Stroke

Overview

A stroke happens when blood flow to part of the brain stops or when a blood vessel in the brain bursts. Blood carries oxygen and nutrients that brain cells need to survive. When blood flow stops, brain cells begin to die within minutes.

Some cells die right away, while others remain weakened for several hours. Swelling and inflammation can cause more damage during this time. A stroke can lead to permanent brain damage within minutes or hours. Early treatment can save lives and reduce disability.

There are two main types of strokes:

• Ischemic stroke is the most common type (about 80% of all strokes) and happens when a blood clot blocks a blood vessel in the brain.
• Hemorrhagic stroke happens when a blood vessel in the brain bursts and bleeds into or around the brain.

Related Terms: A transient ischemic attack is also called a “mini stroke” or “warning stroke.”

Signs and Symptoms

Use the B.E.F.A.S.T. Test

Stroke symptoms appear suddenly, so early identification is key. The sooner treatment begins, the better the outcome. Knowing the signs of a stroke and calling 911 right away can save a life and reduce disability. Fast treatment can protect brain cells and may even reverse some damage.

B.E.F.A.S.T.:

B— Balance Loss: Is there a sudden loss of balance or coordination? Is the person having trouble walking or feeling dizzy?

E— Eye (Vision) Changes: Are there sudden changes in vision? Ask the person if they are having blurry or double vision, or loss of sight in one or both eyes.

F — Face Drooping: Ask the person to smile. Does one side of the face droop?

Arm Weakness: Ask the person to raise both arms. Does one arm drift downward?

S — Speech Difficulty: Ask the person to repeat a simple phrase. Is the speech slurred or strange?

T — Time to Call 911: If you see any of these signs, call 911 right away.

Other Sudden Stroke Symptoms

Call 911 immediately if any of these symptoms appear suddenly:

• Numbness or weakness of the face, arm, or leg, especially on one side of the body
• Confusion, trouble speaking, or trouble understanding speech
• Trouble seeing in one or both eyes
• Trouble walking, dizziness, or loss of balance or coordination
• Sudden severe headache with no known cause

Don’t Ignore Symptoms That Go Away

If stroke symptoms go away after a few minutes, it may be a transient ischemic attack, sometimes incorrectly called a “mini stroke”. A transient ischemic attack happens when blood flow to the brain is blocked for a short time.

A transient ischemic attack is still a medical emergency and a serious warning sign. If a transient ischemic attack is not treated quickly, it could be followed by a major stroke within hours or days. Do not ignore symptoms even if they go away. Treat all stroke symptoms as an emergency.

Stroke Signs Are Often Missed

A person having a stroke may not realize what is happening. The stroke itself can make the person unaware of the problem. Even when people know something is wrong, they may not be able to call for help on their own. That is why it is important for bystanders to act fast.

Stroke in Women

Some risk factors for stroke apply only to women, including pregnancy, childbirth, and menopause. These factors are tied to hormonal changes that affect women at different stages of life. In women of childbearing age, stroke risk is relatively low (with an annual incidence of one in 10,000). However, studies have shown that being pregnant increases that risk threefold.

Stroke in Children

Infants and children who have a stroke usually have the same symptoms as adults. But children are more likely to also have seizures, breathing problems, or loss of consciousness. It can be difficult to identify stroke in younger children.

The effects of stroke in children can be hard to predict. Children who have a stroke generally recover better than adults if they get the right treatment and rehabilitation therapy. Children’s brains are more “plastic.” Brain plasticity is the brain’s ability to reorganize, change, and adapt to after injury or other problems, and to rewire itself to keep working properly. Outcomes are usually worse for children under age one and in those who lose consciousness or have seizures. A stroke in infancy or childhood can cause permanent disability.

Related Health Effects

A stroke can affect the entire body. The effects depend on which part of the brain is damaged. Effects can range from mild to severe and may be temporary or permanent.

Possible effects include:

• Paralysis or weakness, usually on one side of the body
• Slurred speech
• Problems with movement, balance, and coordination, including trouble walking or standing
• Muscle weakness or spasms can make it hard to stand or walk and increase the risk of falling
• Dangerous blood clots in the legs.
• Loss of bone density or strength, usually on one side of the body.
• Trouble controlling when to go to the bathroom
• Trouble speaking or understanding language, severe damage can cause aphasia, a complete inability to speak or understand what others are saying
• Problems with thinking, memory, attention, and judgment
• Emotional problems, such as fear, anxiety, anger, and depression
• Pain and unusual sensations, such as burning, tingling, or numbness
• Trouble swallowing, which can raise the risk for pneumonia
• Loss of vision, hearing, or touch
• Seizures, which are more common in the weeks after a stroke
• Swelling in the brain, which may require medical treatment to relieve pressure

Post-Stroke Depression

Post-stroke depression is a common and serious medical problem. It can delay recovery and rehabilitation and may even lead to death by suicide. Post-stroke depression is treatable with medicines and counseling.

If you are experiencing a mental health crisis after a stroke, call or text 988 to reach the 988 Suicide & Crisis Lifeline. The Lifeline provides free and confidential support to people in suicidal crisis or emotional distress 24 hours a day, 7 days a week. Chat support is also available at 988lifeline.org.

Vascular Cognitive Impairment

Some people have lasting problems with thinking ability following a stroke. This is known as vascular cognitive impairment (VCI). VCI mainly affects the brain’s ability to plan activities — from getting dressed in the morning to managing finances.

Central Pain Syndrome

An uncommon type of pain after stroke is called central pain syndrome. It results from damage to an area of the brain called the thalamus. This pain causes a mix of sensations, including heat, cold, burning, tingling, numbness, and sharp stabbing. It is made worse by movement and cold temperatures.

Causes and Risk Factors

In a healthy brain, neurons do not come into direct contact with blood. The blood-brain barrier controls what enters and leaves the brain through tiny blood vessels.

There are two main types of stroke, ischemic stroke and hemorrhagic stroke.

Ischemic stroke is caused by a blockage in a blood vessel in the brain. The blockage can come from three conditions:

• Thrombosis: A clot forms directly in a blood vessel in the brain or neck.
• Embolism: A clot travels from another part of the body, such as the heart, to the brain.
• Stenosis: A blood vessel in the brain gets thinner, often due to a buildup of fatty deposits called plaque.

An ischemic stroke can trigger swelling, inflammation, and other changes that continue to damage the brain for hours or even days. In large strokes, swelling can raise pressure inside the skull to dangerous levels.

Right after a stroke, one part of the brain has already suffered permanent damage. Another nearby area is still alive but at risk. Doctors must restore blood flow as quickly as possible. This process is called reperfusion. The longer it takes to restore blood flow, the more brain cells will die.

Hemorrhagic stroke is caused when a blood vessel in the brain bursts open. Conditions that make blood vessels more likely to bleed include aneurysms (bulging weakened areas in a blood vessel) and arteriovenous malformations (AVMs), which are tangled, poorly formed blood vessels.

There are two main types of hemorrhagic stroke:

• A subarachnoid hemorrhage occurs when a blood vessel on the surface of the brain ruptures and bleeds into the space between the brain and a thin layer of tissue.
• An intracerebral hemorrhage occurs when bleeding happens inside the brain.

Risk Factors

Stroke can happen to anyone at any age, including children and young adults. While most strokes occur in people over 65, the stroke rate is rising in younger adults.

A risk factor is something that raises your chance of having a stroke. Some risk factors you can control, and some you cannot. The more risk factors you have, the higher your risk.

Factors people can control account for most strokes. These include:

• High blood pressure (hypertension), the most powerful risk factor for stroke
• Smoking
• Physical inactivity
• Obesity
• High cholesterol
• Diabetes
• Heart disease, including atrial fibrillation
• Unhealthy diet
• Drinking too much alcohol
• Using illegal drugs such as cocaine

Other risk factors for stroke that can't be changed include:

• Age: People are much more likely to have a stroke as they get older, but a stroke can occur at any age, even in infancy.
• Family history: Stroke tends to run in families.
• Race and ethnicity: In the United States, stroke occurs more often in adults who are Black, Alaska Native, American Indian, and Hispanic than in White adults. Stoke is more common and more deadly for Black American adults of any age.
• Sex: At younger ages, men are more likely to have a stroke, but women tend to live longer, giving them a higher lifetime risk.
• Prior stroke or transient ischemic attack: If you have had a stroke or transient ischemic attack before, your risk of having another stroke is much higher.

Women and Pregnancy

Some risk factors apply only to women, including:

• High blood pressure during pregnancy (such as preeclampsia)
• Certain types of birth control medicines
• Hormonal changes during menopause
• Hormone replacement therapy (HRT)

Several factors contribute to the increased risk of stroke during pregnancy. Blood clotting proteins are naturally more active during pregnancy. In some cases, clots form in the brain’s large draining veins, leading to stroke, headache, or seizure.

Pregnancy-related stroke is more likely to occur in women who experience certain complications, such as infections or preeclampsia (high blood pressure with fluid retention), or who have other risk factors for stroke, such as high blood pressure or diabetes.

Most strokes occur during the first few weeks after delivery. These strokes may be caused by a drop in blood volume or by the rapid hormonal changes that follow childbirth.

In the same way that hormonal changes during pregnancy and childbirth are associated with increased stroke risk, hormonal changes during menopause can also increase the risk of stroke. Although hormone replacement therapy may help some symptoms of menopause, studies have shown that this therapy may increase the risk of stroke, especially in women more than 10 years post-menopause. Estrogen patches used on the skin have not been found to increase the risk of stroke and may be a better option than estrogen pills for these women. More research is needed in this area. Women should talk with their doctor about their symptoms and risks to find appropriate treatments.

Risk Factors in Children

A child’s risk for having a stroke is highest just before birth and in the first few weeks after birth. An important risk factor for Black children is sickle cell disease, which can cause narrowing of blood vessels in the brain. Other risk factors for children include inherited heart problems, head trauma, and blood-clotting disorders.

Other Risk Factors

• Anxiety, depression, and high stress levels
• Sleep apnea, kidney disease, and migraine headaches
• Living or working in areas with air pollution
• Having AB blood type (which is less common)
• Living in the "stroke belt", a large region of the southeastern United States named for its higher than average stroke risk and mortality.

Prevention Guidance

Using available therapies and monitoring risk, most strokes can be prevented.

There are also ways that you can help prevent stroke, including:

• Treat high blood pressure. Check your blood pressure regularly. If it is high, work with a doctor or other healthcare provider to lower it. NIH’s Mind Your Risks campaign provides information about the importance of controlling blood pressure in midlife to lower the risk of stroke.
• Exercise and be physically active. Try to make physical activity part of your everyday life.
• Eat well. Choose foods low in cholesterol and saturated fats. Include a variety of fruits and vegetables every day. Cut down on salt and get plenty of potassium to help manage high blood pressure, a major risk factor for stroke.
• Control cholesterol. High cholesterol can lead to plaque buildup in arteries, which can block blood flow and lead to stroke.
• Manage diabetes. Untreated diabetes can damage blood vessels and lead to stroke.
• Get Help to Quit smoking. Smoking causes about a two-fold increase in the risk of ischemic stroke and up to a four-fold increase in the risk of hemorrhagic stroke.
• Avoid drugs and alcohol. Using drugs and alcohol can increase your risk of stroke. Work with your doctor to reduce your intake. If you are dependent on drugs or alcohol, a doctor can help you get the treatment you need.

Diagnosis

Doctors use several tools to help diagnose strokes quickly and accurately. When a person is suspected of having a stroke, an emergency room doctor will carry out a detailed assessment of the person’s signs and symptoms. They will also ask when the symptoms began. Because of the importance of early treatment, assessment might even begin in the ambulance. One test that helps doctors judge the severity of a stroke is the standardized National Institutes of Health (NIH) Stroke Scale, which helps doctors and other healthcare providers measure the severity of a stroke by asking the person to answer questions and perform physical and mental tests.

Other scales that may be used include:

• The Glasgow Coma Scale
• The Modified Rankin Scale
• The Barthel Index

These scales can sensitively measure any disabilities that result from stroke.

Additional tools used to diagnose stroke include:

• A medical history and physical exam can assess symptoms and when they started.
• Computed Tomography (CT) uses X-rays and a computer to create detailed images of the brain. This is the commonly used imaging test to check for bleeding in the brain.
• Magnetic Resonance Imaging (MRI) uses magnetic fields and radio waves to produce detailed images of the brain. MRI provides a more accurate and earlier diagnosis of ischemic stroke, especially for smaller strokes and transient ischemic attacks.
• Other tools such as ultrasound, blood tests, electrocardiogram, and a heart monitor worn for a day or more to check heart rhythm can also be used.

Keeping track of the exact time when symptoms first started is important. Knowing this helps doctors or other healthcare providers choose the best treatment.

Treatment and Management

Immediate medical treatment is important for all strokes. Getting to a hospital quickly saves lives and increases the chances for successful recovery.

Treatment after a stroke includes three main approaches:

• Emergency medical or surgical care right after a stroke to limit brain injury.
• Treatment to prevent another stroke.
• Rehabilitation therapy to manage changes in ability and function.

It is important for a doctor or other healthcare provider to identify the type of stroke before starting treatment, because some medicines used for clot (ischemic) strokes can make bleeding (hemorrhagic) strokes worse.

Treating Ischemic Stroke

The window of opportunity to start treatment for ischemic strokes, the most common type, is four and a half hours. But all people who suspect a stroke, even people who wake up with symptoms, need to get to the hospital as soon as possible to be evaluated and receive treatment since some people benefit from treatment up to 24 hours after a stroke.

Treatments include:

• Medicines (antithrombotics and thrombolytics): The most common treatments. Antithrombotic medicines prevent new clots from forming and thrombolytic medicines dissolve existing clots. The medicine t-PA (tissue plasminogen activator) dissolves blood clots that block blood flow to the brain. NIH research shows that stroke patients who were given t-PA within three hours of first symptoms were at least 30% more likely to recover with little or no disability after three months.
• Stenting: A small metal mesh tube is placed in a clogged artery to keep it open.
• Clot removal: Doctors can put a thin tube through an artery to remove a blockage using suction or a small mesh device called a stent that traps and pulls out the clot.
• Carotid endarterectomy: Surgery to remove fatty deposits blocking carotid arteries in the neck, which supply blood to the brain.
• Angioplasty: A tiny inflatable device is expanded inside a blocked artery to improve blood flow.

Treating Hemorrhagic Stroke

Treatment for hemorrhagic stroke involves finding the source of the bleeding and stopping it.

Treatments may include:

• Surgery to stop the bleeding and relieve pressure on the brain.
• Draining excess fluid from the brain.
• Treating a weakened, bulging blood vessel in the brain by sealing it with a clip or tiny coils to stop the bleeding.

Recovering from Stroke

Recovery from stroke is different for every person. Outcomes depend on how much brain damage occurred, which parts of the brain were affected, age, and how well other health conditions are managed.

Rehabilitation is a key part of recovery. It often begins in the hospital within 48 hours of a stroke. Starting early can improve the chances of regaining function.

Rehabilitation therapy may include:

• Physical therapy: Helps a person relearn movement, balance, and activities such as walking, sitting, standing, and switching between types of movement.
• Occupational therapy: Helps a person relearn daily tasks such as eating, bathing, dressing, cooking, reading, writing, and going to the bathroom.
• Speech therapy: Helps a person relearn language and speaking skills or learn other ways to communicate. With time and patience, a person who had a stroke may get back some, and sometimes all, language and speaking abilities.

Devices to Support Stroke Recovery

The U.S. Food and Drug Administration (FDA) has approved several devices to support rehabilitation and recovery after stroke:

The Neurolutions Upper Extremity Rehabilitation System is used to increase range of motion and grasp in people age 18 and older with upper arm disability who are undergoing stroke rehabilitation. The brain-computer interface uses non-invasive electrodes to record brain activity. The electrode reading is then analyzed to determine the intended muscle movement, and a signal is sent to a wireless electronic hand brace, which in turn moves the person’s hand.

The MicroTransponder Vivistim Paired VNS System electronically stimulates the vagus nerve, which runs from the brain down to the abdomen, to improve an individual’s ability to move their arms and hands. The device is approved for use alongside stroke rehabilitation in people with moderate to severe impairments in their upper limbs and motor defects in their extremities caused by ischemic stroke.

Rehabilitation therapy may lead to improved function over months or years by supporting the brain’s ability to form new connections lost after a stroke.

Support from family, friends, and care teams can help people manage emotions and stay on track with therapy.

If depression is a concern, talk to a doctor as soon as possible.

Find Clinical Trials

Clinical trials uncover better ways to prevent, diagnose, treat, and understand diseases and conditions. To ensure results apply to everyone, volunteers of all ages, sexes, and backgrounds, including both healthy individuals and those with specific medical conditions, are needed. Find clinical trials on stroke.

Find Treatment

Talk with a doctor to understand your stroke risk factors and how to lower it.

If you have had a stroke or heart attack in the past, talk with your doctor about ways to reduce your risk.

Community Support

• American Stroke Association
• Brain Aneurysm Foundation
• National Aphasia Association
• Children’s Hemiplegia and Stroke Association
• YoungStroke, Inc.
• Child Neurology Foundation
• Hazel K. Goddess Fund for Stroke Research in Women
• Fibromuscular Dysplasia Society of America
• Heart Rhythm Society
• Joe Niekro Foundation

Note: This resource list is for informational purposes only. It is not comprehensive, and an organization’s inclusion does not constitute an endorsement by NIH. 

Research Information

The National Institutes of Health (NIH) is the largest public funder of biomedical research in the world. NIH invests most of its budget in medical research seeking to enhance life and to reduce illness and disability. NIH-funded research has led to breakthroughs and new treatments helping people live longer, healthier lives, and building the research foundation that drives discovery.

NIH conducts stroke research and funds scientists across the United States. Researchers study how to prevent stroke, diagnose it faster, improve treatment, and help people recover.

Stroke research has already helped lower death rates and improve care. Scientists continue to build on this progress to find better treatments and support recovery.

Researchers study stroke in several ways:

• Understanding causes and risk: Scientists study how stroke happens and how to reduce risk.
• Testing new treatments: Clinical trials test new drugs, devices, and procedures.
• Improving blood flow: Researchers look for better ways to restore blood flow to the brain.
• Protecting brain cells: Studies focus on ways to limit damage during and after a stroke.
• Supporting recovery: Scientists develop therapies to help the brain adapt and regain function.

NIH also leads a national research network called NIH StrokeNet. This network connects hundreds of hospitals and research centers to test new treatments and improve stroke care.

Recent research has helped:

• Expand the time window for some stroke treatments.
• Improve clot removal techniques.
• Develop new medicines to prevent stroke.
• Advance rehabilitation methods, including home-based therapy.

Find NIH-funded research projects using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies.