A stroke is a serious medical condition that occurs when the blood supply to part of the brain is cut off.
Like all organs, the brain needs the oxygen and nutrients provided by blood to function properly. If the supply of blood is restricted or stopped, brain cells begin to die. This can lead to brain damage and possibly death.
Strokes are a medical emergency and prompt treatment is essential because the sooner a person receives treatment for a stroke, the less damage is likely to happen.
Types of stroke
There are two main causes of strokes:
ischaemic (accounting for over 80% of all cases): the blood supply is stopped due to a blood clot
haemorrhagic: a weakened blood vessel supplying the brain bursts and causes brain damage
There is also a related condition known as a transient ischaemic attack (TIA), where the supply of blood to the brain is temporarily interrupted, causing a 'mini-stroke'. TIAs should be treated seriously as they are often a warning sign that a stroke is coming.
Who is at risk from stroke?
In England, strokes are a major health problem. Every year over 150,000 people have a stroke and it is the third largest cause of death, after heart disease and cancer. The brain damage caused by strokes means that they are the largest cause of adult disability in the UK.
People who are over 65 years of age are most at risk from having strokes, although 25% of strokes occur in people who are under 65. It is also possible for children to have strokes.
If you are south Asian, African or Caribbean, your risk of stroke is higher. This is partly because of a predisposition (a natural tendency) to developing diabetes and heart disease, which are two conditions that can cause strokes.
Smoking, being overweight, lack of exercise and a poor diet are also risk factors for stroke. Also, conditions that affect the circulation of the blood, such as high blood pressure, high cholesterol, atrial fibrillation (an irregular heartbeat) and diabetes, increase your risk of having a stroke.
Strokes can be treated and prevented
Strokes can usually be successfully treated and also prevented. Eating a healthy diet, taking regular exercise, drinking alcohol in moderation and not smoking will dramatically reduce your risk of having a stroke. Lowering high blood pressure and cholesterol levels with medication also lowers the risk of stroke substantially.
See the prevention section for more information about reducing the risk of having a stroke.
Strokes can be treated using a combination of medicines and, in some cases, surgery.
However, many people will require a long period of rehabilitation after a stroke and not all will recover fully.
Symptoms
If you suspect that you or someone else is having a stroke, phone 999 immediately and ask for an ambulance.
Even if the symptoms of a stroke disappear while you are waiting for the ambulance to arrive, you or the person having the stroke should still go to hospital for an assessment. Symptoms that disappear may mean you have had a transient ischaemic attack (TIA) and you could be at risk of having a full stroke at a later stage.
After an initial assessment, you may need to be admitted to hospital to receive a more in-depth assessment and, if necessary, for specialist treatment to begin.
Recognising the signs and symptoms of a stroke
The signs and symptoms of a stroke vary from person to person but they usually begin suddenly. As different parts of your brain control different parts of your body, your symptoms will depend upon the part of your brain that has been affected and the extent of the damage.
The main stroke symptoms can be remembered with the word FAST: Face-Arms-Speech-Time.
Face: the face may have dropped on one side, the person may not be able to smile or their mouth or eye may have drooped
Arms: the person with suspected stroke may not be able to lift one or both arms and keep them there because of arm weakness or numbness
Speech: their speech may be slurred or garbled, or the person may not be able to talk at all despite appearing to be awake
Time: it is time to dial 999 immediately if you see any of these signs or symptoms
It is important for everyone to be aware of these signs and symptoms. If you live with or care for somebody in a high-risk group, such as someone who is elderly or has diabetes or high blood pressure, being aware of the symptoms is even more important.
Symptoms in the FAST test identify about nine out of 10 strokes.
Other signs and symptoms may include:
numbness or weakness resulting in complete paralysis of one side of the body
sudden loss of vision
dizziness
communication problems, difficulty talking and understanding what others are saying
problems with balance and coordination
difficulty swallowing
sudden and severe headache, unlike any the person has had before, especially if associated with neck stiffness
The symptoms of a transient ischaemic attack (TIA) are the same as for a stroke but only last from between a few minutes to a few hours, then completely disappear. However, never ignore a TIA as it is a serious warning sign that there is a problem with the blood supply to your brain.
There is about a one in 10 chance that those who have a TIA will experience a full stroke during the four weeks following the TIA. If you have had a TIA, you should contact your GP, local hospital or out-of-hours service, as soon as possible.
Stroke is a largely preventable condition. Many of the key risk factors can be reduced by making lifestyle changes.
There are some risk factors for stroke that cannot be changed, including:
age: you are more likely to have a stroke if you are over 65 years old. However, about a quarter of strokes happen in younger people.
family history:if a close relative (parent, grandparent, brother or sister) has had a stroke, your risk is likely to be higher
ethnicity: if you are south Asian, African or Caribbean, your risk of stroke is higher, partly because rates of diabetes and high blood pressure are higher in these groups
your medical history: if you have previously had a stroke, TIA or heart attack, your risk of stroke is higher
Ischaemic strokes
Ischaemic strokes occur when blood clots block the flow of blood to the brain. Blood clots typically form in areas where the arteries have been narrowed or blocked by fatty cholesterol-containing deposits known as plaques. This narrowing of the arteries is caused by atherosclerosis.
As we get older our arteries become narrower but certain risk factors can dangerously accelerate the process. Risk factors include:
excessive alcohol intake (which can also make obesity and high blood pressure worse, as well as causing heart damage and an irregular heart beat)
Diabetes is also a risk factor, particularly if it is poorly controlled, as the excess glucose in the blood can damage the arteries.
Another possible cause of ischaemic stroke is an irregular heartbeat (atrial fibrillation), which can cause blood clots that become lodged in the brain. Atrial fibrillation can be caused by:
high blood pressure
coronary artery disease
mitral valve disease (disease of the heart valve)
cardiomyopathy (wasting of the heart muscle)
pericarditis (inflammation of the bag surrounding the heart)
hyperthyroidism (overactive thyroid gland)
excessive alcohol intake
drinking lots of caffeine; for example, tea, coffee and energy drinks
Haemorrhagic strokes
Haemorrhagic strokes (also known as cerebral haemorrhages or intracranial haemorrhages) usually occur when a blood vessel in the brain bursts and bleeds into the substance of the brain (intracerebral haemorrhage). In about 5% of cases, the bleeding occurs on the surface of the brain (subarachnoid haemorrhage).
The main cause of haemorrhagic stroke is high blood pressure (hypertension), which can weaken the arteries in the brain and make them prone to split or rupture.
The risk factors for high blood pressure include:
being overweight
drinking excessive amounts of alcohol
smoking
a lack of exercise
stress, which may cause a temporary rise in blood pressure
Another important risk factor for haemorrhagic stroke is treatment with medicines given to prevent blood clots, for example, warfarin.
Haemorrhagic stroke can also occur from rupture of an aneurysm (a balloon-like expansion of a blood vessel) and cerebral blood vessel malformations.
A traumatic head injury can also cause bleeding into the brain. In most cases, the cause is obvious but bleeding into the lining of the brain (subdural haematoma) can occur without any obvious signs of trauma, especially in the elderly. The symptoms and signs can then mimic stroke.
Other causes
Less than 1% of strokes are caused by a blood clot (thrombosis) in the veins of the brain (the cerebral veins). Abnormalities of clotting increase the risk of this type of stroke.
Diagnosis
Strokes are usually diagnosed by studying images of the brain (brain imaging). This can also be helpful in determining the risk of a transient ischaemic attack (TIA).
Even if the physical symptoms of a stroke are obvious, brain imaging should be carried out to determine:
if the stroke has been caused by a blocked artery or a burst blood vessel
which part of the brain has been affected
how severe the stroke is
Different treatment is required for each type of stroke so a rapid diagnosis will make treatment more straightforward.
CT and MRI scans
Two common methods used for brain imaging are a computer tomography (CT) scan and a magnetic resonance imaging (MRI) scan.
A CT scan is like an X-ray but it uses multiple images to build up a more detailed, three-dimensional (3D) picture of your brain. An MRI scan uses a strong magnetic field and radio waves to produce a detailed picture of the inside of your body.
The type of scan you may have in hospital depends on the type of symptoms. In people with suspected major stroke, a CT scan is sufficient to identify whether the stroke is due to bleeding or clotting. It's quicker than an MRI scan and improves the chances of rapidly delivering treatments such as clot-busting (thrombolysis) that might be used in appropriate cases but which are time-limited and require the results of the scan before the treatment can be given safely.
For people with more complex symptoms, where the extent or location of the damage is unknown, and in patients who have recovered from a transient ischaemic attack, an MRI scan is more appropriate. This will provide greater detail of brain tissue, allowing smaller, or more unusually located strokes to be identified.
All patients with suspected stroke should receive a brain scan within 24 hours. Some patients should be scanned within the hour, especially those who:
have had a suspected thrombotic stroke and might benefit from clot-busting drugs (thrombolysis) such as alteplase or early anticoagulant treatment
are already on anticoagulant treatments
have a lower level of consciousness
After the injection of a dye into an arm vein, both CT and MRI can be used to take pictures of the blood vessels in the brain, as well as the blood vessels in the neck that take blood to the brain from the heart. This is known as a CT or MR angiogram and is often done immediately after taking picture of the brain itself.
A swallow test is essential for anybody who has had a stroke.
Swallowing problems affect over a third of people after a stroke. When a person cannot swallow properly, there is a risk that food and drink may get into the windpipe and then into the lungs (called aspiration), which can lead to chest infections and pneumonia.
The test is simple. The person is given a few teaspoons of water to drink. If they can swallow this without choking and coughing they will be asked to swallow half a glass of water.
If they have any difficulty swallowing, they will be referred to the speech and language therapist for a more detailed assessment. They will usually be kept ‘nil by mouth’ until they have seen the therapist and may therefore need to have fluids or food given by an intravenous drip or nasogastric tube.
Heart and blood vessel tests
Further tests on the heart and blood vessels might be carried out later to confirm what caused the stroke. These may include:
Ultrasound (carotid ultrasonography)
An ultrasound scan uses high frequency sound waves to produce an image of the inside of your body. Your doctor may use a wand-like probe (transducer) to send high-frequency sound waves into your neck. These pass through the tissue creating images on a screen that will show if there is any narrowing or clotting in the arteries leading to your brain.
This type of ultrasound scan is sometimes known as a doppler scan or a duplex scan. Where carotid ultrasonography is needed, it should happen within 48 hours.
Catheter angiography (arteriography)
Dye is injected into your carotid or vertebral artery via a catheter. This gives a detailed view of your arteries than can be obtained using ultrasound, CT angiography or MR angiography.
Echocardiogram
In some cases an echocardiogram may be used to produce images of your heart using an ultrasound probe placed on your chest (transthoracic echocardiogram). In addition, transoesophageal echocardiography (TOE) may also be used. This involves an ultrasonic probe which is passed down the foodpipe (oesophagus), usually under sedation. Because it's directly behind the heart, it produces a clear image of blood clots and other abnormalities that may not get picked up by the transthoracic echocardiogram.
Physical examination
Your doctor may check for risk factors of stroke by taking blood tests, checking your pulse and blood pressure and using a stethoscope to listen to the sound of blood in the neck arteries.
The best way to prevent a stroke is to eat a healthy diet, exercise regularly and avoid smoking and excessive consumption of alcohol.
Diet
A poor diet is a major risk factor for a stroke. High-fat foods can lead to the build-up of fatty plaques in your arteries and being overweight can lead to high blood pressure.
A low-fat, high-fibre diet is recommended, including plenty of fresh fruit and vegetables (five portions a day) and whole grains. You should limit the amount of salt that you eat to no more than 6g (0.2oz) a day because too much salt will increase your blood pressure. Six grams of salt is about one teaspoonful.
There are two types of fat: saturated and unsaturated. You should avoid food containing saturated fats because these will increase your cholesterol levels.
Foods high in saturated fat include:
meat pies
sausages and fatty cuts of meat
butter
ghee: a type of butter that is often used in Indian cooking
lard
cream
hard cheese
cakes and biscuits
foods that contain coconut or palm oil.
However, a balanced diet should include a small amount of unsaturated fat, which will help reduce your cholesterol levels.
Combining a healthy diet with regular exercise is the best way to maintain a healthy weight. Having a healthy weight reduces your chances of developing high blood pressure.
Regular exercise will make your heart and blood circulatory system more efficient. It will also lower your cholesterol level and keep your blood pressure at a healthy level.
The recommended level of cholesterol is 5mmol/litre (5 millimoles per litre of blood).
Blood pressure is measured using two figures. One figure represents the pressure of the heart as it contracts to pumps blood around the body. This is known as the systolic pressure. The second figure represents the pressure of the heart as it expands and fills with blood, while waiting for the next contraction. This is known as the diastolic pressure.
For most people, a healthy blood pressure is a systolic pressure of 90-120 millimeters of mercury (mmHg) and a diastolic pressure of 60-80mmHg. Or, as blood pressure is normally expressed, a level between 90/60mmHg and 120/80mmHg.
For most people, at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity (i.e. cycling or fast walking) every week is recommended.
If you are recovering from a stroke, you should discuss possible exercise plans with the members of your rehabilitation team. Regular exercise may be impossible in the first weeks or months following a stroke but you should be able to begin exercising once your rehabilitation has progressed.
Smoking doubles your risk of having a stroke. This is because it narrows your arteries and makes your blood more likely to clot.
If you stop smoking, you can reduce your risk of having a stroke by up to half. Not smoking will also improve your general health and reduce your risk of developing other serious conditions, such as lung cancer and heart disease.
The NHS Smoking Helpline can offer advice and encouragement to help you quit smoking. You can call on 0800 022 4332, or visit NHS Smokefree.
Excessive alcohol consumption can lead to high blood pressure and an irregular heartbeat (atrial fibrillation). Both are major risk factors for stroke.
Because alcoholic drinks are rich in energy (high in calories) they also cause weight gain. Heavy drinking multiplies the risk of stroke by more than three times.
The damage caused by a stroke can interrupt your normal swallowing reflex, making it possible for small particles of food to enter your respiratory tract (windpipe).
Problems with swallowing are known as dysphagia. Dysphagia can lead to damage to your lungs, which can trigger a lung infection (pneumonia).
To prevent any complications from dysphagia, you may be fed using a feeding tube. The tube is usually put into your nose and then passed into your stomach, but it may be directly connected to your stomach during surgery.
How long you will need a feeding tube can vary from a few weeks to a few months but it is rare to have to use a tube for more than six months.
Hydrocephalus
Hydrocephalus is a condition that occurs when there is too much cerebrospinal fluid in the ventricles (cavities) of the brain. About 10% of people who experience a haemorrhagic stroke will develop hydrocephalus.
Cerebrospinal fluid (CSF) is produced in the brain and protects it and spinal cord and carries away waste from brain cells. CSF flows continuously through the ventricles (cavities inside the brain) and over the surface of the brain and spinal cord. Any excess CSF usually drains away from the brain and is absorbed by the body.
Damage caused by a haemorrhagic stroke can stop the CSF from draining, and an excess of fluid can build up. Symptoms include:
headaches
sickness and vomiting
loss of balance
However, the condition can be treated by placing a tube into the brain to allow the fluid to drain properly.
Deep vein thrombosis
Around 5% of people who have had a stroke will experience a further blood clot in their leg, known as deep vein thrombosis (DVT).
This normally occurs in people who have lost some or all of the movement in their leg, as immobility will slow the blood flow in their veins, increasing blood pressure and the chances of a blood clot.
Symptoms of a DVT include:
swelling
pain
warm skin
tenderness
redness, particularly at the back of the leg, below the knee
If you have a DVT, prompt treatment is required because there is a chance that the clot may move into your lungs, which is known as a pulmonary embolism and can be fatal.
DVTs can be treated using anti-clotting medicines. If it is felt that you are at risk of a DVT, your stroke team may recommend that you wear a compression stocking. This is a specially designed stocking that can reduce the blood pressure in your legs.
