MRI Suggests Awareness in "Minimally Conscious"
Tuesday November 13
By E.J. Mundell

NEW YORK (Reuters Health) - Although they may be only able to communicate briefly and in the most basic way, MRI data suggest that patients in a "minimally conscious" state are aware of the world around them.

These patients' "understanding or interaction may be greater" than it appears to family, caregivers and friends, according to Dr. Joy Hirsch, a neurologist at Memorial Sloan-Kettering Cancer Center in New York. Her research was presented Tuesday at the Society for Neuroscience's annual meeting in San Diego, California.

Each year over 200,000 individuals in the US sustain serious brain injury resulting in significant neurological damage. Close to half of these patients will permanently lose the ability to live and function on their own, according to experts.

Compared with patients in a persistent vegetative state, "minimally conscious" patients display occasional, inconsistent signs of consciousness.

"For example," Dr. Hirsch said, "on one occasion a patient may be able to vocalize the name of a family member but then not be able to repeat that name for another 6 months." Or the patient might one day draw in on a straw, move their eyes in response to a question or grasp a family member's hand.

"Unfortunately, we do not know what this means in terms of the patient's [overall] level of consciousness or potential for recovery of function," Dr. Hirsch explained, and crucial questions--"Can they hear me? Do they understand?"--remain unanswered for family and friends.

Attempting to delve deeper into this mystery, the New York researchers used functional MRI (fMRI) to evaluate two minimally conscious male patients, 22 and 33 years old, both of whom had been unable to communicate consistently since their respective accidents.

The researchers played two audio tapes as the patients underwent fMRI scanning. In one tape, a friend or family member recited a short narrative of some kind. In the second audio test, the investigators simply ran the tape backwards--it was still recognizable as human speech, but became meaningless and garbled.

In an interview with Reuters Health, Dr. Hirsch and her colleague Dr. Nicholas Schiff said that speech processing areas of the brain showed high activity during the forward-playing storytelling, much as they would in healthy individuals. However, this activity subsided when patients were exposed to the nonsense/backwards tape.

The investigators conclude that the neurological tools necessary for the understanding of speech "appear to be operational" in these patients, which suggests that "certain brain functions are more preserved than previously imagined." But they stressed the findings "do not indicate what level of understanding--or possible suffering--if any, is present."

More study is needed to better understand just how conscious the minimally conscious are. Still, Dr. Hirsch believes the findings give researchers a new "humanitarian imperative" to continue to seek therapies for these patients.