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. 2022 Aug 5:16:971315.
doi: 10.3389/fnhum.2022.971315. eCollection 2022.

What names for covert awareness? A systematic review

Caroline Schnakers  1 , Chase Bauer  2 , Rita Formisano  3 , Enrique Noé  4 , Roberto Llorens  4   5 , Nicolas Lejeune  6   7 , Michele Farisco  8   9 , Liliana Teixeira  10 , Ann-Marie Morrissey  11 , Sabrina De Marco  12 , Vigneswaran Veeramuthu  13 , Kseniya Ilina  14   15 , Brian L Edlow  16 , Olivia Gosseries  7   17 , Matteo Zandalasini  18 , Francesco De Bellis  19 , Aurore Thibaut  7   17 , Anna Estraneo  19   20
Affiliations

What names for covert awareness? A systematic review

Caroline Schnakers et al. Front Hum Neurosci. .

Abstract

Background: With the emergence of Brain Computer Interfaces (BCI), clinicians have been facing a new group of patients with severe acquired brain injury who are unable to show any behavioral sign of consciousness but respond to active neuroimaging or electrophysiological paradigms. However, even though well documented, there is still no consensus regarding the nomenclature for this clinical entity.

Objectives: This systematic review aims to 1) identify the terms used to indicate the presence of this entity through the years, and 2) promote an informed discussion regarding the rationale for these names and the best candidates to name this fascinating disorder.

Methods: The Disorders of Consciousness Special Interest Group (DoC SIG) of the International Brain Injury Association (IBIA) launched a search on Pubmed and Google scholar following PRISMA guidelines to collect peer-reviewed articles and reviews on human adults (>18 years) published in English between 2006 and 2021.

Results: The search launched in January 2021 identified 4,089 potentially relevant titles. After screening, 1,126 abstracts were found relevant. Finally, 161 manuscripts were included in our analyses. Only 58% of the manuscripts used a specific name to discuss this clinical entity, among which 32% used several names interchangeably throughout the text. We found 25 different names given to this entity. The five following names were the ones the most frequently used: covert awareness, cognitive motor dissociation, functional locked-in, non-behavioral MCS (MCS*) and higher-order cortex motor dissociation.

Conclusion: Since 2006, there has been no agreement regarding the taxonomy to use for unresponsive patients who are able to respond to active neuroimaging or electrophysiological paradigms. Developing a standard taxonomy is an important goal for future research studies and clinical translation. We recommend a Delphi study in order to build such a consensus.

Keywords: cognitive motor dissociation; consciousness; covert awareness; functional locked-in; minimally conscious state; non-behavioral MCS; unresponsive wakefulness syndrome; vegetative state.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
PRISMA flow diagram.
Figure 2
Figure 2
Year of publication (between 2006 and 2020) of the 161 relevant manuscripts included in our systematic review.
See this image and copyright information in PMC

References

    1. Annen J., Laureys S., Gosseries O. (2020). Brain-computer interfaces for consciousness assessment and communication in severely brain-injured patients. Handb. Clin. Neurol. 168, 137–152. 10.1016/B978-0-444-63934-9.00011-1 - DOI - PubMed
    1. Bruno M. A., Vanhaudenhuyse A., Thibaut A., Moonen G., Laureys S. (2011). From unresponsive wakefulness to minimally conscious PLUS and functional lockedin syndromes: recent advances in our understanding of disorders of consciousness. J. Neurol. 258, 1373–1384. 10.1007/s00415-011-6114-x - DOI - PubMed
    1. Edlow B. L., Chatelle C., Spencer C. A., Chu C. J., Bodien Y. G., O'Connor K. L., et al. . (2017). Early detection of consciousness in patients with acute severe traumatic brain injury. Brain 140, 2399–2414. 10.1093/brain/awx176 - DOI - PMC - PubMed
    1. Fernández-Espejo D., Rossit S., Owen A. M. (2015). A thalamocortical mechanism for the absence of overt motor behavior in covertly aware patients. JAMA Neurol. 72, 1442–1450. 10.1001/jamaneurol.2015.2614 - DOI - PubMed
    1. Formisano R., D'Ippolito M., Catani S. (2013). Functional locked-in syndrome as recovery phase of vegetative state. Brain Inj. 27, 1332. 10.3109/02699052.2013.809555 - DOI - PubMed

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