HEALTH / Second Opinion

ASKED about health fears, most people over 50 would put having a heart attack or stroke, developing cancer, or going blind high on the list. Blindness seems to be feared more than deafness, though it may be socially less handicapping - untreatable deafness is severely isolating.

One important cause of blindness in middle to old age is giant cell arteritis, also called temporal arteritis, which affects about 5,000 people a year in Britain, although most people have never heard of it. If recognised and treated, giant cell arteritis is curable; if either diagnosis or treatment is delayed for more than a few days one or both eyes may become blind.

The illness begins with a persistent headache in the region between the eye and the top of the ear. The artery that runs through the temple into the hair line, the temporal artery, is often tender and may be visibly swollen. This tenderness may affect the scalp in the temple region. These symptoms may be on one or both sides of the head. Other symptoms may include fever, poor appetite, lack of energy and pain on chewing.

When a sample of blood is tested the red blood cells will be found to be unusually sticky: the result of the erythrocyte sedimentation (ESR) test will be very high, often exceeding 100, a result seen in few other conditions. Sometimes a section of the temporal artery may be removed for examination under a microscope to confirm the diagnosis. This will show that the lining of the artery is inflamed and that it contains many of the giant immune cells which give the disease its name. The cause of this inflammation is a malfunction of the immune system in which the body's natural defence mechanisms are turned against its own blood vessels, but why this happens is unknown.

If the inflammation in the temporal artery spreads to other arteries nearby it may reach the arteries supplying blood to the back of the eye, and these may become narrow or totally blocked, causing loss of vision or complete blindness. Less often arteries in other parts of the body, such as the legs, may be affected.

Treatment with steroids will halt the inflammation and protect against blindness. A high dose is given at first - between 20mg and 40mg of Prednisolone a day - but this is reduced as soon as possible. The treatment is assessed by repeated measurement of the blood sedimentation rate, and as this becomes lower the dose of steroids may be reduced. Eventually it will be lowered to a maintenance dose of around 5mg a day, but this may need to be continued for two years and in some cases for as long as four years. Unfortunately some people develop side effects such as weight gain, altered face shape, skin changes, thinning of the bones, raised blood pressure and diabetes. In the words of a review in the British Medical Journal, 'there is a fine line between too rapidly reducing the dose of steroids, which leads to relapse, and too slowly reducing the dose, which leads to side effects.'

Giant cell arteritis is a nasty illness with a treatment that has a sinister reputation. But the steroid treatment is completed within two years in around half of all sufferers - and these will have had their sight saved. As most people eventually make a full recovery, early recognition is crucial.