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A stroke happens when blood flow to the brain is blocked. This prevents the brain from getting oxygen and nutrients from the blood. Without oxygen and nutrients, brain cells begin to die within minutes. Sudden bleeding in the brain can also cause a stroke if it damages brain cells.
A stroke is a medical emergency. A stroke can cause lasting brain damage, long-term disability, or even death. Signs of a stroke can range from mild weakness to paralysis or numbness on one side of the face or body. Other signs include a sudden and severe headache, sudden weakness, trouble seeing, and trouble speaking or understanding speech.
If you think you or someone else is having a stroke, call 9-1-1 right away. Do not drive to the hospital or let someone else drive you. Call an ambulance so that medical personnel can begin life-saving treatment on the way to the emergency room. During a stroke, every minute counts.
At the hospital, a stroke team will assess your condition and treat your stroke with medicine, surgery, or another procedure. Your recovery will depend on how severe your stroke was and how quickly you got treatment. A rehabilitation plan may help you do the same things you used to do before your stroke.
This animation describes the different types of strokes and how they happen. The most common type is ischemic stroke. This happens when plaque or a blood clot blocks blood flow to an artery in or on the brain. Hemorrhagic stroke is less common. This happens when a blood vessel breaks open and leaks blood into the brain. A transient ischemic attack (TIA) is similar to an ischemic stroke, but the blood clot breaks up after a short time, usually before there is long-term damage. Medical Animation Copyright © 2020 Nucleus Medical Media, All rights reserved.
Explore this Health Topic to learn more about stroke, our role in research and clinical trials, and where to find more information.
There are two main types of stroke that have different causes. Ischemic strokes are caused by a blockage of a blood vessel. Hemorrhagic strokes are caused by sudden bleeding in the brain. Sometimes the doctor may not be able to figure out the cause of your stroke.
Ischemic strokes are usually caused by a piece of plaque or a blood clot that blocks blood flow to the brain.
Plaque buildup
When a fatty substance called plaque builds up on the inner walls of the arteries, it can lead to a disease called atherosclerosis. Plaque hardens and narrows the arteries, which limits blood flow to tissues and organs.
Plaque can build up in any artery in the body, including arteries in the brain and neck. Carotid artery disease is when plaque builds up in the carotid arteries in the neck that supply blood to the brain. It is a common cause of ischemic stroke.
Blood clots in the brain or elsewhere in the body
Plaque in an artery can break open. Blood platelets stick to the site of the plaque injury and clump together to form blood clots. These clots can partly or fully block an artery.
A blood clot that forms in one part of the body can also break loose and travel to the brain. This type of ischemic stroke is called an embolic stroke. Certain heart and blood conditions, such as atrial fibrillation and sickle cell disease, can cause blood clots that lead to stroke.
Inflammation
Chronic (long-term) inflammation contributes to ischemic stroke. Researchers are still trying to understand this fully. We know that inflammation can damage the blood vessels and contribute to atherosclerosis, however. In addition, ischemic stroke can lead to inflammation that further damages brain cells.
A transient ischemic attack (TIA) is caused by a blockage in the brain just like an ischemic stroke. But the blockage breaks up before there is any damage to your brain. It typically lasts less than an hour but can come and go. Eventually, it can progress to a full stroke. A TIA is also called a mini-stroke.
Sudden bleeding can cause a hemorrhagic stroke. This can happen when an artery in or on top of the brain breaks open. The leaked blood causes the brain to swell, putting pressure on it that can damage brain cells.
Some conditions make blood vessels in the brain more likely to bleed.
There are many risk factors for stroke. You can treat or control some of your risk factors, such as high blood pressure and smoking. But you cannot control others such as your age or sudden changes in your health—for example, if you have an aneurysm.
Risk factors for stroke. This animation discusses some of the main risk factors for stroke, which are also described below. Medical Animation Copyright © 2020 Nucleus Medical Media, All rights reserved.
The major risk factors for stroke include:
Other risk factors for stroke—some of which you can control—include:
The signs and symptoms of a stroke often develop quickly. However, they can develop over hours or even days, such as when a transient ischemic attack (TIA) turns into a stroke.
The type of symptoms depends on the type of stroke and the area of the brain that is affected.
This animation discusses symptoms of stroke, also described below. Medical Animation Copyright © 2020 Nucleus Medical Media, All rights reserved.
Signs and symptoms of a TIA or stroke may include:
The FAST test can help you remember what to do if you think someone may be having a stroke:
F—Face: Ask the person to smile. Does one side of the face droop?
A—Arms: Ask the person to raise both arms. Does one arm drift downward?
S—Speech: Ask the person to repeat a simple phrase. Is their speech slurred or strange?
T—Time: If you observe any of these signs, call 9-1-1 right away. Early treatment is essential.
If you think you or someone else is having a TIA or stroke, don’t drive to the hospital or let someone else drive you. Call an ambulance so that medical personnel can begin life-saving treatment on the way to the emergency room. During a stroke, every minute counts.
A stroke can cause lasting brain damage, long-term disability, or even death. When you have a stroke, your doctor may rate how severe it is. A more severe stroke means more brain tissue was damaged. When there has been significant damage, your doctor may call it a massive stroke. This can mean more severe complications.
After having a stroke, you may develop complications such as:
Your doctor will diagnose a stroke based on your signs and symptoms, your medical history, a physical exam, and test results. Your doctor will want to find out the type of stroke you’ve had, its cause, the part of the brain that is affected, and whether you have bleeding in the brain. If your doctor thinks you’ve had a transient ischemic attack (TIA), he or she will look for its cause to help prevent a future stroke.
Your doctor will ask you or a family member about your risk factors for stroke. Tell your doctor if you or someone in your family has had a stroke. Your doctor will also ask about your signs and symptoms and when they began.
During the physical exam, your doctor will check you for:
The exam will help your doctor determine how severe your stroke was and plan your treatment.
Your doctor will look for signs of carotid artery disease, a common cause of ischemic stroke. He or she will listen to your carotid arteries with a stethoscope. A whooshing sound called a bruit may suggest changed or reduced blood flow due to plaque buildup in the carotid arteries.
Your doctor will order tests to help rule out other health problems with similar signs or symptoms.
Your doctor will order an imaging test to look at the blood vessels in your brain. This will help determine what type of stroke you have and where exactly it happened. The quicker these tests can be done, the better your doctor can treat you. Tests to diagnose stroke include the following:
Your doctor may also order the following blood or heart tests.
A stroke requires emergency care. You will probably receive treatment in a specialized stroke unit of the hospital. A team of specialists will oversee your care. Treatment will depend on whether the stroke was ischemic or hemorrhagic, how much time has passed since symptoms began, and whether you have other medical conditions.
This animation discusses different treatments for stroke. Treatment for a stroke depends on whether it is ischemic or hemorrhagic but may include medicines or a procedure. Medical Animation Copyright © 2020 Nucleus Medical Media, All rights reserved.
Treatment for an ischemic stroke or transient ischemic (TIA) may include medicines and medical procedures.
Medicines
The main treatment for an ischemic stroke is a medicine called tissue plasminogen activator (tPA). It breaks up the blood clots that block blood flow to your brain. A doctor will inject tPA into a vein in your arm. This type of medicine must be given within 3 hours after your symptoms start. In some cases, it is given up to 4.5 hours. The sooner treatment begins, the better your chances of recovery.
If you cannot have tPA, your doctor may give an anticoagulant or blood thinning medicine, such as aspirin or clopidrogrel. This helps stop blood clots from forming or getting larger. The main side effect of these medicines is bleeding.
Medical procedures
You may need a procedure to open up blocked arteries and restore blood flow to the brain. This can be done several ways.
A thrombectomy removes the clot from the blood vessel. A surgeon will put a long, flexible tube called a catheter into your groin (upper thigh) and thread it to the blocked artery in your neck or brain. They will then use angioplasty and stenting or a device called a stent retriever to open up the blocked artery.
If carotid artery disease caused your stroke, your doctor may suggest carotid endarterectomy, a surgery to remove plaque from the carotid artery in your neck. Visit our Carotid Artery Disease Health Topic to learn more about how these procedures work.
Hemorrhagic stroke can happen suddenly and grow worse quickly. Just as with an ischemic stroke, getting treatment as quickly as possible is essential for a full recovery. The type of treatment you receive depends on what part of your brain is bleeding and how severe it is.
Medicines
You may be given blood pressure medicine to lower the pressure and strain on blood vessels in the brain. You will also be taken off any anticoagulant or blood-thinning medicines that may have led to bleeding. Depending on the type of medicine you were taking, you may be given vitamin K to help stop bleeding.
Medical procedures
Procedures may include:
In addition to treating the blockage or bleeding causing the stroke, your healthcare team may suggest additional treatments or tests.
Stroke is a life-threatening condition that can cause severe disability. Palliative care or hospice care may help some patients have a better quality of life with fewer symptoms.
It can take weeks, months, or even years to recover from a stroke. Some people recover fully, while others have long-term or lifelong disabilities. A stroke team will work with you to manage your care. Your team may include specialists in neurology (brain, spinal cord, and nerves), rehabilitation, or mental health. You will also want to take steps to prevent another stroke and be aware of possible long-term complications. Call 9-1-1 if you have any signs of another stroke.
Heart-healthy lifestyle changes can help you recover from a stroke and may help prevent another one.
It is important to get routine medical care after your stroke. Follow your treatment plan and talk with your doctor about how often you should schedule office visits.
After a stroke, you may need rehabilitation (rehab) to help you recover. Rehab may include working with speech, physical, and occupational therapists. Your care team may also recommend medicines to manage pain, muscle spasms, or other problems as you recover.
Canes, braces, grab bars, special eating utensils, wheelchairs, and other devices can make it easier to keep doing your regular activities after a stroke.
After a stroke, you may have changes in your behavior or judgment. For example, your mood may change quickly. Because of these and other changes, you may feel scared, anxious, and depressed. Recovering from a stroke can be slow and frustrating. Some people develop symptoms of post-traumatic stress disorder (PTSD).
Talk about how you feel with your healthcare team. Your doctor may recommend:
Your doctor may recommend strategies to help prevent another stroke. This will depend on what caused your first stroke.
If you recognize any signs of stroke, call 9-1-1 right away.
The most common side effect of taking blood thinners to reduce your stroke risk is bleeding. This happens if the medicine thins your blood too much. This side effect can be life-threatening. Bleeding can occur inside your body cavities or from the surface of your skin.
Know the warning signs of bleeding so you can get help right away. They include:
Easy bruising or bleeding may mean that your blood is too thin. Call your doctor right away if you have any of these signs. If you have severe bleeding, call 9-1-1.
The NHLBI is part of the U.S. Department of Health and Human Services’ National Institutes of Health (NIH)—the Nation’s biomedical research agency that makes important scientific discoveries to improve health and save lives. We are committed to advancing science and translating discoveries into clinical practice to promote the prevention and treatment of heart, lung, blood, and sleep disorders, including stroke. Learn about current and future NHLBI efforts to improve health through research and scientific discovery.
Learn about the following ways the NHLBI continues to translate current research into ways to prevent, diagnose, and treat stroke. Research on this topic is part of the NHLBI’s broader commitment to advancing heart and vascular diseases scientific discovery.
Learn about some of the pioneering research contributions we have made over the years that have improved clinical care.
In support of our mission, we are committed to advancing stroke research in part through the following ways.
Learn about exciting research areas the NHLBI is exploring about stroke.
We lead or sponsor many studies on stroke. See if you or someone you know is eligible to participate in our clinical trials and observational studies.
Learn more about participating in a clinical trial.
View all trials from ClinicalTrials.gov.
Visit Children and Clinical Studies to hear experts, parents, and children talk about their experiences with clinical research.
After reading our Stroke Health Topic, you may be interested in additional information found in the following resources.
The National Heart, Lung, and Blood Institute (NHLBI) and the National Institute of Environmental Health Sciences (...