A 'Mini Stroke' or Transient Ischaemic Attack (TIA) is a stroke that gets completely better within 24 hours. They don't leave any long lasting problems, but if you have had a TIA you are likely to have a stroke, so it's important to get investigated early.

Let's imagine that one day a blood clot gets stuck and blocks the supply of oxygen and fuel to part of the brain. It could be any part of the brain, the part that controls your eyes, your arms, or your legs, but let's imagine that it gets stuck in the part of brain that helps you find words to express what you want to say.

The first thing you notice is that you can't find the words to say what you mean. You know what you want to say but the words just won't come out. No words, at all. It's quite common that you can think of something but aren't able to find the word, but this time it's different, whatever object you think of you can't think of the word. You know where you are and you are thinking clearly. If you are on your own, you will struggle to call for help, because if you pick up the telephone and dial 999, you can't ask for an ambulance. If you try and read, the words don't make any sense.

The blood clot is stuck in the artery that supplies blood to the area that controls the production of language. If you are unlucky, the blood clot will stay there and that area of the brain will die and never be able to function again. You may be able to learn to speak again, but you'll have to train other parts of the brain to do the job, and that will take weeks or months. If you're lucky then the blood clot will move on before the brain is seriously damaged, and a few minutes or hours later every thing is back to normal.

This isn't a stroke, because the damage isn't permanent, it's a 'Mini Stroke'; doctors call this a 'Transient Ischaemic Attack' or TIA.

• Transient - because it didn't last long
• Ischaemic - because that's the word for interruption to blood supply
• Attack - well because it's not friendly is it?

How do I Know if I've had a TIA?

A TIA might cause a weakness of an arm or leg, or both. If it affects two limbs, then it's probably going to affect the arm and leg on the same side, rather than both arms or both legs. Often it can affect the part of the brain controlling the movement of the face, so that you notice that part of the face goes floppy and people might say that you can't smile properly.

It might affect the part of the brain that processes the signals from the eyes. That would mean that you can't see anything on one side of your body. Your eyes are working just fine, but the part of the brain that interprets what they see is not working. So you see a black curtain coming down over part of your visual field¹. It might cause a problem with your speech: it might be that you can speak, but the words are slurred, or it might be that you know what to say, but the words don't just come out correctly. Because the TIA can cause a problem in almost any part of the brain it can cause a great deal of different symptoms, including problems swallowing, and feeling of pins and needles in certain parts of the body.

Are TIAs Important?

Although the TIA will not have caused any permanent damage, it can be an early warning sign that a stroke is on the way. That's why it's important to get medical help very soon to reduce the risk of a more serious stroke.

Not Everything that Looks like a TIA is a TIA

There are several other things that can cause symptoms that are a bit like TIAs. This includes low blood sugar, migraines and some more serious things like brain tumours and multiple sclerosis.

What Should I do if I Think I'm Having a TIA?

When you first start having symptoms of a stroke you should call for an ambulance immediately. This might be weakness of the arms or legs, a problem with loss of vision or speech or a weakness of one side of the face. If your symptoms have resolved by the time you see the doctor, then she may be able to make a diagnosis of a TIA. If that's the case, she will be able to start treatment with aspirin right away and refer you to a specialist, to see you as soon as possible. The specialist will be able to decide if you have had a TIA and do some tests to check that there are no other causes. Then they will do everything they can to stop you having a stroke.

What Causes TIAs and Strokes?

There are a number of things that are definitely proved to cause an increased risk of TIA and stroke. If you have had a TIA and you have one or more of these factors you are at increased risk of having a serious stroke compared to someone who has had a TIA that doesn't have any of these.

• Age

  Older people are more likely to have serious strokes or TIAs. That's not saying that it can't happen to younger people, but it's more likely to happen to older people. People over the age of 65 are at the highest risk.

• High Blood Pressure

  High blood pressure causes damage to arteries, and damaged arteries are more likely to form blood clots.

• Diabetes

  People with diabetes are more likely to get arteriosclerosis - the narrowing of the arteries that can increase the risk of TIAs. They are also more likely to get heart disease and other problems with the arteries. If you have diabetes you can reduce the risk of having a stroke by making sure that your diabetes is well controlled.

• Smoking

  Smoking increases formation of arteriosclerosis; it also makes the blood clots form more easily. Stopping smoking will reduce your risk of TIA or future stroke.

• Atrial Fibrillation

  Atrial fibrillation is an irregular heart beat. If the heart is beating irregularly, it can make it more likely that a blood clot will form on the heart, which can 'fly off' to the brain. People with atrial fibrillation are sometimes advised to take warfarin to reduce their risk of stroke.

• Carotid Stenosis

  There are two carotid arteries that carry blood up each side of the neck to the brain. Often arteriosclerosis can affect these arteries and if they are severely narrowed (more than 70% of the artery is occluded) then they can be the site for a stroke. After a TIA one of the most important tests is a scan of the carotid artery; if there is narrowing, then surgery might be needed.

• High Cholesterol

  High cholesterol in the blood will increase the risk of the arteries narrowing, so it's important that the cholesterol is reduced. Most people will need to take medication to reduce the cholesterol.

What Tests do you Need if you have had a TIA?

A brain scan² is usually normal after a TIA - if it is a genuine TIA, the clot will not have caused any lasting damage to the brain. But the symptoms of a TIA can also be caused by other things, including a bleed, or a brain tumour, so a brain scan is usually needed to rule out these things.

An ultrasound scan of the carotid arteries is often needed to find if there is any narrowing. If they are significantly narrowed, an operation may be needed to prevent a stroke happening in the near future.

There will usually also be blood tests to check for diabetes and high cholesterol, as well as other conditions, and a heart tracing (ECG) to check for atrial fibrillation. Some people may need to have an echocardiogram to look at the structure of the heart in more detail.

What Treatment do you Need?

Treatment for a TIA is constantly updated based on the latest scientific research. At the moment the general principles are:

• Treatment to stop the blood clotting - this can be aspirin or other tablets that act against the platelets in the blood. People with atrial fibrillation often need warfarin, which is a more powerful way of stopping the blood clotting.

• Reduction of risk factors - stopping smoking, making sure your blood pressure and cholesterol are both ok. Diabetics need to make sure their blood sugar is well controlled.

Getting Back to Normal

Most people can get back to their normal life very soon after a TIA. However in the UK, the DVLA does not allow you to drive for four weeks after a TIA.

A TIA can be a scary event, but most people make a good recovery and are left with no after effects. The important thing is that it's taken seriously, as it can be an early warning that a stroke is just around the corner.

Please Note: h2g2 is not a definitive medical resource. If you have any health concerns you must always seek advice from your local GP. You can also visit NHS Direct or BBC Health Conditions.