LEADING ARTICLE : Life and death: the line gets finer

Nightmares do not come much worse than this: lying in a hospital bed, you hear relatives agonising over whether to let you die; you try to cry out, but you cannot speak or move. Yet over the past few weeks evidence has emerged that raises the possibility that the nightmare, for some, is already a reality.

Despite years spent apparently oblivious to the world, several brain- damaged patients have managed to start communicating. A former businessman is responding to hospital staff after seven years diagnosed in the same "Persistent Vegetative State" (PVS) as the Hillsborough victim Tony Bland. Meanwhile, the musician Geoffrey Wildsmith has managed to tap out a message for police with his little finger, two years after attackers put him in a coma. The British Medical Association was right to announce this weekend that it would be reviewing its guidelines on PVS, as these latest cases reveal them to be woefully inadequate.

Tony Bland was diagnosed as PVS: awake but unaware of himself or of the world around him. In the words of Lord Justice Hoffman, "The stark reality is that Anthony Bland is not living a life at all." Facing up to the difficult fact that medical science allows us to keep people alive after meaningful life is gone, the courts agreed to allow artificial feeding to be stopped and permit Tony Bland to die. Doctors can now ask the courts to do the same for any patient suffering PVS for more than a year.

The principle that people should be allowed to die in such cases remains unquestioned. In practice, however, it is hard to be sure of anything about the human brain. Doctors already distinguish between PVS and "locked- in syndrome". Unlike the PVS patients, those with locked-in syndrome are conscious of the world around them, but they are unable to register their consciousness by communicating with anyone else. As yet there is no physiological test to separate the two conditions. Work with specialists may enable them to respond through eye movements and codes, but they are easily misdiagnosed.

Research at the Royal Hospital for Neurodisability in Putney suggests that PVS patients may have a greater chance of recovery than previously thought. Be under no illusion, "recovery" from severe brain damage can mean no more than responding to simple sounds. But so long as people have the chance to regain consciousness and participate in decisions about their lives, the state cannot allow them to die. While we know so little about the brain, and while we have so much scope for making mistakes, we must proceed with caution and humility. The brain dead should not be condemned by law to life, but while there is any doubt about their condition, they must be kept alive.