Publications of Olivier BODART
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See detailPrevalence of signs of nociception during physiotherapy in patient with disorders of consciousness.
Bonin, Estelle ULiege; Fossati, Mariachiara; Filippini, Maria Maddalena et al

Conference (2020, March 05)

Patients with disorders of consciousness (DOC) may suffer from neuro-orthopaedics disorders that can lead to potential pain during physiotherapy (PT). These patients are unable to communicate it is ... [more ▼]

Patients with disorders of consciousness (DOC) may suffer from neuro-orthopaedics disorders that can lead to potential pain during physiotherapy (PT). These patients are unable to communicate it is therefore a real challenge for clinicians to assess pain and adapt treatment. This randomized double-blind placebo-controlled study aimed to investigate the prevalence of signs of nociception during PT and their changes in relation to a pain-killer. During baseline (D0), pain responsiveness was assessed using the NCS-R (Nociception Coma Scale-Revised): at rest; during a tactile stimulation (TS); during a nociceptive stimulation (NS); and during PT. Then, patient with signs of potential pain during PT was assessed during a placebo and a pain-killer condition (D1 and D2). Our results show that most DOC patients present signs of potential pain during PT (14/19; 73.4%), and a few of them already received analgesic treatment before the study (5/14, 35.7%). During baseline, we found significant differences between the NCS-R score during PT than the three others stimulation, suggesting that passive mobilizations are potentially painful for DOC patient. These difference remains during placebo and treatment condition expect with the NS. We do not found an effect of pain-killer on the NCS-R score during PT and NS. This could be explained by the fact that the NCS-R failed to detect the effect of pain-killer or that this effect was not strong enough. This study point-out that PT may be painful for DOC patients and appropriate assessment and treatment before and during mobilizations should become a priority in clinical setting. [less ▲]

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See detailGeneral Anesthesia: A Probe to Explore Consciousness
BONHOMME, Vincent ULiege; STAQUET, Cécile ULiege; Montupil, Javier ULiege et al

in Frontiers in Systems Neuroscience (2019)

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See detail2 EEG-based methods for the diagnosis of disorders of consciousness
Sanz, Leandro ULiege; Wolff, Audrey ULiege; Fecchio, Matteo et al

Poster (2019, May 17)

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See detailA fast and general method to empirically estimate the complexity of brain responses to transcranial and intracranial stimulations.
Comolatti, Renzo; Pigorini, Andrea; Casarotto, Silvia et al

in Brain Stimulation (2019), 12(5), 1280-1289

BACKGROUND: The Perturbational Complexity Index (PCI) was recently introduced to assess the capacity of thalamocortical circuits to engage in complex patterns of causal interactions. While showing high ... [more ▼]

BACKGROUND: The Perturbational Complexity Index (PCI) was recently introduced to assess the capacity of thalamocortical circuits to engage in complex patterns of causal interactions. While showing high accuracy in detecting consciousness in brain-injured patients, PCI depends on elaborate experimental setups and offline processing, and has restricted applicability to other types of brain signals beyond transcranial magnetic stimulation and high-density EEG (TMS/hd-EEG) recordings. OBJECTIVE: We aim to address these limitations by introducing PCI(ST), a fast method for estimating perturbational complexity of any given brain response signal. METHODS: PCI(ST) is based on dimensionality reduction and state transitions (ST) quantification of evoked potentials. The index was validated on a large dataset of TMS/hd-EEG recordings obtained from 108 healthy subjects and 108 brain-injured patients, and tested on sparse intracranial recordings (SEEG) of 9 patients undergoing intracranial single-pulse electrical stimulation (SPES) during wakefulness and sleep. RESULTS: When calculated on TMS/hd-EEG potentials, PCI(ST) performed with the same accuracy as the original PCI, while improving on the previous method by being computed in less than a second and requiring a simpler set-up. In SPES/SEEG signals, the index was able to quantify a systematic reduction of intracranial complexity during sleep, confirming the occurrence of state-dependent changes in the effective connectivity of thalamocortical circuits, as originally assessed through TMS/hd-EEG. CONCLUSIONS: PCI(ST) represents a fundamental advancement towards the implementation of a reliable and fast clinical tool for the bedside assessment of consciousness as well as a general measure to explore the neuronal mechanisms of loss/recovery of brain complexity across scales and models. [less ▲]

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See detailEvaluation of the effect of TDCS on TMS-EEG responses in patients with disorders of consciousness
Mensen, Armand ULiege; BODART, Olivier ULiege; Thibaut, Aurore ULiege et al

in Frontiers in Neuroscience (2018, June 21)

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See detailPCI & Auditory ERPs for the diagnosis of disorders of consciousness: a EEG-based methods comparison study
Blandiaux, Séverine ULiege; Raimondo, Federico ULiege; Wolff, Audrey ULiege et al

Conference (2018, June 15)

INTRODUCTION Diagnosing the level of consciousness in patients suffering from severe brain lesions is still a major challenge. EEG-based systems can help discriminate conscious from unconscious patients ... [more ▼]

INTRODUCTION Diagnosing the level of consciousness in patients suffering from severe brain lesions is still a major challenge. EEG-based systems can help discriminate conscious from unconscious patients. This study aims to confront the results from two of the most reliable methods: the Perturbational Complexity Index (PCI) which is based on Transcranial Magnetic Stimulation (TMS-EEG), and a recent machine learning approach using EEG-extracted markers from a standardized oddball auditory stimulation paradigm (EEG-ERP). METHODS Patients presenting either an unresponsive wakefulness syndrome (UWS), a minimally conscious state (MCS) or an emergence of MCS (EMCS) underwent both TMS-EEG and EEG-ERP. We computed PCI value by compressing the spatiotemporal pattern of cortical responses to the perturbation of the cortex with TMS. For EEG-ERP, we extracted 60 markers corresponding to quantification of power spectrum and complexity in individual EEG sensors and information sharing between them. Using machine-learning, we predicted the individual probability of being (minimally) conscious. RESULTS PCI and EEG markers, when considered categorically (i.e. UWS vs MCS), were consistent for all UWS and EMCS patients, whereas the results for MCS patients showed less consistency. Nevertheless, we found a significant correlation between PCI values and the probability of being conscious with the multivariate classifier. CONCLUSION PCI correlated positively with the combination of EEG markers in severely brain-injured patients. These findings imply that EEG signatures of consciousness can be reliably extracted from different contexts and combined into coherent predictive models, encouraging future efforts in large-scale data-driven clinical neuroscience. [less ▲]

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See detailGlobal structural integrity and effective connectivity in patients with disorders of consciousness
BODART, Olivier ULiege; Amico, Enrico; Gomez, Francisco et al

in Brain Stimulation (2018)

Background Previous studies have separately reported impaired functional, structural, and effective connectivity in patients with disorders of consciousness (DOC). The perturbational complexity index (PCI ... [more ▼]

Background Previous studies have separately reported impaired functional, structural, and effective connectivity in patients with disorders of consciousness (DOC). The perturbational complexity index (PCI) is a transcranial magnetic stimulation (TMS) derived marker of effective connectivity. The global fractional anisotropy (FA) is a marker of structural integrity. Little is known about how these parameters are related to each other. Objective We aimed at testing the relationship between structural integrity and effective connectivity. Methods We assessed 23 patients with severe brain injury more than 4 weeks post-onset, leading to DOC or locked-in syndrome, and 14 healthy subjects. We calculated PCI using repeated single pulse TMS coupled with high-density electroencephalography, and used it as a surrogate of effective connectivity. Structural integrity was measured using the global FA, derived from diffusion weighted imaging. We used linear regression modelling to test our hypothesis, and computed the correlation between PCI and FA in different groups. Results Global FA could predict 74% of PCI variance in the whole sample and 56% in the patients' group. No other predictors (age, gender, time since onset, behavioural score) improved the models. FA and PCI were correlated in the whole population (r = 0.86, p < 0.0001), the patients, and the healthy subjects subgroups. Conclusion We here demonstrated that effective connectivity correlates with structural integrity in brain-injured patients. Increased structural damage level decreases effective connectivity, which could prevent the emergence of consciousness. [less ▲]

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See detailNeuronal surface antibody-mediated encephalopathy as manifestation of chronic graft-versus-host disease after allogeneic hematopoietic stem cell transplantation
Pirotte, Michelle ULiege; Forte, Florence ULiege; Lutteri, Laurence ULiege et al

in Journal of Neuroimmunology (2018), 323

Although it remained controversial for a long time, central nervous system (CNS) involvement of graft-versus-host disease (GVHD) is now becoming recognized as a real nosological entity. Previous case ... [more ▼]

Although it remained controversial for a long time, central nervous system (CNS) involvement of graft-versus-host disease (GVHD) is now becoming recognized as a real nosological entity. Previous case reports have suggested heterogeneous clinical presentations and it is not excluded that the whole spectrum of manifestations has not yet been fully described. Here, we report the case of a 58-year-old man with chronic GVHD who developed a rapidly ingravescent encephalopathy. There was no evidence for CNS immune-mediated lesions on conventional imaging nor for cellular infiltration in the cerebrospinal fluid. Serum analyses revealed the presence of anti-neuronal antibodies directed against anti-contactin-associated protein 2 (anti-Caspr2), a protein associated with voltage-gated potassium neuronal channels. Functional imaging with 2-deoxy-2-[fluorine-18] fluoro- D-glucose integrated with computed tomography (18F-FDG PET-CT) demonstrated diffuse cortical and subcortical hypometabolism. The patient was treated with a combination of immunosuppressive agents (corticosteroids, cyclophosphamide and rituximab) and progressively recovered normal neurocognitive functions. Taken together, these data suggest that CNS-GVHD may manifest as a reversible antibody-mediated functional encephalopathy. This report suggests for the first time the interest of screening for anti-neuronal antibodies and functional imaging with brain 18F-FDG PET-CT in diagnosing this severe complication of allogeneic hematopoietic cell transplantation (alloHSCT). © 2018 Elsevier B.V. [less ▲]

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See detailResistance to eye opening in patients with disorders of consciousness
van Ommen, H. J.; Thibaut, Aurore ULiege; VANHAUDENHUYSE, Audrey ULiege et al

in Journal of Neurology (2018)

Introduction: Resistance to eye opening (REO) is a commonly encountered phenomenon in clinical practice. We aim to investigate whether REO is a sign of consciousness or a reflex in severely brain-injured ... [more ▼]

Introduction: Resistance to eye opening (REO) is a commonly encountered phenomenon in clinical practice. We aim to investigate whether REO is a sign of consciousness or a reflex in severely brain-injured patients. Methods: We recorded REO in chronic patients with disorders of consciousness during a multimodal diagnostic assessment. REO evaluations were performed daily in each patient and clinical diagnosis of unresponsive wakefulness syndrome (UWS), minimally conscious state with (MCS+) or without (MCS−) preserved language processing was made using the Coma Recovery Scale-Revised (CRS-R). Results: Out of 150 consecutive patients, 79 patients fit inclusion criteria. REO was seen in 19 patients (24.1%). At the group level, there was a significant relationship between the presence of REO and the level of consciousness. We also observed a difference in the repeatability of REO between patients in UWS, MCS− and MCS+. Out of 23 patients in UWS, six showed REO, in whom five showed atypical brain patterns activation. Conclusion: Our findings suggest a voluntary basis for REO and stress the need for multiple serial assessments of REO in these patients, especially since most patients show fluctuating levels of consciousness. © 2018 Springer-Verlag GmbH Germany, part of Springer Nature [less ▲]

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See detailResistance to eye opening in patients with disorders of consciousness.
van Ommen, H.; Thibaut, Aurore ULiege; VANHAUDENHUYSE, Audrey ULiege et al

Poster (2018)

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See detailPrevalence of coma-recovery scale-revised signs of consciousness in patients in minimally conscious state
Wannez, Sarah ULiege; Gosseries, Olivia ULiege; Azzolini, Deborah et al

in Neuropsychological Rehabilitation (2018), 28(8), 1350-1359

Different behavioural signs of consciousness can distinguish patients with an unresponsive wakefulness syndrome from patients in minimally conscious state (MCS). The Coma Recovery Scale-Revised (CRS-R) is ... [more ▼]

Different behavioural signs of consciousness can distinguish patients with an unresponsive wakefulness syndrome from patients in minimally conscious state (MCS). The Coma Recovery Scale-Revised (CRS-R) is the most sensitive scale to differentiate the different altered states of consciousness and eleven items detect the MCS. The aim of this study is to document the prevalence of these items. We analysed behavioural assessments of 282 patients diagnosed in MCS based on the CRS-R. Results showed that some items are particularly frequent among patients in MCS, namely fixation, visual pursuit, and reproducible movement to command, which were observed in more than 50% of patients. These responses were also the most probably observed items when the patients only showed one sign of consciousness. On the other hand, some items were rarely or never observed alone, e.g., object localisation (reaching), object manipulation, intelligible verbalisation, and object recognition. The results also showed that limiting the CRS-R assessment to the five most frequently observed items (i.e., fixation, visual pursuit, reproducible movement to command, automatic motor response and localisation to noxious stimulation) detected 99% of the patients in MCS. If clinicians have only limited time to assess patients with disorders of consciousness, we suggest to evaluate at least these five items of the CRS-R. © 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group. [less ▲]

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See detailMeditation-induced modulation of brain response to transcranial magnetic stimulation
BODART, Olivier ULiege; Fecchio, M.; Massimini, Marcello et al

in Brain Stimulation (2018), 11(6), 1397-1400

[No abstract available]

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See detailSleep-like cortical OFF-periods disrupt causality and complexity in the brain of unresponsive wakefulness syndrome patients
Rosanova, Mario; Fecchio, M.; Casarotto, Silvia et al

in Nature Communications (2018), 9(1),

Unresponsive wakefulness syndrome (UWS) patients may retain intact portions of the thalamocortical system that are spontaneously active and reactive to sensory stimuli but fail to engage in complex causal ... [more ▼]

Unresponsive wakefulness syndrome (UWS) patients may retain intact portions of the thalamocortical system that are spontaneously active and reactive to sensory stimuli but fail to engage in complex causal interactions, resulting in loss of consciousness. Here, we show that loss of brain complexity after severe injuries is due to a pathological tendency of cortical circuits to fall into silence (OFF-period) upon receiving an input, a behavior typically observed during sleep. Spectral and phase domain analysis of EEG responses to transcranial magnetic stimulation reveals the occurrence of OFF-periods in the cortex of UWS patients (N = 16); these events never occur in healthy awake individuals (N = 20) but are similar to those detected in healthy sleeping subjects (N = 8). Crucially, OFF-periods impair local causal interactions, and prevent the build-up of global complexity in UWS. Our findings link potentially reversible local events to global brain dynamics that are relevant for pathological loss and recovery of consciousness. © 2018, The Author(s). [less ▲]

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