Everything you need to know about stroke
Stroke occurs due to a decrease in oxygen to the brain. A bleed or blockage in the brain’s blood supply can cause it. Immediate emergency treatment may help prevent life-threatening consequences.
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Stroke is the fifth leading cause of death in the United States. In fact, nearly 800,000 people have a stroke each year. That equates to around one person every 40 seconds.
There are three main types of stroke:
- Ischemic stroke: This is the most common type of stroke, making up 87% of all cases. A blood clot prevents blood and oxygen from reaching an area of the brain.
- Hemorrhagic stroke: This occurs when a blood vessel ruptures. These are usually the result of aneurysms or arteriovenous malformations (AVMs).
- Transient ischemic attack (TIA): This occurs when blood flow to a part of the brain is inadequate for a brief period of time. Normal blood flow resumes after a short amount of time, and the symptoms resolve without treatment. Some people call this a ministroke.
Stroke can be fatal. According to the American Heart Association (AHA), the age-adjusted mortality rate for 2017 was 37.6 in every 100,000 stroke diagnoses. Doctors have made a great deal of progress in managing strokes, meaning that this mortality rate is 13.6% lower than it was in 2007.
This article explains why strokes occur and how to treat them. It also explores the different types of stroke, as well as the steps a person can take to prevent them.
What is a stroke?
A stroke occurs when a blockage or bleed of the blood vessels either interrupts or reduces the supply of blood to the brain. When this happens, the brain does not receive enough oxygen or nutrients, and brain cells start to die.
Stroke is a cerebrovascular disease. This means that it affects the blood vessels that feed the brain oxygen. If the brain does not receive enough oxygen, damage may start to occur.
This is a medical emergency. Although many strokes are treatable, some can lead to disability or death.
Because ischemic and hemorrhagic strokes have different causes and effects on the body, both require different treatments.
Rapid diagnosis is important for reducing brain damage and enabling the doctor to treat the stroke using a suitable method for the type.
The sections below cover the treatment options for ischemic stroke and hemorrhagic stroke, as well as some general rehabilitation tips for both types.
Ischemic stroke occurs due to blocked or narrowed arteries. Treatment tends to focus on restoring an adequate flow of blood to the brain.
Treatment starts with taking drugs that break down clots and prevent others from forming. A doctor may administer blood thinners such as aspirin or an injection of tissue plasminogen activator (TPA).
TPA is very effective at dissolving clots. However, the injection needs to take place within 4.5 hours of the stroke symptoms starting.
Emergency procedures include administering TPA directly into an artery in the brain or using a catheter to physically remove the clot. Research is ongoing as to the benefits of these procedures.
There are other procedures that surgeons can perform to reduce the risk of strokes or TIAs. A carotid endarterectomy, for example, involves opening the carotid artery and removing plaque that could break and travel to the brain.
Another option is angioplasty. This involves a surgeon inflating a small balloon inside a narrowed artery using a catheter. Afterward, they will insert a mesh tube, or a stent, into the opening. This prevents the artery from narrowing again.
Blood leaking into the brain can cause a hemorrhagic stroke. Treatment focuses on controlling the bleeding and reducing the pressure on the brain.
Treatment often begins with taking drugs that reduce pressure in the brain and control overall blood pressure, as well as preventing seizures and any sudden constrictions of blood vessels.
If a person is taking blood-thinning anticoagulants or antiplatelet medication, such as warfarin or clopidogrel, they can receive medications to counter the effects of the blood thinners.
Surgeons can repair some of the problems with blood vessels that have led or could lead to hemorrhagic strokes.
When an aneurysm — or a bulge in a blood vessel that may burst — causes a hemorrhagic stroke, a surgeon can place small clamps at the base of the aneurysm or fill it with detachable coils to stop the blood flow and shrink the aneurysm.
If the hemorrhage occurs due to an AVM, a surgeon can remove it. AVMs are connections between arteries and veins that can be at risk of bleeding.
Stroke is a potentially life changing event that can have lasting physical and emotional effects.
Successful recovery from a stroke will often involve specific therapies and support systems, including:
- Speech therapy: This helps with problems producing or understanding speech. Practice, relaxation, and changing communication style can all make communicating easier.
- Physical therapy: This can help a person relearn movement and coordination. It is important to stay active, even though this may be difficult at first.
- Occupational therapy: This can help a person improve their ability to carry out daily activities, such as bathing, cooking, dressing, eating, reading, and writing.
- Support groups: Joining a support group can help a person cope with common mental health issues that can occur after a stroke, such as depression. Many find it useful to share common experiences and exchange information.
- Support from friends and family: Close friends and relatives should try to offer practical support and comfort after a stroke. Letting friends and family know what they can do to help is very important.
Rehabilitation is an important and ongoing part of stroke treatment. With the right assistance and the support of loved ones, regaining a normal quality of life is usually possible, depending on the severity of the stroke.
The best way to prevent a stroke is to address the underlying causes. People can achieve this by making lifestyle changes such as:
- eating a healthful diet
- maintaining a moderate weight
- exercising regularly
- not smoking tobacco
- avoiding alcohol, or only drinking moderately
Eating a nutritious diet means including plenty of:
- whole grains
Be sure to limit the amount of red and processed meat in the diet, as well as cholesterol and saturated fats. Also, moderate salt intake to support healthy blood pressure levels.
Other measures a person can take to help reduce the risk of stroke include:
- controlling their blood pressure levels
- managing diabetes
- getting treatment for heart disease
As well as making these lifestyle changes, taking anticoagulant or antiplatelet medications can also reduce the risk of experiencing another stroke.
Undergoing cardiac artery, carotid artery, or brain aneurysm surgery can also lower the risk of additional strokes, as can some other surgical options still under investigation.
Causes and risk factors
Each type of stroke has a different set of potential causes. Generally, however, stroke is more likely to affect a person if they:
- have overweight or obesity
- are 55 years of age or older
- have a personal or family history of stroke
- have high blood pressure
- have diabetes
- have high cholesterol
- have heart disease, carotid artery disease, or another vascular disease
- are sedentary
- consume alcohol excessively
- use illicit drugs
Some studies have found that males have a higher risk of death from stroke than females. However, one 2016 review of studies suggests that these differences do not take into account adjustments for race, age, the severity of the stroke, and other risk factors.
The review explains that the risk of stroke mortality often increases due to age and demographic, rather than the biological differences between males and females.
According to a 2016 analysis, African American people have a significantly higher risk of experiencing a first-time stroke. They are also around 60% more likely to experience another stroke within 2 years.
The following sections describe the specific causes of each type of stroke.
This type of stroke occurs due to blockages or narrowing in the arteries that provide blood to the brain. This causes ischemia, or a severely reduced blood flow, which damages brain cells.
Blood clots often cause ischemic stroke. Clots can form in the brain arteries and other blood vessels in the body. The bloodstream carries these into narrower arteries in the brain.
Fatty plaque deposits within the arteries can also cause clots that result in ischemia.
Leaky or burst arteries in the brain can give rise to hemorrhagic strokes.
Leaked blood puts pressure on brain cells and damages them. It also reduces the blood supply that can reach the brain tissue after the hemorrhage.
Blood vessels can burst and spill blood into the brain or near the surface of the brain. This may also send blood into the space between the brain and the skull.
Having hypertension, experiencing physical trauma, taking blood-thinning medications, and having an aneurysm can all make a blood vessel leak or burst.
Intracerebral hemorrhage is the most common type of hemorrhagic stroke. This occurs when brain tissue floods with blood after an artery bursts.
Subarachnoid hemorrhage is another type of hemorrhagic stroke. These are less common. In a subarachnoid hemorrhage, bleeding occurs in the area between the brain and the thin tissues that cover it.
TIAs only briefly interrupt the flow of blood to the brain. They are similar to ischemic strokes, in that they occur due to clots.
People should treat them as medical emergencies, even if the symptoms are temporary. They serve as warning signs for future strokes and indicate a partially blocked artery or clot source in the heart.
According to the Centers for Disease Control and Prevention (CDC), over a third of people who experience a TIA have a major stroke within a year if they do not receive any treatment. Around 10–15% of people will have a major stroke within 3 months of experiencing a TIA.
The symptoms of a stroke often appear without warning. Some of the main symptoms include:
- confusion, including difficulty speaking and understanding speech
- a headache, possibly with altered consciousness or vomiting
- numbness or an inability to move parts of the face, arm, or leg, particularly on one side of the body
- vision problems in one or both eyes
- difficulty walking, including dizziness and a lack of coordination
Stroke can lead to long-term health problems. Depending on the speed of the diagnosis and treatment, a person can experience temporary or permanent disabilities after a stroke.
Some people may also experience:
- bladder or bowel control problems
- paralysis or weakness on one or both sides of the body
- difficulty controlling or expressing their emotions
Symptoms vary and may range in severity.
Learning the acronym “FAST” is a good way to remember the symptoms of stroke. This can help a person seek prompt treatment. FAST stands for:
- Face drooping: If the person tries to smile, does one side of their face droop?
- Arm weakness: If the person tries to raise both their arms, does one arm drift downward?
- Speech difficulty: If the person tries to repeat a simple phrase, is their speech slurred or unusual?
- Time to act: If any of these symptoms are occurring, contact the emergency services immediately.
The outcome depends on how quickly someone receives treatment. Prompt care also means that they would be less likely to experience permanent brain damage or death.
Stroke begins rapidly. For the best outcome, a person should receive treatment at a hospital within 3 hours of their symptoms first appearing.
There are several different diagnostic tests a doctor can use to determine the type of stroke. These include:
- Physical examination: A doctor will ask about the person’s symptoms and medical history. They will check muscle strength, reflexes, sensation, vision, and coordination. They may also check blood pressure, listen to the carotid arteries in the neck, and examine the blood vessels at the back of the eyes.
- Blood tests: A doctor may perform blood tests to determine if there is a high risk of bleeding or blood clots, measuring levels of particular substances in the blood, including clotting factors, and checking whether or not an infection is present.
- CT scan: A series of X-rays can show hemorrhages, strokes, tumors, and other conditions within the brain.
- MRI scan: These use radio waves and magnets to create an image of the brain, which a doctor can use to detect damaged brain tissue.
- Carotid ultrasound: A doctor may carry out an ultrasound scan to check blood flow in the carotid arteries and to see if there is any narrowing or plaque present.
- Cerebral angiogram: A doctor may inject a dye into the brain’s blood vessels to make them visible under X-ray or MRI. This provides a detailed view of the blood vessels in the brain and neck.
- Echocardiogram: This creates a detailed image of the heart, which doctors can use to check for any sources of clots that could have traveled to the brain.
It is only possible to confirm the type of stroke using a brain scan in a hospital environment.