The mysterious and bizarre psychiatric diagnosis of Munchausen’s syndrome by proxy (MSBP), in which parents actively induce life-threatening conditions in their children, has emerged from its traditional psychiatric obscurity. It is now in the headlines as the evidence of medical experts that led to criminal convictions, particularly in several alleged cot death cases, is being questioned. Up to 5,000 parents whose children were taken into care on the basis of discredited expert opinion will have their cases reviewed.

Because teachers play a significant role in children’s lives, they will at times come up against the complex and confusing issues that surround MSBP.

It was first described in 1977 by British paediatrician Professor Sir Roy Meadow and was supposed to be an extremely rare condition. But the number of cases has escalated, with around 700 now having been reported in academic medical literature.

MSBP is described as an extreme form of child abuse because, instead of self-inflicted injury, parents lie about symptoms in their children, or deliberately produce symptoms. The deception is repeated many times, resulting in hospital admissions and sometimes death. Diagnosis is controversial as it rests on clinical observation and on the question of motivation - why would parents do such terrible things to their children?

There are various psychological theories. One is that a mother, scared of losing her partner, believes a sick child will persuade him to stay.

Another theory is that some parents find they can’t cope, emotionally or physically, with their children. Getting the child admitted to hospital or looked after by professionals is a way of gaining relief.

But the roots of the disorder could lie buried in the miserable childhoods of the parents. They recall the startling difference in the attention they received from medical staff when they were ill and may associate hospitals and clinics with love and care, which they find reassuring when they become anxious about bringing up their own children. It is thought up to a third of mothers with MSBP have Munchausen’s syndrome themselves - that is, they feign symptoms - or some features suggestive of it, and a quarter have, or claim to have, a personal history of abuse.

To overcome the difficulty of making a diagnosis, specialists suggest four cardinal features of MSBP:

* the child’s illness is simulated or produced by the parentcarer;

* there are persistent presentations for medical evaluation and treatment;

* the parentcarer denies any knowledge about the aetiology of the illness;

* the acute symptoms abate when the child is separated from his or her parentcarer - as in a hospital admission.

MSBP represents huge problems in establishing a diagnosis as there is no definitive test. Doctors and nurses work under enormous pressure to secure the protection of children. The last thing they need is the kind of current witch-hunt we have, where the media swings to the other extreme of accusing the experts involved of, ironically enough, fabricating the illness itself.

Dr Raj Persaud is a consultant psychiatrist at the Maudsley hospital and senior lecturer at the Institute of Psychiatry in London. For more information on Munchausen’s syndrome by proxy and related disorders, read his book From the Edge of the Couch, published by Bantam Press, pound;12.99