Labels matter. Indeed, they can be the difference between life and death. Someone lying in a hospital bed labelled “minimally conscious state” will be kept on life support indefinitely. If the label says “vegetative state”, however, that life support could be turned off any time. A layman might not be able to tell the difference. But a doctor can.

Or can he? A worrying study just published in BioMed Central Neurology by Caroline Schnakers, Steven Laureys and their colleagues at the University of Liège’s coma science group suggests that perhaps he cannot—or, perhaps worse, that he prefers to use his intuition rather than the latest diagnostic techniques to tell the difference. As a result, many people may be at risk of early termination even when they show flickering signs that their consciousness has not departed entirely.
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Distinguishing between these different kinds of coma patients has, everyone acknowledges, never been easy. Indeed, in 1996 Keith Andrews and his colleagues at the Royal Hospital for Neurodisability in London found that 40% of the patients in their hospital who had been diagnosed as being in a vegetative state, were not. But earlier this decade, two new tools became available, so things might have been expected to get better.
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Dr Laureys’s measured conclusion is that neurologists do not like their skills to be replaced or upstaged by a scale. Minimally conscious state being a relatively new diagnosis, he says, it may be that some doctors are unfamiliar with its criteria, but that is all the more reason for deferring to the coma recovery scale. The trouble with a diagnosis based on conviction rather than measurement is that it is vulnerable to external influence. Insurance companies, for example, prefer a diagnosis of vegetative to one of minimally conscious, Dr Laureys says, because no expensive rehabilitation is required for those in a vegetative state.

“Turn off the machines, nurse, he’s used up his insurance.”