A man presumed to have been in a deep coma for 23 years has hailed his “second birth” after doctors realised that he had been fully conscious all along but unable to communicate.

Rom Houben, 46, was paralysed in a car accident and declared to be in a persistent vegetative state, while in fact he remained aware of his surroundings and could hear his doctors gradually give up hope on him.

Researchers using new diagnostic techniques discovered that his brain was still active and trained him to use his right forefinger to express himself on an adapted keyboard.

Mr Houben’s case is being highlighted in his native Belgium by doctors who are pioneering new ways of understanding coma patients, hundreds of whom around the world could actually be conscious but locked in paralysis — and able to feel pain, unlike a true coma patient.

“I shall never forget the day when they discovered what was truly wrong with me — it was my second birth,” Mr Houben tapped out on his keyboard at the nursing home east of Brussels where he still needs constant care. “All that time I just literally dreamt of a better life. Frustration is too small a word to describe what I felt.”

Mr Houben had been written off as being in an “extinct” state after the athletic former martial arts enthusiast, keen wind-surfer and engineering student was gravely wounded in a car crash in 1983 when aged only 20.

Asked what he felt, Mr Houben said: “Powerlessness. Utter powerlessness. At first I was angry, then I learnt to live with it.”

His reawakening came three years ago thanks to coma specialists at Liège University Hospital who have spoken this week about the case for the first time to try to draw attention to the condition and save other misdiagnoses.