NHS Direct Online Health Encyclopaedia
Introduction A stroke is when the normal blood supply to your brain is cut off. If your brain cells do not get a constant supply of oxygen from the blood, they become damaged or die. Blood is supplied to your brain by four main arteries, which then divide into smaller arteries. The amount of damage done, and the part of the brain that is damaged, depends on which artery is affected. If a small artery is affected, you may only have mild symptoms. But if a major artery is affected, it can cause severe symptoms, and even death. In the UK, someone has a stroke every five minutes. They are more common among those over the age of 55, but can happen at any age. Strokes are the leading cause of disability in the UK, and the third most common cause of death, after cancer and heart disease. A stroke is a medical emergency. You should get to hospital straight away, as limiting the damage from a stroke is very important to your chances of recovery.
Definition The two main types of stroke are ischaemic and haemorrhagic: Ischaemic stroke Ischaemic strokes are the most common type, making up 17 out of every 20 cases of stroke. An ischaemic stroke is when a blood clot blocks an artery and so restricts the amount of blood that can reach the brain. In many cases the blood clot forms in the artery itself, often due to athersclerosis (furring and narrowing of the arteries). A blood clot can be triggered by a patch of atheroma (a mixture of cholesterol and other debris) in the artery. Sometimes though, a blood clot will form elsewhere in the body and be taken in the bloodstream to the arteries near the brain. A transient ischaemic attack (TIA) is also known as a mini-stroke. This is when the blood supply to your brain is cut off, as with a stroke, but only for a short time from a few minutes up to around twenty-four hours. It is usual to recover completely from a mini-stroke, but it is a good idea to see your GP, as it may mean you will have a full stroke in the future. Your GP will be able to advise you on how you can reduce the risk of a full stroke happening, such as taking a small amount of aspirin every day to reduce the stickiness of the platelets in your blood. Haemorrhagic stroke Haemorrhagic strokes occur in 3 out of 20 cases. In these cases, the stroke is caused by a weakened artery bursting, which allows blood to seep out of the artery wall. The blood damages the brain tissue by pressing on it, and at the same time other brain cells can be damaged because theyre not receiving enough oxygen.
Symptoms The symptoms of a stroke vary from person to person, because different parts of your brain control different parts of your body. Your symptoms will depend upon the part of the brain that has been affected, and the extent of the damage. However, symptoms usually come on suddenly, and can include: numbness or weakness down one side - ranging in severity from weakness in your hand to complete paralysis of the whole side of your body, weakness in your face, which can make you drool saliva, dizziness, problems talking and understanding what others are saying, problems with balance and coordination, difficulty swallowing, severe headache, and loss of consciousness (in more severe cases). Symptoms can often improve after a few weeks, when the swelling around the damaged part of the brain goes down. With treatment and time, the symptoms can then continue to get better, but you may find that some effects dont completely go away. However, around 50% of people are fully independent again within six months of having the stroke.
Treatment A stroke is a medical emergency. You should get to hospital straight away, as limiting the damage from a stroke is very important to your chances of recovery. When you are in hospital, the doctors will be able to assess how the stroke has affected you, and carry out any necessary tests. Once they have assessed your condition, they will be able to decide whether you need any treatment. Treatment after a stroke consists of a variety of therapies, and aims to help you get back as much independence as possible. This process of rehabilitation will be specific to you, depending on your symptoms, and their severity. A team of specialists are available to help you, including physiotherapists, psychologists, occupational therapists, speech therapists and specialist nurses and doctors. An essential part of your rehabilitation is exercise. The type and amount of exercise you will need depends upon the severity of your stroke, and the parts of your body that have been affected. A common effect of a stroke is weakness in an arm or leg, and without exercise and physiotherapy this can lead to a loss of muscle strength. If your muscles lose strength they begin to contract (shorten), pulling your arm or leg into a curled position, which would make day-to-day tasks difficult.
Exercise also helps to keep your overall health up to scratch, and reduces your chances of developing heart disease, osteoporosis, or another stroke. Your GP or physiotherapist will talk with you about ways of exercising that will suit you and your lifestyle. You may also be advised to take medication to help prevent another stroke occurring. A low dose of aspirin is often prescribed, which helps to stop blood clots from forming. Medication may also be prescribed if you have high blood pressure or blood cholesterol, as these conditions increase your risk of having a stroke.
Risks There are some factors that increase the chances of atheroma (cholesterol and other debris) forming in your arteries, which in turn increases your chances of having a stroke. These factors can often be controlled, and therefore you can reduce the risk of having another stroke. Main risk factors include: high blood pressure this can be treated with medication, high blood cholesterol and blood lipids (fats) the best way to prevent high cholesterol is to eat a healthy diet which is low in animal fats, but medication can also help, diabetes treatment to keep your blood sugar level as normal as possible will help reduce your chances of having a stroke, lack of exercise regular exercise reduces your chances of developing atheroma, but check with your GP before starting physical activity for the first time, obesity if you are obese, losing some weight will reduce your chances of having a stroke, smoking quitting smoking can greatly reduce your chances of damaging your arteries and therefore will reduce your chances of having a stroke, alcohol in excess alcohol can be very damaging because it raises your blood pressure. Try to keep your drinking down to no more than 1-2 glasses of wine, or a pint of beer, per day. Rarer risk factors are normally related to genetic problems, blood disorders, antibody abnormalities, other diseases of the heart and blood vessels, and migraine. Stroke can also be a side effect of some medicines, for example low dose oestrogen oral contraceptives. Prevention Whether you have had a stroke or not, it is well worth knowing the ways to prevent a stroke occurring in the future.
The main points to remember include: Obesity if you are seriously overweight you at risk of developing high blood pressure, heart disease, and diabetes. These conditions all increase your chances of having a stroke. Exercise keeping to a regular exercise routine helps to prevent many conditions including stroke, heart disease and cancer. It also helps to keep your weight down and makes you feel better mentally and emotionally too. Healthy eating eating sensibly obviously affects your weight, but it also helps you to keep your arteries healthy. Salt raises your blood pressure, so keep an eye on how much is in your food. Processed foods, for example, often contain hidden salt, so remember to check the label. Try to limit the amount of fat you eat too much saturated (animal) fat, like butter, can clog up your arteries. Try to eat five portions of fruit and vegetables a day. And also try to eat more fibre, such as wholemeal bread and brown rice instead of the white varieties. It helps to control your blood fat levels, which will help to prevent a stroke. Alcohol do not drink more than the recommended limits of alcohol (2-3 units per day maximum for women, and 3-4 units per day maximum for men). This helps to control your blood pressure. Binge drinking causes your blood pressure to shoot up, which seriously increases your risk of having a stroke. Smoking smoking doubles your chances of having a stroke. This is because smoking furs up your arteries and affects your blood, making it more likely to clot. Quitting smoking can be difficult, but its worth it it could help you avoid a stroke
Glossary Blood Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.
Heart The heart is a muscular organ that pumps blood around the body.
Brain The brain controls thought, memory and emotion. It sends messages to the body controlling movement, speech and senses.
Tissue Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.
Cholesterol Cholesterol is a fatty substance made by the body that lives in blood and tissue. It is used to make bile acid, hormones and vitamin D.
Oxygen Oxygen is an odourless, colourless gas that makes up about 20% of the air we breathe.
Blood vessel Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.
Artery Arteries are blood vessels that carry blood from the heart to the rest of the body.
Antibody Antibodies and immunoglobins are proteins in the blood. They are produced by the immune system to fight against bacteria, viruses and disease.
Platelet Platelets are cells in the blood that control bleeding by plugging the broken blood vessel and helping the blood to clot.
Physiotherapy Physiotherapy is a treatment that uses physical movements, massage and exercise to relieve illness or injury.
Genetic Genetic is a term that refers to genes- the characteristics inherited from a family member.
Numbness Numbness refers to a lack of sensation in a part of the body.
Inflammation Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
High blood pressure Hypertension is when the pressure of the blood in your bloodstream is regularly above 140/90 mmHG.
Obesity Obesity is when a person has an abnormally high amount of body fat.
Dose Dose is a measured quantity of a medicine to be taken at any one time, such as a specified amount of medication.
© Queen's Printer and Controller of HMSO, 2005
Crown copyright material is reproduced with the permission of the controller of HMSO and the Queens Printer for Scotland.