause death of brain tissue within minutes to hours. Then, most strokes become stable, causing little or no further damage. Strokes that remain stable for 2 to 3 days are called completed strokes. Sudden blockage by an embolus is most likely to cause this kind of stroke.

In about 10 to 15% of strokes, damage continues to occur and symptoms continue to worsen for up to 2 days, as a steadily enlarging area of brain tissue dies. Such strokes are called evolving strokes. In some people, symptoms affect one arm, then spread to other areas on the same side of the body. The progression of symptoms and damage usually occurs in steps, interrupted by somewhat stable periods. During these periods, the area temporarily stops enlarging or some improvement occurs. Such strokes are usually due to the formation of clots in a narrowed artery.

Strokes caused by an embolus often occur during the day, and a headache may be the first symptom. Strokes caused by a blood clot in a narrowed artery often occur at night and are first noticed when the person wakes up.

Many different symptoms can occur, depending on which artery is blocked and thus which part of the brain is deprived of blood and oxygen (see Brain Dysfunction by Location).

When the arteries that branch from the internal carotid artery (which carry blood along the front of the neck to the brain) are affected, the following are most common:

  • Blindness in one eye
  • Loss of vision on the same side of both eyes (either the left or right side of both eyes)
  • Abnormal sensations, weakness, or paralysis in one arm or leg or on one side of the body

When the arteries that branch from the vertebral arteries (which carry blood along the back of the neck to the brain) are affected, the following are most common:

  • Dizziness and vertigo
  • Double vision or loss of vision in both eyes
  • Generalized weakness on one or both sides of the body

Many other symptoms, such as difficulty speaking (for example, slurred speech), impaired consciousness (such as confusion), loss of coordination, and urinary incontinence, can occur.

Severe strokes may lead to stupor or coma. In addition, strokes, even milder ones, can cause depression or an inability to control emotions. For example, people may cry or laugh inappropriately.

Some people have a seizure when the stroke begins. Seizures may also occur months to years later. Late seizures result from scarring or materials that are deposited from blood in the damaged brain tissue.

Occasionally, fever develops. It may be caused by the stroke or another disorder.

If symptoms, particularly impaired consciousness, worsen during the first 2 to 3 days, the cause is often swelling due to excess fluid (edema) in the brain. In large strokes, the swelling in the brain is typically at its worst about 3 days after the stroke begins. Symptoms usually lessen within a few days, as the fluid is absorbed. Nonetheless, the swelling is particularly dangerous because the skull does not expand. The resulting increase in pressure can cause the brain to shift, further impairing brain function, even if the area directly damaged by the stroke does not enlarge. If the pressure becomes very high, the brain may be forced sideways and downward in the skull, through the rigid structures that separate the brain into compartments. The resulting disorder is called herniation, which can be fatal.

Complications of stroke

Strokes can lead to other problems (complications):

  • If swallowing is difficult, people may not eat enough and become malnourished and dehydrated.
  • Food, saliva, or vomit may be inhaled (aspirated) into the lungs, resulting in aspiration pneumonia.
  • Being in one position too long can result in pressure sores and lead to muscle loss.
  • Not being able to move the legs can result in the formation of blood clots in deep veins of the legs and groin (deep vein thrombosis).
  • Clots can break off, travel through the bloodstream, and block an artery to a lung (a disorder called pulmonary embolism).
  • People may have difficulty sleeping.

The losses and problems resulting from the stroke may make people depressed.

Diagnosis of Ischemic Stroke

  • A doctor's evaluation
  • Computed tomography and sometimes magnetic resonance imaging
  • Laboratory tests, including those to measure blood sugar

Doctors can usually diagnose an ischemic stroke based on the history of events and results of a physical examination. Doctors can usually identify which artery in the brain is blocked based on symptoms. For example, weakness or paralysis of the left leg suggests blockage of the artery supplying the area on the right side of the brain that controls the left leg’s muscle movements.

When Specific Areas of the Brain Are Damaged

Different areas of the brain control specific functions. Consequently, where the brain is damaged determines which function is lost.

When Specific Areas of the Brain Are Damaged

Computed tomography (CT) is usually done first. CT helps distinguish an ischemic stroke from a hemorrhagic stroke, a brain tumor, an abscess, and other structural abnormalities.

Doctors also measure the blood sugar level to rule out a low blood sugar level (hypoglycemia), which can cause similar symptoms.

If available, diffusion-weighted magnetic resonance imaging (MRI), which can detect ischemic strokes within minutes of their start, may be done next.

As soon as possible, doctors may also do imaging tests (CT angiography or magnetic resonance angiography) to check for blockages in large arteries. Prompt treatment of these blockages can sometimes limit the amount of brain damage caused by the stroke.

Tests to identify the cause

Identifying the precise cause of an ischemic stroke is important. If the blockage is a blood clot, another stroke may occur unless the underlying disorder is corrected. For example, if blood clots result from an abnormal heart rhythm, treating that disorder can prevent new clots from forming and causing another stroke.

Tests for causes may include the following:

  • Electrocardiography (ECG) to look for abnormal heart rhythms
  • Continuous ECG monitoring (done at home or in the hospital) to record the heart rate and rhythm continuously for 24 hours (or more), which may detect abnormal heart rhythms that occur unpredictably or briefly
  • Echocardiography to check the heart for blood clots, pumping or structural abnormalities, and valve disorders
  • Imaging tests—color Doppler ultrasonography, magnetic resonance angiography, CT angiography, or cerebral angiography (done using a catheter inserted into an artery)—to determine whether arteries, especially the internal carotid arteries, are blocked or narrowed
  • Blood tests to check for anemia, polycythemia, blood clotting disorders, vasculitis, and some infections (such as heart valve infections and syphilis) and for risk factors such as high cholesterol levels or diabetes
  • Urine drug screen for cocaine and amphetamines

Imaging tests enable doctors to determine how narrowed the carotid arteries are and thus to estimate the risk of a subsequent stroke or TIA. Such information helps determine which treatments are needed.

For cerebral angiography, a thin, flexible tube (catheter) is inserted into an artery, usually in the groin, and threaded through the aorta to an artery in the neck. Then, a substance that can be seen on x-rays (radiopaque contrast agent) is injected to outline the artery. Thus, this test is more invasive than other tests that provide images of the brain’s blood supply. However, it provides more information. Cerebral angiography is done before atheromas are surgically removed from the neck (carotid endarterectomy ) and before any endovascular procedure that uses a catheter to treat a blocked or narrowed arteries. Cerebral angiography is also done when vasculitis is suspected.

Because CT angiography is less invasive, it has largely replaced cerebral angiography done with a catheter. The exceptions are endovascular procedures (such as mechanical thrombectomy or placement of a stent).

Prognosis of Ischemic Stroke

The sooner a stroke is treated with a drug that breaks up blood clots (thrombolytic drug), the less severe brain damage is likely to be and the better the chances for recovery.

During the first few days after an ischemic stroke, doctors usually cannot predict whether a person will improve or worsen. Younger people and people who start improving quickly are likely to recover more fully.

About 50% of people with one-sided paralysis and most of those with less severe symptoms recover some function by the time they leave the hospital, and they can eventually take care of their basic needs. They can think clearly and walk adequately, although use of the affected arm or leg may be limited. Use of an arm is more often limited than use of a leg.

About 10% of people who have an ischemic stroke recover all normal function.

Some people are physically and mentally devastated and unable to move, speak, or eat normally.

About 20% of people who have an ischemic stroke die in the hospital. The proportion is higher among older people. About 25% of people who recover from a first stroke have another stroke within 5 years. Subsequent strokes impair function further.

Most impairments still present after 12 months are permanent.

Treatment of Ischemic Stroke

  • Measures to support vital functions, such as breathing
  • Drugs to break up blood clots or make blood less likely to clot
  • Sometimes surgery to remove a blockage or angioplasty with a stent
  • Measures to manage problems that stroke can cause, such as difficulty swallowing
  • Measures to prevent blood clots in the legs
  • Rehabilitation

When a stroke occurs, minutes matter. The longer blood flow to the brain is reduced or stopped, the more brain damage there will be. People who have any symptom suggesting an ischemic stroke should immediately call 911 and go to an emergency department. Treatment to remove or break up clots is most effective when done as soon as possible. For such drug treatments to be effective, they must be started within 4.5 hours of when the stroke began. Procedures to remove clots through a catheter (mechanical thrombectomy) can be effective up to 6 hours after a stroke began and sometimes even later. Starting treatment as soon as possible is crucial because the earlier blood flow is restored to the brain, the less brain damage there is and the better are the chances for recovery. Thus, doctors try to rapidly determine when the stroke began and confirm that the stroke is an ischemic stroke, not a hemorrhagic stroke, which is treated differently.

Another priority is to restore the person’s breathing, heart rate, blood pressure (if low), and temperature to normal. An intravenous line is inserted to provide drugs and fluids when needed. If the person has a fever, it may be lowered using acetaminophen, ibuprofen, or a cooling blanket because brain damage is worse when body temperature is elevated.

Generally, doctors do not immediately treat high blood pressure unless it is very high (over 220/120 mm Hg) because when arteries are narrowed, blood pressure must be higher than normal to push enough blood through them to the brain. However, very high blood pressure can injure the heart, kidneys, and eyes and must be lowered.

If a stroke is very severe and affects a large area of the brain, drugs such as mannitol may be given to reduce swelling and the increased pressure in the brain. Some people need a ventilator to breathe adequately.

Specific treatment of stroke may include drugs to break up blood clots (thrombolytic drugs) and drugs to make blood less likely to clot (antiplatelet drugs and anticoagulants), followed by rehabilitation. At some specialized centers, blood clots are physically removed from arteries (called mechanical thrombectomy).

Measures are taken to prevent problems that stroke can cause, such as blood clots in the legs and pressure sores. Measures to prevent another stroke include control of risk factors (such as high blood pressure, diabetes, and high cholesterol levels), use of drugs that make blood less likely to clot, and sometimes surgery or angioplasty to open blocked arteries.

Thrombolytic (fibrinolytic) drugs

In certain circumstances, a drug called tissue plasminogen activator (tPA) is given intravenously to break up clots and help restore blood flow to the brain.

Because tPA can cause bleeding in the brain and elsewhere, it usually should not be given to people with certain conditions, such as the following:

  • A past occurrence of a hemorrhagic stroke, bleeding within the brain, or a brain tumor
  • Bleeding within the brain or a very large area of dead brain tissue detected by CT or MRI
  • A suspected hemorrhagic stroke, even if CT does not detect evidence of one
  • A tendency to bleed (indicated by a low platelet count or abnormal results of other blood tests)
  • Bleeding (hemorrhage) in the gastrointestinal tract within the past 21 days
  • A recent stroke or head injury (within the past 3 months)
  • A very low blood sugar level
  • A heart infection (such as bacterial endocarditis)
  • Use of an anticoagulant (such as warfarin or heparin) within the past 24 hours
  • A large ischemic stroke
  • Blood pressure that remains high after treatment with an antihypertensive drug
  • Brain or spinal surgery within the past 3 months
  • Sometimes symptoms that are resolving quickly
  • Sometimes a seizure when the stroke began
  • Sometimes major surgery or a serious injury within the past 14 days
  • Sometimes bleeding in the urinary tract within the past 21 days
  • Sometimes pregnancy
  • Sometimes a heart attack in the past 3 months
  • Possibly insertion of a needle in an artery in the past 7 days if the artery cannot be compressed to control bleeding

Before tPA is given, CT is done to rule out bleeding in the brain. To be effective and safe, tPA, given intravenously, must be started within 3 hours of the beginning of an ischemic stroke. Some experts recommend using tPA up to 4.5 hours after an ischemic stroke begins.

But when tPA is given between 3 and 4.5 hours, additional conditions may prohibit its use. These conditions include

  • Being over age 80
  • Taking an anticoagulant by mouth (regardless of its effect on clotting)
  • Having a severe stroke that resulted in substantial loss of function
  • Having a history of both stroke and diabetes mellitus

After 4.5 hours, giving tPA intravenously has no benefit.

Pinpointing when the stroke began may be difficult. So doctors assume that the stroke began the last time a person was known to be well. For example, if a person awakens with symptoms of a stroke, doctors assume the stroke began when the person was last seen awake and well. Thus, tPA can be used in only a few people who have had a stroke.

If people arrive at the hospital up to 6 hours (occasionally, up to 24 hours) after a stroke due to a blockage in a large artery began, they may be given tPA, with or without additional invasive treatment. In these situations, a drug or device must be inserted through a catheter and placed directly in the blocked artery. For this treatment (called thrombectomy), doctors make an incision in the skin, usually in the groin, and insert a catheter into an artery. The catheter is then threaded through the aorta and other arteries to the clot. The clot is partly broken up with the wire on the catheter and may be injected with tPA. This treatment is usually available only at specialized stroke centers.

Mechanical thrombectomy

For mechanical thrombectomy, doctors use a device to physically remove the blood clot. This procedure is often done when people have had a severe stroke and have been ineffectively treated with tPA, given intravenously or by catheter. New evidence suggests that mechanical thrombectomy can effectively treat people who have a stroke, regardless of its severity.

Mechanical thrombectomy is usually done within 6 hours of when symptoms began. The procedure can be done up to 24 hours after symptoms began if imaging tests show undamaged brain tissue. Thus, at some stroke centers, doctors are starting to use a special type of MRI (perfusion MRI) and other imaging tests to determine how much a stroke has progressed, rather than going strictly by time. These tests can show how much blood flow has been reduced and indicate how much brain tissue may be saved. This approach (based on brain tissue status, not time) is especially useful when doctors are unsure of when the stroke began—for example, when people wake up in the morning and have symptoms of a stroke. If imaging tests show that blood flow is only somewhat reduced, treatment with mechanical thrombectomy up to 24 hours after symptoms start may still be able to save brain tissue. But if blood flow has been greatly reduced or has stopped, treatment after only 1 hour may be unable to save any brain tissue.

Different types of devices can be used. For example, the stent retriever may be used. It resembles a tiny wire cage. It can be attached to a catheter, which is inserted through an incision, often in the groin, and threaded to the clot. The cage is opened up, then closed around the clot, which is drawn out through a larger catheter. If done within 6 hours of the stroke's start, mechanical thrombectomy with a stent retriever can dramatically improve outcomes in people with a large blockage. Devices can restore blood flow in 90 to 100% of people.

Mechanical thrombectomy is done only in stroke centers.

Antiplatelet drugs and anticoagulants

If a thrombolytic drug cannot be used, most people are given aspirin (an antiplatelet drug) as soon as they get to the hospital. Antiplatelet drugs make platelets less likely to clump and form clots. (Platelets are tiny cell-like particles in the blood that help it clot in response to damaged blood vessels.)

If symptoms seem to be worsening despite other treatments, anticoagulants such as heparin and warfarin are used. They may also be used to treat specific types of strokes (such as those due to a blood clot in a vein in the brain, or atrial fibrillation, or dissection of an artery in the neck). Anticoagulants inhibit proteins in blood that help it to clot (clotting factors).

If people have been given a thrombolytic drug, doctors usually wait at least 24 hours before antiplatelet drugs or anticoagulants are started because these drugs add to the already increased risk of bleeding in the brain. Anticoagulants are not given to people who have uncontrolled high blood pressure or who have had a hemorrhagic stroke.

Long-term treatment of stroke usually consists of aspirin or another antiplatelet drug to reduce the risk of blood clots and thus of subsequent strokes. Clopidogrel (another antiplatelet drug) is used instead of aspirin if people are allergic to aspirin. People who have had a minor stroke may be given clopidogrel plus aspirin. This combination, given within 24 hours of when symptoms began, may be more effective than aspirin alone for reducing the risk of stroke, but only during the first 3 months after the stroke. After that, the combination has no advantage over taking aspirin alone. Also, taking clopidogrel plus aspirin increases the risk of bleeding by a small amount.

People who have atrial fibrillation or a heart valve disorder are given anticoagulants (such as warfarin) instead of antiplatelet drugs, which do not seem to prevent blood clots from forming in the heart. Occasionally, people at high risk of another stroke are given both aspirin and an anticoagulant.

Dabigatran, apixaban, and rivaroxaban are new anticoagulants that are sometimes used instead of warfarin. These newer anticoagulants are more convenient to use because they, unlike warfarin, do not require regular monitoring with blood tests to determine how long it takes blood to clot. Also, they are not affected by foods and are unlikely to interact with other drugs. The new anticoagulants have some disadvantages. Dabigatran and apixaban must be taken twice a day. (Warfarin is taken once a day.) Also, people must not miss any doses of the newer drugs for the drugs to be effective, and these drugs are significantly more expensive than warfarin.


Once an ischemic stroke is completed, surgical removal of fatty deposits (atheromas, or plaques) due to atherosclerosis or clots in an internal carotid artery may be done (see figure Supplying the Brain With Blood). This procedure, called carotid endarterectomy, can help if all of the following are present:

  • The stroke resulted from narrowing of a carotid artery by more than 70% (more than 60% in people who have been having transient ischemic attacks).
  • Some brain tissue supplied by the affected artery still functions after the stroke.
  • The person’s life expectancy is at least 5 years.

In such people, carotid endarterectomy may reduce the risk of subsequent strokes. This procedure also reestablishes the blood supply to the affected area, but it cannot restore lost function because some brain tissue is dead.

For carotid endarterectomy, a general anesthetic is used. The surgeon makes an incision in the neck over the area of the artery that contains the blockage and an incision in the artery. The blockage is removed, and the incisions are closed. For a few days afterwards, the neck may hurt, and swallowing may be difficult. Most people stay in the hospital 1 or 2 days. Heavy lifting should be avoided for about 3 weeks. After several weeks, people can resume their usual activities.

Carotid endarterectomy can trigger a stroke because the operation may dislodge clots or other material that can then travel through the bloodstream and block an artery. However, after the operation, the risk of stroke is lower than it is when drugs are used, and this risk is lower for several years. The procedure can result in a heart attack because people who have this procedure often have risk factors for coronary artery disease.

People should find a surgeon who is experienced doing this operation and who has a low rate of serious complications (such as heart attack, stroke, and death) after the operation. If people cannot find such a surgeon, the risks of endarterectomy may outweigh its expected benefits.


If endarterectomy is too risky or cannot be done because of the artery's anatomy, a less invasive procedure can be done. A catheter may be used to place a wire mesh tube (stent) with an umbrella filter at its tip in the partly blocked carotid artery. Once in place the stent is expanded to help keep the artery open. The filter catches any debris that may break off during the procedure. The filter is removed once the stent is in place.

After a local anesthetic is given, the catheter is inserted through a small incision into a large artery near the groin or in the arm and is threaded to the internal carotid artery in the neck. A substance that can be seen on x-rays (radiopaque contrast agent) is injected, and x-rays are taken so that the narrowed area can be located. After the stent is placed, the filter and catheter are removed. People remain awake for the procedure, which usually takes 1 to 2 hours.

Placement of a stent appears to be as safe as endarterectomy and as effective in preventing strokes and death.

A similar procedure can be done for other types of large blocked arteries (see figure Understanding Percutaneous Coronary Intervention (PCI)).

Long-term treatment of strokes

Long-term treatment of stroke includes measures to do the following:

  • Control problems that can make the effects of stroke worse
  • Prevent or treat problems caused by strokes
  • Prevent future strokes
  • Treat any disorders that are also present

During the recovery period, high blood sugar (hyperglycemia) and fever can make brain damage worse after a stroke. Lowering them limits the damage and results in better functioning.

Before people who have had a stroke start to eat, drink, or take drugs by mouth, they are checked for problems with swallowing. Problems with swallowing can lead to aspiration pneumonia. Measures to prevent this problem are started early. If problems are detected, a therapist can teach people how to swallow safely. Sometimes people need to be fed through a tube (tube feeding).

If people cannot move on their own or have difficulty moving, they are at risk of developing blood clots in their legs (deep vein thrombosis) and pressure sores. Pneumatic compression stockings may be used to prevent blood clots. Powered by an electric pump, these stockings repeatedly squeeze the calves and move blood into and through the veins. People at high risk of developing blood clots may also be given an anticoagulant (such as heparin), injected under the skin of the abdomen or arm. Sometimes an anticoagulant pill is given by mouth.

Measures to prevent pressure sores are started early. For example, staff members periodically change the person's position in bed to help prevent pressure sores from forming. They also regularly inspect the skin for any sign of pressure sores.

Controlling or treating risk factors for stroke (such as high blood pressure, diabetes, smoking, consumption of too much alcohol, high cholesterol levels, and obesity) can help prevent future strokes.

Statins (such as atorvastatin) are drugs that lower levels of cholesterol and other fats (lipids). They are often given when strokes result from the buildup of fatty deposits in an artery (atherosclerosis). Such therapy can help prevent strokes from recurring.

Antiplatelet drugs (such as aspirin or clopidogrel), taken by mouth may be used to prevent strokes due to atherosclerosis. These drugs include aspirin, a combination tablet of low-dose aspirin plus dipyridamole, clopidogrel, or clopidogrel plus aspirin. Clopidogrel is indicated for people who are allergic to aspirin.

Taking clopidogrel plus aspirin appears to reduce the risk of future strokes more than taking aspirin alone, but only for the first 3 months after a stroke. After that, the combination has no advantage over aspirin alone. Also, taking clopidogrel plus aspirin for a long time increases the risk of bleeding by a small amount. Usually, antiplatelet drugs are not given to people who are taking warfarin because antiplatelet drugs add to the risk of bleeding. but occasionally, there are exceptions.

Anticoagulants (such as warfarin), taken by mouth, may be used to prevent strokes due to blood clots. Dabigatran, apixaban, and rivaroxaban are newer anticoagulants that are sometimes used instead of warfarin. These newer anticoagulants are more convenient to use because they, unlike warfarin, do not require regular monitoring with blood tests to measure how long it takes blood to clot. Also, they are not affected by foods and are unlikely to interact with other drugs. But the new anticoagulants have some disadvantages. Dabigatran and apixaban must be taken twice a day (warfarin is taken once a day). Also, people must not miss any doses of the newer drugs for the drugs to be effective. Also, these drugs are significantly more expensive than warfarin.

If other disorders such as heart failure, abnormal heart rhythms, and lung infections are present, they must be treated.

Because a stroke often causes mood changes, especially depression, family members or friends should inform the doctor if the person seems depressed. Depression can be treated with antidepressants and psychotherapy.

Drugs Mentioned In This Article

Generic Name Select Brand Names
acetaminophen TYLENOL
dipyridamole PERSANTINE
atorvastatin LIPITOR
Clopidogrel PLAVIX
rivaroxaban XARELTO
ibuprofen ADVIL, MOTRIN IB
warfarin COUMADIN
apixaban ELIQUIS
aspirin No US brand name

Copyright © 2022 Merck & Co., Inc., known as MSD outside of the US, Kenilworth, New Jersey, USA. All rights reserved. Merck Manual Disclaimer