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See detailLes expériences de mort imminente: Que nous apprennent les neurosciences?
Martial, Charlotte ULiege

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See detailFrom unconscious to conscious: a spectrum of states
Barra, Alice ULiege; Carrière, Manon ULiege; LAUREYS, Steven ULiege et al

in Overgaard, M; Mogensen, J; Kirkeby-Hinrup, A (Eds.) Beyond the Neural Correlates of Consciousness (in press)

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See detailLes expériences de mort imminente
Cassol, Helena ULiege; Martial, Charlotte ULiege; Laureys, Steven ULiege et al

in MethIS (in press)

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See detailLes expériences de mort imminente : où en est la recherche ?
Martial, Charlotte ULiege

Conference given outside the academic context (2019)

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See detailLes expériences de mort imminente
Martial, Charlotte ULiege

Conference given outside the academic context (2019)

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See detailLes expériences de mort imminente: que nous apprennent les neurosciences?
Martial, Charlotte ULiege

Conference (2019, March 30)

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See detailDiagnostic accuracy of a CRS-R modified score in patients with disorders of consciousness.
Annen, Jitka ULiege; Filippini, Maria Maddalena ULiege; Bonin, Estelle ULiege et al

in Brain Injury (2019, March 16)

Introduction The Coma Recovery Scale-Revised (CRS-R) is the gold standard diagnostic tool for assessing patients with disorders of consciousness (DOC) after severe acquired brain injury (Giacino, Kalmar ... [more ▼]

Introduction The Coma Recovery Scale-Revised (CRS-R) is the gold standard diagnostic tool for assessing patients with disorders of consciousness (DOC) after severe acquired brain injury (Giacino, Kalmar and Whyte, 2004; Seel et al., 2010). Differential diagnosis of DOC includes the unresponsive wakefulness syndrome (UWS;(Laureys et al., 2010)), characterized by the recovery of eye-opening but no behavioral evidence of self or environmental awareness, and the minimally conscious state (MCS; (Giacino et al., 2002)) defined by clearly discernible but inconsistent behavioral signs of conscious awareness. The CRS-R assesses reflexes and cognitively mediated behavior in six domains, namely auditory (4 items), visual (5 items), motor (6 items), oromotor (3 items), communication (2 items) and arousal (3 items). Items in every subscale are hierarchically ordered (i.e. reflexive to cognitively-mediated behaviors; higher level behaviors correspond to higher level of neurologic functioning and ability to demonstrate lower-level behaviors or disappearance of pathological behaviors as sign of recovery) and can be used to infer the patient’s level of consciousness (La Porta et al., 2013; Gerrard, Zafonte and Giacino, 2014). Several studies on DOC investigating markers of consciousness, recovery and treatment used the CRS-R total score (i.e. addition of the highest scores reached for each subscale) as regressor in neuroimaging analyses (Bruno et al., 2012; Thibaut et al., 2012; Margetis et al., 2014; Bagnato et al., 2015). However, ignoring the hierarchy of the subscales in the CRS-R total score reduces the sensitivity for the diagnosis of MCS patients (i.e., 100% specificity for UWS but false negative diagnostic error of 22%, with a cut-off CRS-R total score of 10 (Bodien et al., 2016)). In addition, the ordinal nature of the CRS-R total score make it limited to use with parametric statistical tests (e.g., requiring normal distribution). A solution to this problem has been proposed by Sattin and colleagues (2015) who computed a CRS-R modified score (CRS-R MS1), by considering reflexes and cognitively mediated behaviors separately, reliably distinguishing between UWS and MCS patients. These authors also argue that the interpretation of the total CRS-R scores is limited due to “the underlying assumption that if a patient is able to show higher-level behaviors, he/she is also able to show lower-level responses”. Sattin et al. (2015) propose to account for the number of presented responses in every subscale (i.e., every items in a subscale should be assessed and scored). One major drawback to this approach is that according to the CRS-R guidelines, the assessor should start assessing the highest item and move to the next subscale once an item is scored, in line with the hierarchical organization of the scale. This means that, if the CRS-R is performed according to the guidelines (for which the CRS-R has been validated), the CRS-R modified score cannot be calculated. Even if assessing all items might be valid, it is unlikely to be done in many clinical and research settings as it would increase assessment time and fatigue the patient. We here propose to adapt the CRS-R MS1 by considering only the highest score reached on every subscale, respecting the CRS-R guidelines. Methods One-hundred twenty-four patients admitted to the University Hospital of Liège were assessed multiple times with the CRS-R, at least once including the assessment of all items. Patients for whom the CRS-R assessment including all items provided the same diagnosis as the patient’s final diagnosis were selected. The study was approved by the ethics committee of the University Hospital of Liège and the legal guardians of patients gave written informed consent for participation in the study, in accordance with the Declaration of Helsinki. The CRS-R total score and two CRS-R MS were calculated for every patient. The CRS-R MS combines scores for reflexes and cognitive behaviors of every CRS-R subscale which can be used to obtain the CSR-R MS from a transposition matrix. The CRS-R MS1 was calculated as previously described (Sattin et al., 2015), and the CRS-R MS2 only used the highest score in every subscale (i.e., assuming that lower items were successful). Statistics were performed in R (R Core team, 2012). We assessed group differences in age (two sample t-test), time since injury (two sample t-test) and etiology (χ2 test). Receiver Operating Characteristic were calculated to obtain the sensitivity and specificity at several classification thresholds (package pROC (Robin et al., 2011)). We calculated the correlation between the CRSR MS1 and CRSR MS2 using Pearson correlation, and both scores with the CRS-R total score using Spearman correlation. Finally, we used a Kolmogorov-Smirnoff test to evaluate whether CRSR MS1 and CRSR MS2 come from different distributions (i.e., if one approach provides additional information over the other). Results Eighty-five MCS patients (26 females; mean age 40.4 (SD±17.4) years old; 43 traumatic; mean time since injury 2.7 (SD±4.0) years) and 39 UWS patients (14 females; mean age 50.6 (SD±16.5) years old; 29 traumatic; mean time since injury 1.2 (SD±1.8) years) were included in the study. MCS patients were older (t(77.6)-3.15, p<0.002 95%CI[-16.7, -3.7]), were in a more chronic stage (t(121.9)=2.9, p = 0.005, 95%CI[974,427]), and suffered more often from a traumatic brain injury (χ2=6.8, p = 0.01) than UWS patients. The ROC analysis for both MS showed an AUC of 1 (cut-off:8.315, 100% specificity and sensitivity). The ROC analysis for the CRS-R total score showed an AUC of 0.94 (cut-off:9, sensitivity = 100%, specificity = 67%). A correlation was found between the CRSR total score and both the CRSR MS1 (r = 0.94, p < 0.0001, figure 1A) and CRSR MS2 (r = 0.96, p < 0.0001, figure 1B). The two CRS-R MS correlated (r = 0.96, p = 0.0001, figure 1C). CRSR MS1 and CRSR MS2 were drawn from the same distribution (D(124)= 0.13, p = 0.25). Discussion CRSR MS2 correlated strongly with the CRSR MS1, and perfectly discriminated UWS from MCS patients. As for accurate diagnosis the CRS-R should be repeated (preferably five times (Wannez et al., 2018)) short assessments are preferred, and possibly also reduce effects of fatigue. Second, the CRSR MS2 can be calculated with CRS-R assessments performed according to the CRS-R guidelines, facilitating its use in clinical environments, and in research settings where CRSR MS2 can be used pro- and retrospectively for research protocols. Furthermore, the results indicate that the two modified scores share the same distribution. This suggests that assessing all CRS-R items as proposed previously does not significantly contribute to the stratification of patients. The CRSR MS2 code is available via: Github A remaining limitation of the proposed score is that it does not allow to distinguish MCS minus (i.e. showing language independent signs of awareness, like visual pursuit) from MCS plus (i.e. showing language dependent signs of awareness) patients, or emergence from MCS. However, a clear consensus about the diagnostic criteria is needed before an updated modified score can be provided. In conclusion, the current analyses show that the calculation of the CRS-R modified score using the highest item in every subscale is valid for clinical diagnosis, and provides perspective for its use for research. Figure Figure 1. Correlation between the CRS-R total score and the CRS-R MS1 (1A), CRSR MS2 (1B), and between the two modified CRS-R scores (1C). MCS plus patients are here characterized by command following, intelligible verbalization and/or intentional communication. Acknowledgements This project has received funding from the University and University Hospital of Liege, the Belgian National Funds for Scientific Research (FRS-FNRS), the European Union’s Horizon 2020 Framework Programme for Research and Innovation under the Specific Grant Agreement No. 785907 (Human Brain Project SGA2) the Luminous project (EU-H2020-fetopenga686764), the Center-TBI project (FP7-HEALTH- 602150), the Public Utility Foundation ‘Université Européenne du Travail’, “Fondazione Europea di Ricerca Biomedica”, the Bial Foundation, the Mind Science Foundation and the European Commission, the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 778234, European Space Agency (ESA) and the Belgian Federal Science Policy Office (BELSPO) for their support in the framework of the PRODEX Programme. CC is a post-doctoral Marie Sklodowska-Curie fellow (H2020-MSCA-IF-2016-ADOC-752686), and SL is research director at FRS-FNRS. We are highly grateful to the members of the Liège Coma Science Group for their assistance in clinical evaluations, and we thank all the patients and their families and the Neurology department of the University hospital of Liège. [less ▲]

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See detailIs auditory localization a sign of consciousness? Evidence from neuroimaging and electrophysiology
Carrière, Manon ULiege; Cassol, Helena ULiege; Aubinet, Charlène ULiege et al

Conference (2019, March 16)

Background Auditory localization is often part of the clinical evaluation of patients recovering from coma. There is however no clear consensus whether it should be considered as a reflex or as a ... [more ▼]

Background Auditory localization is often part of the clinical evaluation of patients recovering from coma. There is however no clear consensus whether it should be considered as a reflex or as a conscious behavior. For example, auditory localisation corresponds to the diagnosis of unresponsive wakefulness syndrome (UWS) in the Coma Recovery Scale-Revised, while it is considered a sign of consciousness in other post-coma scales. This study aims to determine if auditory localization reflects conscious processing in patients with disorders of consciousness. Methods We first evaluated the proportion of patients with and without auditory localisation in 186 patients with severe brain injury, including 64 UWS, 28 minimally conscious minus (MCS-), 71 minimally conscious plus (MCS+), i.e., language relatively preserved) and 23 who emerged from MCS (EMCS). We then measured brain metabolism using fluorine-18 fluorodeoxyglucose positron emission tomography, functional connectivity using magnetic resonance imaging (MRI) and high-density electroencephalography (EEG) in patients in UWS with and without auditory localization. Findings Auditory localization was observed in 12% of patients in UWS, 46% of patients in MCS-, 62% of patients in MCS+ and 78% of patients in EMCS. Brain metabolism of patients in UWS without auditory localization was mostly restricted to primary areas, whereas a more widespread activity, including associative areas, was observed in patients in UWS with auditory localisation. Brain functional connectivity was also higher in patients in UWS with auditory localisation in the frontoparietal fMRI resting state network, along with higher EEG connectivity in alpha frequency band, compared to patients without auditory localization. Finally, differences were also found regarding the outcome, as the survival rate at two years appeared to be significantly higher in UWS patients with auditory localization as compared to those without auditory localization. Interpretation. Both clinical data in post-comatose patients and neuroimaging examinations in UWS patients with and without auditory localization support the idea that auditory localization should be considered as a sign of consciousness. [less ▲]

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See detailInternational validation of the Phone Outcome Questionnaire for patients with Disorders Of Consciousness
Wolff, Audrey ULiege; Estraneo, Anna; Noé, Quique et al

Poster (2019, March 15)

Assessing the evolution of severely brain-injured patients with disorders of consciousness (DOC) with current tools like the Glasgow Outcome Scale-Extended (GOS-E) remains a challenge. At the bedside, the ... [more ▼]

Assessing the evolution of severely brain-injured patients with disorders of consciousness (DOC) with current tools like the Glasgow Outcome Scale-Extended (GOS-E) remains a challenge. At the bedside, the most reliable diagnostic tool is currently the Coma Recovery Scale-Revised. The CRS-R distinguishes patients with unresponsive wakefulness syndrome (UWS) from patients in minimally conscious state (MCS) and patients who have emerged from MCS (EMCS). This international multi-centric study aims to validate a phone outcome questionnaire (POQ) based on the CRS-R and compare it to the CRS-R performed at the bedside and to the GOS-E which evaluates the level of disability and assigns patient’s in outcomes categories. The POQ will allow clinicians to probe the evolution of patient’s state of consciousness based on caregivers feedback. This research project is part of the International Brain Injury Association, Disorders of Consciousness-Special Interest Group (DOCSIG) and DOCMA consortium. [less ▲]

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See detailNociception Coma Scale Revised allows to identify patients with preserved neural basis for pain experience.
Bonin, Estelle ULiege; Lejeune, Nicolas; Thibaut, Aurore ULiege et al

Poster (2019, March 14)

The Nociception Coma Scale-Revised (NCS-R) was developed to help assessing pain in non-communicative patients with disorders of consciousness (DOC). Several studies have shown its sensitivity in assessing ... [more ▼]

The Nociception Coma Scale-Revised (NCS-R) was developed to help assessing pain in non-communicative patients with disorders of consciousness (DOC). Several studies have shown its sensitivity in assessing responses to acute noxious stimuli. However, they failed to determine a reliable cut-off score that could be used to infer pain processing in these patients. This retrospective cross-sectional study aimed to determine an NCS-R cut-off score supporting preserved neural basis for pain experience, based on brain metabolism as measured by fluorodeoxyglucose positron emission tomography (FDG-PET). We included FDG-PET confirmed patient with unresponsive wakefulness syndrome (UWS) (n=13) and looked at their highest NCS-R total scores. As the highest score was 4, we determined the cut-off of 5 and compared the brain metabolism of these patients with matched DOC patients with a cut-off score ≥ 5 (i.e., potential pain) and healthy controls. We found a higher global cerebral metabolism in healthy subjects compared with both patients’ groups and also in patients with potential pain compared with FDG-PET confirmed UWS. We observed a preserved metabolism in the left insula in patients with potential pain when compared with FDG-PET confirmed UWS. We also found a preservation of the connectivity between the left insula and the medial frontal gyrus in patients with potential pain compared with FDG-PET confirmed UWS. Our data suggest that using the cut-off score of 5 can be helpful to improve pain management in DOC patients. Future studies should focus on patients showing scores below this cut-off to better characterize their profile and improve cares. [less ▲]

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See detailMemories of near-death experiences: are they self-defining?
Cassol, Helena ULiege; D'Argembeau, Arnaud ULiege; Charland-Verville, Vanessa ULiege et al

in Neuroscience of Consciousness (2019), 5(1),

Some people report memories of near-death experiences (NDEs) after facing situations of impending death and these memories appear to have significant consequences on their lives (here referred to as “real ... [more ▼]

Some people report memories of near-death experiences (NDEs) after facing situations of impending death and these memories appear to have significant consequences on their lives (here referred to as “real NDE experiencers”; real NDErs). We assessed to what extent NDE memories are considered self-defining: memories that help people to define clearly how they see themselves. We screened 71 participants using the Greyson NDE scale (48 real NDErs and 23 NDErs-like who had lived a similar experience in absence of a threat to their life). Participants described their two main self-defining memories (SDMs). For each SDM, they completed the Centrality of Event Scale (CES) to assess how central the event is to their identity. The two subgroups did not differ regarding the proportion of NDErs who recalled their NDE (30 real NDErs out of 48 and 11 NDErs-like out of 23). Real NDErs and NDErs-like who recalled their NDE (n ¼ 41) reported richer experiences as assessed by the Greyson NDE scale. Furthermore, these participants rated their NDE memory as more central to their identity as compared to other SDMs, and the richness of the NDE memory was positively associated to its centrality (CES scores). Overall, these findings suggest that the self-defining aspect of the experience might be related to its phenomenological content rather than its circumstances of occurrence. The self-defining status of NDE memories confirms that they constitute an important part of NDErs’ personal identity and highlights the importance for clinicians to facilitate their integration within the self. [less ▲]

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See detailNeurochemical models of near-death experiences: a large-scale study based on the semantic similarity of written reports
Martial, Charlotte ULiege; Cassol, Helena ULiege; Charland-Verville, Vanessa ULiege et al

in Consciousness and Cognition (2019)

The real or perceived proximity to death often results in a non-ordinary state of consciousness characterized by phenomenological features such as the perception of leaving the body boundaries, feelings ... [more ▼]

The real or perceived proximity to death often results in a non-ordinary state of consciousness characterized by phenomenological features such as the perception of leaving the body boundaries, feelings of peace, bliss and timelessness, life review, the sensation of traveling through a tunnel and an irreversible threshold. Near-death experiences (NDEs) are comparable among individuals of different cultures, suggesting an underlying neurobiological mechanism. Anecdotal accounts of the similarity between NDEs and certain drug-induced altered states of consciousness prompted us to perform a large-scale comparative analysis of these experiences. After assessing the semantic similarity between ≈15,000 reports linked to the use of 165 psychoactive substances with 625 NDE narratives, we determined that the N-methyl-D-aspartate (NMDA) receptor antagonist ketamine consistently resulted in reports most similar to those associated with NDEs. Ketamine was followed by Salvia divinorum (a plant containing a potent and selective κ receptor agonist) and a series of serotonergic psychedelics, including the endogenous serotonin 2A receptor agonist N,N Dimethyltryptamine (DMT). This similarity was driven by semantic concepts related to consciousness of the self and the environment, but also by those associated with the therapeutic, ceremonial and religious aspects of drug use. Our analysis sheds light on the long-standing link between certain drugs and the experience of “dying“, suggests that ketamine could be used as a safe and reversible experimental model for NDE phenomenology, and supports the speculation that endogenous NMDA antagonists with neuroprotective properties may be released in the proximity of death. [less ▲]

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See detailHuman consciousness is supported by dynamic complex patterns of brain signal coordination
Demertzi, Athina ULiege; Tagliazucchi, Enzo; Dehaene, S et al

in Science Advances (2019), 5(2), 7603

Adopting the framework of brain dynamics as a cornerstone of human consciousness, we determined whether dynamic signal coordination provides specific and generalizable patterns pertaining to conscious and ... [more ▼]

Adopting the framework of brain dynamics as a cornerstone of human consciousness, we determined whether dynamic signal coordination provides specific and generalizable patterns pertaining to conscious and unconscious states after brain damage. A dynamic pattern of coordinated and anticoordinated functional magnetic resonance imaging signals characterized healthy individuals and minimally conscious patients. The brains of unresponsive patients showed primarily a pattern of low interareal phase coherence mainly mediated by structural connectivity, and had smaller chances to transition between patterns. The complex pattern was further corroborated in patients with covert cognition, who could perform neuroimaging mental imagery tasks, validating this pattern’s implication in consciousness. Anesthesia increased the probability of the less complex pattern to equal levels, validating its implication in unconsciousness. Our results establish that consciousness rests on the brain’s ability to sustain rich brain dynamics and pave the way for determining specific and generalizable fingerprints of conscious and unconscious states. [less ▲]

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See detailLes états altérés de conscience : où en est la recherche ?
Martial, Charlotte ULiege

Conference given outside the academic context (2018)

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See detailNear-death experiences Are they self-defining?
Cassol, Helena ULiege; D'Argembeau, Arnaud ULiege; Charland-Verville, Vanessa ULiege et al

Poster (2018, October 19)

Background: Near-Death Experiences (NDEs) are profound psychological events with highly emotional and self-related content, typically encompassing transcendental and mystical elements and occurring when ... [more ▼]

Background: Near-Death Experiences (NDEs) are profound psychological events with highly emotional and self-related content, typically encompassing transcendental and mystical elements and occurring when people come close to death (Greyson, 2000). These experiences appear to have significant consequences on peoples’ lives (so-called "NDE experiencers" or "NDErs"; e.g., Noyes, 1980). Given their documented life-transforming effects and their reported importance, NDE memories appear to share similarities with a particular type of autobiographical memories referred to as a self-defining memories (SDMs; Blagov and Singer, 2004). SDMs are the building blocks of identity (Blagov and Singer, 2004) and contribute, in particular, to the sense of self-continuity (Conway et al., 2004) which represents the ability to consider oneself as an entity that extends back into the past and forward into the future (Chandler, 1994). <br />Objectives: This study aimed at 1) assessing if NDE memories are considered as SDMs and 2) determining whether the potential self-defining dimension of NDEs is due to their phenomenal content or their circumstances of appearance (i.e., presence or absence of impeding death). <br />Methods: 71 participants were screened using the Greyson NDE scale (48 real NDErs and 23 NDErs-like who had lived a similar experience in absence of life threat; Greyson, 1983). This 16-item multiple-choice validated scale enables to quantify the richness of the experience (scores ranging from 0 to 32) and allows a standardized identification of NDEs (cut-off score of 7). Participants described their two main self-defining memories (SDMs) and completed the Centrality of Event Scale (CES; Berntsen and Rubin, 2006) for each one of them. The CES is a 20-item scale (scores ranging from 0 to 100) designed to assess how central the event is to their identity. Proportions of NDErs who recalled their NDE were calculated for each subgroup (real NDErs and NDErs-like) and a Pearson’s chi square test was performed to compare ratios between them. Later, all participants were divided into two subgroups depending on whether or not they recalled their NDE (no matter its context of occurrence; "NDE recalled" and "NDE not recalled"). The last step of analyses focused on the CES scale and was only carried out on the “NDE recalled” subgroup. Differences in CES total scores between the NDE memory and the other SDM were assessed using a Student’s t-test. Additionally, a Spearman’s correlation was performed to examine associative strength between CES and Greyson NDE scale total scores. <br />Results: Real NDErs and NDErs-like did not differ regarding the proportion of NDErs who recalled their NDE (30 real NDErs out of 48 and 11 NDErs-like out of 23; p=0.24), suggesting that the self-defining aspect of the experience could be explained by its phenomenological content rather than context of occurrence. These participants (n=41) rated the NDE memory as more central to their identity as compared to the other SDM (p<0.001). Furthermore, the richness of the NDE memory (Greyson NDE scale scores) was positively associated to its centrality (CES scores; p<0.01). <br />Conclusions: The self-defining status of NDE memories confirms that they constitute an important part of NDErs’ personal identity and highlights the importance for clinicians to facilitate their integration within the self. SDMs are indeed essential to one’s sense of self-continuity, which is crucial for psychological well-being. [less ▲]

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See detailConsciousness and near-death experiences: what is known, what is new
Martial, Charlotte ULiege

Conference given outside the academic context (2018)

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See detailA Heartbeat Away From Consciousness: Heart Rate Variability Entropy can discriminate disorders of consciousness and is correlated with resting-state fMRI brain connectivity of the Central Autonomic Network
Riganello, Francesco ULiege; Larroque, Stephen Karl ULiege; Bahri, Mohamed Ali ULiege et al

Poster (2018, October)

Motivation: Heart rate variability (HRV) reflects the heart-brain two-way dynamic interactions[1-5]. HRV entropy analysis quantifies the unpredictability and complexity of the heart rate beats intervals ... [more ▼]

Motivation: Heart rate variability (HRV) reflects the heart-brain two-way dynamic interactions[1-5]. HRV entropy analysis quantifies the unpredictability and complexity of the heart rate beats intervals and over multiple time scales using multiscale entropy (MSE)[6-8]. The complexity index (CI) provides a score of a system’s complexity by aggregating the MSE measures over a range of time scales[8]. Most HRV entropy studies have focused on acute traumatic patients using task-based designs[9]. We here investigate the CI and its discriminative power in chronic patients with unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS) at rest, and its relation to brain functional connectivity. Methods: We investigated the CI in short (CIs) and long (CIl) time scales in 16 UWS and 17 MCS sedated. CI for MCS and UWS groups were compared using a Mann-Whitney exact test. Spearman’s correlation tests were conducted between the Coma Recovery Scale-revised (CRS-R) and both CI. Discriminative power of both CI was assessed with One-R machine learning model. Correlation between CI and brain connectivity (detected with functional magnetic resonance imagery using seed-based and hypothesis-free intrinsic connectivity) was investigated using a linear regression in a subgroup of 12 UWS and 12 MCS patients with sufficient image quality. Results and Discussion: Significant differences were found between MCS and UWS for CIs and CIl (0.0001≤p≤0.006). Significant correlations were found between CRS-R and CIs and CIl (0.0001≤p≤0.026). The One-R classifier selected CIl as the best discriminator between UWS and MCS with 85% accuracy, 19% false positive rate and 12% false negative rate after a 10-fold cross-validation test. Positive correlations were observed between CI and brain areas belonging to the autonomic system. CI was found to be significantly higher in MCS compared to UWS patients, with high discriminative power and lower false negative rate than the reported misdiagnosis rate of human assessors, providing an easy, inexpensive and non-invasive diagnosis tool. CI is correlated to functional connectivity changes in brain regions belonging to the autonomic nervous system, suggesting that CI can provide an indirect way to screen and monitor connectivity changes in this neural system. Future studies should investigate further the extent of CI’s predictive power for other pathologies in the disorders of consciousness spectrum. [less ▲]

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See detailUn si brillant cerveau: les états limites de conscience
Martial, Charlotte ULiege

Conference given outside the academic context (2018)

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See detailA Heartbeat Away From Consciousness: Heart Rate Variability Entropy Can Discriminate Disorders of Consciousness and Is Correlated With Resting-State fMRI Brain Connectivity of the Central Autonomic Network
Riganello, Francesco ULiege; Larroque, Stephen Karl ULiege; Bahri, Mohamed Ali ULiege et al

in Frontiers in Neurology (2018), 9

Background: Disorders of consciousness are challenging to diagnose, with inconsistent behavioral responses, motor and cognitive disabilities, leading to approximately 40% misdiagnoses. Heart rate ... [more ▼]

Background: Disorders of consciousness are challenging to diagnose, with inconsistent behavioral responses, motor and cognitive disabilities, leading to approximately 40% misdiagnoses. Heart rate variability (HRV) reflects the complexity of the heart-brain two-way dynamic interactions. HRV entropy analysis quantifies the unpredictability and complexity of the heart rate beats intervals. We here investigate the complexity index (CI), a score of HRV complexity by aggregating the non-linear multi-scale entropies over a range of time scales, and its discriminative power in chronic patients with unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS), and its relation to brain functional connectivity. Methods: We investigated the CI in short (CIs) and long (CIl) time scales in 14 UWS and 16 MCS sedated. CI for MCS and UWS groups were compared using a Mann-Whitney exact test. Spearman's correlation tests were conducted between the Coma Recovery Scale-revised (CRS-R) and both CI. Discriminative power of both CI was assessed with One-R machine learning model. Correlation between CI and brain connectivity (detected with functional magnetic resonance imagery using seed-based and hypothesis-free intrinsic connectivity) was investigated using a linear regression in a subgroup of 10 UWS and 11 MCS patients with sufficient image quality. Results: Higher CIs and CIl values were observed in MCS compared to UWS. Positive correlations were found between CRS-R and both CI. The One-R classifier selected CIl as the best discriminator between UWS and MCS with 90% accuracy, 7% false positive and 13% false negative rates after a 10-fold cross-validation test. Positive correlations were observed between both CI and the recovery of functional connectivity of brain areas belonging to the central autonomic networks (CAN). Conclusion: CI of MCS compared to UWS patients has high discriminative power and low false negative rate at one third of the estimated human assessors' misdiagnosis, providing an easy, inexpensive and non-invasive diagnostic tool. CI reflects functional connectivity changes in the CAN, suggesting that CI can provide an indirect way to screen and monitor connectivity changes in this neural system. Future studies should assess the extent of CI's predictive power in a larger cohort of patients and prognostic power in acute patients. [less ▲]

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