London, Nov 24 (IANS) The doctor who discovered a Belgian patient presumed to have been in a deep coma for 23 years while being conscious all along has said the breakthrough highlights a 'locked-in syndrome'. The condition is described as one where patients are unable to show that they are conscious.

Steven Laureys, head of the Coma Science Group and neurology department at the University of Liege in Belgium, has this week spoken about a case where a car-crash victim was diagnosed as being in a coma for 23 years although he was conscious all along.

Rom Houben's case was discovered three years ago with the help of new brain scanning technology that was not available at the time of his accident. He is able to communicate with the help of a computer and read books.

After a 16-month study of coma patients in the light of the Houben case, Laureys and his team found that 41 percent of those diagnosed as being in a persistent vegetative state showed signs of consciousness.

Many doctors were not aware of a new diagnosis of those who are 'minimally conscious', which reflects occasional signs of life such as eyebrow flickers.

The difference can determine whether life support machines are switched off or patients allowed to live.

'Misdiagnosis can lead to grave consequences, especially in the end-of-life decision-making,' Laureys said.

Laureys and his team examined 44 patients believed to be in a coma, and found that 18 of them responded to communication.

Laureys, a world expert in coma, said patients suspected of being in a non-reversible coma should be 'tested 10 times' and that comas, like sleep, have different stages that need to be monitored.

Houben, now 46, could hear every word said around him but was unable to communicate the fact.

'I meditated - I dreamt myself away,' he told the German magazine Der Spiegel, adding: 'I shall never forget the day when they discovered what was truly wrong with me - it was my second birth.'