AT THE age of 19, Terry Wallis was thrown from his pick-up truck during an accident near his home in Massachusetts. He was found a day later in a coma with massive brain injuries. That was in 1984.
Within a few weeks he was stable, but in a minimally conscious state which his doctors thought would last indefinitely. Nineteen years later, in 2003, Wallis started to speak. Over the next three days, he regained the ability to move and communicate, and got to know his daughter, who was now 20. He also had to come to terms with the news that he was no longer a teenager, and that Ronald Reagan was not president of the United States.
“Only now is it clear how this medical miracle occurred. Terry Wallis’s brain has rewired itself in ways never thought possible”
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Only now is it clear how this medical miracle occurred. Wallis’s brain had rewired itself in ways never thought possible. What is more, there is compelling evidence that some patients in a supposedly permanent vegetative state may actually show signs of awareness, a finding that could force a review of how such patients are treated.
Over the past 20 years, a number of high profile cases including that of Terri Schiavo in the US and Tony Bland in the UK have highlighted the dilemmas facing doctors and family members caring for patients in a vegetative state. Often the courts have had to decide on what treatment is appropriate and whether it should be withdrawn (see “The grey area”). Wallis’s case, like those of a few others, is likely to make such decisions even more difficult in the future.
Nicholas Schiff and colleagues from the Weill Medical College of Cornell University in New York have been studying Wallis’s brain since his awakening using a new imaging technique called diffusion tensor imaging. The system tracks the flow of water molecules in the brain, revealing how the brain’s wiring and white matter has changed over time. These images were combined with others from more traditional PET scans that show which brain areas are active.
Their results, published this week in the Journal of Clinical Investigation, are astounding. Wallis’s brain seems to have slowly grown new axons – the branches that connect neurons together – establishing novel working brain circuits. But these circuits look nothing like they should. The connections have grown across the back of his brain, forming structures that don’t exist in normal brains. This extraordinary anatomy appears to compensate for axons destroyed during the accident, especially a bundle called the corpus collosum that usually passes from one side of the brain to the other. Scans taken at two months and 18 months after his recovery also show stark differences: some new pathways have receded while others have taken their place as Wallis continued to improve.
“It seems like the bounds on the extent of neural plasticity that is possible just keep on shifting,” says Krish Sathian, a neurologist and specialist in brain rehabilitation at Emory University School of Medicine in Atlanta, Georgia. “Classical teaching would not have predicted any of these changes.”
It is not just Wallis who is challenging dogma. A team led by Stephen Laureys of the University of Liège, Belgium, together with Adrian Owen from the MRC Cognition and Brain Sciences Unit in Cambridge, UK, have found that some patients in a vegetative state show certain patterns of brain activity that suggest they can understand speech. Their response goes further than merely passively responding to sounds or voices, and their patterns are unlike those of anaesthetised patients, who show no signs of comprehension.
Another patient diagnosed as being in a vegetative state showed activity in the face recognition area of her brain when shown pictures of the faces of her friends and family. “Consequently there was a massive input from nursing staff, who treated her differently, and also from friends and family,” says Owen. “Nine months later she started to make a recovery. She has done incredibly well.”
Do such cases reveal that a doctor’s initial diagnosis is often wrong, that such brain activity is a sign of awareness, that occasional miracles happen, or that rehabilitation can work if the right patients can be identified? No one knows. “It’s completely anecdotal,” says Owen. “We have no idea whether the efforts had any effect on recovery.”
Another preliminary and as yet unpublished study from this group revealed last week at the annual meeting of the Association for the Scientific Study of Consciousness (ASSC10) in Oxford, UK, highlighted the difficulties of making accurate diagnoses of unconscious patients, bringing into question what should be taken as a sign of awareness.
Mélanie Boly from the University of Liège, described how a patient diagnosed as being in a persistent vegetative state seemed to show signs of awareness. Normal healthy people produce reliable and different functional brain imaging signals when asked to imagine specific things, for example, seeing faces, or performing certain actions.
“There is specific activation relevant to the task,” Boly says. Surprisingly, the patient in a vegetative state showed the same brain signals. “Her brain showed volitional activity,” Boly told the meeting. “Clinically she is in a vegetative state, but she is conscious. For us there is no other explanation.”
It is very hard to believe that these commands could trigger brain activity without being consciously processed, says Patrick Wilken of the University of Magdeburg, Germany, and chair of the ASSC. “This opens up the possibility of directly testing for consciousness in patients who are unable to move, and who may or may not be in a coma.”
“The message shouldn’t be that patients in a vegetative state could be conscious and that we should never stop treatment”
Laureys says any interpretation of the consciousness or otherwise of patients in a vegetative state must be made very carefully. “The message shouldn’t be that vegetative state patients could be conscious and therefore we should never decide to stop treatment,” he says. Some patients show sensory responses to pain, yet their nervous system isn’t connected to the higher centres of the brain that cause us to experience it, Laureys has shown. “I am reassured as a clinician that they fail to show cerebral integration for pain and suffering.”
“Sometimes the futility of care is a reality, and to withdraw treatment is the right answer,” he says. “But this type of study will increase our understanding, and help establish who is in the grey zone.”
That appears to be a matter of some urgency, suggests Schiff. After eight weeks potentially vegetative patients are given an initial diagnosis, but there is no systematic re-examination after that “though their whole prognosis might change”, he says.
For example, Wallis was often described as being in a permanent vegetative state. Though his family fought for a re-evaluation after seeing many promising signs that he was trying to communicate, their requests were turned down. “A careful bedside exam at 6 months would have unequivocally said he was not in a vegetative state,” says Schiff. Although still rare, there is much more chance of a late recovery from a minimally conscious state. “The Wallis case will force the issue,” he believes.
Levels of unconsciousness
Consciousness is generally thought of as having two features: arousal, the level of wakefulness, and awareness, the knowledge and response to the surroundings and self. Though consciousness is often thought of as a continuum of arousal and awareness, the following clinical categories exist.
Brain death
No sign of either awareness or arousal. Considering that this is the accepted definition of death, it is surprising that its clinical diagnosis varies from country to country. Generally taken as no sign of brainstem reflexes or breathing.
Coma
A completely unresponsive state, eyes closed, with a total lack of arousal, wakefulness and awareness. To be considered a coma, the condition must persist for more than one hour.
Vegetative state
A state of wakeful unawareness. The patient has sleep-wake cycles and periods of eye opening. After one month the patient is said to be in a persistent vegetative state. After three months or one year, depending upon the type of brain injury, the condition is often considered irreversible, and may be called a permanent vegetative state.
Minimally conscious
Wakefulness, but only inconsistent or rare signs of awareness. Patients may show sporadic attempts to communicate, with occasional purposeful speech or movements.
Locked-in syndrome
Awareness and wakefulness with complete paralysis. Blindness or deafness in a locked-in patient can make this near impossible to diagnose.
The grey area
Who will recover and who will not? That’s the question everyone working with unconscious patients would like to answer. In many cases, a vegetative state is permanent, and despite some encouraging signs such as eye opening, waking and sleeping, and signs of activity in basic sensory areas of the brain in response to pain, some researchers have shown there are no responses in the higher brain that would allow these pain signals to be interpreted, or felt, by the patient.
Nancy Cruzan
Left in a persistent vegetative state after a car accident in 1983. Her father signed a consent form for the procedure to insert a feeding tube, then four years later, after accepting she would not recover, found he would be considered a murderer if he took her home and removed it. Finally, in 1990 after a long legal dispute, a judge ruled that Cruzan could be allowed to die by withdrawal of feeding. The case established that the prior wishes of the patient in the US would be taken into account.
Terry Wallis
Left in a minimally conscious state after a car accident in 1984. Remarkably, he recovered the ability to speak and move again after almost two decades.
Tony Bland
Never regained consciousness after a terrible crowd crush during a football match in Hillsborough, UK, and was allowed to die by removing his feeding tube four years later in 1993. Before Bland’s case, only newborns in the UK could be knowingly allowed to die if treatment was removed.
Terri Schiavo
Collapsed after a cardiac arrest in 1990. After seven years in a persistent vegetative state, a bitter legal battle began as her parents and husband disagreed about her right to die. After eight more years, the dispute reached the White House and Vatican, leading to removal and reinsertion of a feeding tube three times before Schiavo was finally allowed to die in 2005.
