A man who suffered severe brain injuries in a car crash has claimed his family had to prevent doctors turning off his life-support machine while he was in a coma.
Steven Thorpe, 21, was so badly injured when his car crashed in Warwickshire that doctors told his family he was not expected to recover, he said.
"I was out of hospital seven weeks later," Mr Thorpe said.
An NHS spokesperson said his case was "unique" because a brain rarely survived "such excessive trauma".
Mr Thorpe, from Kenilworth, Warwickshire, had been travelling home from Leamington in February 2008 when the vehicle he was in was involved in a collision with two other cars and a horse that had run loose on the A452.
One man died and the horse was fatally injured in the incident.
Mr Thorpe was taken to University Hospital in Coventry where he says doctors put him into an induced coma, and performed a craniotomy to help alleviate any swelling on his brain.
The 21-year-old said medical staff gave up hope of any recovery after two days, but his parents refused to believe they had lost him.
"When they sat around the bed they had the feeling I was there and some words they said to me I reacted to," Mr Thorpe said.
"It wasn't that they'd get a kick or a swing of the arm - there would be something that flickered.
"If my parents hadn't asked for the second opinion, and if Julia hadn't been there, I wouldn't be here."
Dr Julia Piper, a GP who runs a private practice in Leicester, had been recommended to Mr Thorpe's father by a work colleague and agreed with the family.
"She believed in them and listened," he said. "Perhaps the NHS should have listened."
Dr Piper said when she was seeking further advice she was told by fellow professionals that Mr Thorpe's parents should accept the fact that four doctors had claimed he was brain dead. She eventually got a positive verdict from a neurologist.
Against the odds
She said: "I had this strong feeling that this wasn't right and then eventually I got someone else to look at him and of course it proved to have been the right thing to have done.
"One feels this may happen more often. We don't have any figures but I think it's important to always ask and if you're not sure about something to push as hard as you can.
"As with all human beings, we can sometimes have procedures in place and they sometimes fail. We need to understand why they're failing."
Mr Thorpe said it took two weeks for him to wake from the coma. He said he was "disappointed" with the NHS but insisted there was "no problem".
However, he added: "It's very worrying to think that...more than one specialist has written me off pretty much and I am lucky to be here really due to having a second opinion."
In a statement, University Hospitals Coventry and Warwickshire NHS Trust said: "The injury to Steven's brain was extremely critical and several CT scans of the head showed almost irreversible damage.
"It is extremely rare that a patient with having suffered such extensive trauma to the brain should survive.
"However, critical care and other specialist teams continued to support his systems through his critical period and we were delighted to see Steve recover and make progress against all the odds.
"He is truly a unique case."
More than four years on from his accident, Mr Thorpe continues to have treatment relating to his injuries. He has already had four operations to reconstruct his face and is receiving physiotherapy to help him get some use of his left arm.
He is also studying an accountancy course at a college in Coventry.
Mr Thorpe said: "I don't think my outlook's changed. I'm a very driven person. I'm living to succeed in life.
"I think there's still another operation to come. I don't know when they'll end but they're not affecting me."