In 2003, almost 20 years after suffering a severe brain injury during a car accident, Terry Wallis suddenly emerged from what doctors call a "minimally conscious state" -- somewhere between being awake and being in a vegetative state.
Now, researchers believe the "miracle" that allowed the 42-year-old to rejoin the world was actually a very slow process in which his brain grew new connections to heal its injured parts.
What is remarkable about this is that up until now, brain experts did not know to what extent the brain could still heal itself so many years after an injury.
"In essence, Terry's brain may have been seeking out new pathways to re-establish functional connections to areas involved in speech and motor control -- to compensate for those lost due to damage," said Nicholas Schiff, the senior author of a study on brain damage published in the July 1 issue of The Journal of Clinical Investigation.
The study used a combination of new and standard brain imaging techniques to look at the state of Wallis' brain at various points after he became fully conscious.
While technically conscious, he still suffers from complete amnesia. He's convinced that it's still the 1980s, and he can't walk and needs helps eating.
"High-tech brain imaging is suggesting that cells in the relatively undamaged areas of Terry's brain slowly grew important, novel connections over a period of years," said Schiff, who is also the director of the Laboratory of Cognitive Neuromodulation at Weill Cornell Medical College in New York City.
Not too many years ago, conventional wisdom said that the nervous system -- and certainly the brain -- stopped growing once it fully developed during childhood and that it did not regenerate or repair itself.
However, this study confirms there is still a lot to be learned about the brain and its cells, known as neurons.
"Currently, there is very little known about this process," said Joy Hirsch, professor of radiology and psychology in the Center for Neurobiology and Behavior at Columbia University Medical Center in New York City. "This study is a landmark study because of its potential clinical relevance."
Although the goal is to eventually be able to predict which patients have the best chance of recovering consciousness, experts warn that this research is only one step in that direction.
"The brain is the most complicated organ, and trauma is the most complicated injury," said David Hovda, director of the UCLA Brain Injury Research Center. "We need to study multiple patients over time and the same patients at different times in their recovery before we'll be able to predict which patients have the best chance of recovery."
Wallis was 19 when he was severely injured in an automobile crash. After emerging from a coma -- meaning he had been unresponsive to stimuli -- in the early months following his accident, his doctors determined he would likely spend the rest of his life in a vegetative state. His eyes had opened but he was still unresponsive.
When his parents were told nothing more could be done, they took him back to a nursing home near their Arkansas home, where they helped care for him. His ordeal was showcased in the documentary "The Man Who Slept for 19 Years."