A stroke causes damage to the brain. A common cause of stroke is a blood clot that forms in a brain blood vessel (artery). Immediate treatment may include a clot-busting medicine to dissolve the blood clot. Other treatments include medication to reduce risk factors for further strokes. Rehabilitation is a major part of treatment. Disability following a stroke depends on factors such as the part of the brain affected, how quickly treatment was given and the extent of the damage to the brain. Call for an ambulance immediately if you suspect someone is having a stroke. Common symptoms are listed below.
What causes a stroke?
A stroke means that the blood supply to a part of the brain is suddenly cut off. The brain cells need a constant supply of oxygen from the blood. Soon after the blood supply is cut off, the cells in the affected area of brain become damaged or die. A stroke is sometimes called a brain attack.
The blood supply to the brain comes mainly from four blood vessels (arteries) – the right and left carotid arteries and the right and left vertebrobasilar arteries (see diagram below). These 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 – caused by a blood clot
Ischaemic means a reduced blood and oxygen supply to a part of the body. It is usually caused by blood clot in an artery, which blocks the flow of blood. This occurs in about 7 in 10 cases.
- The blood clot often forms within the artery itself. This commonly occurs over a patch of fatty material called atheroma. Atheroma is often called furring or hardening of the arteries. Small patches of atheroma form on the inside of arteries in most older people. If a patch of atheroma becomes thick, it can trigger the blood to clot.
- In some cases, the blood clot forms in another part of the body and then travels in the bloodstream – this is called an embolus. The most common example is a blood clot which forms in a heart chamber as a result of abnormal turbulent blood flow. This may occur in a condition called atrial fibrillation. The blood clot is then carried in the bloodstream until it gets stuck in an artery in the brain.
- There are other rare causes of ischaemic stroke.
Haemorrhagic stroke – caused by bleeding
A damaged or weakened artery may burst and bleed:
- An intracerebral haemorrhage occurs when the blood vessel bursts inside the brain. The blood then spills into the nearby brain tissue. This can cause the affected brain cells to lose their oxygen supply. They become damaged or die. This happens in about 1 in 10 strokes.
- A subarachnoid haemorrhage occurs when a blood vessel bursts in the subarachnoid space. This is the narrow space between the brain and the skull. This space is normally filled with a fluid called the cerebrospinal fluid. About 1 stroke in 20 is due to a subarachnoid haemorrhage.
Uncertain cause
The cause is uncertain in a small number of strokes.
Who is affected by stroke?
Stroke is one of Australia’s biggest killers and a leading cause of disability. Stroke kills more women than breast cancer and more men than prostate cancer. In 2017 there were more than 56,000 new and recurrent strokes – that is one stroke every 9 minutes. More than 80% of strokes can be prevented. In 2017 there is more than 475,000 people living with the effects of stroke. This number is predicted to increase to one million by 2050. Around 30% of stroke survivors are of working age (under the age of 65). 65% of stroke survivors suffer a disability which impedes their ability to carry out daily living activities unassisted. This financial cost of stroke in Australia is estimated to be $5 billion each year.
Stroke symptoms
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.
- Headache.
- Confusion.
- Loss of consciousness (occurs in severe cases).
What is a transient ischaemic attack (TIA)?
A TIA causes symptoms similar to a stroke but the symptoms last for less than 24 hours. It is due to a temporary lack of blood to a part of the brain. In most cases, 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. The affected part of the brain is without oxygen for just a few minutes and soon recovers. This is because the blood clot either breaks up quickly or nearby blood vessels are able to compensate.
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.
A quick guide for the general public to remember
Both a stroke and a TIA are medical emergencies and need immediate medical attention. As a way of helping the general public to become more aware of the symptoms of a stroke or TIA, a simple symptom checklist to remember has been devised and publicised. This is to think of the word FAST. That is:
Facial weakness. Can the person smile? Has their mouth or eye drooped?
Arm weakness. Can the person raise both arms?
Speech disturbance. Can the person speak clearly? Can they understand what you say?
Time to call Triple Zero (000)
If any of these symptoms suddenly develop then the person needs to see a doctor urgently. So call an ambulance FAST. The FAST checklist does not cover every possible symptom of stroke or TIA. However, it is easy to remember and it is estimated that about 8 or 9 in 10 people with a stroke or TIA will have one or more FAST symptoms.
After effects of a stroke
The type and extent of disability caused by a stroke can vary greatly. It depends on the extent of the damage to the brain.
A large stroke can cause death. A small stroke may cause minor problems, which may go completely over time. In many cases the effects are somewhere in between these two extremes.
The sort of problems that may occur include one or more of the following:
- Weakness of one side of the body. This may cause problems with walking if a leg is affected or problems using an arm or hand properly.
- Problems with balance and co-ordination.
- Swallowing problems are common. In some cases this can be dangerous, as food may go down the windpipe rather than down the gullet when you eat. Because of this, it is usual to do a swallow test on all people with a stroke before they are allowed to eat or drink. This is to make sure that swallowing is safe. If there is severe difficulty with swallowing then you may need to have food and drinks passed into your stomach via a tube.
- Speech and communication difficulties. This may range from a difficulty in finding the correct words to say in the middle of a sentence to being completely unable to speak. Also, understanding speech, reading or writing may be affected.
- Difficulty with vision. If a part of the brain that deals with vision is affected then problems may arise. For example, some people who have had a stroke have double vision. Some people lose half of their field of vision.
- Difficulties with mental processes. For example, difficulty in learning, concentrating, remembering, etc.
- Inappropriate emotions. For example, following a stroke, some people cry or laugh at times for no apparent reason.
- Tiredness.
The above are just some examples of what may occur following a stroke. Every stroke is different and the problems and difficulties have to be assessed for each affected person.
In the first few weeks after a stroke the swelling and inflammation around the damaged brain tissue settles down. Some symptoms may then improve. In time, sometimes other parts of the brain can compensate for the damaged part of the brain. With rehabilitation and appropriate therapy, there may be a gradual improvement.
Of those people who survive a stroke, about 3 in 10 are fully independent within three weeks. This rises to about 5 in 10 within six months. However, it is common for some degree of disability to remain.
Stroke prevention
As described above, a common reason why a blood clot forms is because it develops over a patch of atheroma on the lining of a blood vessel (artery). Certain risk factors increase the chance of atheroma forming – which increase your risk of having a stroke (and heart attack). You can reduce the risk of having a stroke (or a further stroke) if you reduce your risk factors. Briefly, risk factors that can be modified are:
- Smoking. If you smoke, you should make every effort to stop. The chemicals in tobacco are carried in your bloodstream and can damage your arteries. If you smoke, stopping smoking can greatly cut your risk of having a stroke.
- High blood pressure. Make sure your blood pressure is checked at least once a year. If it is high it can be treated. High blood pressure usually causes no symptoms but can be damaging to the arteries. If you have high blood pressure, treatment of the blood pressure is likely to have the greatest effect on reducing your risk of having a stroke.
- If you are overweight, losing some weight is advised.
- A high cholesterol level. This can be treated if it is high.
- Inactivity. If able, you should aim to do some moderate physical activity on most days of the week for at least 30 minutes. For example, brisk walking, swimming, cycling, dancing, gardening, etc.
- Diet. You should aim to eat a healthy diet. Briefly, a healthy diet means:
- AT LEAST five portions or ideally 7-9 portions of a variety of fruit and vegetables per day.
- A THIRD OF MOST MEALS should be starch-based foods (such as cereals, wholegrain bread, potatoes, rice, pasta), plus fruit and vegetables.
- NOT MUCH fatty food such as fatty meats, cheeses, full-cream milk, fried food, butter, etc. Use low-fat, mono- or poly-unsaturated spreads.
- INCLUDE 2-3 portions of fish per week. At least one of these should be oily (such as herring, mackerel, sardines, kippers, pilchards, salmon or fresh tuna).
- If you eat red meat, it is best to eat lean red meat or poultry such as chicken.
- If you do fry, choose a vegetable oil such as sunflower, rapeseed or olive.
- Try not to add salt to food, and limit foods which are salty.
- Alcohol. Men and women should drink no more than 14 units of alcohol per week. These units should be spread out through the week and there should be at least two alcohol-free days each week.
- Diabetes is a risk factor. If you have diabetes, treatment to keep your blood sugar as near normal as possible is important.
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