Stroke

What is a stroke?

A stroke is the result of blood supply to a part of the brain being suddenly cut off. The brain cells need a constant supply of oxygen from the blood. If the blood supply is restricted for long enough, the cells in the affected area of brain become damaged and die. A stroke is sometimes called a brain attack. If the blood supply is temporarily restricted but returns before any permanent damage is done it is called a transient ischaemic attack (TIA), or ‘mini-stroke’.

What causes a stroke?

  • The blood supply to the brain comes mainly from four arteries. They 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, depends on which blood vessel is affected.
  • If you lose the blood supply from a main artery, then a large area of your brain is affected, which can cause severe symptoms.
  • If a small branch artery is affected, then only a small area of brain is damaged which may cause relatively minor symptoms.
  • Stroke can be caused by ischaemia (a blockage from a blood clot which reduces blood flow and therefore oxygen to the brain) or a haemorrhage, which refers to bleeding from one of the brain blood vessels.

What is an ischaemic stroke?

  • An ischaemic stroke is caused by a blood clot. ‘Ischaemic’ means the blood and oxygen supply to part of the brain has been reduced. This is normally due to a blood clot in an artery which blocks the flow of blood. This is the case for 70% of people diagnosed with stroke.
  • The clot commonly forms in the artery over an area of fatty material called atheroma. The common name for atheroma is ‘hardening of the arteries’, or ‘narrowing of the arteries’.Atheroma forms in the artery and if this becomes thick, it can trigger the blood to clot.
  • In some cases a blood clot forms in another part of the body and then travels in the blood stream until it gets stuck in an artery in the brain. This is called an embolus, and commonly comes from the heart and/or the neck.

What is a haemorrhagic stroke?

  • A haemorrhagic stroke is caused by bleeding. A damaged or weakened artery may burst and bleed.
  • When a blood vessel bursts inside the brain, it is called an intracerebral haemorrhage. The blood leaks out into the brain tissues and may cause the affected brain cells to lose their oxygen supply. As a result the brain tissue dies.
  • When the blood vessel bursts in the lining of the brain, this is called a subarachnoid haemorrhage. This is less common than other causes.

Who is affected by stroke?

Each year around 120,000 people in the UK have a first stroke, and about 30,000 have a recurrent stroke. Most cases occur in people aged over 65. Each year about one in 100 people over the age of 75 will have a stroke. But a stroke can occur at any age – even in babies.

What are the symptoms of a stroke?

The symptoms will vary depending on which part of the brain has been affected. 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.
  • Facial weakness
  • Problems with balance and coordination, vision, speech, communication, or swallowing.
  • Dizziness or unsteadiness.
  • Numbness in a part of the body.
  • Headache.
  • Confusion.
  • Loss of consciousness (occurs in severe cases).

What is a mini-stroke?

  • A mini-stroke is a set of symptoms similar to a stroke but the person recovers within 24 hours.
  • It is due to a temporary lack of blood to a part of the brain. The medical term is a transient ischaemic attack (TIA).
  • Normally a TIA is caused by a tiny blood clot that becomes stuck in a small blood vessel (artery) in the brain. This blocks the blood flow and a part of the brain is starved of oxygen for just a few minutes, and soon recovers.
  • Unlike a stroke, the symptoms of a TIA soon go. However, you should see a doctor urgently if you have a TIA, as you are at increased risk of having a full stroke.

Facial palsy caused by brain damage versus Facial palsy caused by facial nerve damage

  • Facial palsy in non-stroke cases is a result of damage to the lower part of the facial nerve. In non-stroke cases the damage occurs after the nerve has left the brain and travels down to the facial muscles. There are many causes of damage to the lower part of the facial nerve.
  • Facial palsy in stroke cases is a result of damage to the facial nerve inside the brain. In case of an ischaemic stroke, damage to the brain tissue and nerves is caused by lack of oxygen. In case of a haemorrhagic stroke, the bleeding puts pressure on the nearby tissue and nerves. In both cases, cells are killed within minutes.

What are the symptoms of facial palsy caused by stroke?

  • The lower part of one side of the face is normally affected. (the forehead is spared)
  • The hand, arm and or leg on one side of the body may become weak.
  • The brow and upper eyelid remain fully functional although the lower eyelid may be pulled down by the weight of the cheek. This happens because the cheek muscle loses its tone and strength.
  • The face tends to droop but a spontaneous or involuntary smile may be preserved. A voluntary smile is more difficult to achieve.
  • The corner of the mouth is weak, resulting in drooling.
  • There may be difficulty in understanding what is being said.
  • There may be difficulty in finding the right words and speech may be very difficult for the listener to understand.
  • Speech may be slurred because of weakness of the muscles responsible for speech.
  • Eating and drinking may also become difficult.
  • Confusion and loss of consciousness may develop.

These are the main symptoms but every stroke is different.

What are the symptoms of facial palsy when NOT caused by stroke?

  • There will be loss of movement, expression and function throughout one entire side of the face.
  • Difficulty blinking and closing the eye.
  • No ability to express emotion on the affected side.
  • The only muscles affected are the facial muscles. There is no weakness of the arm or leg.
  • Speech may be slurred but easily understood.
  • Understanding is not affected.
  • There is no difficulty finding the correct words for speech as may be the case in stroke.
  • Food and drink may leak from the weak corner of the mouth.
  • Confusion and loss of consciousness is not a symptom.

Remember

A stroke and a TIA are medical emergencies and need immediate medical attention. If you are worried that a person has had a stroke or TIA, think of the word FAST. That is:

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

Last reviewed: 31-05-2015    ||    Next review due: 31-05-2017