Neurologists say the story of a Belgian man wrongly diagnosed as vegetative for 23 years is a rare case but that new technologies are evolving to find others who might be in the same state.

Rom Houben was locked in his own body for more that two decades after a car crash in 1983, fully awake but unable to move. A neurologist named Dr. Steven Laureys finally realized Houben was fully conscious after conducting new testing at the urging of his family. 

While the discovery was made three years ago, the case only came to light when Laureys, head of the Coma Science Group and department of neurology at Liege University hospital, published a study in BMC Neurology.

Then this week, Houben, a former engineering student who speaks four languages, agreed to an interview with the German magazine Der Spiegel. In the interview, he told the story of what it was like to be fully awake but unable to be heard.

"I screamed, but there was no one to hear," he says in the interview.

"I became the witness to my own suffering as doctors and nurses tried to speak to me and eventually gave up."

Dr. Peter Carlens, a neurologist at the University Health Network in Toronto, wonders whether locked-in syndrome, while rare, may be a little more common than we realize.

"Some of these patients who are apparently in a persistent vegetative state in fact aren't and they have some consciousness. So it's a very frightening thing. But modern technology is helping us to bring out and understand these patients," Carlens told Canada AM Tuesday.

Carlens explained that the standard way of evaluating someone's consciousness is the Glasgow Coma Scale, which is particularly useful after trauma or "acute brain dysfunction." 

But since the scale evaluates eye movement as well as verbal and motor responses, it isn't helpful for someone who is fully paralyzed but also conscious.

"Because this patient was totally paralyzed, he couldn't signal to them -- or they missed the signals -- that in fact he was conscious -- and in fact, frighteningly, fully conscious," Carlens said.

Dr. Laureys said he discovered some degree of consciousness in Houben after putting him through a PET brain scan and other tests.

Members of Laureys' team have explained that one of the tests they use measures auditory perception by making the patient listen to a neutral sound, like a repeated "beep" and then saying their name.

If the brain reacts differently when the person's name is spoken, doctors can determine if there is some level of consciousness.

Laurey's team noticed from Houben's tests some brain activity, so they began attempting to communicate with him. They were finally able to break through when they realized Houben was answering yes or no questions by moving his foot.

Houben has said the moment that his doctors realized he was awake was like being born again.

"I'll never forget the day that they discovered me," he says in the interview with Der Spiegel. "It was my second birth."

Following intensive physiotherapy, Houben now communicates with one finger, using a touch screen computer attached to his wheelchair. The keyboard is designed so that it's activated with the slightest movement of his right hand.

Houben's doctors say it is now clear that the now 46-year-old has "almost normal" level of cognitive brain activity.

Dr. Laureys says he has used his PET scans on other patients diagnosed as persistently vegetative and found other patients with some degree of consciousness, though none as extreme as Houben.

He won't say how many he has found but in an interview with AP Television News, he says he looks at about 50 cases around the world a year. He says his studies suggest that some 40 per cent of patients with "consciousness disorders" are wrongly diagnosed as vegetative.

"It is clearly unacceptable. It is four times out of 10 that they think the patient is in a vegetative state but in reality he is minimally conscious," Laureys said.

For the most part, the patients have only minimal consciousness but often times that is the good news their families want to hear.

Other times, he says, families bring patients to his center in Liege for a second opinion and tests confirm there is no error and the patient is fully vegetative.

"But that too helps the family accept reality," Laureys tells APTN.

Dr. Carlens says the story of Rom Houbens will "certainly change things for practising clinicians."

"Because you don't want to miss these cases. So I think they'll be looking more carefully at these patients," he says.

"But this is an unusual patients in that he was quite cognizant, which is very unusual. There are a lot of patients who are sort of in between states, which is more problematic."