Between the living and the dead

A brain-damaged accident victim who had been in a coma for two years uses his little finger to tap out a message telling the police that his injuries were the result of an assault. Another man, unconscious for six months and almost abandoned as brain dead not only makes a complete recovery but demonstrates that he had been aware of what was happening to him throughout the ordeal. An American policeman, shot in the head in 1988, suddenly speaks after seven and a half years in a coma.

Any one of those cases could have come from the plot of a feature film, yet each was the basis of a news item in the past three weeks. Together they show how much we have still to learn about the functioning of the human brain, and emphasise the elusive nature of any understanding of consciousness. Most of all, they show how difficult is the decision to allow a person, apparently devoid of all mental or physical sensation, to die with dignity, when there just might be an infinitesimal chance of a miracle recovery.

We all have a good idea of what consciousness is: an awareness of one's own existence, and an ability to react to one's surroundings. Unconsciousness, however, poses more of a problem, with a continuum stretching from sleep through anaesthesia and coma to persistent vegetative state and brain death. All unconscious states are characterised by insensitivity to one's environment; what differentiates one such state from another are the degree and cause of that insensitivity and the ease with which it may be reversed.

When we are asleep, a loud noise, pain, or even the sudden silence of a clock stopping may be enough to wake us up. We clearly have a low level of perception of our environment - somehow aware of it, but not enough to register anything unless it breaks though a certain barrier level.

Anaesthesia, or hibernation in animals, is a deeper level of unconsciousness. Induced by chemical changes - whether natural or through external intervention - they are states in which any amount of shouting or injury may produce no reaction. But the state is still reversible, again by chemical changes, natural or induced.

Any recovery from a coma, however, may be quite unpredictable. Characterised by a complete lack of reaction to external stimuli, and often associated with brain injury, a coma is the deepest state of unconsciousness. The brain continues functioning sufficiently to keep the body alive, but perhaps no more. No voluntary movement, no indication of any reaction to the outside world, no consciousness.

And when a patient emerges from a coma, sits up, blinks and yawns, this may still not be a sign of anything approaching a full recovery. In a persistent vegetative state, or PVS, a person may sleep and wake, apparently as normal, and show a full range of normal reflexes. They may even smile and grimace, yet show no signs of reacting to the outside world, or of any high-level mental processes going on at all.

As the state of coma demonstrates, the body may continue living, while the person normally inhabiting that body has departed, but how can we tell whether that departure is temporary or permanent?

Geoffrey Lean, the environment correspondent of the Independent on Sunday, recalled recently his own time in a coma after an operation had gone wrong: "I spent much of the time either in total blackness or in a strange, white, humpy world, as if surrounded by rumpled sheets. I could not see my body, but I could feel myself being pulled around on the bed ... I could also feel my wife, Judy's, hand in mine, our fingers entwined together. I could hear her telling me that I was being brave, that the children were all right, that their schools and my office were being supportive. I could not work out what she was doing in this strange new world, but her presence was reassuring."

There was no entry into Geoffrey's world for his family or medical staff. Nobody could know whether he felt anything, recognised anybody, or knew anything of what was happening to him. Nobody knew if he was mentally dead or alive.

The concept of brain death - as verified by no reflexes, no breathing and a flat electroencephalogram - has recently been extended to the idea of brain-stem death - similar but with a possible reading on the EEG. Yet some of the recent remarkable cases of recovery have followed readings that would have justified, under the current rules, turning off all life- support systems.

The most celebrated recent case was that of Mark Newton, reported last month. His mother had given permission for his machine to be switched off and his organs donated before suddenly changing her mind, hurling herself across him and begging doctors to keep the life-support running. His first word on regaining consciousness was "Mum". Improvements in the treatment of patients in coma, simply enabling them to stay alive, are resulting in more causes of spontaneous recovery, even after several years.

As anyone who has read the case studies of Oliver Sacks will realise, the brain has a remarkable ability, even when severely damaged, to find a mode of functioning and to reconstruct a personality that together make internal sense to its owner. Some of the recent accounts of patients who have come out of long-lasting comas provide a powerful confirmation of that facility. These people may have been apparently unhearing and unfeeling for years, yet when they emerge, we learn that they heard what was happening, they felt the injections, they knew when their loved ones were holding their hands and they understood what was being said to them.

These moving tales also underline how we can have little hope of coming to grips with the nature of unconsciousness until we understand the physical basis, within the brain, of consciousness itself. And that, despite the numerous theories of consciousness that have been advocated in recent years, still seems a very long way off indeed.

Last weekend, when Geoffrey Wildsmith tapped out that message to the police, two years after he had been found on a train in a pool of blood, with part of his skull and brain missing, it also confirmed another important lesson. Every coma patient is a different individual. There are, at our present state of knowledge, no general rules.

This all adds up to perhaps the most difficult moral dilemma facing the medical profession today. Every patient in a coma is different. Every one needs an individual decision.

The parents of the Hillsborough stadium disaster victim Tony Bland had to fight legal battles to let their son die after 47 months on a life- support system. Other court cases have been fought over relatives' desires to have a patient kept alive against the judgement of the medical profession. The cases of the past three weeks only serve to highlight the dilemma. They are life or death decisions at their most stark, and we do not know enough to be sure we are doing the right thing.