What is stroke?
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 which cause brain cells to die.
There are three main kinds of stroke; ischemic, hemorrhagic and TIA.
Stroke is also more likely to affect people if they are overweight, aged 55 or older, have a personal or family history of stroke, do not exercise much, drink heavily, smoke or use illicit drugs.
What causes stroke?
The different forms of stroke have different specific causes.
Ischemic stroke is the most common form of stroke, accounting for around 85% of strokes. This type of stroke is caused by blockages or narrowing of the arteries that provide blood to the brain, resulting in ischemia – severely reduced blood flow.
These blockages are often caused by blood clots, which can form either in the arteries connecting to the brain, or in other blood vessels before being swept through the bloodstream and into narrower arteries within the brain. Clots can be caused by fatty deposits within the arteries called plaque.
Hemorrhagic stroke are caused by arteries in the brain either leaking blood or bursting open. The leaked blood puts pressure on brain cells and damages them. Blood vessels can burst or spill blood in the middle of 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 such as hypertension, trauma, blood-thinning medications and aneurysms (weaknesses in blood vessel walls).
Intracerebral hemorrhage is the most common type of hemorrhagic stroke and occurs when brain tissue is 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 subarachnoid space – the area between the brain and the thin tissues that cover it.
Transient ischemic attack (TIA)
TIAs are different from the aforementioned kinds of stroke 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 debris.
TIAs should be regarded as medical emergencies just like the other kinds of stroke, even if the blockage of the artery is 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 go on to have a major stroke within a year if they have not received any treatment. Between 10-15% will have a major stroke within 3 months of a TIA.
Symptoms of stroke
Strokes occur quickly and as such symptoms of stroke often appear suddenly without warning.
The main symptoms of stroke are as follows:
- Confusion, including trouble with speaking and understanding
- Headache, possibly with altered consciousness or vomiting
- Numbness of the face, arm or leg, particularly on one side of the body
- Trouble with seeing, in one or both eyes
- Trouble with walking, including dizziness and lack of co-ordination.
Strokes can lead to long-term problems. Depending on how quickly it is diagnosed and treated, the patient can experience temporary or permanent disabilities in the aftermath of a stroke. In addition to the persistence of the problems listed above, patients 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.
How to diagnose a stroke
Strokes happen fast and will often occur before an individual can be seen by a doctor for a proper diagnosis.
The acronym F.A.S.T. is a way to remember the signs of stroke, and can help identify the onset of stroke more quickly:
- 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?
The faster a person with suspected stroke receives medical attention, the better their prognosis and the less likely they will be to experience lasting damage or death.
In order for a stroke patient to get the best diagnosis and treatment possible, they will need to be treated at a hospital within 3 hours of their symptoms first appearing.
Both ischemic strokes and hemorrhagic strokes require different kinds of treatment. Unfortunately, it is only possible to be sure of what type of stroke someone has had by giving them a brain scan in a hospital environment.
There are several different types of diagnostic tests that doctors can use in order to determine which type of stroke has occurred:
- Physical examination: a doctor will ask about the patient’s 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, all to check for indications of clotting
- Blood tests: a doctor may perform blood tests in order to find out how quickly the patient’s blood clots, the levels of particular substances (including clotting factors) in the blood, and whether or not the patient has an infection
- CT scan: a series of X-rays that 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 of 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, in order to give a detailed view of the brain and neck arteries
- Echocardiogram: a detailed image of the heart is created to check for any sources of clots that could have traveled to the brain to cause a stroke.
Treatments for stroke
As the two main different kinds of stroke, ischemic and hemorrhagic, are caused by different factors, 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 treatment suitable for one kind of stroke can be harmful to someone who has had a different kind.
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 can begin with drugs to break down clots and prevent further ones from forming. Aspirin can be given, as can an injection of a tissue plasminogen activator (TPA). TPA is very effective at dissolving clots but needs to be injected within 4.5 hours of stroke symptoms manifesting themselves.
Emergency procedures include administering TPA via catheter directly into an artery in the brain or using a catheter to physically remove the clot from its obstructive position. Recent studies have cast doubt as to the effectiveness of these methods, and so research is still ongoing as to how beneficial these procedures are.
There are other procedures that can be carried out to decrease the risk of future 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 stent (a mesh tube) into the opening in order to prevent the artery from narrowing again.
Hemorrhagic strokes are caused by bleeding into the brain and so treatment focuses on controlling the bleeding and reducing the pressure on the brain that it is causing.
Treatment can begin with drugs being given to reduce the pressure in the brain, overall blood pressure, prevent seizures and prevent sudden constrictions of blood vessels. If the patient is taking anti-coagulant or anti-platelet medication like Warfarin or Clopidogrel, they can be given drugs or blood transfusions to counter the medication’s effects.
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 to them and prevent rupture.
Surgery can also be used to remove small arteriovenous malformations (AVMs) if they are not too big and not too deep within 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, temporarily or permanently. After a stroke, successful recovery will often involve specific rehabilitative activities such as:
- Speech therapy – to help with problems producing or understanding speech. Practice, relaxation and changing communication style, using gestures or different tones for example, all help
- Physical therapy – to help a person relearn movement and co-ordination. It is important to get out and about, even if it is difficult at first
- Occupational therapy – to help a person to improve their ability to carry out routine daily activities, such as bathing, cooking, dressing, eating, reading and writing
- Joining a support group – to help with common mental health problems such as depression that can occur after a stroke. Many find it useful to share common experiences and exchange information
- Support from friends and family – to provide practical support and comfort. Letting friends and family know what can be done to help is very important.
Preventing a stroke
The best way to prevent a stroke is to address the underlying causes. This is best done by living healthily, which means:
- Eating a healthy diet
- Maintaining a healthy weight
- Exercise regularly
- Not smoking
- Avoiding alcohol or moderating consumption.
Eating a healthy diet means getting plenty of fruits, vegetables and healthy whole grains, nuts, seeds and legumes; eating little or no red or processed meat; limiting intake of cholesterol and saturated fat (typically found in foods of animal origin); and minimizing salt intake so as to support healthy blood pressure.
Other measures taken to help reduce the risk of stroke include:
- Keeping blood pressure under control
- Managing diabetes well
- Treating obstructive sleep apnea
As well as these lifestyle changes, a health care provider can help to reduce the risk of future strokes through prescribing anti-coagulant and anti-platelet medication. In addition to this, the arterial surgery previously mentioned can also be used to lower the risk of repeat strokes.