Image of brain challenges notions on vegetative state
Too bad Terri Schiavo didn't have this brain scan.
Some caution that not everyone will have such active results
By THOMAS H. MAUGH II and KAREN KAPLAN
Los Angeles Times
Sophisticated brain-imaging techniques suggest that a young woman in a vegetative state five months after a traffic accident has some mental functioning, even though she is unable to physically respond to her environment, British researchers report today.
The woman's brain showed mental activity virtually identical to that of healthy people when she was addressed in complex sentences and when told to imagine physical activities, such as playing tennis, the physicians report in the journal Science.
The findings challenge the standard diagnosis of a vegetative state, implying that some patients might have what Dr. Lionel Naccache of the French National Institute of Health and Medical Research called "a rich mental life" in an accompanying editorial.
"I was absolutely stunned" by the results, said Dr. Adrian Owen, a neuroscientist whose Medical Research Council Cognition and Brain Sciences Unit in Cambridge led the study. "This showed that she is aware."
That conclusion inevitably will bring hope to large numbers of people with relatives in comas or vegetative states, along with demands for further testing — an expensive and difficult proposition because most hospitals do not possess the expensive equipment required.
But Dr. Joseph Fins of Cornell University's Weill Medical College in New York cautioned that because so little is known, such brain scans might complicate decision-making.
"This one picture may require a thousand words," he said. "The technology is going to answer some questions, but it will create some difficult choices for families."
But Owen cautioned against drawing generalizations based on a single subject. "This is just one patient," Owen said. "The result in one patient does not tell us whether any other patient will show similar results, or whether this result will have any bearing on her."
Other experts were more critical.
"You don't really know whether the patient is imagining a tennis game or simply responding to the word 'tennis' " in much the same way that she would respond to a pin prick, Dr. Paul Matthews of Imperial College London told the journal Nature. "There is a lot that's interesting about this research, but I think their result is overclaimed."
The 23-year-old woman in the current study was injured in July 2005. Within weeks, she opened her eyes and began sleep-wake cycles — typical in a vegetative state — but she showed no sign of awareness.
A persistent vegetative state, in which the patient is awake but has no awareness of self or surroundings, is a state between coma and brain death.
As many as 35,000 Americans are in such a state at any time.
Owen and his colleagues studied her brain for five months using a technology called functional magnetic resonance imaging or fMRI. The technique highlights areas of the brain that are receiving increased blood flow when in use.
When they spoke sentences to her, a specific part of the brain showed activity — the same part that lights up in healthy people hearing the same sentences. Random noises generated no response.
Finally, when they asked her to imagine playing tennis or wandering through her house, different areas of the brain were illuminated — again identical to the areas responding in healthy volunteers.
Six months later, the team reported, the woman began tracking a small mirror with her eyes, a sign she might be transitioning to what is known as a minimally conscious state, often a sign of further recovery.
Fins speculated that she already had begun undergoing this transition when the fMRI tests were conducted and that those tests simply detected it earlier.
Houston Chronicle
Friday Sept 8, 2006 |
