(CBS News) AUBURN, Ala. -- The carnage Lee Warren encountered in the combat hospital at Balad, Iraq, in 2005 was like nothing he had ever seen as a neurosurgeon. And no patient was worse-off than a soldier brought in by helicopter after being hit by a roadside bomb.
"I unwrapped his head in the emergency room and looked at him and thought he was dead," Warren says.
He was, Warren later wrote, "one of the most horrifically injured people I have ever operated on."
"His scalp and the front part of his face was all gone, and then I could see his frontal lobe on the left side sort of protruding out onto his face," he says. "His brain was exposed and hanging out."
After four hours in surgery, Warren and three other doctors managed to get him on a medevac flight out of Iraq still alive. Warren called the soldier's father but could offer little hope.
"I just didn't see how anybody with that injury could survive," he says.
Warren left the military and started a successful practice, but he had nightmares about all the wounded soldiers whose fates he never learned.
Finally, he faced his demons by opening a trunk he had brought back from Iraq. He found bullets and shrapnel he had pulled from brains and a thumb-drive with files of his cases, including the soldier with that horrible head wound. Warren looked him up online.
"And he popped up on a CBS interview -- very much alive and well," Warren says.
He was Army Spc. Paul Statzer, and CBS had met him at Walter Reed Army Medical Center six months after he was hit.
He took off his helmet to show his injuries. Statzer had lost part of his frontal lobe but was still cogent.
"I'm a little slow on certain things but not that bad," he said at the time.
Asked what lesson a brain surgeon can draw from Statzer's case, Warren says, "The power of the human spirit and -- and indomitable faith can do a lot, sometimes more than I can with my two hands."
Over the years, Paul Statzer has suffered multiple infections and seizures. He's not able to work, and he's not up for another television interview. But when they met, he told the surgeon who thought he would never make it that he is up for living.
"That was one of the questions I asked him: 'Are you happy?' and he said, 'Yeah,' and he said, 'Thanks for saving me,'" Warren says.
And with that, the patient helped save the doctor from his own demons of Iraq.