Publications of Aurore Thibaut
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See detailDisruption in structural-functional network repertoire and time resolved subcortical-frontoparietal connectivity in disorders of consciousness
Panda, Rajanikant ULiege; THIBAUT, Aurore ULiege; Lopez-Gonzalez, Ane et al

E-print/Working paper (2021)

Understanding recovery of consciousness and elucidating its underlying mechanism is believed to be crucial in the field of basic neuroscience and medicine. Ideas such as the global neuronal workspace and ... [more ▼]

Understanding recovery of consciousness and elucidating its underlying mechanism is believed to be crucial in the field of basic neuroscience and medicine. Ideas such as the global neuronal workspace and the mesocircuit theory hypothesize that failure of recovery in conscious states coincide with loss of connectivity between subcortical and frontoparietal areas, a loss of the repertoire of functional networks states and metastable brain activation. We adopted a time-resolved functional connectivity framework to explore these ideas and assessed the repertoire of functional network states as a potential marker of consciousness and its potential ability to tell apart patients in the unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS). In addition, prediction of these functional network states by underlying hidden spatial patterns in the anatomical network, i.e. so-called eigenmodes, were supplemented as potential markers. By analysing time-resolved functional connectivity from fMRI data, we demonstrated a reduction of metastability and functional network repertoire in UWS compared to MCS patients. This was expressed in terms of diminished dwell times and loss of nonstationarity in the default mode network and fronto-parietal subcortical network in UWS compared to MCS patients. We further demonstrated that these findings co-occurred with a loss of dynamic interplay between structural eigenmodes and emerging time-resolved functional connectivity in UWS. These results are, amongst others, in support of the global neuronal workspace theory and the mesocircuit hypothesis, underpinning the role of time-resolved thalamo-cortical connections and metastability in the recovery of consciousness. [less ▲]

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See detailPosterior integration and thalamo-frontotemporal broadcasting are impaired in disorders of consciousness
Panda, Rajanikant ULiege; López-González, Ane; Gilson, Matthieu et al

E-print/Working paper (2021)

The study of the brain’s dynamical activity is opening a valuable source of assistance for the clinical diagnosis of patients with disorders of consciousness (DOC). For example, dysfunctional spread of ... [more ▼]

The study of the brain’s dynamical activity is opening a valuable source of assistance for the clinical diagnosis of patients with disorders of consciousness (DOC). For example, dysfunctional spread of naturalistic and synthetic stimuli has proven useful to characterize hampered consciousness. However, understanding of the mechanisms behind loss of consciousness following brain injury is still missing. Here, we study the propagation of endogenous and in-silico exogenous perturbations in patients with DOC, based upon directed and causal interactions estimated from resting-state fMRI. We found that patients with DOC suffer decreased capacity for neural propagation and responsiveness to events. Particularly, that loss of consciousness is related to the malfunctioning of two neural circuits: the posterior cortical regions failing to convey information, in conjunction with reduced broadcasting of information from subcortical, temporal, parietal and frontal regions. These results seed light on the mechanisms behind DOC, thus opening new possibilities for clinical applications. [less ▲]

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See detailSimplified Evaluation of CONsciousness Disorders (SECONDs) in individuals with severe brain injury: A validation study
Aubinet, Charlène ULiege; Cassol, Helena ULiege; BODART, Olivier ULiege et al

in Annals of Physical and Rehabilitation Medicine (2021), 64(5), 101432

Background The Coma Recovery Scale-Revised (CRS-R) is the gold standard to assess severely brain-injured patients with prolonged disorders of consciousness (DoC). However, the amount of time needed to ... [more ▼]

Background The Coma Recovery Scale-Revised (CRS-R) is the gold standard to assess severely brain-injured patients with prolonged disorders of consciousness (DoC). However, the amount of time needed to complete this examination may limit its use in clinical settings. Objective. We aimed to validate a new faster tool to assess consciousness in individuals with DoC. Methods This prospective validation study introduces the Simplified Evaluation of CONsciousness Disorders (SECONDs), a tool composed of 8 items: arousal, localization to pain, visual fixation, visual pursuit, oriented behaviors, command-following, and communication (both intentional and functional). A total of 57 individuals with DoC were assessed on 2 consecutive days by 3 blinded examiners: one CRS-R and one SECONDs were performed on 1 day, whereas 2 SECONDs were performed on the other day. A Mann-Whitney U test was used to compare the duration of administration of the SECONDs versus the CRS-R, and weighted Fleiss’ kappa coefficients were used to assess inter-/intra-rater reliability as well as concurrent validity. Results In the 57 participants, the SECONDs was about 2.5 times faster to administer than the CRS-R. The comparison of the CRS-R versus the SECONDs on the same day or the best of the 3 SECONDs led to “substantial” or “almost perfect” agreement (kappa coefficients ranging from 0.78 to 0.85). Intra-/inter-rater reliability also showed almost perfect agreement (kappa coefficients from 0.85 to 0.91 and 0.82 to 0.85, respectively). Conclusions The SECONDs appears to be a fast, reliable and easy-to-use scale to diagnose DoC and may be a good alternative to other scales in clinical settings where time constraints preclude a more thorough assessment. [less ▲]

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See detailNeurophysiological Biomarkers of Persistent Post-Concussive Symptoms: A Scoping Reveiw
Mortaheb, Sepehr ULiege; Filippini, Maria Maddalena; Kaux, Jean-François ULiege et al

in Frontiers in Neurology (2021), 12

Background and Objectives: Persistent post-concussive symptoms (PCS) consist of neurologic and psychological complaints persisting after a mild traumatic brain injury (mTBI). It affects up to 50% of mTBI ... [more ▼]

Background and Objectives: Persistent post-concussive symptoms (PCS) consist of neurologic and psychological complaints persisting after a mild traumatic brain injury (mTBI). It affects up to 50% of mTBI patients, may cause long-term disability, and reduce patients’ quality of life. The aim of this review was to examine the possible use of different neuroimaging modalities in PCS. Methods: Articles from Pubmed database were screened to extract studies that investigated the relationship between any neuroimaging features and symptoms of PCS. Descriptive statistics were applied to report the results. Results: A total of 80 out of 939 papers were included in the final review. Ten examined conventional MRI (30% positive finding), 24 examined diffusion weighted imaging (54.17% positive finding), 23 examined functional MRI (82.61% positive finding), nine examined electro(magneto)encephalography (77.78% positive finding), and 14 examined other techniques (71% positive finding). Conclusion: MRI was the most widely used technique, while functional techniques seem to be the most sensitive tools to evaluate PCS. The common functional patterns associated with symptoms of PCS were a decreased anti-correlation between the default mode network and the task positive network and reduced brain activity in specific areas (most often in the prefrontal cortex). Significance: Our findings highlight the importance to use functional approaches which demonstrated a functional alteration in brain connectivity and activity in most studies assessing PCS. [less ▲]

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See detailTherapies to Restore Consciousness in Patients with Severe Brain Injuries: A Gap Analysis and Future Directions
Edlow, Brian; Sanz, Leandro ULiege; Polizzotto, Len et al

in Neurocritical Care (2021), 35

Background/Objective For patients with disorders of consciousness (DoC) and their families, the search for new therapies has been a source of hope and frustration. Almost all clinical trials in patients ... [more ▼]

Background/Objective For patients with disorders of consciousness (DoC) and their families, the search for new therapies has been a source of hope and frustration. Almost all clinical trials in patients with DoC have been limited by small sample sizes, lack of placebo groups, and use of heterogeneous outcome measures. As a result, few therapies have strong evidence to support their use; amantadine is the only therapy recommended by current clinical guidelines, specifically for patients with DoC caused by severe traumatic brain injury. To foster and advance development of consciousness-promoting therapies for patients with DoC, the Curing Coma Campaign convened a Coma Science Work Group to perform a gap analysis. Methods We consider five classes of therapies: (1) pharmacologic; (2) electromagnetic; (3) mechanical; (4) sensory; and (5) regenerative. For each class of therapy, we summarize the state of the science, identify gaps in knowledge, and suggest future directions for therapy development. Results Knowledge gaps in all five therapeutic classes can be attributed to the lack of: (1) a unifying conceptual framework for evaluating therapeutic mechanisms of action; (2) large-scale randomized controlled trials; and (3) pharmacodynamic biomarkers that measure subclinical therapeutic effects in early-phase trials. To address these gaps, we propose a precision medicine approach in which clinical trials selectively enroll patients based upon their physiological receptivity to targeted therapies, and therapeutic effects are measured by complementary behavioral, neuroimaging, and electrophysiologic endpoints. Conclusions This personalized approach can be realized through rigorous clinical trial design and international collaboration, both of which will be essential for advancing the development of new therapies and ultimately improving the lives of patients with DoC. [less ▲]

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See detailEvaluation of the effect of analgesic treatment on signs of nociception-related behaviors during physiotherapy in patients with disorders of consciousness: a pilot crossover randomized controlled trial
Bonin, Estelle ULiege; Binda Fossati, Mariachiara Luisella ULiege; Filippini, Maddalena et al

in Pain (2021)

Neuro-orthopedic disorders are common in patients with disorders of consciousness (DOC) and can lead to potential pain. However, the patients' inability to communicate makes pain detection and management ... [more ▼]

Neuro-orthopedic disorders are common in patients with disorders of consciousness (DOC) and can lead to potential pain. However, the patients' inability to communicate makes pain detection and management very challenging for clinicians. In this crossover randomized double-blind placebo-controlled study, we investigated the effects of an analgesic treatment on the presence of nociception-related behaviors. At baseline, the Nociception Coma Scale-Revised (NCS-R) was performed in 3 conditions: a non-noxious stimulation, a noxious stimulation, and during a physiotherapy session. Patients with a NCS-R total score during physiotherapy equal or above the score observed after the noxious stimulation could participate to the clinical trial, as well as patients with a score above 5. They received an analgesic treatment and a placebo on 2 consecutive days in a randomized order followed by an assessment with the NCS-R. Of the 18 patients, 15 displayed signs of potential pain during physiotherapy. Patients showed higher NCS-R scores during physiotherapy compared with the other conditions, suggesting that mobilizations were potentially painful. Of these 15 patients, 10 met the criteria to participate in the placebo-controlled trial. We did not find any effect of analgesic treatment on the NCS-R scores. This study highlights that physiotherapy may be potentially painful for patients with DOC, while analgesic treatments did not reduced NCS-R scores. Therefore, careful monitoring with appropriate assessment and treatment before and during mobilization should become a priority in clinical settings. Future studies should focus on the development of assessment tools sensitive to analgesic dosage to manage pain in DOC. [less ▲]

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See detailCircadian and ultradian rhythms depend on the level of consciousness in disorders of consciousness
van der Lande, Glenn ULiege; Sanz, Leandro ULiege; Frasso, Gianluca ULiege et al

Conference (2021, June 01)

Background and aims: Eye opening in patients with disorders of consciousness (DOC) marks the onset of a cyclic pattern with and without arousal. In minimally conscious state (MCS) arousal may be ... [more ▼]

Background and aims: Eye opening in patients with disorders of consciousness (DOC) marks the onset of a cyclic pattern with and without arousal. In minimally conscious state (MCS) arousal may be accompanied with awareness, unlike in unresponsive wakefulness syndrome (UWS). The presence of circadian and/or ultradian rhythmicity in patients with DOC has not been well established. To this end, we analyzed actigraphy data with a method well-suited to account for the variable rhythms within and across days observed in this population. Methods: We collected actigraphy data from 73 subjects (19 controls, 35 MCS, 19 UWS) over seven days and performed analyses using PyActigraphy. Singular Spectrum Analysis, a data-driven technique, was used to decompose the signal into circadian and ultradian rhythms. Next, we will evaluate these results statistically and correlate patients’ clinical diagnoses using the Coma Recovery Scale-Revised with the phase of detected circadian rhythms. Results: Data cleaning resulted in exclusion of one control (5.3%), 10 MCS (28.6%) and nine UWS (45%) subject(s). Our preliminary results show that the strength of circadian and ultradian rhythms in actigraphy data decreases with consciousness from healthy controls to MCS and almost disappearing in UWS (Figure 1).Conclusion: Preservation of circadian/ultradian rhythms seems associated with the level of consciousness. Rhythms appear almost absent in UWS patients, which suggests limited behavioral evidence for a sleep/wake cycle although eye opening is observed. Overall, the use of actigraphy could contribute to clinical assessments in DOC, and although data quality might be suboptimal, acquisition can be repeated easily. [less ▲]

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See detailApomorphine therapy for patients with disorders of consciousness: a multimodal open-label study
Sanz, Leandro ULiege; Lejeune, Nicolas ULiege; Bonin, Estelle ULiege et al

Conference (2021, June 01)

Introduction: Apomorphine, a repurposed dopaminergic drug, is a promising therapy to improve the recovery of patients with disorders of consciousness (DOC), with a postulated action on the mesocircuit ... [more ▼]

Introduction: Apomorphine, a repurposed dopaminergic drug, is a promising therapy to improve the recovery of patients with disorders of consciousness (DOC), with a postulated action on the mesocircuit. This prospective open-label study aimed to confirm preliminary results on clinical efficacy and investigate its action on brain function. Methods: 6 patients with chronic DOC (4 male, 4 traumatic, 38.8 year-old average, 99 days post-onset average) received daily subcutaneous apomorphine therapy for 30 days. Multimodal monitoring was performed from 30 days before to 30 days after treatment. Outcome measures included repeated behavioural scales, high-density electroencephalography (hdEEG) and positron emission tomography (PET). Results: Compared to baseline, 3 patients improved their behavioural diagnosis during treatment, 2 additional patients improved during the 12-month follow-up and the last patient emerged before treatment start but improved on all rehabilitation scales during treatment. Mean Coma Recovery Scale-Revised scores improved during treatment (2.1 points) and 30-day washout (5.2 points) periods, compared to baseline (Table 1). Healthcare staff and family rated the patient’s clinical condition 20.5% and 30.9% better after treatment, respectively (Table 2). Alpha-band hdEEG functional connectivity measured by network centrality increased by 13.6% on average after treatment (Figure 1). Wholebrain fluorodeoxyglucose metabolism increased by 12.4% on average between PET before and after treatment. Conclusion: Multimodal improvements were observed in chronic DOC patients after a 30-day treatment regimen with apomorphine. These results suggest a beneficial action on consciousness that is associated with increased brain connectivity and metabolism. These results will need to be confirmed in a subsequent multicentre randomized placebo-controlled trial (EudraCT: 2018-003144-23; Clinicaltrials.gov: NCT03623828). [less ▲]

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See detailPreservation of brain activity in unresponsive patients identifies MCS star
Thibaut, Aurore ULiege; Panda, Rajanikant ULiege; Annen, Jitka ULiege et al

in Annals of Neurology (2021), 90(1), 89-100

Objectives: Brain-injured patients who are unresponsive at the bedside (i.e., vegetative state/unresponsive wakefulness syndrome – VS/UWS) may present brain activity similar to patients in minimally ... [more ▼]

Objectives: Brain-injured patients who are unresponsive at the bedside (i.e., vegetative state/unresponsive wakefulness syndrome – VS/UWS) may present brain activity similar to patients in minimally conscious state (MCS). This peculiar condition has been termed “nonbehavioural MCS” or “MCS*”. In the present study we aimed to investigate the proportion and underlying brain characteristics of patients in MCS*. Methods: Brain 18F-fluorodeoxyglucose Positron Emission Tomography (FDG-PET) was acquired on 135 brain-injured patients diagnosed in prolonged VS/UWS (n=48) or MCS (n=87). From an existing database, relative metabolic preservation in the fronto-parietal network (measured with standardized uptake value) was visually inspected by 3 experts. Patients with hypometabolism of the fronto-parietal network were labelled “VS/UWS”, while its (partial) preservation either confirmed the behavioural diagnosis of “MCS” or, in absence of behavioural signs of consciousness, suggested a diagnosis of “MCS*”. Clinical outcome at 1-year follow-up, functional connectivity, grey matter atrophy, and regional brain metabolic patterns were investigated in the three groups (VS/UWS, MCS* and MCS). Results: 67% of behavioural VS/UWS presented a partial preservation of brain metabolism (i.e., MCS*). Compared to VS/UWS patients, MCS* patients demonstrated a better outcome, global functional connectivity and grey matter preservation more compatible with the diagnosis of MCS. MCS* patients presented lower brain metabolism mostly in the posterior regions compared to MCS patients. Interpretation: MCS* is a frequent phenomenon that is associated with better outcome and better brain preservation than the diagnosis of VS/UWS. Complementary exams should be provided to all unresponsive patients before taking medical decisions. [less ▲]

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See detailSECONDs administration guidelines: A fast tool for assessing consciousness in brain-injured patients
Sanz, Leandro ULiege; Aubinet, Charlène ULiege; Cassol, Helena ULiege et al

in Journal of Visualized Experiments (2021), (168), 61968

Establishing an accurate diagnosis is crucial for patients with disorders of consciousness (DoC) following a severe brain injury. The Coma Recovery Scale-Revised (CRS-R) is the recommended behavioral ... [more ▼]

Establishing an accurate diagnosis is crucial for patients with disorders of consciousness (DoC) following a severe brain injury. The Coma Recovery Scale-Revised (CRS-R) is the recommended behavioral scale for assessing the level of consciousness among these patients, but its long administration duration is a major hurdle in clinical settings. The Simplified Evaluation of CONsciousness Disorders (SECONDs) is a shorter scale that was developed to tackle this issue. It consists of six mandatory items, observation, command-following, visual pursuit, visual fixation, oriented behaviors, and arousal, and two conditional items, communication and localization to pain. The score ranges between 0 and 8 and corresponds to a specific diagnosis (i.e., coma, unresponsive wakefulness syndrome, minimally conscious state minus/plus, or emergence from the minimally conscious state). A first validation study on patients with prolonged DoC showed high concurrent validity and intra- and inter-rater reliability. The SECONDs requires less training than the CRS-R and its administration lasts about 7 minutes (interquartile range: 5-9 minutes). An additional index score allows the more precise tracking of a patient’s behavioral fluctuation or evolution over time. The SECONDs is therefore a fast and valid tool for assessing the level of consciousness in patients with severe brain injury. It can easily be used by healthcare staff and implemented in time-constrained clinical settings, such as intensive care units, to help decrease misdiagnosis rates and to optimize treatment decisions. These administration guidelines provide detailed instructions for administering the SECONDs in a standardized and reproducible manner, which is an essential requirement for achieving a reliable diagnosis. [less ▲]

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See detailManuel de soutien à la soumission d’un protocole d’expérimentation au Comité d’Ethique Hospitalo-Facultaire Universitaire de Liège
THIBAUT, Aurore ULiege

Learning material (2021)

Dans ce manuel de soutien à la soumission d’un protocole d’expérimentation au Comité d’Ethique Hospitalo-Facultaire Universitaire de Liège, vous trouverez une description des documents à soumettre au ... [more ▼]

Dans ce manuel de soutien à la soumission d’un protocole d’expérimentation au Comité d’Ethique Hospitalo-Facultaire Universitaire de Liège, vous trouverez une description des documents à soumettre au Comité d'Ethique et des informations complémentaires afin que votre dossier comporte l'ensemble des informations nécessaires. Dans la seconde partie de ce document, vous trouverez un exemple de dossier complet à soumettre au Comité d'Ethique pour une étude interventionnelle non-pharmacologique. [less ▲]

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See detailNeural responses to heartbeats detect residual signs of consciousness during resting state in post-comatose patients
Candia-Rivera, Diego; Annen, Jitka ULiege; Gosseries, Olivia ULiege et al

in Journal of Neuroscience (2021)

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See detailLoss of consciousness reduces the stability of brain hubs and the heterogeneity of brain dynamics
López-González, Ane; Panda, Rajanikant ULiege; Ponce-Alvarez, Adrián et al

in Communications Biology (2021)

Low level states of consciousness are characterized by disruptions of brain activity that sustain arousal and awareness. Yet, how structural, dynamical, local and network brain properties interplay in the ... [more ▼]

Low level states of consciousness are characterized by disruptions of brain activity that sustain arousal and awareness. Yet, how structural, dynamical, local and network brain properties interplay in the different levels of consciousness is unknown. Here, we study fMRI brain dynamics from patients that suffered brain injuries leading to a disorder of consciousness and from healthy subjects undergoing propofol induced sedation. We show that pathological and pharmacological low-level states of consciousness display less recurrent, less connected and more segregated synchronization patterns than conscious state. We use whole-brain models built upon healthy and injured structural connectivity to interpret these dynamical effects. We found that low-level states of consciousness were associated with reduced network interactions, together with more homogeneous and more structurally constrained local dynamics. Notably, these changes lead the structural hub regions to lose their stability during low level states of consciousness, thus attenuating the differences between hubs and non hubs brain dynamics. [less ▲]

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See detailA novel closed-loop EEG-tDCS approach to promote responsiveness of patients in minimally conscious state: a study protocol.
Martens, Géraldine ULiege; Ibáñez-Soria, David; Barra, Alice ULiege et al

in Behavioural Brain Research (2021)

Transcranial direct current stimulation (tDCS) applied over the prefrontal cortex has been shown to improve behavioral responsiveness in patients with disorders of consciousness following severe brain ... [more ▼]

Transcranial direct current stimulation (tDCS) applied over the prefrontal cortex has been shown to improve behavioral responsiveness in patients with disorders of consciousness following severe brain injury, especially those in minimally conscious state (MCS). However, one potential barrier of clinical response to tDCS is the timing of stimulation with regard to the fluctuations of vigilance that characterize this population. Indeed, a previous study showed that the vigilance of MCS patients has periodic average cycles of 70 minutes (range 57-80 minutes), potentially preventing them to be in an optimal neural state to benefit from tDCS when applied randomly. To tackle this issue, we propose a new protocol to optimize the application of tDCS by selectively stimulating at high and low vigilance states. Electroencephalography (EEG) real-time spectral entropy will be used as a marker of vigilance and to trigger tDCS, in a closed-loop fashion. We will conduct a randomized controlled crossover clinical trial on 16 patients in prolonged MCS who will undergo three EEG-tDCS sessions 5 days apart (1. tDCS applied at high vigilance; 2. tDCS applied at low vigilance; 3. tDCS applied at a random moment). Behavioral effects will be assessed using the Coma Recovery Scale-Revised at baseline and right after the stimulations. EEG will be recorded throughout the session and for 30 minutes after the end of the stimulation. This unique and novel approach will provide patients' tailored treatment options, currently lacking in the field of disorders of consciousness. [less ▲]

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See detailDecreased evoked slow-activity after tDCS in disorders of consciousness
Mensen, Armand; BODART, Olivier ULiege; Thibaut, Aurore ULiege et al

in Frontiers in Systems Neuroscience (2020), 14(62),

Due to life-saving medical advances, the diagnosis and treatment of disorders of consciousness (DOC) has become a more commonly occurring clinical issue. One recently developed intervention option has ... [more ▼]

Due to life-saving medical advances, the diagnosis and treatment of disorders of consciousness (DOC) has become a more commonly occurring clinical issue. One recently developed intervention option has been non-invasive transcranial direct current stimulation. This dichotomy of patient responders may be better understood by investigating the mechanism behind the transcranial direct current stimulation (tDCS) intervention. The combination of transcranial magnetic stimulation and electroencephalography (TMS-EEG) has been an important diagnostic tool in DOC patients. We therefore examined the neural response using TMS-EEG both before and after tDCS in seven DOC patients (four diagnosed as in a minimally conscious state and three with unresponsive wakefulness syndrome). tDCS was applied over the dorsolateral prefrontal cortex, while TMS pulses were applied to the premotor cortex. None of the seven patients showed relevant behavioral change after tDCS. We did, however, find that the overall evoked slow activity was reduced following tDCS intervention. We also found a positive correlation between the strength of the slow activity and the amount of high-frequency suppression. However, there was no significant pre-post tDCS difference in high frequencies. In the resting-state EEG, we observed that both the incidence of slow waves and the positive slope of the wave were affected by tDCS. Taken together, these results suggest that the tDCS intervention can reduce the slow-wave activity component of bistability, but this may not directly affect high-frequency activity. We hypothesize that while reduced slow activity may be necessary for the recovery of neural function, especially consciousness, this alone is insufficient. [less ▲]

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See detailBrain metabolism but not grey matter volume underlies the presence of language function in the minimally conscious state
Aubinet, Charlène ULiege; Cassol, Helena ULiege; Gosseries, Olivia ULiege et al

in Neurorehabilitation and Neural Repair (2020), 34(2), 172-184

Background. The minimally conscious state (MCS) is subcategorized into MCS- and MCS+, depending on the absence or presence of high-level behavioral responses such as command following. Objective. We aim ... [more ▼]

Background. The minimally conscious state (MCS) is subcategorized into MCS- and MCS+, depending on the absence or presence of high-level behavioral responses such as command following. Objective. We aim to investigate the functional and structural neuroanatomy underlying the presence of these responses in MCS- and MCS+ patients. Methods. In this cross-sectional retrospective study, chronic MCS patients were diagnosed using repeated Coma Recovery Scale-Revised assessments. Fluorodeoxyglucose-positron emission tomography data were acquired on 57 patients (16 MCS-; 41 MCS+) and magnetic resonance imaging with voxel-based morphometry analysis was performed on 66 patients (17 MCS-; 49 MCS+). Brain glucose metabolism and grey matter integrity were compared between patient groups and control groups. A metabolic functional connectivity analysis testing the hypothesis of preserved language network in MCS+ compared to MCS- was also done. Results. Patients in MCS+ presented higher metabolism mainly in the left middle temporal cortex, known to be important for semantic processing, compared to the MCS- group. The left angular gyrus was also functionally disconnected from the left prefrontal cortex in MCS- compared to MCS+. No significant differences were found in grey matter volume between patient groups. Conclusions. The clinical sub-categorization of MCS is supported by differences in brain metabolism but not in grey matter structure, suggesting that brain function in the language network is the main support for recovery of command-following, intelligible verbalization and/or intentional communication in the MCS. Better characterizing the neural correlates of residual cognitive abilities of MCS patients contributes to reduce their misdiagnosis and to adapt therapeutic approaches. [less ▲]

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See detailTranscutaneous Auricular Vagal Nerve Stimulation and Disorders of Consciousness: A Hypothesis for Mechanisms of Action
Briand, Marie-Michèle ULiege; Gosseries, Olivia ULiege; Staumont, Bernard ULiege et al

in Frontiers in Neurology (2020), 11

Disorders of consciousness (DoC) are the hallmark of severe acquired brain injuries characterized by abnormal activity in important brain areas and disruption within and between brain networks. As DoC's ... [more ▼]

Disorders of consciousness (DoC) are the hallmark of severe acquired brain injuries characterized by abnormal activity in important brain areas and disruption within and between brain networks. As DoC's therapeutic arsenal is limited, new potential therapies such as transcutaneous auricular vagal nerve stimulation (taVNS) have recently been explored. The potential of taVNS in the process of consciousness recovery has been highlighted in recent studies with DoC patients. However, it is not clear how taVNS plays a role in the recovery of consciousness. In this article, we first describe the neural correlates of consciousness, the vagus nerve anatomy and functions, along with the results of functional magnetic resonance imaging studies using taVNS. Based on consciousness recovery and taVNS mechanisms, we propose the Vagal Cortical Pathways model. This model highlights four consecutive pathways (A. Lower brainstem activation, B. Upper brainstem activation, C. Norepinephrine pathway, and D. Serotonin pathway) likely to have an impact on patients with a brain injury and DoC. Additionally, we suggest six different mechanisms of action: (1) Activation of the ascending reticular activating system; (2) Activation of the thalamus; (3) Re-establishment of the cortico-striatal-thalamic-cortical loop; (4) Promotion of negative connectivity between external and default mode networks by the activation of the salience network; (5) Increase in activity and connectivity within the external network through the norepinephrine pathway; and (6) Increase in activity within the default mode network through the serotonin pathway. This model aims to explain the potential therapeutic effects that taVNS has on brain activity in the process of consciousness recovery. © Copyright © 2020 Briand, Gosseries, Staumont, Laureys and Thibaut. [less ▲]

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See detailCan the Nociception Coma Scale-Revised be used in patients with a tracheostomy?
Lejeune, Nicolas ULiege; Thibaut, Aurore ULiege; Martens, Géraldine ULiege et al

in Archives of Physical Medicine and Rehabilitation (2020)

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