WHAT IS A TIA?
A TIA is a temporary upset in the function of part of the brain resulting from an interruption of its blood supply. The brain depends on a constant flow of blood to bring it food and oxygen so that it can work properly and it quickly suffers if the blood supply reduces or stops. Blood is pumped by the heart along arteries to all parts of the body including the brain. The arteries branch many times to become very fine and narrow so they can reach all parts of the brain substance. Temporary blockage of an artery reduces or stops the flow of blood to part of the brain which then stops working for the duration of the blockage.

WHAT ARE THE SYMPTOMS OF TIA OR SMALL STROKE?
The symptoms depend on which bit of the brain has been deprived of blood flow. They can include weakness down one side of the body, numbness or odd feelings down one side, difficulty talking - pronouncing or selecting the right words, loss of vision in one eye, difficulty using everyday items or knowing what they are for, not knowing how to find your way about. In a TIA the symptoms usually last about 20-40 minutes although in a few cases the symptoms may last a few hours. The formal medical definition includes attacks which fully reverse within 24 hours. A stroke lasts over 24 hours.

WHAT EXACTLY HAPPENS?
Normally blood remains fluid as it flows along the arteries which have a very smooth inner lining. Parts of this lining can be damaged by the disease known as hardening of the arteries or arteriosclerosis. The lining becomes rough causing small clots to form in the blood as it flows by. The clot is carried along in the blood and eventually gets stuck in an artery which is too small for it, blocking the flow of blood to part of the brain. Fortunately, the body has ways of attacking and dissolving these clots. If successful, normal blood flow resumes and the affected part of the brain revives. If a blockage does not clear then the affected part of the brain does not revive and is permanently damaged.

WHY IS IT IMPORTANT
A TIA or small stroke warns us that blood flow to the brain is faulty. Further TIAs or a serious stroke may occur. A stroke is due to permanent damage and total loss of function in a part of the brain because an artery has become permanently blocked. The symptoms of a stroke are like those listed earlier except they may be more severe and do not recover fully in minutes or hours. The symptoms may improve over weeks or months. The result is drastic for the patient and family.

Figures from large studies show that someone with a TIA has a 30% chance of developing a stroke over 5 years. Put another way, the chance of getting a stroke in the first year after a TIA is increased 13 times and 7 times in later years, compared to the average person of the same age. The TIA is important because it is a warning.

WHAT CAN WE DO ABOUT TIAs?
Firstly, Aspirin at a dose of 75mg or 150mg daily reduces the formation of these small clots lessening the risk of stroke by about a quarter from 30% to about 23% over a 5 year period. Recent evidence suggests an extra drug - Persantin LA 200 mg twice daily doubles the level of protection.

Secondly, an operation may help in a minority of cases. At the moment we can only operate on the major arteries in the neck (carotid arteries) because they are close to the surface and accessible. Severe carotid artery disease needing surgery is present in only about 10% of patients with TIAs and the worse the condition of the artery the higher is the risk of stroke. If the artery is narrowed by more than 70% then an operation to widen it up is worthwhile and carries less risk of stroke than just continuing with Aspirin. If the artery is roughened or narrowed but not to the point of 70% then it is safer not to operate.

Cross Section View of the Carotid Artery

HOW DO WE TELL IF YOUR ARTERIES ARE AFFECTED?
We can tell how damaged the carotid artery is by an ultrasound scan. This is quite painless and involves directing inaudible sound waves into the neck from a device pressed on the skin, the waves are reflected from the structures within and computers produce information and pictures of the artery. The scan is done at North Manchester General Hospital within about 2 to 4 weeks. We will telephone you and your GP with the result to say whether "it is normal", "there is some narrowing and roughening but no further action is needed", or "there is severe narrowing and we are referring you to a Vascular Surgeon".

Rarely we find an artery is totally blocked but this is not as bad as it sounds. A blocked artery of course has no flow at all so clots are not carried into the brain which continues to receive blood from three other arteries. In this case an operation is not usually needed but because the situation is unusual we will discuss it with the Vascular Surgeon.

90% OF THOSE SCANNED DO NOT NEED AN OPERATION
For you we suggest that you continue with Aspirin and Persantin LA. A few patients cannot take Aspirin because of severe indigestion, internal bleeding or allergy and in these cases we can discuss other measures. If your blood pressure is high it should be controlled and if you smoke you should stop.

If the attacks continue in spite of Aspirin and Persantin LA we consider additional treatment with the anticoagulant drug Warfarin.

10% NEED THE OPERATION - RISKS AND BENEFITS
Nearly 10% of those scanned have severe narrowing and we send their details to the specialists at North Manchester General Hospital. They will wish to see you to check your general fitness and perform other tests before deciding whether or not to recommend the operation which is called carotid endarterectomy. This is done under a general anaesthetic. Patients continue with Aspirin afterwards and are advised about smoking and blood pressure control if necessary.

As with all operations there is some risk. In the case of this operation there is a risk of either stroke or heart attack in about 3%. The level of risk varies and may be higher if you have already had heart problems or a previous stroke and the surgeon will discuss this with you. The benefit is that the operation reduces the risk of stroke from 26% before operation to 9% afterwards.

IF YOU NEED TO CONTACT US
Telephone Dr Ahmed's secretary on 0161 720 2790
FAX us on 0161 720 2613, or write to us at:

Dr U Ahmed
Consultant Physician/General Medicine/Geriatric Medicine/Stroke Medicine
North Manchester General Hospital
Manchester
M8 5RB

ANY COMMENTS?
We would like to know your views about this help sheet and the service we offer. Please write to Dr Ahmed at the above address.

Dr U Ahmed, February 2002

TIAs and DRIVING
TIAs can happen at any time and there is never any warning so one could come whilst you are actually driving. The DVLA rules say that you must stop driving for FOUR WEEKS after your last attack. You must also notify the DVLA.