The idea of being trapped in one's own body without being able to communicate is, for some, just about the most terrible thing imaginable.
But this scenario isn't just hypothetical. Over the past few decades, scientists have used brain-imaging techniques to figure out that some people in vegetative states really do seem to retain consciousness — they just can't communicate with the outside world. So researchers have also been trying to figure out whether it's possible to talk to these people.
This won't necessarily work for everyone who's in a vegetative state. The few small studies done so far have found that about 13 to 19 percent of them seem to have some kind of conscious awareness. And even for that fraction, it's not clear what level of cognitive function they really have. It's important to stress that much more research is needed.
Still, some scientists are cautiously hopeful that they might be able to reach some of these people. "Just because a patient appears to be unconscious from the outside with their external behavior doesn't mean they're not capable of doing much more," says Damian Cruse, a researcher who's been working on this problem in the laboratory of Adrian Owen at Western University in Canada.
The implications are potentially huge. It's possible — though not at all certain — that some people in vegetative states might benefit from new treatments that could improve their conditions or increase the chances that they wake up.
And it would be a huge deal if patients in vegetative states could communicate, even if only through their brainwaves. Doctors could find out if they were in pain. Patients might be able to have conversations with their families. And it would raise new — and difficult — ethical questions around decisions like whether to keep a feeding tube in or let a loved one die.
So here's what we know so far about talking to people in vegetative states:
Consciousness isn't a binary thing
Consciousness is not a binary thing — where it's completely on or off. People can have a range of levels of awareness.
A person in a coma, for instance, might be lying there with his or her eyes closed and no movement. A person in a persistent vegetative state, however, might have reflexes or automatic movements — such as opening their eyes from a loud noise — yet appear to be completely unaware of themselves and their environments. More recently, a new diagnostic category has been added: minimal consciousness, in which patients sometimes exhibit some awareness.
And recent research seems to be suggesting that there may be a subset of vegetative patients who actually are consciously aware within their own minds — even though they show no outward signs of it.
Scientists have had limited communication with a few vegetative patients
"Essentially, up until kind of the late 1990s, the general consensus was that patients in a vegetative state were completely unaware of themselves and their environments," says Cruse.
But that changed when a group of researchers published a study in Lancet in 1998. The study showed that the area of the brain that turns on when a normal person sees a familiar face also lit up on a PET scan for a 26-year-old woman who had been diagnosed as in a vegetative state. In other words, her brain could still recognize people she knew.
The study's authors, a group from Cambridge, began pursuing further work in the field, collaborating with researchers at the University of Liege in Belgium and Western University in Canada.
In 2006, some of them went on to publish a study in Science of one 23-year-old patient in a vegetative state who seemed to show some conscious awareness on fMRI brain scans. Specifically, the researchers asked her to imagine playing tennis. Although she couldn't reply, the part of her brain involved in controlling movement appeared to activate. Then, the researchers asked her to imagine navigating through every room in her house — and that activated regions of her brain involved with navigation.
Essentially, her brain behaved the same as a healthy volunteer's would. It seemed that she could both listen and respond to those requests. And it seemed unlikely that this was simply some kind of unconscious, reflexive response.
So could scientists take advantage of this scenario to create some kind of meaningful communication with patients in vegetative states? In 2010, they showed evidence that they could. They asked people questions and told them to imagine tennis to signal "yes" and to imagine navigating a house or city to signal "no." Using this design, they were able to demonstrate that people could communicate via brain scanner just by thinking.
This method worked for 16 healthy people. And they also tested one vegetative patient, known as Patient 23, who was able to correctly answer five out of six questions about his life. (The sixth answer was indecipherable.) The resulting paper was published in the New England Journal of Medicine.
A follow-up study published in 2013 demonstrated similar results. Researchers asked simple questions like "Are you in a supermarket?" and "Is your name Steve?" This time, patients were instructed to respond "yes" or "no" by counting the number of times they heard either "yes" or "no" in a stream of words. Two patients with disorders of consciousness, including one diagnosed as vegetative, were able to correctly answer questions this way.
But it still was a complex and cumbersome process. The device used to perform these tests was an fMRI machine, which is very large, expensive, and slow. It requires moving the patient to the machine. So researchers also started experimenting with technology that could be used at a patient's bedside.
In 2011, Cruse and colleagues published a paper in the Lancet that used a removable hat of electrodes to detect the brain's electrical signals (called EEG) and do similar testing. They asked 16 patients to imagine either squeezing their right hand or wiggling all their toes. (They needed brain activity that could be easily read from outside of the head, and these tasks fit the bill.)
"What we found was that three of these patients produced patterns similar to the types we saw in healthy people, showing that there really is this significant minority of patients who have been misdiagnosed and could potentially benefit from communication devices," says Cruse.
Note that the case still isn't closed. There have been some public disagreements from other scientists over how to analyze the complex data from these bedside studies, and whether the patients really were communicating. Still, Owen and Cruse's group asserts that the results are real.
So can communication with vegetative patients be practical?
Here's one catch: If doctors wanted to go around testing all of their patients in vegetative states for signs of consciousness, they would have trouble coming up with a test that works for everyone.
Asking people to answer questions by thinking about moving their hand or wiggling their toes doesn't even work in a quarter of people who are fully healthy and awake. And that failure rate might be even worse in people whose brains are damaged. So researchers are working to find a better test of conscious activity.
For example, Cruse says that having healthy people imagine complex music seems to be a better test than having them imagine moving their bodies. That could also be a better test for people with brain injuries. The researchers are also exploring tests that rely on attention and language processing. Owen, for his part, has suggested using jokes, which require conscious processing that can be picked up with brain imaging.
No matter what test ends up being the best, failing such a test won't necessarily mean that the patient has no conscious ability. It just means that the person didn't show conscious ability according to that particular test.
Then there is the interface problem. For communication to be at all practical on a large scale, it's going to need an interface far less cumbersome, expensive, and slow than a giant fMRI scanner — not to mention software that can quickly provide results.
That part of the equation seems to be coming along in projects involving a group of people who have limited mobility, but are very clearly conscious: people with paralysis. For example, a small handful of paralyzed people — after extensive training — have been able to use a small electrode implant called BrainGate to move a cursor on a computer screen or get a robotic hand to bring them a cup of coffee. If someday something like that could be hooked up to perhaps some kind of text messaging with audio feedback, it's possible that some of these vegetative patients could say anything they want.
This could transform our obligations to people in vegetative states
If there is indeed a subclass of patients in vegetative states who retain conscious awareness, that would raise an entirely new group of questions — which would likely take decades to answer.
Why and how are certain vegetative patients different from others? Does being different mean they shouldn't be called "vegetative," but be given some other new category? And do these people have better potential for recovery, in general? Can anything be done to improve their odds?
The ethical dilemmas that such communication might raise are just as important. Researchers will need to be exceptionally careful not to over-interpret results and assume that patients have more cognitive ability than they really do. And families could end up knowing that their loved ones can hear them, but not be able to have them in a brain scanner all the time in order to have them talk back. Even the research itself needs to be conducted carefully — so as to not give families false hope or destroy their hope if a patient doesn't respond to a particular test.
But if there's a way to tell that someone's still in there, there also seems to be an ethical obligation to at least try to communicate. To at least try to help.