Measurements of consciousness in the vegetative state

Overgaard, Morten; Overgaard, Rikke

doi:10.1016/s0140-6736(11)61591-2

Cited by 20 publications

(17 citation statements)

References 9 publications

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“…Consciousness is likely to vanish in the presence of many small, short-lived, and highly unstable neuronal assemblies that perform their operations totally independent of one another (functional disconnection) and are not capable of supporting any content to be experienced subjectively. 6,29,69 An independent line of support for this conclusion comes from the study of non-rapid eye movement sleep 88 and pharmacologically induced loss Table 1 for concrete values).…”

Section: Discussionmentioning

confidence: 94%

Dissociation of Vegetative and Minimally Conscious Patients Based on Brain Operational Architectonics

Fingelkurts

Bagnato

et al. 2013

Clin EEG Neurosci

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Discrimination between patients in vegetative (VS) and minimally conscious state (MCS) is currently based upon the behavioral gold standard. Behavioral assessment remains equivocal and difficult to interpret as evidence for the presence or absence of consciousness, resulting in possible clinical misdiagnosis in such patients. Application of an operational architectonics (OA) strategy to electroencephalogram (EEG) analysis reveals that absence of consciousness in patients in VS is paralleled by significant impairment in overall EEG operational architecture compared to patients in MCS: neuronal assemblies become smaller, their life span shortened, and they became highly unstable and functionally disconnected (desynchronized). However, in a previous study, patients with different brain damage etiologies were intermixed. Therefore, the goal of the present study was to investigate whether the application of OA methodology to EEG could reliably dissociate patients in VS and MCS independent of brain damage etiology. We conclude that the observed EEG OA structure impairment in patients in VS and partial preservation in patients in MCS is a marker of consciousness/unconsciousness rather than physiological damage. Results of this study may have neuroscientific, clinical, and ethical implications.

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Section: Discussionmentioning

confidence: 94%

Dissociation of Vegetative and Minimally Conscious Patients Based on Brain Operational Architectonics

Fingelkurts

Bagnato

et al. 2013

Clin EEG Neurosci

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“…The subjective experience is the patient's own experience of unconsciousness and has little relation to the level of consciousness. 28 An unconscious patient may, therefore, experience pain, fear, so forth, and not manifest visible clinical markers, such as restlessness or grimacing. The patient's experience of unconsciousness is much harder to measure.…”

Section: Discussionmentioning

confidence: 99%

“…An important consideration then, when comparing observational scales and BISs, is to understand they do not measure the same thing. 7,28 A significant disconnect can exist between the two when a patient experiences discomfort or distress sufficient to arouse them while not altering their perceived level of consciousness. An example of this ''covert consciousness'' 30 is found in several anecdotal reports.…”

Section: Discussionmentioning

confidence: 99%

Correlation Between Observational Scales of Sedation and Comfort and Bispectral Index Scores

Barbato

Barclay

Potter

et al. 2017

Journal of Pain and Symptom Management

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“…It is important to emphasize that the concept of "consciousness" is used in a clinical sense to denote the assessment of a patient and not the subjective conscious experience of the patient, which in principle cannot be known. These two definitions are often confused in the literature, where the former is taken as direct evidence for the latter, although there is no scientific evidence to support such a claim (M. Overgaard, 2009; M. Overgaard and R. Overgaard, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…While the diagnostic determinants that define a VS or MCS patient are inferred uniquely from the patient's behaviour, nothing can, in principle, be known about the patient's awareness of the external world. This is because the nature of their condition precludes any report of stimulus awareness through standardised neuropsychological or psychophysical testing (M. Overgaard and R. Overgaard, 2011).…”

Section: Introductionmentioning

confidence: 99%

Dissecting the coma spectrum using Bayesian classification

Dietz

Zareini

Näätänen

et al. 2019

Preprint

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A patient who does not regain full consciousness after coma is typically classified as being in a vegetative state or a minimally conscious state. While the key determinants in this differential diagnosis are inferred uniquely from the observed behaviour of the patient, nothing can, in principle, be known about the patient's awareness of the external world. Given the subjective nature of current diagnostic practice, the quest for neurophysiological markers that could complement the nosology of the coma spectrum is becoming more and more acute. We here present a method for the classification of patients based on electrophysiological responses using Bayesian model selection. We validate the method in a sample of fourteen patients with a clinical disorder of consciousness (DoC) and a control group of fifteen healthy adults. By formally comparing a set of alternative hypotheses about the nosology of DoC patients, the results of our validation study show that we can disambiguate between alternative models of how patients are classified. Although limited to this small sample of patients, this allowed us to assert that there is no evidence of subgroups when looking at the MMN response in this sample of patients. We believe that the methods presented in this article are an important contribution to testing alternative hypotheses about how patients are grouped at both the group and single-patient level and propose that electrophysiological responses, recorded invasively or non-invasively, may be informative for the nosology of the coma spectrum on a par with behavioural diagnosis.

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Measurements of consciousness in the vegetative state

Cited by 20 publications

References 9 publications

Dissociation of Vegetative and Minimally Conscious Patients Based on Brain Operational Architectonics

Dissociation of Vegetative and Minimally Conscious Patients Based on Brain Operational Architectonics

Correlation Between Observational Scales of Sedation and Comfort and Bispectral Index Scores

Dissecting the coma spectrum using Bayesian classification

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