A stroke is a serious, life-threatening medical condition that occurs when the blood supply to part of the brain is cut off.
Strokes are a medical emergency and urgent treatment is essential because the sooner a person receives treatment for a stroke, the less damage is likely to happen.
Signs and symptoms
The main symptoms of stroke 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 dropped.
- Arms – the person with suspected stroke may not be able to lift both arms and keep them there because of arm weakness or numbness in one arm.
- 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 102 immediately if you see any of these signs or symptoms.
Why do strokes happen?
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 injury, disability and possibly death.
There are two main causes of strokes:
- ischaemic – where the blood supply is stopped due to a blood clot (this accounts for 85% of all cases)
- haemorrhagic – where a weakened blood vessel supplying the brain bursts
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" often lasting between 30 minutes and several hours. TIAs should be treated seriously as they are often a warning sign that you are at risk of having a full stroke in the near future.
Causes of stroke
There are two main types of stroke – ischaemic strokes and haemorrhagic strokes – which affect the brain in different ways and can have different causes.
Ischaemic strokes are the most common type of stroke. They occur when a blood clot blocks the flow of blood and oxygen to the brain.
These blood clots typically form in areas where the arteries have been narrowed or blocked over time by fatty deposits known as plaques. This process is known as atherosclerosis.
As you get older, the arteries can naturally narrow, but certain things can dangerously accelerate the process. These include:
- high blood pressure (hypertension)
- high cholesterol levels
- an excessive alcohol intake
Another possible cause of ischaemic stroke is a type of irregular heartbeat called atrial fibrillation, which can cause blood clots in the heart that break up and escape from the heart and become lodged in the blood vessels supplying the brain.
Atrial fibrillation can have a number of different causes, including lung disease, heart valve disease, excessive alcohol intake, coronary heart disease, and an overactive thyroid gland (hyperthyroidism). Read more about the causes of atrial fibrillation.
Haemorrhagic strokes (also known as cerebral haemorrhages or intracranial haemorrhages) are less common than ischaemic strokes. They occur when a blood vessel within the skull bursts and bleeds into and around the brain.
The main cause of haemorrhagic stroke is high blood pressure, which can weaken the arteries in the brain and make them prone to split or rupture.
Things that increase the risk of high blood pressure include:
- being overweight or obese
- drinking excessive amounts of alcohol
- a lack of exercise
- stress, which may cause a temporary rise in blood pressure
Haemorrhagic strokes can also occur as the result of the rupture of a balloon-like expansion of a blood vessel (brain aneurysm) and badly-formed blood vessels in the brain.
Strokes are usually diagnosed by carrying out physical tests and studying images of the brain produced during a scan.
When you first arrive at hospital with a suspected stroke, a doctor will usually want to find out as much as they can about your symptoms.
A number of tests can then be carried out to help confirm the diagnosis and determine the cause of the stroke.
This may include blood tests to determine your cholesterol and blood sugar levels, checking your pulse for an irregular heartbeat and taking a blood pressure measurement.
Even if the physical symptoms of a stroke are obvious, brain scans should also be carried out to determine:
- if the stroke has been caused by a blocked artery (ischaemic stroke) or burst blood vessel (haemorrhagic stroke)
- which part of the brain has been affected
- how severe the stroke is
Different treatment is required for the different types of stroke, so a rapid diagnosis will make treatment more straightforward.
Everyone with suspected stroke should receive a brain scan within 24 hours and some people should be scanned within an hour of the onset of symptoms, especially those who:
- 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
The two main types of scan used to assess the brain in people who have had a suspected stroke are a computerised tomography (CT) scan and a magnetic resonance imaging (MRI) scan. The type of scan you may have largely depends on your symptoms.
A CT scan is like an X-ray, but uses multiple images to build up a more detailed, three-dimensional picture of your brain to help your doctor identify any problem areas.
During the scan, you may be given an injection of a special dye into one of the veins in your arm to help improve the clarity of the CT image and look at the blood vessels that supply the brain.
If it is suspected you are experiencing a major stroke, a CT scan is usually able to show whether you have had an ischaemic stroke or a haemorrhagic stroke. It's generally quicker than an MRI scan and can mean you are able to receive appropriate treatment sooner.
An MRI scan uses a strong magnetic field and radio waves to produce a detailed picture of the inside of your body.
For people with more complex symptoms, where the extent or location of the damage is unknown – and in people who have recovered from a transient ischaemic attack (TIA) – an MRI scan is more appropriate. This will provide greater detail of brain tissue, allowing smaller, or more unusually located areas affected by a stroke to be identified.
As with a CT scan, special dye can be used to improve MRI scan images.
A swallow test is essential for anybody who has had a stroke, as swallowing ability is commonly affected early 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 such as 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 not be allowed to eat or drink normally until they have seen the therapist and may therefore need to have fluids or food given directly into an arm vein (intravenously) or through a tube inserted into their stomach via their nose.
Heart and blood vessel tests
Further tests on the heart and blood vessels might be carried out later to confirm what caused your stroke. Some of the tests that may be carried out are described below.
A carotid ultrasound scan can help show if there is any narrowing or blockages in the neck arteries leading to your brain.
An ultrasound scan involves using a small probe (transducer) to send high-frequency sound waves into your body. When these sound waves bounce back, they can be used to create an image of the inside of your body.
When carotid ultrasonography is needed, it should happen within 48 hours.
In some cases another type of ultrasound scan called an echocardiogram may be carried out to produce images of your heart and check for any problem with it that could be related to your stroke.
This will normally involve using an ultrasound probe moved across your chest (transthoracic echocardiogram).
In some cases, an alternative type of echocardiogram called transoesophageal echocardiography (TOE) may also be used.
This involves passing an ultrasound probe down your gullet (oesophagus), usually under sedation. As this allows the probe to be placed directly behind the heart, it produces a clear image of blood clots and other abnormalities that may not get picked up by a transthoracic echocardiogram.
Brain imaging is often used to identify which part of the brain has been affected by stroke and how severe it is
CT scans can produce detailed images of many structures inside the body, including the internal organs, blood vessels and bones.
Effective treatment of stroke can prevent long-term disability and save lives.
The specific treatments recommended depend on whether a stroke is caused by a blood clot obstructing the flow of blood to the brain (ischaemic stroke) or by bleeding in or around the brain (haemorrhagic stroke).
Treatment will usually involve taking one or more different medications, although some people may also need surgery.
The main treatment strategies for the two types of stroke are outlined below.
Treating Ischaemic Stroke
If you have had an ischaemic stroke, a combination of medications to treat the condition and prevent it from happening again will usually be recommended.
Some of these medications will need to be taken immediately and only for a short time, while others may only be started once the stroke has been treated and may need to be taken in the long-term.
Ischaemic strokes can often be treated using injections of a medication called alteplase that dissolves blood clots and restores the flow of blood to the brain. This use of "clot-busting" medication is known as thrombolysis.
Alteplase is most effective if started as soon as possible after the stroke occurs and is not generally recommended if more than four-and-a-half hours have passed, because it's not clear how beneficial it is when used after this time.
However, before alteplase can be used, it is very important that a brain scan to confirm a diagnosis of an ischaemic stroke is carried out because the medication can make the bleeding that occurs in haemorrhagic strokes worse.
Most people will also be offered a regular dose of aspirin which – as well as being a painkiller – makes the cells in your blood called platelets less sticky, reducing the chances of another clot forming.
In addition to aspirin, other antiplatelet medicines such as clopidogrel and dipyridamole are also available.
Some people may also be offered an additional medication called an anticoagulant to help reduce their risk of developing further blood clots in the future.
Anticoagulants prevent blood clots by changing the chemical composition of the blood in a way that prevents clots from occurring. Warfarin, rivaroxaban, dabigatran and apixaban are examples of anticoagulants for long term use. There are also a number of anticoagulants called heparins that can only be given by injection and are used in the short term.
Anticoagulants may be offered if you:
- have a type of irregular heartbeat called atrial fibrillation that can cause blood clots
- have a history of blood clots
- are at risk of developing clots in your leg veins – known as deep vein thrombosis (DVT) – because a stroke has left you unable to move one of your legs
If your blood pressure is too high, you may be offered medicines to lower it. Medicines that are commonly used include:
- thiazide diuretics
- angiotensin-converting enzyme (ACE) inhibitors
- calcium channel blockers
If the level of cholesterol in your blood is too high, you will be advised to take a medicine known as a statin. Statins reduce the level of cholesterol in your blood by blocking an enzyme (chemical) in the liver that produces cholesterol.
You may be offered a statin, even if your cholesterol level is not particularly high, because a statin may help reduce your risk of stroke whatever your cholesterol level is.
Some ischaemic strokes are caused by narrowing of an artery in the neck called the carotid artery, which carries blood to the brain. The narrowing, known as carotid stenosis, is caused by a build-up of fatty plaques.
If the carotid stenosis is particularly severe, surgery may be offered to unblock the artery. This is done using a surgical technique called a carotid endarterectomy. It involves the surgeon making an incision in your neck to open up the carotid artery and remove the fatty deposits.
Treating Haemorrhagic Stroke
As with ischaemic strokes, some people who have had a haemorrhagic stroke will also be offered medication, such as ACE inhibitors, to lower blood pressure and prevent further strokes from occurring.
If you were previously taking anticoagulant medicine before you had your stroke, you may also need treatment to reverse the effects of the medication and reduce your risk of further bleeding.
Occasionally, emergency surgery may be needed to remove any blood from the brain and repair any burst blood vessels. This is usually done using a surgical procedure known as a craniotomy.
During a craniotomy, a section of the skull is cut away to allow the surgeon access to the cause of the bleeding. The surgeon will repair any damaged blood vessels and ensure there are no blood clots present that may restrict the blood flow to the brain.
After the bleeding has been stopped, the piece of bone removed from the skull is replaced, often by an artificial metal plate.
Surgery for hydrocephalus
Surgery can also be carried out to treat a complication of haemorrhagic strokes called hydrocephalus.
This is where damage resulting from a stroke causes cerebrospinal fluid to build up in the cavities (ventricles) of the brain, causing symptoms such as headaches, sickness, vomiting and loss of balance.
Hydrocephalus can be treated by surgically placing an artificial tube called a shunt into the brain to allow the fluid to drain properly.
In addition to the treatments mentioned above, you may also need further short-term treatment to help manage some of the problems that can affect people who have had a stroke.
For example, you may require:
- a feeding tube inserted into your stomach through your nose (nasogastric tube) to provide nutrition if you have difficulty swallowing (dysphagia)
- nutritional supplements if you are malnourished
- fluids given directly into a vein (intravenously) if you are at risk of dehydration
- oxygen through a nasal tube or face mask if you have low levels of oxygen in your blood