Transient Ischaemic Attack

A transient ischaemic attack (TIA) is a set of symptoms that lasts a short time and occurs because of a temporary lack of blood to part of the brain. It is sometimes called a ‘mini stroke’. However, unlike a stroke, the symptoms are transient and usually go away within an hour. (The word ‘ischaemic’ means a reduced supply of blood and oxygen to a part of the body.)

What is the cause of a transient ischaemic attack (TIA)?

A TIA is usually caused by a blood clot that becomes lodged in a small vessel in the brain. This blocks the blood flow and deprives the brain of oxygen. The affected part of the brain usually recovers within minutes as the blood clot either breaks up quickly or nearby blood vessels compensate. There are other less common causes of a TIA, such as blood clotting problems, bleeding into the brain, blood disorders, brain artery spasms, and other uncommon problems. These are not covered in this leaflet.

Where does a blood clot come from to cause a TIA?

A small blood clot (thrombus) can form on a patch of atheroma in a main artery in the neck. The carotid and vertebral arteries are the main arteries in the neck that take blood to the brain. Either the small blood clot may break off from the atheroma, or a tiny part of the blood clot may break off. This then travels up the artery carried by the bloodstream until it becomes stuck in a smaller artery in the brain.

In some cases, a small clot form in a heart chamber and is carried in the bloodstream to the brain.

A small blood clot is likely to break up quickly when it gets stuck. Therefore, no permanent damage is done to the brain during a TIA, and symptoms soon go. (However, if a larger blood clot forms and breaks away into the bloodstream, it is likely to cause a stroke – where permanent damage to the brain can occur. There is a separate leaflet that deals with stroke.)

Why does a blood clot form in a blood vessel or heart chamber?

A blood clot can form if platelets stick to a patch (plaque) of atheroma.

Platelets are tiny particles in the blood which help the blood to clot when a blood vessel (an artery or vein) is cut.

Atheroma plaques are like fatty lumps that develop within the inside lining of arteries.

Platelets sometimes stick onto an atheroma plaque inside an artery and form a clot.

A common site for atheroma to develop, and a blood clot to form, is in a large artery in the neck. A blood clot may also form as a complication of some heart conditions. For example, people with a condition called ‘atrial fibrillation’ have a turbulent (rough) flow of blood in the heart which may cause a small blood clot to form.

What are the symptoms of a TIA?

Symptoms of a TIA are transient. They develop suddenly, and usually peak in less than a minute. The duration of symptoms varies, but symptoms usually go within an hour. Sometimes symptoms last up to 24 hours. The symptoms that develop depend on which part of the brain is affected. Different parts of the brain control different parts of the body. Therefore, symptoms may include one or more of the following.

  • Weakness or clumsiness of a hand, arm, or leg.
  • Difficulty with speech.
  • Difficulty with swallowing.
  • Numbness or pins and needles of a part of the body.
  • Brief loss of vision, or double vision.

How common is a TIA?

The exact number of transient ischemic attacks (TIAs) is unknown, as many sufferers do not report the symptoms due to their fleeting nature and lack of recognition of their importance. However, it is estimated that around 35 people per 100,000 in the UK experience a TIA each year. Furthermore, approximately one in five stroke victims have had a TIA in the past.

How serious is a TIA?

Transient ischemic attacks (TIAs) are temporary episodes of neurological dysfunction caused by a lack of blood flow to the brain. While they do not cause any permanent damage, they are a warning sign that a person is at an increased risk of developing a larger blood clot that could lead to a stroke or heart attack. As such, it is important to take TIAs seriously and seek medical attention as soon as possible. If left untreated, the consequences can be far more serious and potentially life-threatening.

The risk of stroke and heart attack following a transient ischemic attack (TIA) is significantly higher than normal. Without treatment, 1-2 in 10 people who have a TIA will suffer a stroke within the following year. The most dangerous period is within the first month, and so treatment should be sought as soon as possible. In addition, 3 in 100 people who have had a TIA will have a heart attack within a year, due to a blood clot in a blood vessel of the heart.

Early intervention is key to reducing the risk of further stroke after a transient ischemic attack (TIA) or minor stroke. According to 2007 study, those who initiated existing treatments soon after their TIA or minor stroke experienced an 80% reduction in the risk of recurrent stroke. Therefore, it is essential to seek medical attention immediately if a TIA is suspected. Tests should be conducted quickly, within days of the event, and treatment should be started promptly. Doing so can greatly reduce the risk of further stroke.

What tests are usual after a TIA?

Patients experiencing a transient ischemic attack (TIA) are typically advised to undergo a series of tests. The purpose of these tests is to identify any potential risk factors that may lead to the formation of blood clots, as well as to investigate other uncommon causes of TIA. Common tests include brain scans, ultrasound scans of the carotid arteries to detect severe narrowing caused by atheroma, electrocardiograms to check for abnormal heart rhythms such as atrial fibrillation, and a variety of blood tests.

What is the treatment if you have a TIA?

The goal of treatment following a transient ischemic attack (TIA) is to reduce the risk of stroke, heart attack, or additional TIAs. This can be achieved through a combination of medications to reduce the risk of blood clots forming, and addressing any risk factors the patient may have. In some cases, surgery may be an appropriate option.

MEDICATION

Medication can reduce the risk of further blood clots forming. Antiplatelet drugs, such as aspirin, are typically prescribed for those who have had a TIA. This helps to reduce the ‘stickiness’ of platelets, thereby preventing blood clots from forming in the arteries. Warfarin is usually recommended for those whose TIA is caused by a condition called atrial fibrillation. Warfarin works by reducing the chemicals in the blood that are needed to make it clot. Regular blood tests are needed to ensure the dose of warfarin is just right.

Warfarin is usually prescribed if you have a TIA and the source of the blood clot is from your heart. (Usually if you have a condition called atrial fibrillation.) Warfarin works by reducing some of the chemicals in the blood that are needed to make the blood clot (it is an anticoagulant). The aim is to get the dose of warfarin just right so the blood is ‘thinner’ than normal (less clotable), but not so much as to cause bleeding problems. Therefore, you need regular blood tests if you take warfarin. See separate leaflets called ‘Atrial Fibrillation’ and ‘Atrial Fibrillation and Warfarin’ for details.

REDUCING RISK FACTORS:

A common reason why a blood clot forms is because it develops over a patch of atheroma on the lining of an 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 these if you reduce your ‘risk factors’. These are briefly mentioned below, but see a separate leaflet called’Preventing Cardiovascular Diseases’ for more detail. Briefly, risk factors that can be modified are:

– high blood pressure

– high cholesterol

– smoking

– diabetes

You can also reduce your risk by:

– taking regular exercise

– eating a healthy diet

– maintaining a healthy weight

– not drinking too much alcohol

Smoking is a leading risk factor for stroke. 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 is another leading risk factor for stroke. 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. Carrying too much weight around your waist increases your risk of stroke.

A high cholesterol is another risk factor for stroke. This can be treated if it is high.

Inactivity is also a risk factor for stroke.

Diet. You should aim to eat a healthy diet. Briefly, a healthy diet means:

o AT LEAST five portions of a variety of fruit and vegetables per day.

o THE BULK OF MOST MEALS should be starch-based foods (such as cereals, wholegrain bread, potatoes, rice, and pasta), plus fruit and vegetables.

o NOT MUCH fatty food such as fatty meats, cheeses, full-cream milk, fried food, butter, etc. Use low-fat, mono-, or poly-unsaturated spreads.

o INCLUDE 2-3 portions of fish per week. At least one of which should be ‘oily’ (such as herring, mackerel, sardines, kippers, pilchards, salmon, or fresh tuna).

o If you eat meat it is best to eat lean meat or poultry such as chicken.

o If you do fry, choose a vegetable oil such as sunflower, rapeseed, or olive oil.

o Try not to add salt to food, and limit foods that are salty.

o Alcohol. A small amount of alcohol (1-2 units per day) may be beneficial. One unit is in about half a pint of normal strength beer, or two thirds of a small glass of wine, or one small pub measure of spirits. However, too much can be harmful. In particular, binge drinking can increase your blood pressure.

o Men should drink no more than 21 units per week (and no more than four units in any one day).

o Women should drink no more than 14 units per week (and no more than three units in any one day).

o Diabetes is a risk factor. If you have diabetes, treatment to keep your blood sugar as near normal as possible is important.

SURGERY:

Approximately 1 in 20 people who have a transient ischemic attack (TIA) also have severe narrowing of the carotid artery due to a large build-up of atheroma. If this is the case for you, your doctor may recommend surgery to remove the blockage. This surgery can reduce your risk of having a future stroke by about 50%. However, as with all operations, there is a small risk of complications. A specialist will advise you on the pros and cons of this operation if it is determined that you have severe narrowing of a carotid artery.

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