A stroke happens when the blood supply to the brain is disturbed in some way. As the brain needs the oxygen (provided by the blood), 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 - Most strokes happen when a blood clot blocks one of the blood vessels (arteries) that carries blood to the brain
Haemorrhagic: a weakened blood vessel supplying the brain bursts and causes brain damage.
The main types of stroke are therefore as follows:
Transient ischaemic attack (TIA) or 'mini-stroke' – this is a short-term stroke that lasts for less than 24 hours, when the supply of blood to the brain is temporarily interrupted. The oxygen supply to the brain is quickly restored and symptoms disappear. A transient stroke needs prompt medical attention because they are often a warning sign that a full stroke is coming.
Cerebral thrombosis is when a blood clot (thrombus) forms in an artery that supplies blood to the brain, preventing blood flowing to the brain and starving the brain of oxygen. If the blood vessels are furred up with fatty deposits, it makes a blockage more likely.
Cerebral embolism is a blood clot that forms elsewhere in the body before travelling through the blood vessels and lodging in the brain.
Cerebral haemorrhage is when a blood vessel bursts inside the brain and bleeds (haemorrhages). With a haemorrhage, blood seeps into the brain tissue and causes extra damage.
It is estimated by the NHS that over 111,000 people in England suffer a stroke every year, and the brain damage caused for those who survive is the largest cause of adult disability in the UK.
People who are over 65 years of age are most at risk of having strokes, but they can affect people of any age, including children. Smoking, obesity, poor diet and excessive alcohol consumption can also increase the risk of a stroke, as well as condition affecting the circulation of the blood, such as diabetes or hypertension (high blood pressure).
Symptoms of a stroke
Strokes usually happen suddenly, and will affect people in different ways. Depending on which part of the brain is affected, the symptoms will be different. For example some parts of the brain affect speech, memory, swallowing and movement, and the symptoms will depend on the area of the brain which is damaged.
Face-arm-speech test (FAST) - The Stroke Association says three simple checks can help you recognise whether someone has had a stroke or mini-stroke.
- Facial weakness: can the person smile? Has the mouth or eye drooped?
- Arm weakness: can the person raise both arms?
- Speech problems: can the person speak clearly and understand you?
- Test these symptoms.
If you see any of these signs, call 999 for an ambulance.
Other signs and symptoms may include:
- communication problems, difficulty talking and understanding what others are saying,
- problems with balance and coordination,
- difficulty swallowing,
- severe headaches,
- numbness/weakness resulting in complete paralysis of one side of the body, and
- loss of consciousness (in severe cases).
Prompt emergency treatment for strokes is important because according to the NHS typically 1.9 million brain cells are lost during every minute a stroke goes untreated. In addition, one of the treatments for strokes called thrombolysis (clot busting medication) must be given within three hours of the stroke happening.
'Mini-stroke' or transient ischaemic attack (TIA)
The symptoms of a transient ischaemic attack (TIA) are the same as for a stroke, but they only last from between a few minutes to a few hours, then completely disappear. However, a TIA as it is a serious warning sign that there is a problem with the blood supply to your brain. It is estimated by the NFS that there is about a 1 in 5 chance that those who have a TIA will experience a full stroke during the four weeks following the TIA.