Introduction: Reconsidering Disorders of Consciousness in Light of Neuroscientific Evidence
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ORIGINAL PAPER
Introduction: Reconsidering Disorders of Consciousness in Light of Neuroscientific Evidence Ralf J. Jox & Katja Kuehlmeyer
Received: 22 August 2011 / Accepted: 7 September 2011 / Published online: 23 September 2011 # The Author(s) 2011. This article is published with open access at Springerlink.com
Abstract Disorders of consciousness pose a substantial ethical challenge to clinical decision making, especially regarding the use of life-sustaining medical treatment. For these decisions it is paramount to know whether the patient is aware or not. Recent brain research has been striving to assess awareness by using mainly functional magnetic resonance imaging. We review the neuroscientific evidence and summarize the potential and problems of the different approaches to prove awareness. Finally, we formulate the crucial ethical questions and outline the different articles in this special issue on disorders of consciousness. Keywords Disorders of consciousness . Vegetative state . Minimally conscious state . End-of-life decisions . Functional magnetic resonance imaging
Progress in medicine allows more and more people in critical conditions to be kept alive. Some of these patients, however, do not fully regain consciousness due to substantial brain damage. If life-sustaining treatment is applied, they may remain in chronic R. J. Jox (*) : K. Kuehlmeyer Institute for Ethics, History and Theory of Medicine, University of Munich, Lessingstraße 2, D-80336 München, Germany e-mail: [email protected] URL: www.egt.med.uni-muenchen.de
disorders of consciousness for decades, living in a vegetative state (VS) or a minimally conscious state (MCS). The VS is characterized by preserved sleepwake-cycles and spontaneous breathing, which is due to a largely intact brainstem function, yet there are no signs of behavioural reactions to stimuli, interaction, or communication. It is assumed that a patient in the VS is awake but not aware of himself or his surroundings [1]. Due to the pejorative connotation of the term ‘vegetative’ the European Task Force on Disorders of Consciousness has recently suggested the term unresponsive wakefulness syndrome (UWS) [2]. In contrast to the VS, a patient in MCS displays inconsistent, but reproducible purposeful behaviour, heralded by subtle signs such as visual pursuit, correct object use, intelligible verbalisation, or following simple commands [3]. It is assumed that awareness is preserved in the MCS, at least at a basic level. Both disorders of consciousness have to be strictly distinguished from the locked-in state (LiS). Patients in a LiS are usually fully conscious, but cannot express themselves due to extensive paralysis, yet many are able to use vertical eye or eyelid movements to communicate. The LiS demonstrates that awareness does not necessarily hinge on the ability to express oneself or interact with others, be it verbally or through behaviour. Therefore, the absence of evidence for awareness is not tantamount to evidence for the absence of awareness. How can we then deter
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