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The echo of consciousness
1/13/14

Are we wending our way towards a mathematical approach to consciousness, that would allow us to assess its residual presence in severely brain-damaged patients? An international team including researchers from the universities of Milan, Sao Paulo, Wisconsin and Liège recently showed that the level of consciousness can be translated into figures by measuring the complexity of the brain’s response to a magnetic impulse.

ComaIn 2002, Joseph Giacino, of the New Jersey Neuroscience Institute, demonstrated that another state, the minimally conscious state, existed alongside the vegetative state, and that it was a mistake to confuse them. In a minimally conscious state, the subject is incapable of following simple instructions in a “consistent” manner, but they nevertheless have a fluctuating awareness of their environment. For instance, they can execute voluntary movements from time to time or smile at close friends and family; on the other hand, they can’t communicate their thoughts. Contrary to this type of subject, the patient in a vegetative state (or, according to new, less pejorative terminology, unresponsive wakefulness syndrome) is not conscious of the outside world.

The line between the two entities is difficult to define by simply examining the motor response of the brain-damaged patient. As a result, a sort of grey area sometimes surrounds “bedside” diagnoses. Several studies undertaken in the past few years have in fact revealed that as regards highly altered states of consciousness, the diagnosis based on a classic clinical examination was wrong one in three times, and even two in five. Hence, some people have been declared in a vegetative/unresponsive state, when they were actually in a minimally conscious state, or even suffering from locked-in syndrome (LIS), where their consciousness is intact but in a hopelessly immobile body.

For the moment, the relative uncertainty surrounding certain diagnoses continues to fuel the ethical debate. All the more so since an extensive investigation carried out by the Coma Science Group among more than 2000 European health professionals underlines that end-of-life opinions concerning seriously brain-damaged patients differ depending on whether the latter are declared in a chronic minimally conscious state or in a chronic vegetative/unresponsive state, and depending on whether or not they are supposed to feel physical pain, which is the case in patients in a minimally conscious state, as shown in the work(1)(2)(3) of the Coma Science Group at the University of Liège’s Cyclotron Research Centre (CRC) and the neurology department at Liège CHU. For instance, there is a strong reluctance to stop artificial nutrition and hydration in a patient who is considered capable of perceiving nociceptive stimuli. Why? "One hypothesis would be that this ability to feel pain can be considered a more general sign of awareness of the environment", points out Steven Laureys, head of the Coma Science Group.

It is therefore essential to try and determine, for each severely brain-damaged patient, if there is any indication of residual consciousness. “Furthermore, when there are signs of consciousness, it is vital to try and establish a dialogue with the patient concerned in order to allow them to express their feelings, needs (are they suffering?) and desires, especially regarding end-of-life decisions”, says Steven Laureys.

(1) M. Boly, M.-E. Faymonville, C. Schnakers, Ph. Peigneux, B. Lambermont, C. Phillips, P. Lancellotti, A. Luxen, M. Lamy, G. Moonen, P. Maquet et S. Laureys, Perception of pain in the minimally conscious state with PET activation : an observational study, in The Lancet Neurology, 2008.
(2) Demertzi A et al. (2013) 6, 1, 37-50, Pain Perception in Disorders of Consciousness: Neuroscience, Clinical Care, and Ethics in Dialogue.
(3) Bodart O, Laureys S, Gosseries O. Coma and disorders of consciousness: scientific advances and practical considerations for clinicians. Seminars in Neurology 2013 33(2):83-90

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