A stroke occurs when the blood supply to a part of the brain is suddenly cut off. As brain cells need a constant supply of oxygen from the blood any disruption or blockage of that supply will soon lead to the cells in the affected area of brain becoming damaged or dying.
The blood supply to the brain comes mainly from four blood vessels (arteries), which branch into many smaller arteries which supply blood to all areas of the brain. The area of brain affected and the extent of the damage depend on which blood vessel is affected. For example, if you lose the blood supply from a main carotid artery then a large area of your brain is affected, which can cause severe symptoms or death. In contrast, if a small branch artery is affected then only a small area of brain is damaged which may cause relatively minor symptoms.
There are two main types of stroke - ischaemic and haemorrhagic.
- Ischaemic stroke - when a blood clot forms inside a vessel, blocking the passage of blood.
- Haemorrhagic stroke - when an artery becomes damaged and ruptures, causing blood to leak into surrounding areas of the brain.
How common are strokes?
Each year around 120,000 people in the UK have a first stroke and about 30,000 have a recurrent stroke. Stroke is the largest cause of disability in the UK and the third most common cause of death (after heart disease and cancer). Most cases occur in people aged over 65. Each year about 1 in 100 people over the age of 75 will have a stroke. But a stroke can occur at any age - even in babies. About one million people in the UK are living with the effects of stroke. Half of these people depend on others for help with everyday activities.
What are the symptoms of a stroke?
The functions of the different parts of the body are controlled by different parts of the brain. So, the symptoms vary depending on which part of the brain is affected and on the size of the damaged area. Symptoms develop suddenly and usually include one or more of the following:
- Weakness of an arm, leg, or both. This may range from total paralysis of one side of the body to mild clumsiness of one hand.
- Weakness and twisting of one side of the face. This may cause you to drool saliva.
- Problems with balance, co-ordination, vision, speech, communication or swallowing.
- Dizziness or unsteadiness.
- Numbness in a part of the body.
- Loss of consciousness (occurs in severe cases).
FAST - An easy way for you to remember
F - Facial weakness. Can the person smile? Has their mouth or eye drooped?
A - Arm weakness. Can the person raise both arms?
S - Speech disturbance. Can the person speak clearly? Can they understand what you say?
T - Time to call 999/112/911.