A stroke is caused by the interruption of the blood supply to the brain, usually because a blood vessel bursts or is blocked by a clot. This cuts off the supply of oxygen and nutrients, causing damage to the brain tissue.
There are two main forms of stroke:
- An ischaemic stroke is the most common form of stroke (accounting for around 85% of all strokes), caused by a clot blocking or narrowing an artery carrying blood to the brain. The likelihood of suffering an ischaemic stroke increases with age.
- A haemorrhagic stroke is a less common form of stroke caused when a weakened blood vessel supplying the brain bursts and causes brain damage. It accounts for around 15% of all strokes but its mortality risk is greater than for ischaemic stroke.
A Transient Ischaemic Attack (TIA) is a temporary stroke that occurs when the blood supply to part of the brain is cut off for a short time only. The symptoms are very similar to an ischaemic stroke but are temporary, lasting a few minutes or hours and normally disappearing completely within 24 hours. There is a 20% risk of major stroke in the first 4 weeks following a TIA and TIA should be treated as an emergency as treatment can minimise risk of further stroke by 80%.
Who does it affect?
Approximately 152,000 people in the UK every year experience a stroke. There are approximately 1.1 million stroke survivors living in the UK – and over half of all survivors are left with a disability which leaves them dependent on others for support with activities of daily living.
Stroke incidence is 25% higher in men than in women, but more woman experience strokes because women live longer. African-Caribbean and South Asian people are twice as likely to have a stroke, it is unclear whether this is due to genetic or lifestyle factors but it is likely to be a combination of both.
Approximately 46,000 people in the UK each year experience their first transient ischaemic attack – and one in ten of these leads to a major stroke within a week. Risk of recurrent stroke is highest in the first month following the first stroke. Incidence of stroke increases rapidly with age. In 2010/11, 1% of all NHS inpatient episodes in England and 2% in Scotland were due to stroke. 81% of patients admitted to hospital with stroke have a history of known vascular risk factors, about 29% have had a previous stroke or TIA and 57% have high blood pressure. 5% of strokes occur in people already in hospital.
What are the symptoms?
The most common symptom of a stroke is sudden weakness or numbness of the face, arm or leg, most often on one side of the body.
- Other stroke symptoms include:
- Difficulty speaking or understanding speech
- Difficulty seeing with one or both eyes
- Difficulty walking, dizziness, loss of balance or coordination
- Severe headache with no known cause
- Fainting or unconsciousness.
The effect of a stroke depends on which part of the brain is injured and how severely it is affected. A very severe stroke can cause sudden death.
How is it diagnosed?
A paramedic will use the F.A.S.T. test to determine whether someone is likely to have had a stroke:
- Facial weakness: Can the person smile? Has their face fallen on one side?
Arm weakness: Can the person raise both arms and keep them there?
Speech problems: Can the person speak clearly and understand what you say? Is their speech slurred?
- Time to call 999
If the person tests positive for just one of these symptoms they will be admitted urgently to a specialist stroke unit where a brain scan will reveal if they have had a stroke and if so which kind. This will determine the treatment they need. The faster the treatment is administered the more of the brain can be saved.
How is it treated?
The National stroke strategy sets out the following standards for stroke treatment and care:
- a rapid response to a 999 call for suspected stroke
- prompt transfer to a hospital providing specialist care
- an urgent brain scan (for example, computerised tomography [CT] or magnetic resonance imaging [MRI]) undertaken as soon as possible
- immediate access to a high quality stroke unit
- early multidisciplinary assessment, including swallowing screening
- stroke specialised rehabilitation
- planned transfer of care from hospital to community and longer term support