Detecting consciousness in vegetative patients – experts respond

What if you were trapped in your own body, unable to move or communicate in any way? How would any one know you are conscious? New research has offered an insight into detecting awareness in such situations.

A new study,  published the leading medical journal the Lancet, shows that awareness can be detected in people previously thought to be in a permanently vegetative state.

Being in a ‘vegetative state’ is defined as wakefulness without conscious awareness of self and environment.

While MRI machines have been used in the past to detect awareness in seemingly unresponsive patients, their use is very limited due to involuntary movement in patients and the common presence of metal pins and plates in accident victims.

Now, a team of researchers has shown that an electroencephalograph (EEG), a simple, non-invasive and cheap method of detecting brainwave activity, can identify conscious responses in some patients diagnosed as vegetative using official criteria. Of 16 technically vegetative patients included in the study, three were found to be able to give robust and reliable conscious responses to researchers – as detected by EEG.

These patients were able to respond to requests such as ‘try to squeeze your right hand into a fist’ or ‘wiggle your toes’. Although the patients were unable to move voluntarily, their brain wave activity, as recorded by EEG, showed responses consistent with such motor activity.

The authors conclude in their article, “Our findings show that this EEG method can identify covert awareness in patients diagnosed in the vegetative state with a similar degree of accuracy to other methods of detection; it is a considerably cheaper and more portable bedside technique…this method could reach all vegetative patients and fundamentally change their bedside assessment.”

Further to detecting awareness, the authors suggest that the techniques could be used for communication. “The development of techniques for the real-time classification of these forms of mental imagery will enable routine two-way communication with some of these patients, allowing them to share information about their inner worlds, experiences, and needs.”

While the detection of awareness in vegetative patients offers a medical insight into consciousness, it also raises a number of ethical issues.

Commenting on the research, Julian Savulescu, Director, Oxford Centre for Neuroethics said, “People who are deeply unconscious don’t suffer. But are these patients suffering? How bad is their life? Do they want to continue in that state? If they could express a desire, should it be respected?

“Science is invaluable in discovering what the world, including ourselves, is like. But it can never alone tell us what we should do. The big question – how such patients should be treated – remains as open as ever.”

You can listen to a webcast of the authors discussing their research, courtesy of the Science Media Centre Canada, below.

Our friends at the UK Science Media Centre provided the following expert commentary.  If you’d like to speak to a local expert, contact the SMC.

Professor Susan Gathercole, Director of the MRC Cognition and Brain Sciences Unit in Cambridge, comments:

“An accurate diagnosis is vital to enable doctors to provide the best treatment and care options available. We are very pleased that the Medical Research Council has been involved in this fascinating study, which brings us one step closer towards improving diagnostic tools for patients thought to be in a vegetative state and pinpointing levels of awareness that were not previously possible.”

Julian Savulescu, Director, Oxford Centre for Neuroethics, comments:

“This important scientific study raises more ethical questions than it answers. People who are deeply unconscious don’t suffer. But are these patients suffering? How bad is their life? Do they want to continue in that state? If they could express a desire, should it be respected?

“The important ethical question is not: are they conscious? It is: in what way are they conscious? Ethically, we need answers to that. Life prolonging treatment has been and legally can be withdrawn from patients who are permanently unconsciousness. We need guidelines for when life-prolonging treatment should be withdrawn in these minimally conscious states. Paradoxically, it could be worse for some than being permanently unconscious. And in countries like the Netherlands, we need guidelines on whether and when active euthanasia should be performed. For some of these patients, consciousness could be the experience of a living hell.

“Previous research by some of these authors shows importantly that some patients who are “locked-in” – who are clearly conscious and can communicated but cannot move at all – find their lives worth living. Even this finding would not settle what should be done. What makes each person’s own living hell is a matter for that person. It is subjective. And we can adapt to terrible disability. That is important for all of us to know. But it does not change the rights of individuals to make what they will of their lives, including choosing the conditions under which and the time to end them. One possible solution to these issues is to form a living will about what should happen to you, if you were to be in such a state.

“Such cases also raise ethical issues of futility and the appropriate allocation of limited resources on patients with severely impaired quality of life. That is, they raise questions of distributive justice. Even if such patients are minimally conscious, is it fair and just to use public resources to keep them alive for many years? Very poor quality of life has been used as ground for withholding or withdrawing medical treatment.

“Science is invaluable in discovering what the world, including ourselves, is like. But it can never alone tell us what we should do. The big question – how such patients should be treated – remains as open as ever. We need more science to find out what the life of such patients is like. But we also need ethics to decide what we do when we discover that.”

Paul Matthews, Prof of Clinical Neurosciences, Dept of Medicine, Imperial College, London, comments:

“This thoughtful paper describes use of brain waves that can be detected on the scalp to detect apparently meaningful brain responses (thinking about moving either a hand or toes) in patients in a “vegetative state” after severe brain injury.

“Severe brain injury can leave patients in either a deep sleep- like coma, a vegetative state in which they show sleep-wake cycles and make eye and facial movements that look aware but are not meaningful (or “willed”) or a minimally conscious state in which meaningful responses to the outside world are demonstrated at some times.  Patients are classified in these ways based on repeated observation of their responses to sensory stimuli or commands.  The distinctions have implications for longer term prognosis, particularly early after an injury.

“Owen and his colleagues have pioneered the use of functional MRI brain imaging to “see” brain activity with commands, e.g., imaging a game of tennis.  These results suggested that the brains of minority of patients thought to be vegetative could respond meaningfully, even if they could not express this with a movement or sound.  It was inferred that the awareness demonstrated could be more general.

“A limitation of the MRI method was that it demanded highly specialist equipment and was difficult to perform.

“Here they have adapted an electroencephalographic  (EEG) “brain wave” test to the same purpose, using commands from an examiner to move either a hand or the toes as specific stimuli to test for awareness.  Again, they found that a significant small number of patients- 3 from their total group of 16- displayed brain wave changes consistent with appropriate “thinking” on command.  This suggests that a relatively simple and inexpensive EEG  test  could be used to improve the accuracy of diagnosis of patients in vegetative or minimally conscious states.

“However, this study provides simply a “reason to believe” that a clinically important advance could be made in this way.  The details of the method are not well enough described for standardised application.  The reproducibility of the measures in the patients and controls was not explored, e.g., do the patients displaying awareness always respond in this way?  It is likely that the sensitivity of the method is limited, as not all of the healthy volunteers would have been classified as “aware” by this method!  Most importantly- the significance of the findings for the longer term clinical outcomes of the patients is not known-do patients classified as “aware” by this method have a higher probability of substantial clinical recovery?  Can they be taught to use EEG to communicate more generally, rather as eye blinks can be used by patients with “locked in syndrome” (see  J-D Bauby,The Butterfly and the Diving Bell“)?

“Nonetheless, this is an important clinical study that promises the potential a improvement in  the care of these severely brain-damaged patients.  It illustrates the innovative application of principles of modern brain science to an important clinical problem- showing how basic research can be taken right from the laboratory to the bedside.  To say that more work is needed is to acknowledge its significance and the need for prioritisation of this work.

“Owen and his colleagues suggest that brain waves can be used to sense meaningful responses from patients who appear unresponsive in a vegetative state after severe brain injuries.  This and their previous work challenges the current ways in which these patients are diagnosed, suggesting that a small proportion of them may show at least a limited awareness of what goes on around them.  More important, the approach suggests a simple, practical way in which some of these patients might be helped to communicate.  This innovative work has taken fundamental brain science right to the bedside.  Efforts to further evaluate this and related approach in the clinic should be prioritised”