But researchers caution against giving families false hope
WEDNESDAY, Feb. 3 (HealthDay News) -- Some patients thought to be in a vegetative state actually show signs of consciousness when assessed with a brain scan.
A team of British and Belgian neuroscientists conducted functional magnetic resonance imaging (fMRI) on 54 patients who were diagnosed as being in a vegetative or a minimally conscious state because of traumatic brain injury, brain stem stroke, meningitis or other brain injury.
When the patients were asked to think about hitting a tennis ball or walking around their home or neighborhood, brain scans for five of them showed they could "willfully modulate their brain activity," or show evidence of conscious thought, said lead study author Martin Monti, a neuroscientist at the Medical Research Council Cognition and Brain Sciences Unit in Cambridge, England.
Researchers could tell the brain activity was conscious thought because the patients' brain activity was similar to that of healthy controls performing the same mental tasks, according to the study in the Feb. 2 issue of the New England Journal of Medicine.
Additional tests found three patients could follow commands or make small movements that further showed some level of awareness. Two had been considered vegetative and one minimally conscious.
In the other two, however, researchers could not find any discernible evidence that they could respond.
As a result of the testing, four patients originally diagnosed as being in a vegetative state were reclassified as being minimally conscious.
"There is no 'consciousness meter' we can put next to the brain and say if someone is conscious. We can only look at how people behave and infer if they are conscious or not," Monti said. "The problem is behavior is not always a good measure of consciousness. fMRI seems to be one way of determining if a patient who is
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