When patients in coma eventually open their eyes on being intensively stimulated, this return of “wakefulness without awareness of self and environment” is accompanied by reflexive motor activity only, devoid of any voluntary interaction with the environment, and the condition is called a vegetative state.
Details of the study
To come up with this finding, lead author Martin M. Monti, PhD, of the UK Medical Research Council, and colleagues focused on patients with severe brain injury; 23 patients in a "vegetative state" and 31 patients in a minimally conscious state.
For the study, all the patients underwent functional magnetic resonance imaging (fMRI), a specialized type of brain scan that shows which parts of the brain are active.
To see whether these patients were conscious, scientists gave them careful instructions and told them to imagine that they were playing tennis with an instructor, or that they were navigating through their house, room by room.
Few patients in "vegetative state" signaled alert brain activity
On analysis of the brain scans, the researchers found that five of the patients in the "vegetative state" exhibited alert brain activity, though they were not fully conscious.
To their surprise, three of the patients even exhibited physical motion when they were tested at their bedside, while two of the patients responded via the brain scan.
The researchers noted that patients who responded to the brain scans included those who had suffered physical brain injuries. However, patients whose brains were damaged by lack of oxygen (for instance, those who had a stroke) remained unresponsive of the instructions given by the researchers.
"It was incredible," said Adrian M. Owen, a neuroscientist at the Medical Research Council, and co-author of the study. “These are patients who are totally unable to perform functions with their bodies -- even blink an eye or move an eyebrow -- but yet are entirely conscious. It's quite distressing, really, to realize this."
Young man who emerged from the car accident
One of the patients, who suffered severe brain injury in a road accident in 2003 and went into a state of coma, showed significant signs of brain activity, the researchers stated. He is 29 now.
He was asked few autobiographical questions like “Is your father’s name Thomas?”, “Do you have any brothers?” etc.
The researchers found that he was able to think of “yes” or “no” answers, and communicate via fMRI by willfully changing his brain activity.
"We were astonished when we saw the results of the patient's scan and that he was able to correctly answer the questions that were asked by simply changing his thoughts," Owen said.
"Not only did these scans tell us that the patient was not in a vegetative state but, more importantly, for the first time in five years it provided the patient with a way of communicating his thoughts to the outside world," he added.
Need for more research
The researchers have cautioned that the findings do not suggest that all the patients in a “vegetative state” are really conscious, or capable of changing their brain activity at will. More research is required to confirm the findings, they said.
However, they remain hopeful that the study will have significant implications and could help in better understanding of the human consciousness.
The fMRI technology may help in better diagnosis of brain injuries, and offer potential treatments.
It may also aid in communicating with some patients, and understand their state of mind whether they are in pain, and need relief, the researchers said.
The study has been published in the early online edition of the New England Journal of Medicine.
Post new comment