WHEN Maureen Lahiff had a call last October telling her that her son David, an epileptic, was in the casualty department at the local hospital, she assumed that he had been taken there to recover from a fit and now wanted a lift home.

Her husband, Kerry, went to Atkinson Morley's Hospital in Wimbledon, where he was told that David had been discovered in the library of the art college he attended. He had apparently had a fit, and was not breathing. An ambulance team had managed to resuscitate him, but he had suffered profound brain damage. David, aged 20, died 36 hours later.

'I've been a nurse for 40 years and no one ever told me this could happen. We were always taught that a fit was not in itself life-threatening,' says Mrs Lahiff, a lecturer at the Royal College of Nursing in London.

Sudden unexplained death in epilepsy (SUDE) has been recognised since the turn of the century, yet very little is known about it. The syndrome is thought to affect mainly young adults between their teens and late thirties, and is triggered by a seizure. About 350,000 people in the UK suffer from epilepsy, and each year there are an estimated two to three hundred deaths from SUDE. There is compelling evidence that many others go unrecognised.

A study published in the Journal of the Royal Society of Medicine in October 1992 followed up the first 1,000 patients referred to the Epilepsy Research Unit at Western Infirmary in Glasgow. It found that 12 patients had died suddenly and unexpectedly. Epilepsy was given as the main cause of death in just two cases, and post-mortems were carried out only on two patients.

According to Dr Martin Brodie, director of the research unit, all the other deaths were attributed to asphyxiation and other related causes, although there was no firm evidence to back this up. 'Most of these deaths were just brushed under the carpet. In how many conditions do young people just die? It's the stigma of epilepsy makes people indifferent and turn away. It's a scandal that all these young people are dying and no one is interested.' Most doctors, nurses and pathologists have never heard of SUDE, Dr Brodie said, and the accepted wisdom is that a fit cannot suddenly kill you.

When one bereaved mother asked a leading specialist why patients are rarely told about the risk of sudden death, he replied that it was bad enough for patients to live with epilepsy, without their having to hear about SUDE. But for many of those who lose a child to SUDE, this over-protective attitude is unacceptable.

For Maureen and Kerry Lahiff, it means living with the knowledge that if they had known the full facts, they might have been able to prevent David's death. He suffered from photosensitive epilepsy, and his occasional fits were provoked by flickering lights from a video, TV or computer. On the day David had his fatal fit, he had just been watching a video in the college library.

'I could be maligning the medical profession, but I think their attitude that it is kinder not to tell is a leftover from a patriarchal view of the world,' Mrs Lahiff says. Her husband feels more strongly: 'I think it is criminal to hide it. I very much resent that doctors haven't the courage to be honest.'

Now the Lahiffs have banded together with 26 families of epileptics who died in similar circumstances. To challenge attitudes towards SUDE, they have formed a support group called Epilepsy Bereaved? Jane Hanna, one of the founders, says: 'We thought for a long time about what to call ourselves. We wanted something that would convey the question mark over this whole area. I have asthma and I know it can be fatal, yet I have learnt to live with it. Why treat epilepsy differently?'

The group aims to educate patients about the syndrome and press for more research, and is co-operating in a new systematic investigation of SUDE. The Epilepsy Research Group based at the National Hospital for Neurology and Neurosurgery in London, and the National Society for Epilepsy in Chalfont St Peter, Buckinghamshire, have begun work on a series of studies that may provide answsers to three main questions: how common is the syndrome, what causes it, and can it be prevented?

Scientists also hope to identify the risk of SUDE in different types of epilepsy. An initial study of the one in 10 patients with the most poorly controlled severe epilepsy established that one in every 250 will die of the syndrome every year. Dr David Fish, a consultant neurophysiologist, is one of the doctors involved in the study. 'One might assume that people are more at risk if they have the more severe kind of epilepsy. That's not necessarily true. One of the largest studies in the US found quite a number of deaths in people with relatively infrequent seizures.'

To try to establish the causes of these deaths, doctors will monitor the pulse, heart and respiration of around 100 patients who come to the National Hospital for a routine electroencephalograph to measure their brainwaves during a fit. 'We want to find out,' says Dr Fish, 'what changes take place during a seizure that could in some circumstances trigger a sudden death. Is it that they stop breathing or is it something to do with the heart? Once we establish that, we hope to work backwards to discover chain of events leads to heart or respiratory failure.'

Among the possibilities is that the electrical activity produced in the brain during a seizure discharges into those parts of the brain responsible for regulating the heart or respiration. Or the seizure may lead to neurochemical changes in the brain that affect breathing, or victims of SUDE may have some minor heart abnormality that makes them prone to a fatally irregular heart rhythm during a fit.

As part of a longer-term study, the researchers are collating details of cases of SUDE among their own patients and cases reported through Epilepsy Bereaved? 'We want to recruit as many relatives as possible of people who have died suddenly in a seizure to try to elicit the circumstances,' says Dr Fish. 'We will need to look at hundreds of cases and trace the medical histories and, if they exist, post mortems.

'It will be much easier to talk about sudden death in epilepsy with patients once we have information to give. We may be able to prevent these deaths in future but at present the emphasis must be on the need to control seizures as much as possible.'

Epilepsy Bereaved? P0 Box 1777, Bournemouth, BH5 1YR. The National Society for Epilepsy, Chalfont St Peter, Bucks, SL9 ORJ.