A Scottish reader has also written about eczema — a recurrent eczematous rash in his groin that he has had for many years. Betnovate keeps it in check. Recently a young woman doctor joined his general practice and she suggested that he should mix a bit of Canesten with the Betnovate. As our reader says: “It has worked like a miracle. Could this advice be passed on to your other readers?”

Eczema and dermatitis are terms used to describe very similar skin conditions. The affected skin is red, oozes, becomes crusty and can be appallingly itchy. Technically, dermatitis refers to this skin trouble when it is the result of a known external factor, whereas eczema is endogenous, that is to say, its causes are from within and no one can pinpoint an obvious, external cause. Occupational contact dermatitis is a good example of a reaction to external causes. Boat builders, for example, may develop dermatitis from handling hardwood dust, jewellers acquire dermatitis from nickel, and hairdressers from the soaps and detergents they use on their clients’ hair.

Eczema is divided into many different types. The most frequent form is atopic eczema, which is often associated with asthma and hay fever. Seborrhoeic eczema causes inflammation of eyebrows and skin creases around the nose and mouth. The eczema of small children is usually an atopic eczema. Conversely, in old age, people suffer so-called varicose or gravitational eczema, inflamed itchy skin of the lower, often swollen, part of the leg. In suitable cases this potentially severe eczema responds to varicose-vein surgery.

Stress can often be a factor in development of most forms of eczema — so reducing stress will help. Many children outgrow eczema but it can last into the teens or adult life. Eczema may be triggered by house-mite dust, changes in clothing, bedding, temperature or pollen. In about 30 per cent of cases of childhood eczema diet may be a factor, but it is rarely a principal precipitating factor.

Any secondary infection may encourage persistence in eczema, the infection is usually bacterial, sometimes fungal, hence our second reader's question. Eczema affecting potentially infected moist areas such as the groin, armpits, the cleft of the bottom, or feet, needs an anti-fungal preparation, of which Canesten is a good example. Betnovate — a steroid — should be used sparingly, and is too strong to be used for long periods on any skin that is thin and sensitive.

Eczema is treated with topical steroids, soothing mixtures to add to the bathwater, and antihistamines against irritation. Recently tacrolimus ointment, marketed as Prograf or Protopic, has been introduced as an alternative to steroid preparations (it is available only on prescription).

A Cheshire reader has written to ask about her observation that people who have recently had a long anaesthetic, or especially two close together, show cognitive and personality changes afterwards. In everyday language, they are not quite as sharp as they were, and may show evidence of some change in character.

One of the greatest and most welcome changes over the past half century has been the development of anaesthetics. Fifty years ago ether and chloroform were still used in dental and general medical practice, and the doctor, or dentist, was always slightly tense lest a patient didn’t wake up. Now anaesthetics are amazingly safe and the increase in the knowledge in the science of anaesthesia has revolutionised surgery.

The risk of disaster from the anaesthetic is so small that even a doctor who knows about medical hazards will have an anaesthetic without concern. However, in a small minority of operations a combination of anaesthetic and blood loss, coupled with some relative de-oxygenation of the blood, leaves a patient fractionally less astute than he or she was. If the blood pressure has dropped very low, possibly because of a bleed, there may also show signs of localised damage to the brain.

Our reader’s friend went into surgery rather introverted, reserved and generally a very private person. After the surgery he was transformed into a more ebullient and emotional man. Other patients, for example, lose, almost imperceptibly, some mental agility, may be even less good at remembering names, or fail to recognise acquaintances, or even friends.

In others the ability to find their way around previously well-known cities may have diminished. The good news is that the changes, which are often so subtle that they are not readily recognisable to other people, usually improve over a period of weeks, or months.

People don’t have surgery unnecessarily. Many owe their lives to it and are prepared to sacrifice a few brain cells in exchange for survival. If occasionally they don’t immediately remember old colleagues, it is a price worth paying.

E-mail Dr Thomas Stuttaford your questions on eczema

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