Magnetic resonance imaging (fMRI) for persistent vegetative state

Originally published in MedPage Today

by Michael Smith, MedPage Today North American Correspondent

Researchers in England are reporting they have been able to establish limited communication with a man in a persistent vegetative state by using functional magnetic resonance imaging (fMRI).

Magnetic resonance imaging (fMRI) for persistent vegetative state The 34-year-old man was able to answer simple Yes or No questions by imagining different types of activity, which caused changes in brain activity that could be seen in the machine, according to Martin Monti, PhD, of the Medical Research Council Cognition and Brain Sciences Unit in Cambridge, England, and colleagues.

The finding shows that at least some patients who are otherwise unresponsive may have some residual awareness, the researchers reported online in the New England Journal of Medicine.

“The incredible thing is that we could never do something like that at the bedside,” Monti told MedPage Today. Outside of the fMRI machine, he said, the patient remained unresponsive to standard tests.

The study is likely to arouse controversy, Monti conceded, especially in the light of such high-profile cases as that of Terry Schiavo, which eventually went to the U.S. Supreme Court.

In the Schiavo case, relatives were bitterly divided on whether to withdraw life support for the woman, who had been in a persistent vegetative state for several years.

“People will have a tendency to overinterpret this,” Monti said, adding “this finding in one patient does not imply that all patients may or may not have the ability to do this.”

Indeed, the researchers tested 54 people and found only five who could apparently respond to direction by imagining either motor or spatial activity. Imagining those activities uses different parts of the brain and their activation can be seen by the fMRI scan.

Several of the responders were already what is called “minimally responsive,” meaning that occasionally they were able to react to external stimuli.

Of those five, the researchers only tried to communicate with one — the man in a persistent vegetative state — using his ability to reliably activate different brain areas when asked to imagine either playing tennis or looking around a room in his house.

While in the machine, he was asked simple questions, such whether his father’s name was Alexander. To answer Yes, he was to imagine playing tennis, while for No he was to imagine looking around the room.

He was able to answer five out of six questions, the researchers reported, adding it was unclear why he was unable to answer the sixth but no brain activity was seen in response to the question.

Outside experts also cautioned against overinterpreting the results.

“The percentage of patients showing a response was low, and longer-term follow-up studies are needed to determine whether such fMRI findings by themselves have meaningful predictive value,” argued Alan Faden, MD, of the University of Maryland School of Medicine in Baltimore.

“This study may well raise questions for some with regard to medical or legal decisions based upon state of consciousness,” Faden said in an e-mail, “but the findings primarily underscore the limitations of current categorizations for diminished states of consciousness.”

He said that as technology gets better, it will likely mean that doctors will have to modify their diagnostic categories for what he called “states of diminished consciousness.”

In an accompanying editorial in the journal, Allan Ropper, MD, of Brigham and Women’s Hospital in Boston, wrote that such research is “easily subject to overinterpretation and sensationalism.”

He cautioned that brain activation was seen only in a few patients and only in those with a traumatic brain injury, rather than global ischemia and anoxia.

And, he wrote, the brain activity seen in the patients is not evidence of such things as memory, self-awareness, anxiety, or despair. “We cannot be certain whether we are interacting with a sentient, much less a competent, person” Ropper wrote.

Despite such caveats, the research is “critically important,” according to Michael DeGeorgia, MD, of University Hospitals Case Medical Center in Cleveland.

It “illustrates both the complexities of this area and the limitations of our bedside clinical examination,” he said in an e-mail, adding that more research will be needed to figure out how to use the technology and how to interpret the results.

The research “does raise difficult medical and legal questions,” DeGeorgia said.

“We always need to be upfront and honest with families about what we know for certain and what we do not know for certain,” he said. “In many of these cases, the honest answer is that we cannot be absolutely 100% certain that their loved one isn’t ‘in there somewhere.’”

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