Breaking through the silence of the seemingly unconscious: Researchers read minds of the vegetative
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British neuroscientist Martin Monti says he and his colleagues were ‘absolutely stunned’ as they began to discover that by reading images of patients’ brains while those patients were asked questions, the researchers could not only detect signs of life in the minds of patients thought to be vegetative, they could enable a patient locked in by injury to communicate.
Monti is the lead author of a widely hailed study published Wednesday in the New England Journal of Medicine’s Early Online edition and detailed in an article here. In an interview, he described the process by which he and colleagues in Cambridge, Britain, and Liege, Belgium, broke through the silence of five grievously brain-injured patients who had been diagnosed as ‘vegetative’ or (in one case) ‘minimally conscious.’
Although those diagnoses assume that a patient is ‘wakeful without awareness,’ Monti and colleagues found that of 54 patients they tested, five were aware enough to respond to instructions to imagine playing tennis. Those patients responded with brain activity that looked just like that of healthy people thinking the same thing. Four of the vegetative patients showed brain activity suggesting the same level of awareness and intent when researchers asked them to imagine walking through the rooms of their home.
In one patient, then a 22-year-old man who had been thought vegetative since a car accident five years earlier, the researchers devised a way to get him to answer yes-or-no questions. By thinking about playing tennis, he responded -- correctly -- that, yes, one name provided by researcher was his father’s first name. And by imagining navigating the rooms of his home, he responded ‘no’ to simple questions about his siblings and family.
Monti said the researchers hope to use the technique to explore the minds of other ‘locked in’ patients, such as those with amyotrophic lateral sclerosis, or Lou Gehrig’s disease -- and to explore simpler techniques, such as EEGs to detect intent and awareness in patients thought to be vegetative.
He also said they hope to see the young man, now in his late 20s, again and use their brain-imaging techniques to communicate further with him. He said he is not haunted by the idea that, having seen flickering signs of mental life in the young man known as Subject No. 23, the researchers had to send him back to his silent world.
‘I am proud we could give him a chance to tell us he was conscious, and to interact with his environment,’ said Monti, who said he hopes that techniques like those described in the study can be used to help patients tell their caregivers if they are in pain or distress. He added that the technique should improve the precision and accuracy of the techniques now used to diagnose patients who are unresponsive after head injury or illness that has blocked the flow of oxygen to their brains.
UCLA neuroscientist David A. Hovda, commenting on the study, noted that all but one of the patients who responded to the British-Belgian research team were young -- in their 20s -- and all of those who responded had suffered traumatic brain injury rather than stroke or illness that shut off the flow of oxygen to their brains.
That finding, he said, underscores two important things that the families of unresponsive patients will need to keep in mind: that traumatic brain injury, which kills 50,000 people a year and has left about 5.3 million Americans disabled, behaves differently from conditions that block oxygen flow to the brain, and may leave patients with more residual mental activity; and that younger brains are probably more resilient in the wake of injury than are older brains and may be more likely to show signs of awareness.
-- Melissa Healy
