A stroke is a serious life-threatening medical condition, regarded as a medical emergency.
It occurs when the blood supply to part of the brain is cut off, which injures the brain and can leave victims with long-term problems.
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, known as ischaemic and haemorrhagic strokes.
Ischaemic is when a blood clot blocks the flow of blood and oxygen to the brain, and accounts for 85 per cent of all stroke cases.
Blood clots typically form in areas where the arteries have been narrowed or blocked over time by fatty deposits known as plaques. This is known as atherosclerosis.
As we get older, the arteries can naturally narrow but certain things can dangerously accelerate the process.
Haemorrhagic is when a weakened blood vessel within the skull bursts and bleeds into and around the brain.
The main cause is high blood pressure, which can weaken the arteries in the brain and make them prone to split or rupture.
The risk of having a stroke is also increased by other factors such as age, family history and ethnicity.
According to the NHS, strokes are more likely to happen in people over the age of 65, although about a quarter of strokes happen in younger people.
If a close relative has had a stroke, your risk is also likely to be higher.
South Asian, African or Caribbean people are also more at risk, as rates of diabetes and high blood pressure are higher in those groups.
“It’s not possible to completely prevent strokes because some things that increase your risk of the condition can’t be changed,” said the NHS.
“However, it’s possible to significantly reduce your risk of having a stroke by making lifestyle changes to avoid problems such as atherosclerosis and high blood pressure.”
People who survive a stroke are often left with long-term problems caused by injury to their brain.
Some people need a long period of rehabilitation before they can recover, while many never fully recover and need support adjusting to living with the effects of their stroke.
Signs and symptoms of a stroke
The signs of a stroke vary from person to person, but they usually begin suddenly and without warning.
Symptoms include a face that’s dropped on one side, and difficulty raising arms.
Speech may become slurred or garbled, or the patient may not be able to talk at all.
Other stroke symptoms include struggling to smile, or having weak or numb limbs.