Voluntary brain processing in disorders of consciousness

Schnakers, Caroline; Perrin, Fabien; Schabus, Manuel; Majerus, Steve; Ledoux, Didier; Damas, Pierre; Boly, Mélanie; Vanhaudenhuyse, Audrey; Bruno, Marie-Aurélie; Moonen, Gustave; Laureys, Steven

doi:10.1212/01.wnl.0000334754.15330.69

Cited by 252 publications

(197 citation statements)

References 25 publications

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“…It is not yet clear if these significant differences were really P300 potentials since, sometimes, the polarity was inversed and their occurrence was very much delayed. However, Perrin et al [20] and Schnakers et al [41] also reported P300 potentials with latencies between 600 ms and 800 ms in MCS patients. They concluded that MCS patients might have a slower processing speed than healthy subjects, an assumption that is also in line with Kotchoubey et al [9].…”

Section: Discussionmentioning

confidence: 97%

The auditory P300-based single-switch brain–computer interface: Paradigm transition from healthy subjects to minimally conscious patients

Pokorny

Klobassa

Pichler

et al. 2013

Artificial Intelligence in Medicine

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Objective: Within this work an auditory P300 brain-computer interface (BCI) based on tone stream segregation, which allows for binary decisions, was developed and evaluated. Materials and methods: Two tone streams consisting of short beep tones with infrequently appearing deviant tones at random positions were used as stimuli. This paradigm was evaluated in 10 healthy subjects and applied to 12 patients in a minimally conscious state (MCS) at clinics in Graz, Würzburg, Rome, and Liège. A stepwise linear discriminant analysis (SWLDA) classifier with 10 × 10 cross-validation was used to detect the presence of any P300 and to investigate attentional modulation of the P300 amplitude. Results:The results for healthy subjects were promising and most classification results were better than random. However, for MCS patients only a small number of classification results were above chance level and none of the results were sufficient for communication purposes. Nevertheless, signs of consciousness were detected in most patients, not on a single-trial basis, but after averaging of corresponding data segments and computing significant differences. These significant results, however, strongly varied across sessions and conditions. Conclusion: This work shows the transition of a paradigm from healthy subjects to MCS patients. Promising results with healthy subjects are, however, no guarantee of good results with patients. Therefore, more investigations are required before any definite conclusions about the usability of this paradigm for MCS patients can be drawn. Nevertheless, this paradigm might offer an opportunity to support bedside clinical assessment of MCS patients and eventually, to provide them with a means of communication.

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Section: Discussionmentioning

confidence: 97%

The auditory P300-based single-switch brain–computer interface: Paradigm transition from healthy subjects to minimally conscious patients

Pokorny

Klobassa

Pichler

et al. 2013

Artificial Intelligence in Medicine

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“…In one study, patients with DOC listened through headphones to a series of names including their own name or other names, in both passive and active conditions. 126 In the active condition, patients were instructed to count the number of times they heard their own name or another target name, and the increase in P3 amplitude (known to depend on attention) was taken as a marker of response. This approach led to detection of consciousness in a rare case of total LIS.…”

Section: Electrophysiologymentioning

confidence: 99%

Disorders of consciousness after acquired brain injury: the state of the science

et al. 2014

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| The concept of consciousness continues to defy definition and elude the grasp of philosophical and scientific efforts to formulate a testable construct that maps to human experience. Severe acquired brain injury results in the dissolution of consciousness, providing a natural model from which key insights about consciousness may be drawn. In the clinical setting, neurologists and neurorehabilitation specialists are called on to discern the level of consciousness in patients who are unable to communicate through word or gesture, and to project outcomes and recommend approaches to treatment. Standards of care are not available to guide clinical decision-making for this population, often leading to inconsistent, inaccurate and inappropriate care. In this Review, we describe the state of the science with regard to clinical management of patients with prolonged disorders of consciousness. We review consciousness-altering pathophysiological mechanisms, specific clinical syndromes, and novel diagnostic and prognostic applications of advanced neuroimaging and electrophysiological procedures. We conclude with a provocative discussion of bioethical and medicolegal issues that are unique to this population and have a profound impact on care, as well as raising questions of broad societal interest.

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“…Concurrently, cheaper and portable techniques using event related potential or electromyography active paradigms have been developed to detect possible signs of command following not assessable by clinical behavioural examination. Schnakers et al [63] presented a list of names (including their own name) and showed that nine out of 14 studied MCS patients, when instructed to count a target name, showed an increase in amplitude of the P3 potential (known to vary with attention) (none of the eight vegetative/unresponsive patients could do the task). This paradigm also permitted the clinicians to detect consciousness in a rare case of total locked-in syndrome (i.e., characterized by complete immobility including eye movements), behaviourally diagnosed as comatose [43].…”

Section: Para-clinical Neuroimaging Assessment Independent Of Motor Rmentioning

confidence: 99%

From unresponsive wakefulness to minimally conscious PLUS and functional locked-in syndromes: recent advances in our understanding of disorders of consciousness

et al. 2011

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Functional neuroimaging and electrophysiology studies are changing our understanding of patients with coma and related states. Some severely brain damaged patients may show residual cortical processing in the absence of behavioural signs of consciousness. Given these new findings, the diagnostic errors and their potential effects on treatment as well as concerns regarding the negative associations intrinsic to the term vegetative state, the European Task Force on Disorders of Consciousness has recently proposed the more neutral and descriptive term unresponsive wakefulness syndrome. When vegetative/unresponsive patients show minimal signs of consciousness but are unable to reliably communicate the term minimally responsive or minimally conscious state (MCS) is used. MCS was recently subcategorized based on the complexity of patients' behaviours: MCS? describes highlevel behavioural responses (i.e., command following, intelligible verbalizations or non-functional communication) and MCS-describes low-level behavioural responses (i.e., visual pursuit, localization of noxious stimulation or contingent behaviour such as appropriate smiling or crying to emotional stimuli). Finally, patients who show nonbehavioural evidence of consciousness or communication only measurable via para-clinical testing (i.e., functional MRI, positron emission tomography, EEG or evoked potentials) can be considered to be in a functional locked-in syndrome. An improved assessment of brain function in coma and related states is not only changing nosology and medical care but also offers a better-documented diagnosis and prognosis and helps to further identify the neural correlates of human consciousness.

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Voluntary brain processing in disorders of consciousness

Abstract: Background: Disentangling the vegetative state from the minimally conscious state is often diffi-

Cited by 252 publications

References 25 publications

The auditory P300-based single-switch brain–computer interface: Paradigm transition from healthy subjects to minimally conscious patients

The auditory P300-based single-switch brain–computer interface: Paradigm transition from healthy subjects to minimally conscious patients

Disorders of consciousness after acquired brain injury: the state of the science

From unresponsive wakefulness to minimally conscious PLUS and functional locked-in syndromes: recent advances in our understanding of disorders of consciousness

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