Doctors should use extreme caution in pulling the plug on patients in a vegetative state, according to reports presented at the European Neurological Society.

Around 40% of patients in a Belgian study were wrongly diagnosed as being in a vegetative state when they were minimally conscious. And 10% of minimally conscious patients were actually communicating functionally. Furthermore, they found a strong tendency to underestimate levels of consciousness in brain injury patients. The level of misdiagnosis has not decreased in the last 15 years, says Dr Steven Laureys, from the University of Li?ge, in Belgium.

About one-fourth of patients who arrive at hospital in an acute vegetative state have a good chance of recovering a significant proportion of their faculties. And up to a half will regain some level of consciousness. Younger patients usually have a better prognosis.

People suffering traumatic brain injuries have a much better chance of some recovery. Some 70% of those with traumatic injuries were restored to some level of consciousness. People with non-traumatic injuries, such as oxygen deprivation, fared much worse. Only 36% in the study achieved comparable recovery.

"Our data show that acute vegetative state is certainly not rare among patients admitted to intensive care", says Dr Laureys. "What is important to note is that it may be transient and that the prognosis for patients with impaired consciousness depends to a great extent on the nature of the brain damage."

The study thus concluded that many doctors' diagnostic skills remain poor and the level of misdiagnosis has not decreased in the last 15 years. "The study showed how very hard it is to disentangle the minimally conscious state from the vegetative state", says Dr Laureys.