An engineering student thought to be in a coma for 23 years was actually conscious the whole time, it has emerged.

Rom Houben was misdiagnosed as being in a vegetative state after a car crash left him totally paralyzed.

But, in actuality, he was trapped in his own body the whole time with no way of letting friends and family know he could hear every word they were saying.

The 46-year-old, who can now tap out computerized messages and read books on a device above his hospital bed, has revealed: "I screamed, but there was nothing to hear.

"All that time I literally dreamed of a better life. Frustration is too small a word to describe what I felt," he said. "I shall never forget the day when they discovered what was truly wrong with me — it was my second birth. I want to read, talk with my friends via the computer and enjoy life now people know I am not dead."

His misdiagnosis was discovered by neurological expert, Dr. Steven Laureys, who fears there may be similar cases all over the world.

He looked at Houben's case again at the University of Liege, Belgium, using state-of-the-art imaging that showed the patient was aware of what was happening around him even though he had lost control of his body.

Laureys, who leads the Coma Science Group, was unavailable for comment when contacted by Sky News Online.

He told the Daily Telegraph: "In Germany alone each year some 100,000 people suffer from severe traumatic brain injury.

"About 20,000 are followed by a coma of three weeks or longer. Some of them die, others regain health," he continued. But an estimated 3,000 to 5,000 people a year, remain trapped in an intermediate stage: they go on living without ever come back again."

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