Publications of Steven Laureys
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See detailConsciousness and communication BCIs in severe brain-injured patients
Annen, Jitka ULiege; Laureys, Steven ULiege; Gosseries, Olivia ULiege

in Handbook Brain-Computer Interfacing: Neural Devices for paralysis in neurological practise and beyond (in press)

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See detailPET Imaging in Altered States of Consciousness: Coma, Sleep, and Hypnosis
Bonin, Estelle ULiege; Martens, Géraldine ULiege; Cassol, Helena ULiege et al

in van Waarde, A; Otte, A; de Vries, E.F.J (Eds.) et al PET and SPECT in Neurology (in press)

Positron emission tomography (PET) allows studies of cerebral metabolism and blood flow and has been widely used to investigate physiological mechanisms underlying altered states of consciousness ... [more ▼]

Positron emission tomography (PET) allows studies of cerebral metabolism and blood flow and has been widely used to investigate physiological mechanisms underlying altered states of consciousness. Consciousness is characterized by two components: wakefulness and awareness. In this chapter, we review the current literature on brain metabolism during pathological loss of consciousness (vegetative/unresponsive or minimally conscious states), sleep (in healthy subjects and in patients with insomnia), and under hypnosis. By identifying brain areas specifically involved in conscious processing, these studies have contributed to our understanding of the underlying physiology of consciousness. The precuneal and cingulate cortices, for example, seem to be key areas for maintaining conscious awareness. FDG-PET further allowed the identification of the minimal energetic requirement for conscious awareness in this population, which corresponds to 42% of normal cortical activity. Up to now, it is the most accurate neuroimaging tool regarding the diagnosis of patients with disorders of consciousness. In the future, its use as part of multimodal assessment could improve diagnosis and prognosis in this challenging population. In sleep, a greater activity of the precuneus/posterior cingulate cortex and the fronto-parietal areas during non rapid eye movement sleep also seems to play a role in disorders such as insomnia. Other areas such as the hypothalamus, amygdala, or temporo-occipital cortex seem to play a role in different states such as rapid eye movement sleep and hypnosis. PET studies permit a better comprehension of the neural correlates of consciousness and to identify the implication of specific neural areas and networks in altered states of consciousness in post-comatose patients, sleep and induced hypnosis. [less ▲]

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

in Journal of Neuroscience (in press)

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See detailSwallowing in individuals with disorders of consciousness: A cohort study
MELOTTE, Evelyne ULiege; MAUDOUX, Audrey ULiege; DELHALLE, Sabrina ULiege et al

in Annals of Physical and Rehabilitation Medicine (in press)

Background. After a period of coma, a proportion of individuals with severe brain injury remain in an altered state of consciousness before regaining partial or complete recovery. Individuals with ... [more ▼]

Background. After a period of coma, a proportion of individuals with severe brain injury remain in an altered state of consciousness before regaining partial or complete recovery. Individuals with disorders of consciousness (DOC) classically receive hydration and nutrition through an enteral feeding tube. However, the real impact of the level of consciousness on an individual’s swallowing ability remains poorly investigated. Objective. We aimed to document the incidence and characteristics of dysphagia in DOC individuals and to evaluate the link between different components of swallowing and the level of consciousness. Methods. We analyzed clinical data on the respiratory status, oral feeding and otolaryngologic examination of swallowing in DOC individuals. Univariate and multivariate logistic regression was used to analyse the association of components of swallowing and participant groups (i.e., unresponsive wakefulness syndrome [UWS] and minimally conscious state [MCS]). Results. We included 92 individuals with DOC (26 UWS and 66 MCS). Overall, 99% of the participants showed deficits in the oral and/or pharyngeal phase of swallowing. As compared with the MCS group, the UWS group more frequently had a tracheostomy (69% vs 24%), with diminished cough reflex (27% vs 54%) and no effective oral phase (0% vs 21%). Conclusion. Almost all DOC participants had severe dysphagia. Some components of swallowing (i.e., tracheostomy, cough reflex and efficacy of the oral phase of swallowing) were related to consciousness. In particular, no UWS participant had an efficient oral phase, which suggests that its presence may be a sign of consciousness. In addition, no UWS participant could be fed entirely orally, whereas no MCS participant orally received ordinary food. Our study also confirms that objective swallowing assessment can be successfully completed in DOC individuals and that specific care is needed to treat severe dysphagia in DOC. [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)

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 detailHow hot is the hot zone? Computational modelling clarifies the role of parietal and frontoparietal connectivity during anaesthetic-induced loss of consciousness: Computational modelling of anaesthetic-induced LOC.
Ihalainen, Riku; Gosseries, Olivia ULiege; de Steen, Frederik Van et al

in NeuroImage (2021)

In recent years, specific cortical networks have been proposed to be crucial for sustaining consciousness, including the posterior hot zone and frontoparietal resting state networks (RSN). Here, we ... [more ▼]

In recent years, specific cortical networks have been proposed to be crucial for sustaining consciousness, including the posterior hot zone and frontoparietal resting state networks (RSN). Here, we computationally evaluate the relative contributions of three RSNs - the default mode network (DMN), the salience network (SAL), and the central executive network (CEN) - to consciousness and its loss during propofol anaesthesia. Specifically, we use dynamic causal modelling (DCM) of 10 minutes of high-density EEG recordings (N = 10, 4 males) obtained during behavioural responsiveness, unconsciousness and post-anaesthetic recovery to characterise differences in effective connectivity within frontal areas, the posterior 'hot zone', frontoparietal connections, and between-RSN connections. We estimate - for the first time - a large DCM model (LAR) of resting EEG, combining the three RSNs into a rich club of interconnectivity. Consistent with the hot zone theory, our findings demonstrate reductions in inter-RSN connectivity in the parietal cortex. Within the DMN itself, the strongest reductions are in feed-forward frontoparietal and parietal connections at the precuneus node. Within the SAL and CEN, loss of consciousness generates small increases in bidirectional connectivity. Using novel DCM leave-one-out cross-validation, we show that the most consistent out-of-sample predictions of the state of consciousness come from a key set of frontoparietal connections. This finding also generalises to unseen data collected during post-anaesthetic recovery. Our findings provide new, computational evidence for the importance of the posterior hot zone in explaining the loss of consciousness, highlighting also the distinct role of frontoparietal connectivity in underpinning conscious responsiveness, and consequently, suggest a dissociation between the mechanisms most prominently associated with explaining the contrast between conscious awareness and unconsciousness, and those maintaining consciousness. [less ▲]

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See detailThe Near-Death Experience Content (NDE-C) scale: Development and psychometric validation
Martial, Charlotte ULiege; Simon, Jessica ULiege; Puttaert, Ninon ULiege et al

in Consciousness and Cognition (2020)

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See detailEthics of life-sustaining treatment in locked-in syndrome: A Chinese survey
Yan, Yifan; Demertzi, Athina ULiege; Xia, Yinyan et al

in Annals of Physical and Rehabilitation Medicine (2020)

BACKGROUND: Locked-in syndrome (LIS) characterizes individuals who have experienced pontine lesions, who have limited motor output but with preserved cognitive abilities. Despite their severe physical ... [more ▼]

BACKGROUND: Locked-in syndrome (LIS) characterizes individuals who have experienced pontine lesions, who have limited motor output but with preserved cognitive abilities. Despite their severe physical impairment, individuals with LIS self-profess a higher quality of life than generally expected. Such third-person expectations about LIS are shaped by personal and cultural factors in western countries. OBJECTIVE: We sought to investigate whether such opinions are further influenced by the cultural background in East Asia. We surveyed attitudes about the ethics of life-sustaining treatment in LIS in a cohort of medical and non-medical Chinese participants. RESULTS: The final study sample included 1545 respondents: medical professionals (n=597, 39%), neurologists (n=303, 20%), legal professionals (n=276, 18%) and other professionals (n=369, 24%), including 180 family members of individuals with LIS. Most of the participants (70%), especially neurologists, thought that life-sustaining treatment could not be stopped in individuals with LIS. It might be unnecessary to withdraw life-sustaining treatment, because the condition involved is not terminal and irreversible, and physical treatment can be beneficial for the patient. A significant proportion (59%) of respondents would like to be kept alive if they were in that condition; however, older people thought the opposite. Families experience the stress of caring for individuals with LIS. The mean (SD) quality of life score for relatives was 0.73 (2.889) (on a -5,+5 scale), which was significantly lower than that of non-relatives, 1.75 (1.969) (P<0.001). CONCLUSIONS: Differences in opinions about end of life in LIS are affected by personal characteristics. The current survey did not identify a dissociation between personal preferences and general opinions, potentially because of a social uniformity in China where individualism is less pronounced. Future open-ended surveys could identify specific needs of caregivers so that strategic interventions to reduce ethical debasement are designed. [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 (2020)

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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 detailComplete hemispherotomy leads to lateralized functional organization and lower level of consciousness in the isolated hemisphere
Blauwblomme, Thomas; Demertzi, Athina ULiege; Tacchela, Jean‐Marc et al

in Epilepsia Open (2020)

Objective To quantify whole‐brain functional organization after complete hemispherotomy, characterizing unexplored plasticity pathways and the conscious level of the dissected hemispheres. Methods ... [more ▼]

Objective To quantify whole‐brain functional organization after complete hemispherotomy, characterizing unexplored plasticity pathways and the conscious level of the dissected hemispheres. Methods Evaluation with multimodal magnetic resonance imaging in two pediatric patients undergoing right hemispherotomy including complete callosotomy with a perithalamic section. Regional cerebral blood flow and fMRI network connectivity assessed the functional integrity of both hemispheres after surgery. The level of consciousness was tested by means of a support vector machine classifier which compared the intrinsic organization of the dissected hemispheres with those of patients suffering from disorders of consciousness. Results After hemispherotomy, both patients showed typical daily functionality. We found no interhemispheric transfer of functional connectivity in either patient as predicted by the operation. The healthy left hemispheres displayed focal blood hyperperfusion in motor and limbic areas, with preserved network‐level organization. Unexpectedly, the disconnected right hemispheres showed sustained network organization despite low regional cerebral blood flow. Subcortically, functional connectivity was increased in the left thalamo‐cortical loop and between the cerebelli. One patient further showed unusual ipsilateral right cerebello‐cortical connectivity, which was explained by the mediation of the vascular system. The healthy left hemisphere had higher probability to be classified as in a minimally conscious state compared to the isolated right hemisphere. Significance Complete hemispherotomy leads to a lateralized whole‐brain organization, with the remaining hemisphere claiming most of the brain's energetic reserves supported by subcortical structures. Our results further underline the contribution of nonneuronal vascular signals on contralateral connectivity, shedding light on the nature of network organization in the isolated tissue. The disconnected hemisphere is characterized by a level of consciousness which is necessary but insufficient for conscious processing, paving the way for more specific inquiries about its role in awareness in the absence of behavioral output. [less ▲]

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See detailDe NDE als opkomend wetenschappelijk onderzoeksgebied
Martial, Charlotte ULiege; Cassol, Helena ULiege; LAUREYS, Steven ULiege

in Pim van Lommel (Ed.) Het geheim van Elysion: 45 jaar studie naar nabij-de-dood-ervaringen over bewustzijn in liefde zonder waarheen (2020)

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See detailSwallowing in patient with disorders of consciousness: A behavioral study
MELOTTE, Evelyne ULiege; MAUDOUX, Audrey ULiege; KAUX, Jean-François ULiege et al

in Abstract book of 22nd European Congress of Physical and Rehabilitation Medicine (2020, September)

Introduction: After a period of coma, a proportion of patients with severe brain injury remain in an altered state of consciousness before regaining partial or complete recovery. Patients with disorders ... [more ▼]

Introduction: After a period of coma, a proportion of patients with severe brain injury remain in an altered state of consciousness before regaining partial or complete recovery. Patients with disorders of consciousness (DOC) classically receive hydration and nutrition through an enteral feeding tube. However, the real impact of the level of consciousness on a patient’s swallowing ability remains poorly investigated. Objective: The aims of this study were to document the incidence and characteristics of dysphagia in patients DOC and to evaluate the link between different components of swallowing and the level of consciousness. Method: We retrospectively analyzed clinical data on the respiratory status, oral feeding and otolaryngologic examination of swallowing of DOC patients admitted for a one-week multimodal assessment of consciousness. Results: A total of 92 DOC patients were included, 26 patients with unresponsive wakefulness syndrome (UWS) and 66 in minimally conscious state (MCS). Deficits in the oral and/or pharyngeal phase of swallowing were present in 99% of the patients. Compared to MCS patients, UWS patients were more frequently tracheotomized (69% UWS vs 24% MCS) with diminished cough reflex (27% UWS vs 54% MCS) and no effective oral phase (0% UWS vs 21% MCS). Conclusion: almost all patients with DOC presented at least one swallowing disorder, which represents the most important proportion of dysphagia in neurological population. Some components of swallowing (i.e., tracheostomy, cough reflex and efficacy of the oral phase of swallowing) correlate with the level of consciousness. In particular, the efficacy of the oral phase was not observed in any of the UWS patients, suggesting that its presence may be a sign of consciousness, and consequently, it should be taken into account in DOC diagnosis. Our study also confirms that objective swallowing assessment can be completed in DOC patients, and that specific care is needed to treat severe dysphagia in DOC patients. [less ▲]

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See detailAn Echo of Consciousness: Brain Function During Preferred Music
Carrière, Manon ULiege; Larroque, Stephen Karl ULiege; Martial, Charlotte ULiege et al

in Brain Connectivity (2020)

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See detailÉtats de conscience altérée: soins palliatifs et décisions de fin de vie
Lejeune, Nicolas ULiege; van Erp, Willemijn ULiege; Rohaut, Benjamin et al

in Le Berre, Rozenn (Ed.) Manuel de soins palliatifs (2020)

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See detailThe dilemma of hydrocephalus in prolonged disorders of consciousness
Arnts, Hisse; van Erp, Willemijn ULiege; Sanz, Leandro ULiege et al

in Journal of Neurotrauma (2020), 37(20), 2150-2156

Prolonged disorders of consciousness (DOC) are considered to be amongst the most severe outcomes after acquired brain injury. Medical care for these patients is mainly focused on minimizing complications ... [more ▼]

Prolonged disorders of consciousness (DOC) are considered to be amongst the most severe outcomes after acquired brain injury. Medical care for these patients is mainly focused on minimizing complications, since treatment options for patients with unresponsive wakefulness or minimal consciousness remain scarce. The complication rate in patients with DOC is high, both in the acute hospital setting as in the rehabilitation or long-term care phase. Hydrocephalus is one of these well-known complications and usually develops quickly following acute changes in cerebrospinal fluid (CSF) circulation after different types of brain damage. However, hydrocephalus may also develop with a significant delay, weeks or even months after the initial injury, reducing the potential for natural recovery of consciousness. In this phase, hydrocephalus is likely to be missed in DOC patients, since their limited behavioral responsiveness camouflages the classic signs of increased intracranial pressure or secondary normal-pressure hydrocephalus. Moreover, the development of late-onset hydrocephalus may exceed the period of regular outpatient follow-up. Several controversies remain about the diagnosis of clinical hydrocephalus in patients with ventricular enlargement after severe brain injury. In this article, we discuss both the difficulties in diagnosis and dilemmas in treatment of CSF disorders in patients with prolonged DOC and review evidence from the literature to advance an active surveillance protocol for the detection of this late, but treatable complication. Moreover, we advocate a low threshold for cerebrospinal fluid diversion when hydrocephalus is suspected, even months or years after brain injury. [less ▲]

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