Everything you need to know about stroke
This MNT Knowledge Center article will explain why strokes occur and how they are treated, as well as exploring the different types and the steps a person can take to prevent a stroke.
- During a stroke, the brain does not receive enough oxygen or nutrients, causing brain cells to die.
- Strokes need to be diagnosed and treated as quickly as possible to minimize brain damage.
- Treatment depends on the type of stroke.
- The most effective way to prevent strokes is through maintaining a healthy lifestyle and treating underlying conditions that could be a risk factor.
What is a stroke?
A stroke occurs when the supply of blood to the brain is either interrupted or reduced. When this happens, the brain does not get enough oxygen or nutrients, and brain cells start to die.
In the U.S., approximately 40 percent of people who die from stroke are male, with 60 percent of deaths occurring in females.
According to the American Heart Association (AHA), compared with Caucasian people, African-Americans have nearly twice the risk of a first-time stroke and a much higher risk of death from stroke.
As ischemic and hemorrhagic strokes have different causes, both require different forms of treatment.
It is not only important that the type of stroke is diagnosed quickly to reduce the damage done to the brain, but also because a treatment suitable for one type of stroke may be harmful when treating different type.
Ischemic strokes are caused by arteries being blocked or narrowed, and so treatment focuses on restoring an adequate flow of blood to the brain.
Treatment starts with drugs that break down clots and prevent others from forming. Aspirin can be given, as can an injection of tissue plasminogen activator (TPA). TPA is very effective at dissolving clots but needs to be injected within 4.5 hours of 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 still ongoing as to the benefit of these procedures.
There are other procedures that can be carried out to decrease the risk of strokes or TIAs. A carotid endarterectomy involves a surgeon opening the carotid artery and removing any plaque that might be blocking it.
Alternatively, an angioplasty involves a surgeon inflating a small balloon in a narrowed artery via catheter and then inserting a mesh tube called a stent into the opening. This prevents the artery from narrowing again.
Hemorrhagic strokes are caused by blood leaking into the brain, so treatment focuses on controlling the bleeding and reducing the pressure on the brain.
Treatment can begin with drugs given to reduce the pressure in the brain, control overall blood pressure, prevent seizures and prevent sudden constrictions of blood vessels.
If an individual is taking blood-thinning anticoagulants or an antiplatelet medication like warfarin or clopidogrel, they can be given drugs to counter the effects of the medication or blood transfusions to make up for blood loss.
Surgery can be used to repair any problems with blood vessels that have led or could lead to hemorrhagic strokes. Surgeons can place small clamps at the base of aneurysms or fill them with detachable coils to stop blood flow and prevent rupture.
If the hemorrhage is caused by arteriovenous malformations (AVMs), surgery can also be used to remove them if they are not too big and not too deep in the brain. AVMs are tangled connections between arteries and veins that are weaker and burst more easily than other normal blood vessels.
Strokes are life-changing events that can affect a person both physically and emotionally. After a stroke, successful recovery will often involve specific therapies and support, such as:
Rehabilitation is an important and ongoing part of treatment. With the right assistance and the support of loved ones, rehabilitation to a normal quality of life is possible, depending on the severity of the stroke.
The best way to prevent a stroke is to address the underlying causes. This is best achieved through lifestyle changes, including:
- eating a healthy diet
- maintaining a healthy weight
- exercising regularly
- not smoking tobacco
- avoiding alcohol or drinking moderately
Eating a nutritious diet means including plenty of fruits, vegetables, and healthy whole grains, nuts, seeds, and legumes. Be sure to eat little or no red or processed meat and limit intake of cholesterol and saturated fats. Minimize salt intake to support healthy blood pressure.
Other measures taken to help reduce the risk of stroke include:
As well as these lifestyle changes, a doctor can help to reduce the risk of future ischemic strokes through prescribing anticoagulant or antiplatelet medication.
In addition, arterial surgery can also be used to lower the risk of repeat strokes, as well as some other surgical options still being studied.
There are three main types of stroke:
- Ischemic stroke: This is the most common type of stroke. A blood clot prevents blood and oxygen from reaching the brain.
- Hemorrhagic stroke: This occurs when a weakened blood vessel ruptures and normally occur as a result of aneurysms or arteriovenous malformations (AVMs).
- Transient ischemic attacks (TIAs): Also referred to as a mini-stroke, these occur after blood flow fails to reach part of the brain. Normal blood flow resumes after a short amount of time, and symptoms cease.
The different types of stroke have different causes. However, stroke is more likely to affect people if they have the following risk factors:
- being overweight
- being aged 55 years or older
- a personal or family history of stroke
- an inactive lifestyle
- a tendency to drink heavily, smoke, or use illicit drugs
This type of stroke is caused by blockages or narrowing of the arteries that provide blood to the brain, resulting in ischemia. Ischemia is severely reduced blood flow that damages brain cells.
These blockages are often caused by blood clots, which can form in the brain arteries. They can also occur in other blood vessels in the body before being swept through the bloodstream and into narrower arteries in the brain.
Fatty deposits within the arteries called plaque can cause clots that result in ischemia.
Hemorrhagic strokes are caused by arteries in the brain either leaking blood or bursting open.
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, sending blood into the space between the brain and the skull.
The ruptures can be caused by conditions including hypertension, trauma, blood-thinning medications, and aneurysms. Aneurysms are weaknesses in the walls of blood vessels.
Intracerebral hemorrhage is the most common type of hemorrhagic stroke and occurs when brain tissue becomes flooded with blood after an artery in the brain bursts.
Subarachnoid hemorrhage is the second type of hemorrhagic stroke and is less common. In this type of stroke, bleeding occurs in the area between the brain and the thin tissues that cover it.
Transient ischemic attack (TIA)
TIAs are different from the types above because the flow of blood to the brain is only briefly interrupted. TIAs are similar to ischemic strokes in that they are often caused by blood clots or other clots.
They should be regarded as medical emergencies, even if the blockage of the artery and its symptoms are temporary. They serve as warning signs for future strokes and indicate that there is 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 have not received any treatment. Between 10 and 15 percent of people will have a major stroke within 3 months of a TIA.
Symptoms of a stroke often appear without warning.
The main symptoms of stroke are:
- confusion, including trouble with speaking and understanding
- a headache, possibly with altered consciousness or vomiting
- numbness or inability to move parts of the face, arm, or leg, particularly on one side of the body
- vision problems in one or both eyes
- trouble walking, including dizziness and lack of co-ordination
Strokes can lead to long-term health problems. Depending on how quickly it is diagnosed and treated, an individual can experience temporary or permanent disabilities in the aftermath of a stroke.
In addition to the persistence of the problems listed above, people may also experience the following:
- bladder or bowel control problems
- pain in the hands and feet that gets worse with movement and temperature changes
- paralysis or weakness on one or both sides of the body
- trouble controlling or expressing emotions
Symptoms vary and may range in severity.
The acronym F.A.S.T. is a way to remember the signs of stroke, and can help identify the onset of stroke:
- Face drooping: If the person tries to smile, does one side of the 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 strange?
- Time to call 911: If any of these signs are observed, contact the emergency services.
The faster a person with suspected stroke receives medical attention, the better their prognosis will be, and the less likely they will be to experience permanent damage or death.
Signs of a stroke require immediate medical attention.
Strokes onset rapidly and will often occur before an individual can be seen by a doctor for a proper diagnosis.
For a person experiencing a stroke to get the best diagnosis and treatment possible, they should be treated at a hospital within 3 hours of their symptoms first appearing.
There are several different types of diagnostic tests that doctors can use to determine which type of stroke has occurred:
- Physical examination: A doctor will ask about symptoms and medical history. They may check blood pressure, listen to the carotid arteries in the neck, and examine the blood vessels at the back of the eyes to check for indications of clotting.
- Blood tests: A doctor may perform blood tests to find out how quickly the clots occur, the levels of particular substances in the blood, including clotting factors and 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: Radio waves and magnets create an image of the brain to detect damaged brain tissue.
- Carotid ultrasound: An ultrasound scan to check the blood flow in the carotid arteries and to see if there is any plaque present.
- Cerebral angiogram: Dyes are injected into the brain's blood vessels to make them visible under X-ray. This gives a detailed view of the brain and the blood vessels in the neck.
- Echocardiogram: This creates a detailed image of the heart to check for any sources of clots that could have traveled to the brain to cause a stroke.
It is only possible to confirm the type of stroke someone has had by giving them a brain scan in a hospital environment.