Acute stroke occurs when the blood supply to the brain is disrupted, injuring brain cells and tissues.

Recognising stroke symptoms is crucial as people who get rapid treatment have a better chance of a more complete recovery, even if the initial stroke is relatively severe.

The blood, the brain and acute stroke

Brain tissue is very sensitive; it needs a constant supply of blood to deliver oxygen to the thousands of nerve cells that power thought and function.

If the blood supply to the brain is disrupted, even briefly, large numbers of brain cells can die within minutes. This can cause serious damage, which can be permanent as nerve cells in the brain cannot regenerate. Prompt treatment to limit the damage can mean a faster and more complete recovery.

Acute stroke damages the brain and is a physical injury; for this reason GPs and specialists often call a stroke a brain attack, as it is similar to a heart attack but occurs in the brain.

What causes a stroke?

There are three main forms of acute stroke:

  • Ischaemic stroke: this happens when a blood vessel in the brain becomes blocked by a blood clot, or atherosclerosis, which develops because of a build-up of fatty substances in blood vessels. This cuts off the oxygen supply to tissue. The medical term for a lack of oxygen is ischaemia. Around 80% of people who have an acute stroke are diagnosed with an ischaemic stroke.
  • Transient ischaemic attack: occasionally, the blockage in the blood vessel is only temporary. This causes a transient ischaemic attack, often called a mini-stroke.
  • Haemorrhagic stroke: a blood vessel in the brain bursts, spilling blood into the brain and making it difficult for oxygen and nutrients to reach the nerve cells. The blood flow can also raise the pressure inside the skull, causing further brain injury.

The severity of a stroke depends on which blood vessels are affected. A blockage or a rupture in one of the main arteries that supplies the brain will cause widespread damage and severe loss of function.

A blockage in a minor branch of an artery will cause less damage and a full recovery is more likely, although this can depend on the importance of the brain cells that have been damaged.

Symptoms of an acute stroke develop FAST

Acute stroke often gives no warning and stroke symptoms can develop in minutes. If you are with anyone who experiences any of the following symptoms, it is important to call for an ambulance straight away, as spelled out by the FAST campaign:

  • Face: does their face droop on one side, due to loss of feeling or weakness?
  • Arms: Does this weakness and loss of movement extend down that side of the body to their arms or legs? A good test is to ask them to raise both arms; someone having a stroke cannot raise their arm on the affected side.
  • Speech: can they speak, or are they having difficulty speaking or appear confused?
  • Time: call an ambulance quickly, as timely treatment is crucial.

Other symptoms that are also a cause for concern and may happen during a stroke (but can also have other explanations) include:

  • A very painful headache that comes on very suddenly - many people describe it as the worst headache they have ever had.
  • Feeling dizzy or uncoordinated so much that you cannot walk.
  • Finding it hard to see out of one or both eyes.

As the acute stroke continues, more of the brain can be affected. It is important to get emergency medical help immediately so that paramedics and A&E doctors can try to limit the damage.

The long-term effects of acute stroke

The impact of acute stroke can be disabling but the long-term effects depend on how quickly the acute stroke is recognised and treated, which parts of the brain are affected and what type of blood vessel is involved.

In the most serious cases, acute stroke can lead to:

  • Paralysis or weakness that affects one side of the body. This can affect just the face, the limbs, or the whole side of the body. This makes it difficult to cope with normal daily activities like eating, drinking, dressing, walking, or going to the toilet.
  • Poor memory and low attention span.
  • Finding it hard to talk, write, or read.
  • Finding it hard to adapt emotions to specific situations.
  • Depression and pain

Preventing acute stroke

Acute stroke occurs in around 111,000 people every year in the UK and in up to 750,000 people in the US. Although stroke risk increases generally with age, and your genes certainly play a role, there is a lot you can do to avoid having a stroke:

  • Never smoke, or stop smoking.
  • Drink only moderate amounts of alcohol (21 units per week for men and 14 units per week for women, maximum).
  • Eat a healthy, well-balanced diet, rich in fresh fruit and vegetables but low in saturated fats, processed sugar and salt.
  • If you have diabetes, get the proper support to make sure it is tightly controlled.