NBC News
When a brain-injured patient is unresponsive, doctors use basic tests to see if he or she might still be conscious: calling the patient’s name, clapping near the ear or sticking a cotton swab up the patient’s nose.
People who don’t wake up are often thought to have lost consciousness. But a new study suggests that a quarter of brain-injured patients who don’t physically respond to stimuli do so mentally. The results were recently published in the New England Journal of Medicine.
The study looked at 353 patients who, from the outside, appeared to have lost consciousness due to a brain injury. The causes of these injuries ranged from accidents to heart attacks and strokes. 241 of them were diagnosed as being in a coma, vegetative state or minimally conscious state.
Researchers gave patients verbal commands, such as telling them to imagine swimming or to open and close their hands. Sixty of the 241 patients were found to still be able to perform these tasks mentally. The study refers to this as “cognitive motor dissociation.” Some doctors prefer the term “covert awareness.”
The mental tasks were demanding enough that even some of the other patients who had recovered enough to physically respond to verbal commands were unable to perform them, said Nicholas Schiff, a study author and a neurologist at Weill Cornell Medicine.
The results suggest that covert awareness is more common than previously thought: small studies estimated that about 10% to 20% of nonresponders had it. The new study is larger than previous ones.
“It’s an incredible find, but it’s also a little scary,” said Caroline Schnakers, deputy director of the Casa Colina Research Institute, which studies the same phenomenon but was not involved in the new research.
The idea that so many patients “can at least respond to their environment, but are not given the proper tools to do so, is very alarming to physicians,” she said.
Schiff said 1 in 4 patients is probably a conservative estimate.
“We know there are people we miss,” he said. “We also know that patients with severe brain injuries have what are called arousal fluctuations. They have good and bad times during the day.”
His team measured the patients’ mental activity using brain wave tests and functional MRIs. Unlike a standard MRI, which produces three-dimensional images of the brain, an fMRI measures brain activity based on blood flow.
When a conscious person is told to follow an order, certain areas of the brain become more active and blood flow to them increases.
However, not all hospitals have this technology, meaning doctors could miss a patient’s diagnosis. Many hospitals use standard CT or MRI scans — along with physical exams — to determine whether a patient’s mind is still active. If those tests show no signs of consciousness, doctors may mistakenly assume there is no hope for improvement.
“They’re going to be treated as if they’re not responding at all,” Schiff says. “No one is going to assume they’re responding.”
David Greer, head of the department of neurology at Boston University School of Medicine, pointed out a limitation of the study: The patients did not all have the same injuries or the same level of brain dysfunction.
“It’s a pretty heterogeneous group, and I think that should be a warning,” said Greer, who was not involved in the research.
Schiff, however, said brain dysfunction tends to be relatively similar across all injuries.
Among the patients in his study, young people and those with traumatic brain injuries — the kind linked to external events such as falls or car accidents — were more likely to have covert awareness.
“Patients with traumatic brain injuries are notorious for looking pretty bad for weeks or even months, and then making a remarkable recovery six to 12 months later,” Greer says. “I’m always very cautious with them to make sure I don’t jump to judgment.”
But he noted that even if a patient is conscious, it is no guarantee that he or she will return to normal life one day.
“The worst message that people can take away from this as a family is to say, ‘Oh, they’re in there and they’re going to make a full recovery,’” Greer said. “I think it would be very misleading for families to have that kind of false hope, because many of these patients, if not most, will continue to be severely disabled.”
But the findings offer hope for connecting patients to specific treatments in the future. For now, options are limited: One Parkinson’s drug, amantadine, has shown promise in helping people regain consciousness. Some doctors also prescribe Ambien, stimulants or antidepressants.
Brain implants or neuromodulation — using electrical currents to alter brain activity — could represent the next wave of treatments, Schnakers said. He stressed the need to offer families options for their loved ones.
“The family will ask, ‘What can we do? ’ It’s not really something we’ve thought about very seriously,” she said. She added: “That’s not acceptable anymore.”
