The researchers found that in response to commands, the patient's brain flared with activity, lighting the same language and planning regions that are active when healthy people hear the commands. Although previous studies had found similar activity in partly conscious patients, who occasionally respond to commands, it has never been found in someone who was totally unresponsive.
Neurologists did caution that the new report characterized only a single case, and one should not infer that unresponsive brain-damaged people were more likely to recover or treatment was possible. In the study the woman could not communicate with the researchers, and therefore it was not possible to know whether her subjective experience was similar to the consciousness of healthy people. The woman was injured in a traffic accident last year.
However there was such dramatic contradictions in the woman's diagnosed condition that the limitations of standard methods of bedside diagnosis. These findings are bound to raise hopes for tens of thousands of families caring for unresponsive, brain-damaged patients around the world whether those hopes are justified or not, experts said.
Dr. James Bernat, a professor of neurology at the Dartmouth Medical School, who was not involved in the study said, "One always hesitates to make a lot out of a single case, but what this study shows me is that there may be more going on in terms of patients' self-awareness than we can learn at the bedside. Even though we might assume some patients are not aware, I think we should always talk to them, always explain what's going on, always make them comfortable, because maybe they are there, inside, aware of everything."
Dr. Bernat did say that brain imaging promised to improve the diagnosis of unconscious states in certain patients, but that the prospect of imaging could also raise false hopes.
The chances of an unresponsive, brain-damaged patient will eventually emerge depend on the type of injury suffered, and on the length of time he or she has been unresponsive. Traumatic injuries to the head, often from car accidents, tend to sever brain cell connections and leave many neurons intact. About 50 percent of people with such injuries recover some awareness in the first year after the injury, studies find; very few do so afterward.
Dr. Joseph Fins, chief of the medical ethics division of New York Presbyterian Hospital-Weill Cornell Medical Center said that the imaging techniques used in the new study could help identify which patients are most likely to emerge once the tests are studied in larger numbers of unconscious people.
As Dr. Fins said without this context, the imaging tests could create some confusion, because like any medical tests they may occasionally go wrong, misidentifying patients as exhibiting consciousness or lacking it. "For now I think what this study does is to create another shade of gray in the understanding of gray matter," he said.