Terry Wallis showed only fleeting hints of consciousness for 19 years after he suffered a brain injury in a road accident. But then, in 2003, at age 39, he began to speak. It started with “Mom,” and then “Pepsi,” but soon he was slowly stringing sentences together and holding down his end of a conversation.
Far too often, patients like Wallis are given up for gone, left to languish in nursing homes where no one bothers with physical therapy or even to check for glimmers of regained consciousness, says Joseph Fins, a medical ethicist at Weill Cornell Medical College.
That’s at odds with a growing body of research showing that many patients with no outward signs of awareness retain some degree of consciousness. “We began to see patients who looked like they were vegetative, but they weren't,” said Fins. “They were beginning to show responsiveness, they were sort of breaking the rules.”
'In the future, some scientists believe, it may be possible to directly decode these patients’ thoughts.'In Wallis’ case, brain scans revealed evidence that his brain had rewired itself to some extent to compensate for the injury. Although such dramatic recoveries are exceedingly rare, a 2009 study by Belgian researchers found that 41 percent of hospital and rehab patients with a vegetative state diagnosis were actually minimally conscious. “It's like a flickering light, and you're going to miss it unless you systematically look for it,” Fins said.
At a conference last month at Duke University, researchers discussed emerging technology that could help doctors detect that flicker. In recent years, neuroscientists have developed fMRI brain scans and other methods to assess consciousness. In a few cases, this technology has enabled rudimentary communication with patients trapped inside an unresponsive body. In the future, some scientists believe, it may be possible to directly decode these patients’ thoughts.
Getting these methods right is crucial, as pressure mounts to use them in medical decisions, including whether or not to terminate life support, and in the legal battles that sometimes ensue. There are a number of ongoing legal cases in Canada that involve vegetative or minimally conscious patients and end of life decisions, says Adrian Owen, a neuroscientist at the University of Western Ontario. "I'm absolutely sure fMRI is going to play a role in one or more of these cases in the next 12 months."
In a way, it was technology that created these disorders in the first place. James Bernat, a neurologist at Dartmouth Medical School explained that before positive pressure respirators were developed in the 1950s, all three of the essential bodily systems – circulatory, respiratory, and nervous – had to be operational to support life. The respirators changed all that, enabling people with badly damaged brains to stay alive indefinitely.
But a badly damaged brain is not necessarily unconscious. The recent research tells us quite clearly that human consciousness is not binary. It can exist in degrees, fade in and out, even when the body is unresponsive.
And that evokes an age-old terror. In 18th century England, a spate of highly publicized cases of people recovering after apparently drowning created a popular obsession with the idea that a body could be revived despite the outward appearance of death, says Jeffrey Baker, a physician and medical historian at Duke. It also stirred up fears of being buried alive. Families paid attendants to sit with the body of a loved one, or bought “safety coffins” rigged with flags and bells that could be operated from inside.
Today we are still terrified of being too soon given up for dead. And we still look to technology to sound the alarm.
A widely-publicized demonstration of this came in a 2006 Science paper by Owen, who was then at the University of Cambridge. His team used fMRI scans to search for signs of consciousness in an unresponsive 23-year-old British traffic accident victim. The researchers told the woman to imagine herself either playing tennis or walking through her home. In healthy people, these two imagined activities produce different patterns of brain activity, and the same was true for this patient. Owen and his colleagues argued that she had made a conscious decision to follow their instructions.
Other researchers were skeptical. Some suggested that the activity in the woman’s brain was merely a reflex-like response to the spoken instructions rather than a sign of consciousness. At the conference, Owen said he still stands by his original interpretation and argued that subsequent work has borne it out. A 2007 study with healthy volunteers, for example, found that the distinct patterns of brain activity disappear as consciousness fades under general anesthesia. If the activity was automatic, as the critics suggested, it should have persisted, Owen said.
His team has now used the same fMRI method to detect evidence of consciousness in a Canadian man who, according to his doctors, had remained in a vegetative state for 12 years following a traffic accident. “The odds of two patients on two continents having the same pattern I think is very unlikely,” Owen said. “But it's still just two patients.”
Owen also described a new way to assess mental function in unresponsive patients. It involves scanning someone’s brain as they watch an 8 minute clip of an Alfred Hitchcock film. When healthy people do this, various parts of the brain synchronize their activity at certain times in the clip. Owen argues that if brain injury patients exhibit similar patterns, it could be a telltale sign of residual cognitive function.
Communicating with patients who retain some degree of consciousness is the next step in the evolution of this technology, and a handful of research teams are already working on it.
In a 2010 study led by Owen and Steven Laureys, who heads the Coma Science Group at the University of Liège in Belgium, a physically unresponsive patient answered yes-no questions by imagining playing tennis to indicate “yes” and walking through his house to indicate “no.” When the tennis pattern showed up in his fMRI scan, the researchers inferred that he meant yes; when they saw the house pattern they assumed he meant no.
“Just in the past year we’ve moved into a situation where we're asking questions that can be used to improve someone's life in simple ways,” Owen said. Even the current fMRI communication methods, which only allow yes-no answers, can enable a patient to indicate he’s in pain, or that his room is too hot or too cold, for example.
But simple yes-no communication probably isn’t enough to allow patients to participate in decisions about their care. For that, doctors need to know that a patient has understood the choices and has the ability to reason.
At the conference, Owen described an experimental method for assessing reason in unresponsive patients. In a study now in press at NeuroImage: Clinical, his team tested a new fMRI task in one patient, asking him to create a mental picture of either a face or a house in response to an increasingly convoluted series of statements about which of the two should appear in front of the other. "Not only could we demonstrate that he can reason, but also he stops being able to reason when it gets really difficult the same way the rest of us do," Owen said.
The downside of all these fMRI methods is that they require a big machine and can’t be done at the bedside. As a result, the number of patients who’ve benefited so far is limited to a handful who’ve participated in research studies.
Several research groups have developed alternative methods based on EEG, which requires only an electrode cap to record signals from the brain. But while EEG data are easier to get, they’re far harder to analyze. On the final day of the conference, a testy exchange of letters appeared in The Lancet, in response to a paper Owen’s team published last year describing an EEG version of their fMRI task for detecting consciousness. Another research team, which included Fins and Weill Cornell neurologist Nicholas Schiff, one of the foremost experts on disorders of consciousness, re-analyzed the data (which Owen and colleagues willingly shared), and concluded that the statistical analysis was fatally flawed.
“If you follow that method, you’ll end up with false positives,” Schiff said in an interview, meaning that the test would mistakenly detect consciousness in some unconscious patients. Owen vehemently disagrees. “We reject it, absolutely,” he said of Schiff’s analysis. Both men agreed that EEG is far trickier than fMRI to analyze because it requires more statistical analysis and more arbitrary assumptions that can sway the end result.
The most mind-blowing talk at the conference came from Jack Gallant, a computer scientist-turned neuroscientist at the University of California, Berkeley. Gallant is a man of upbeat intensity and a fast talker. He blazed through demos of computational models his team has developed to study how various kinds of information are encoded in the brain. “This one uses latent Dirichlet allocation,” he said at one point. “Believe me, you do not even want to know how that works.” Even some of the neuroscientists in the audience seemed to nod in agreement.
In recent years, Gallant’s lab has shown that it's possible to reconstruct still images and – video clips from the patterns of activity elicited in the brain of the person viewing them. If Gallant can see what your visual cortex is doing, he can tell you, more or less, what you’re looking at.
More recently, they’ve moved into more conceptual realms. A December paper in Neuron described their early attempts to study how the brain encodes semantic information — the concept of a dog, for example, and the understanding that a dog is a kind of animal, and an animal is a kind of thing. Gallant thinks this work could eventually lead to machines that can decode the contents of our thoughts.
“If you could build a brain machine interface that could decode internal speech, the little man or woman in your head that talks to you all the time, it would trump every other brain decoding device you could ever build,” he said. “There would just be no point to build anything else.”
Such a device would have profound ethical and legal implications, particularly if it enables some patients to participate in discussions about their care and end-of-life decisions.
Detecting consciousness and decoding thoughts is exciting stuff, but the patients who could benefit most from such technology – those teetering on the edge of consciousness – are probably only a small minority of those suffering from disorders of consciousness. Vegetative state and minimally conscious patients are among the most neglected groups in our health care system, according to several people who spoke at the conference.
Ken Diviney, a Virginia man whose 24-year-old son Ryan is in a minimally conscious state following a senseless beating outside a convenience store in 2009, gave a heart-wrenching account of caring for his son in the face of apathy from doctors and insurance companies. Diviney said he once called 911 from the ICU because he couldn’t get a doctor to come check on Ryan’s rapidly rising fever. To provide long-term care for their son, he and his wife renovated the ground floor of their home, outfitting it with a special bed and other equipment his insurance company wouldn’t pay for. He quit his job, and now spends his days doing physical therapy with Ryan to keep his muscles flexible and preserve bone density, brushing his teeth every two hours to prevent life-threatening infections like pneumonia. He longs to know if Ryan will ever get better.
Gentle and articulate, Diviney visibly wears the weight of his responsibility to his son. “I have a purpose,” he said. “Damned be that purpose, but I have it.”
The Divineys’ experience is not unique, according to Fins, who is writing a book based on interviews with dozens of families with loved ones in a vegetative or minimally conscious state. Once someone loses consciousness indefinitely, hospitals and insurers seem to want nothing to do with them, Fins says. “I hear the same story over and over,” he told Diviney.
That's a travesty, and not one that technology alone is likely to fix.
