Rom Houben was hailed as a medical miracle
A Belgian man who stunned the world last year by apparently communicating after 23 years in a coma cannot in fact do so, researchers say.
The doctor who believed that Rom Houben was communicating through a facilitator now says the method does not work.
Dr Steven Laureys told the BBC: "The story of Rom is about the diagnosis of consciousness, not communication."
His conclusions follow a study to test the validity of so-called facilitated communication.
Claims that Mr Houben - who was seriously injured in a car crash in 1983 - could communicate, swept around the world last November.
After more than two decades in a coma, he was filmed apparently tapping out messages on a special touchpad keyboard with the help of his speech therapist.
Method 'not valid'
By holding Mr Houben's forearm and finger, the therapist was said to feel sufficient pressure to direct her to the correct keys on the keyboard.
Dr Laureys, a neurologist at Liege University Hospital in Belgium, had earlier established that Mr Houben was more conscious than doctors had previously thought - and that is still thought to be the case.
But he also believed that his interaction with the speech therapist was genuine. Following further study, however, Dr Laureys says the method does not work.
He told the BBC that a series of tests on a group of coma patients, including Mr Houben, had concluded that the method was after all false. The results of the study were presented in London on Friday.
Objects and words were shown to the patients in the absence of the facilitator who was then called back into the room. The patient was then asked to say what they had seen or heard.
"It's easy to watch the video and say this method is not valid, but to prove that it is not true is actually very difficult," Dr Laureys said.
Houben was 'writing a book'
Doubts were expressed about the method by other experts at the time and repeated this week.
"It's like using an Ouija board," Arthur Caplan, a professor of bioethics at the University of Pennsylvania, told Associated Press on Friday. "It was too good to be true and we shouldn't have believed it."
Last November Mr Houben's mother, Fina Houben, told the BBC that she always believed her son could communicate.
"He is not depressed, he is an optimist," she said. "He wants to get out of life what he can."
Last year, Mrs Houben claimed her son was writing a book. "Just imagine," Mr Houben ostensibly typed out via his speech therapist. "You hear, see, feel and think but no one can see that."
Experts say the question of whether people like Houben who have a traumatic brain injury are conscious and alert remains unanswered.
"I hope Rom and his family will stay as an example" of how hard it is to pick up the signs of consciousness, Dr Laureys told the Associated Press.
"Even when we know that patients are conscious, we don't know if there is pain or suffering or what they are feeling."