What is a stroke?

A stroke is a kind of brain injury. It happens when the blood supply to the brain is interrupted. There are two things that can cause this.

A small blood clot can form and block a blood vessel in the brain. This is shown on the left side of the diagram. Sometimes the clot forms elsewhere in your body and then travels to the brain where it gets stuck. This is called an embolus.

The clots stop the blood from flowing through the blood vessels. Since the blood carries oxygen to the brain, this means that the brain is starved of oxygen, which causes the damage. The medical term for this is 'cerebral infarct'.

The second main cause of a stroke is when a blood vessel in the brain bursts and starts to bleed. The medical term for this is 'cerebral haemorrhage'. This is shown on the right side of the diagram.

Only about one in ten strokes are caused by bleeding - blood clots are the more common cause of strokes.

What is a TIA (Transient Ischaemic Attack)?

This is often called a 'mini-stroke'. If someone has one of these, they normally recover within 24 hours and no permanent damage is caused to the brain. Sometimes, however, a TIA is a warning sign that a more damaging stroke may happen in the future, and so you should always take them seriously.

Some people may experience several of these attacks and your doctor will need to know so that they can carry out tests. Treatment at this stage can lower your chances of having more attacks or a bigger stroke.

How would I recognise the symptoms of a stroke?

Stroke can affect you both mentally and physically and can be recognised in different ways, but here are some of the more common signs.

• You may feel weakness or a change in sensation down one side of the body or face.

• There may be difficulty swallowing, or your speech may be slurred.

• You may find it difficult to find words when trying to speak.

• The vision in one or both eyes may be blurred or may be lost altogether.

• These symptoms may only last a few hours (TIA) but should never be ignored. Seek emergency help at once.