Donald Herbert, 43, went into a 10-week coma in 1995 after a burning roof buried him under debris and left him without air for several minutes. Since then he has been nearly blind and displayed little, if any, memory, ability to communicate or awareness of his surroundings.
Then out of the blue, on Saturday, he woke up in the nursing home where he has been for the last seven years and said: "I want to talk to my wife," sending the nurses at the care home in suburban Buffalo, New York, racing out to call his wife, Linda.
But it was his youngest son, Nicholas, 13, who picked up the phone, the New York Times reported. "That can't be," Mr Herbert said. "He's just a baby. He can't talk."
It was the first of several conversations he has since had with family and other friends.
Mr Herbert's uncle, Simon Manka, said he had asked how long he had been away. "We told him almost 10 years," Mr Manka told the Associated Press. "He thought it was only three months."
Mr Herbert, the father of four sons who were 14, 13, 11 and 3, at the time of the accident, was able to recognise voices and said: "I feel great."
"He stayed up till early morning talking with his boys and catching up on what they've been doing over the last several years," said firefighter Anthony Liberatore. Mr Herbert then went back to sleep for 30 hours uninterrupted.
"The extent and duration of his recovery is not known at this time," said Mr Manka. "However we can tell you he did recognise several family members and friends and did call them by name."
"The word of the day was 'amazing'," said Mr Manka.
Dr Rose Lynn Sherr, of New York University medical centre, said when patients recover from brain injuries, they usually do so within two or three years. "It's almost unheard of after 10 years," she said. "But sometimes things do happen and people suddenly improve and we don't understand why."
There have been a few other widely publicised examples of brain-damage patients showing sudden improvement after a number of years.
In 2003, an Arkansas man, Terry Wallis, returned to consciousness 19 years after he was injured in a car accident, stunning his mother by saying "Mom" and then asking for a soda. His brain function remained limited, his family said months later.
Tennessee police officer Gary Dockery, who was brain damaged in a 1988 shooting, began speaking to his family one day in 1996, telling jokes and recounting annual winter camping trips.
But after 18 hours, he never repeated the unbridled conversation of that day, though he remained more alert than he had been. He died the following year of a blood clot on his lung.