How Active Is the Brain in a Coma?

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New technology could help foster a primitive form of communication with patients who are minimally conscious.
Chronis Jons/Getty Images

A new type of brain scan is giving neurologists insight into what is happening in the brains of patients who appear to be in comas.

When doctors recently tested former Israeli Prime Minister Ariel Sharon brain with a functional MRI, they found "robust" brain activity when he was shown pictures of his family and heard his son’s voice. A stroke and brain hemorrhage left Sharon in a coma seven years ago.

While the findings don’t change the prognosis of many patients, doctors are excited because the technology could foster a primitive form of communication with patients who are minimally conscious. It could also help prevent and correct misdiagnosis of patients who appear to be in comas, but are actually in a "locked-in" state.

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"It’s like watching the top of the ocean and thinking you can understand what goes on under the waves," said Dr. Peter Nakaji, a neurosurgeon at the Barrow Neurological Institute in Phoenix, of the bedside techniques commonly used in clinics. He and others are hopeful that new techniques could provide a glimpse into the deeper realms of the brain.

The fMRI technology has been used in brain mapping research since the early 1990s, helping detect the onset of Alzheimer's and providing key information to brain surgeons about where to operate, but researchers in the United Kingdom and Belgium made a breakthrough discovery by applying the technology to patients who could not communicate at the bedside.

Knowing that 40 percent of patients with disorders of consciousness are misdiagnosed, the researchers designed an experiment to see if they could learn more about how their subjects’ brains were functioning. When 54 patients -- in vegetative or minimally conscious states  -- were asked to imagine hitting a tennis ball, the appropriate area lit up on the image of the brains of five of them. One of the patients was able to use the technique to answer yes or no questions. The study was published in The New England Journal of Medicine in 2010.

What actually goes on in the brains of patients with disorders of consciousness depends on where they fall on the spectrum of unconsciousness, although there is some grey area in the terminology of coma vs. vegetative state vs. minimally conscious.

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