What is a stroke?

A stroke is a ‘brain attack’ – a sudden interruption of blood flow to a part of the brain, causing it to stop working and eventually damage brain cells. Urgent medical attention is vital to help minimise damage to the brain. Many strokes can be prevented by addressing risk factors such as high blood pressure and smoking. Stroke is also known as a CVA (cerebrovascular accident).

How common is stroke?

Every year about 7600 people in New Zealand have a stroke (about 21 people per day). Stroke is the leading cause of major disability in New Zealand and the third most common cause of death, with about 2000 fatalities each year.

People of all ages can suffer a stroke, but 75% of strokes happen in people over 65. In New Zealand, Maori and Pacific Island people are more likely to suffer a stroke. Men are more likely than women, although pregnant women have a heightened risk.

What are the signs of a stroke?

It is important to be able to recognise a stroke because prompt medical attention will maximise a person's chances of recovery. Even if the symptoms seem to subside within 24 hours it is still important to see a doctor because these ‘mini-strokes’ - also called transient ischaemic attacks (TIAs) - are a warning sign for future stroke.

The most common symptoms of a stroke are one or more of:

• sudden weakness and/or numbness, tingling, paralysis of the face, arm and/or leg, especially on one side of the body
• sudden blurred or loss of vision in one or both eyes
• sudden difficulty speaking or understanding what others are saying
• sudden dizziness, loss of balance or difficulty controlling movements
• sudden intense headache, often on one side or down the neck
• a brief episode of confusion.

Use the ‘FAST’ test to tell if someone is having a stroke:

Face – has it drooped on one side?
Arm – raise both arms - is one side weak?
Speech – is it slurred, jumbled; can the person speak a simple sentence?
Time – act fast, call 111 for an ambulance. Time lost may mean brain function lost.

If you or someone else has any of these symptoms, call 111 immediately. The sooner medical attention is received, the less damage a stroke will cause.

What causes a stroke?

Oxygen is delivered around the body by red blood cells - they pick up oxygen from the lungs, transport it along blood vessels (arteries and tiny blood vessels called capillaries), and drop it off at the cells that need it. Like any other part of the body, your brain needs a constant supply of blood and oxygen for it to work.

If the brain's blood supply is cut off for long enough, the brain cells in that area are damaged through lack of oxygen and may die.

Types of stroke

There are two main types of stroke; ischaemic stroke and haemorrhagic stroke.

Ischaemic stroke

Ischaemic stroke is the most common type of stroke. A narrowing or blockage forms in a blood vessel leading to the brain and prevents blood supply to a part of the brain.

Causes of ischaemic stroke:

• Disease process: If a person has partly blocked (‘furred up’) arteries from cholesterol build-up (atherosclerosis), this may restrict blood flow to parts of the brain, or the fatty plaques on blood vessel walls can break away and be carried to the brain, causing a blockage.
• Embolus: A blockage may be caused by a blood clot or a clump of debris (this is also called ‘embolic stroke’). The clot may form in the blood vessels of the brain or be carried there in the bloodstream, having been dislodged from elsewhere, including the heart. This can happen after a heart attack, as a result of heart valve disease or an abnormal heart rhythm (especially atrial fibrillation).

Haemorrhagic stroke

Haemorrhagic stroke - only about 10-15% of strokes are due to haemorrhage. A vessel supplying blood to the brain bursts, causing a bleed into or around the brain tissue. This can be due to a congenital weakness in the vessel or weakness caused by blood vessel disease. Subarachnoid haemorrhage (SAH) is when blood leaks into the surface of the brain. Intracranial haemorrhage (ICH) is when there is bleeding into the brain tissue itself.

Diagnosing a stroke

A person with suspected stroke is usually admitted to hospital for initial testing and treatment.

Testing may include blood tests, an electrocardiogram (ECG) to test heart function, a CT or MRI scan of the brain, a carotid ultrasound scan of the neck, an echocardiogram of the heart, and tests to assess what functions may have been affected.

The purpose of this is to find out:

• whether the person has a stroke and not some other disorder
• what caused the stroke and which part of the brain is affected
• whether the person has an underlying disorder that contributed to the stroke
• what risk factors are present.

Treatment for stroke

Prompt treatment increases the chances of survival from stroke and improves the likelihood of recovery.

Initial treatment is aimed at limiting the size of the stroke and preventing further strokes. First-line treatments commonly include medication and, in some cases, surgery to repair a ruptured blood vessel or remove a clot.

Long-term treatment involves supporting the brain to recover and for surviving brain cells to take over the functions of cells that have died or been damaged. This means the brain has to readapt and re-learn various skills.

Back at home after a stroke

Once your condition has been assessed at the hospital, the emphasis will be on helping you to recover your independence, any skills or abilities you have lost, and to minimise the risk of another stroke.

The severity of any problems after stroke varies greatly, depending on the size and location of the stroke. Common problems are:

• loss of strength or some paralysis (often one-sided)
• loss of feeling (often one-sided)
• loss of vision (often one-sided)
• problems with speech, numbers, reading, thinking, planning or understanding
• slowness or clumsiness
• difficulty swallowing or eating
• memory and attention problems
• mood swings, tiredness, stress and depression
• lack of interest and poor motivation.

Professional therapists will help you and your family with an ongoing rehabilitation programme. The team could include doctors, nurses, psychologists, speech therapists, physiotherapists, occupational therapists and social workers. Stroke Foundation field officers are available to provide information and support to families and caregivers.

Your emotions after a stroke

A whole range of strong feelings are likely to surface after a stroke, for the person and their family/whanau. Some of these feelings can be as difficult to cope with as the loss of ability itself. A sense of grief is quite common and normal.

The process of grieving is different for everyone but it is natural and in time this will lead to a more positive approach. Common steps in this grief process are shown in the panel below, but this is not in a fixed order and there can be setbacks along the way.

The grieving process

Few medical problems can create as much frustration as stroke - frustration at not being able to do what you would like to do and frustration that rehabilitation is slow. Little can be done to change this but focusing on one goal at a time, expecting setbacks and remembering the progress already made can all lessen the frustration.

How to reduce stroke risk

The risk of having a stroke is increased by age, high blood pressure (which can be due to too much salt in the diet), high blood cholesterol, smoking (this causes blood to clot more readily), more than the recommended alcohol consumption, obesity and poor fitness, diabetes, irregular heart rhythm, existing disease of the blood vessels and a family or personal history of stroke.

Whether or not you have already had a stroke it is important to reduce your stroke risk. The risk factors are almost identical to those for a heart attack (see our topic on Minimising Heart Risks for beneficial changes you can make to your lifestyle).

If you have had a stroke your doctor will probably also give you medications to help reduce the risks. These are aimed at controlling your blood pressure and reducing the speed with which your blood will clot.

Original material provided by the Stroke Foundation of New Zealand. Edited by everybody, March 2011.