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Riganello F, Sannita WG. Scientific publication rate in disorders of consciousness research. Front Psychol 2024; 15:1389376. [PMID: 38903460 PMCID: PMC11188381 DOI: 10.3389/fpsyg.2024.1389376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 05/27/2024] [Indexed: 06/22/2024] Open
Affiliation(s)
| | - Walter G. Sannita
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, and Mother/Child Sciences (DINOGMI), University of Genova, Genova, Italy
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2
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Tononi G, Boly M, Cirelli C. Consciousness and sleep. Neuron 2024; 112:1568-1594. [PMID: 38697113 PMCID: PMC11105109 DOI: 10.1016/j.neuron.2024.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 04/04/2024] [Accepted: 04/10/2024] [Indexed: 05/04/2024]
Abstract
Sleep is a universal, essential biological process. It is also an invaluable window on consciousness. It tells us that consciousness can be lost but also that it can be regained, in all its richness, when we are disconnected from the environment and unable to reflect. By considering the neurophysiological differences between dreaming and dreamless sleep, we can learn about the substrate of consciousness and understand why it vanishes. We also learn that the ongoing state of the substrate of consciousness determines the way each experience feels regardless of how it is triggered-endogenously or exogenously. Dreaming consciousness is also a window on sleep and its functions. Dreams tell us that the sleeping brain is remarkably lively, recombining intrinsic activation patterns from a vast repertoire, freed from the requirements of ongoing behavior and cognitive control.
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Affiliation(s)
- Giulio Tononi
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA.
| | - Melanie Boly
- Department of Neurology, University of Wisconsin, Madison, WI 53719, USA
| | - Chiara Cirelli
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA
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3
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Gallucci A, Varoli E, Del Mauro L, Hassan G, Rovida M, Comanducci A, Casarotto S, Lo Re V, Romero Lauro LJ. Multimodal approaches supporting the diagnosis, prognosis and investigation of neural correlates of disorders of consciousness: A systematic review. Eur J Neurosci 2024; 59:874-933. [PMID: 38140883 DOI: 10.1111/ejn.16149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 08/30/2023] [Accepted: 09/11/2023] [Indexed: 12/24/2023]
Abstract
The limits of the standard, behaviour-based clinical assessment of patients with disorders of consciousness (DoC) prompted the employment of functional neuroimaging, neurometabolic, neurophysiological and neurostimulation techniques, to detect brain-based covert markers of awareness. However, uni-modal approaches, consisting in employing just one of those techniques, are usually not sufficient to provide an exhaustive exploration of the neural underpinnings of residual awareness. This systematic review aimed at collecting the evidence from studies employing a multimodal approach, that is, combining more instruments to complement DoC diagnosis, prognosis and better investigating their neural correlates. Following the PRISMA guidelines, records from PubMed, EMBASE and Scopus were screened to select peer-review original articles in which a multi-modal approach was used for the assessment of adult patients with a diagnosis of DoC. Ninety-two observational studies and 32 case reports or case series met the inclusion criteria. Results highlighted a diagnostic and prognostic advantage of multi-modal approaches that involve electroencephalography-based (EEG-based) measurements together with neuroimaging or neurometabolic data or with neurostimulation. Multimodal assessment deepened the knowledge on the neural networks underlying consciousness, by showing correlations between the integrity of the default mode network and the different clinical diagnosis of DoC. However, except for studies using transcranial magnetic stimulation combined with electroencephalography, the integration of more than one technique in most of the cases occurs without an a priori-designed multi-modal diagnostic approach. Our review supports the feasibility and underlines the advantages of a multimodal approach for the diagnosis, prognosis and for the investigation of neural correlates of DoCs.
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Affiliation(s)
- Alessia Gallucci
- Ph.D. Program in Neuroscience, School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
- NeuroMi (Neuroscience Center), University of Milano-Bicocca, Milan, Italy
| | - Erica Varoli
- Neurology Service, Department of Diagnostic and Therapeutic Services, Istituto di Ricovero e Cura a Carattere Scientifico-Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione (IRCCS ISMETT), Palermo, Italy
| | - Lilia Del Mauro
- Department of Psychology, University of Milano-Bicocca, Milan, Italy
| | - Gabriel Hassan
- Department of Biomedical and Clinical Sciences, University of Milan, Italy
| | - Margherita Rovida
- Department of Psychology, University of Milano-Bicocca, Milan, Italy
| | - Angela Comanducci
- IRCSS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
- Università Campus Bio-Medico di Roma, Rome, Italy
| | - Silvia Casarotto
- Department of Biomedical and Clinical Sciences, University of Milan, Italy
- IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy
| | - Vincenzina Lo Re
- Neurology Service, Department of Diagnostic and Therapeutic Services, Istituto di Ricovero e Cura a Carattere Scientifico-Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione (IRCCS ISMETT), Palermo, Italy
| | - Leonor J Romero Lauro
- NeuroMi (Neuroscience Center), University of Milano-Bicocca, Milan, Italy
- Department of Psychology, University of Milano-Bicocca, Milan, Italy
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4
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Xu LB, Hampton S, Fischer D. Neuroimaging in Disorders of Consciousness and Recovery. Phys Med Rehabil Clin N Am 2024; 35:51-64. [PMID: 37993193 DOI: 10.1016/j.pmr.2023.06.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2023]
Abstract
There is a clinical need for more accurate diagnosis and prognostication in patients with disorders of consciousness (DoC). There are several neuroimaging modalities that enable detailed, quantitative assessment of structural and functional brain injury, with demonstrated diagnostic and prognostic value. Additionally, longitudinal neuroimaging studies have hinted at quantifiable structural and functional neuroimaging biomarkers of recovery, with potential implications for the management of DoC.
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Affiliation(s)
- Linda B Xu
- Department of Neurology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA.
| | - Stephen Hampton
- Department of Physical Medicine and Rehabilitation, University of Pennsylvania, 1800 Lombard Street, Philadelphia, PA 19146, USA
| | - David Fischer
- Department of Neurology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA.
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5
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Chen W, Maitra R. A practical model-based segmentation approach for improved activation detection in single-subject functional magnetic resonance imaging studies. Hum Brain Mapp 2023; 44:5309-5335. [PMID: 37539821 PMCID: PMC10543117 DOI: 10.1002/hbm.26425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 07/06/2023] [Indexed: 08/05/2023] Open
Abstract
Functional magnetic resonance imaging (fMRI) maps cerebral activation in response to stimuli but this activation is often difficult to detect, especially in low-signal contexts and single-subject studies. Accurate activation detection can be guided by the fact that very few voxels are, in reality, truly activated and that these voxels are spatially localized, but it is challenging to incorporate both these facts. We address these twin challenges to single-subject and low-signal fMRI by developing a computationally feasible and methodologically sound model-based approach, implemented in the R package MixfMRI, that bounds the a priori expected proportion of activated voxels while also incorporating spatial context. An added benefit of our methodology is the ability to distinguish voxels and regions having different intensities of activation. Our suggested approach is evaluated in realistic two- and three-dimensional simulation experiments as well as on multiple real-world datasets. Finally, the value of our suggested approach in low-signal and single-subject fMRI studies is illustrated on a sports imagination experiment that is often used to detect awareness and improve treatment in patients in persistent vegetative state (PVS). Our ability to reliably distinguish activation in this experiment potentially opens the door to the adoption of fMRI as a clinical tool for the improved treatment and therapy of PVS survivors and other patients.
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Affiliation(s)
- Wei‐Chen Chen
- Center for Devices and Radiological HealthFood and Drug AdministrationSilver SpringMarylandUSA
| | - Ranjan Maitra
- Department of StatisticsIowa State UniversityAmesIowaUSA
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6
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Wang J, Gao X, Xiang Z, Sun F, Yang Y. Evaluation of consciousness rehabilitation via neuroimaging methods. Front Hum Neurosci 2023; 17:1233499. [PMID: 37780959 PMCID: PMC10537959 DOI: 10.3389/fnhum.2023.1233499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 08/30/2023] [Indexed: 10/03/2023] Open
Abstract
Accurate evaluation of patients with disorders of consciousness (DoC) is crucial for personalized treatment. However, misdiagnosis remains a serious issue. Neuroimaging methods could observe the conscious activity in patients who have no evidence of consciousness in behavior, and provide objective and quantitative indexes to assist doctors in their diagnosis. In the review, we discussed the current research based on the evaluation of consciousness rehabilitation after DoC using EEG, fMRI, PET, and fNIRS, as well as the advantages and limitations of each method. Nowadays single-modal neuroimaging can no longer meet the researchers` demand. Considering both spatial and temporal resolution, recent studies have attempted to focus on the multi-modal method which can enhance the capability of neuroimaging methods in the evaluation of DoC. As neuroimaging devices become wireless, integrated, and portable, multi-modal neuroimaging methods will drive new advancements in brain science research.
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Affiliation(s)
| | | | | | - Fangfang Sun
- College of Automation, Hangzhou Dianzi University, Hangzhou, China
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7
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Taran S, Gros P, Gofton T, Boyd G, Briard JN, Chassé M, Singh JM. The reticular activating system: a narrative review of discovery, evolving understanding, and relevance to current formulations of brain death. Can J Anaesth 2023; 70:788-795. [PMID: 37155119 PMCID: PMC10203024 DOI: 10.1007/s12630-023-02421-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 08/24/2022] [Accepted: 08/25/2022] [Indexed: 05/10/2023] Open
Abstract
A series of landmark experiments conducted throughout the 20th century progressively localized the regions involved in consciousness to the reticular activating system (RAS) and its ascending projections. The first description of the RAS emerged in 1949 through seminal experiments performed by Moruzzi and Magoun in feline brainstems; additional experiments in the 1950s revealed connections between the RAS and the thalamus and neocortical structures. This knowledge has allowed for the explanation of disorders of consciousness with exquisite anatomic precision. The clinical relevance of the RAS is further apparent in modern definitions of brain death/death by neurologic criteria (BD/DNC), which require demonstration of the complete and permanent loss of capacity for consciousness as one of their core criteria. BD/DNC is currently understood across jurisdictions in terms of "whole brain" and "brainstem" formulations. Although their clinical examination between formulations is indistinguishable, policies for BD/DNC declaration may differ in the rare scenario of patients with isolated infratentorial brain injuries, in which ancillary testing is advised in the whole brain formulation but not the brainstem formulation. Canadian guidelines acknowledge that the distinction between whole brain and brainstem formulations is unclear with respect to clinical implications for patients with isolated infratentorial injuries. This has led to variability in Canadian clinicians' use of ancillary testing when the mechanism of BD/DNC is suspected to be an isolated infratentorial injury. The present narrative review highlights these concepts and explores implications for determination of BD/DNC in Canada, with specific emphasis on the RAS and its relevance to both formulations.
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Affiliation(s)
- Shaurya Taran
- Department of Medicine, University Health Network, Toronto, ON, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
- Toronto Western Hospital, Office 411-L, 2nd Floor McLaughlin, 399 Bathurst St., Toronto, ON, M5T 2S8, Canada
| | - Priti Gros
- Department of Medicine, University Health Network, Toronto, ON, Canada
- Division of Neurology, University Health Network, Toronto, ON, Canada
| | - Teneille Gofton
- Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Gordon Boyd
- Department of Medicine (Neurology) and Critical Care Medicine, Queen's University, Kingston, ON, Canada
| | - Joel Neves Briard
- Department of Neuroscience, Université de Montréal, Montreal, QC, Canada
| | - Michaël Chassé
- Department of Medicine, Université de Montréal, Montreal, QC, Canada
- Université de Montréal Hospital Research Centre, Montreal, QC, Canada
| | - Jeffrey M Singh
- Department of Medicine, University Health Network, Toronto, ON, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
- Ontario Health - Trillium Gift of Life Network, Toronto, ON, Canada
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8
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Sannita WG. Time, Consciousness, and the Readiness Potential. J PSYCHOPHYSIOL 2022. [DOI: 10.1027/0269-8803/a000304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Walter G. Sannita
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics and Mother/child sciences (DINOGMI), University of Genova, Italy
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9
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Han J, Chen C, Zheng S, Yan X, Wang C, Wang K, Hu Y. High-Definition Transcranial Direct Current Stimulation of the Dorsolateral Prefrontal Cortex Modulates the Electroencephalography Rhythmic Activity of Parietal Occipital Lobe in Patients With Chronic Disorders of Consciousness. Front Hum Neurosci 2022; 16:889023. [PMID: 35712532 PMCID: PMC9196904 DOI: 10.3389/fnhum.2022.889023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 05/10/2022] [Indexed: 11/13/2022] Open
Abstract
BackgroundDisorders of consciousness (DOC) are a spectrum of pathologies affecting one’s ability to interact with the external world. At present, High-Definition Transcranial Direct Current Stimulation (HD-tDCS) is used in many patients with DOC as a non-invasive treatment, but electrophysiological research on the effect of HD-tDCS on patients with DOC is limited.ObjectivesTo explore how HD-tDCS affects the cerebral cortex and examine the possible electrophysiological mechanisms underlying the effects of HD-tDCS on the cerebral cortex.MethodsA total of 19 DOC patients were assigned to HD-tDCS stimulation. Each of them underwent 10 anodal HD-tDCS sessions of the left dorsolateral prefrontal cortex (DLPFC) over 5 consecutive days. Coma Recovery Scale-Revision (CRS-R) scores were recorded to evaluate the consciousness level before and after HD-tDCS, while resting-state electroencephalography (EEG) recordings were obtained immediately before and after single and multiple HD-tDCS stimuli. Depending on whether the CRS-R score increased after stimulation, we classified the subjects into responsive (RE) and non-responsive (N-RE) groups and compared the differences in power spectral density (PSD) between the groups in different frequency bands and brain regions, and also examined the relationship between PSD values and CRS-R scores.ResultsFor the RE group, the PSD value of the parieto-occipital region increased significantly in the 6–8 Hz frequency band after multiple stimulations by HD-tDCS. After a single stimulation, an increase in PSD was observed at 10–13 and 13–30 Hz. In addition, for all subjects, a positive correlation was observed between the change in PSD value in the parieto-occipital region at 10–13 and 6–8 Hz frequency band and the change in CRS-R score after a single stimulation.ConclusionRepeated anodal HD-tDCS of the left DLPFC can improve clinical outcomes in patients with DOC, and HD-tDCS-related increased levels of consciousness were associated with increased parieto-occipital PSD.
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Affiliation(s)
- Jinying Han
- Department of Neurology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
- Collaborative Innovation Center of Neuropsychiatric Disorders and Mental Health, Hefei, China
- Anhui Province Key Laboratory of Cognition and Neuropsychiatric Disorders, Hefei, China
- The School of Mental Health and Psychological Sciences, Anhui Medical University, Hefei, China
| | - Chen Chen
- Department of Neurology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
- Collaborative Innovation Center of Neuropsychiatric Disorders and Mental Health, Hefei, China
- Anhui Province Key Laboratory of Cognition and Neuropsychiatric Disorders, Hefei, China
- The School of Mental Health and Psychological Sciences, Anhui Medical University, Hefei, China
| | - Shuang Zheng
- Department of Neurology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
- Collaborative Innovation Center of Neuropsychiatric Disorders and Mental Health, Hefei, China
- Anhui Province Key Laboratory of Cognition and Neuropsychiatric Disorders, Hefei, China
- The School of Mental Health and Psychological Sciences, Anhui Medical University, Hefei, China
| | - Xiaoxiang Yan
- Department of Neurology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Changqing Wang
- Department of Neurology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Kai Wang
- Department of Neurology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
- Collaborative Innovation Center of Neuropsychiatric Disorders and Mental Health, Hefei, China
- Anhui Province Key Laboratory of Cognition and Neuropsychiatric Disorders, Hefei, China
- The School of Mental Health and Psychological Sciences, Anhui Medical University, Hefei, China
- Hefei Comprehensive National Science Center, Institute of Artificial Intelligence, Hefei, China
- *Correspondence: Kai Wang,
| | - Yajuan Hu
- Department of Neurology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
- Collaborative Innovation Center of Neuropsychiatric Disorders and Mental Health, Hefei, China
- Anhui Province Key Laboratory of Cognition and Neuropsychiatric Disorders, Hefei, China
- The School of Mental Health and Psychological Sciences, Anhui Medical University, Hefei, China
- Yajuan Hu,
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10
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Lei L, Liu K, Yang Y, Doubliez A, Hu X, Xu Y, Zhou Y. Spatio-temporal analysis of EEG features during consciousness recovery in patients with disorders of consciousness. Clin Neurophysiol 2021; 133:135-144. [PMID: 34864400 DOI: 10.1016/j.clinph.2021.08.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 08/10/2021] [Accepted: 08/29/2021] [Indexed: 12/17/2022]
Abstract
OBJECTIVE As consciousness recovery is not only dynamic but also involves interactions between various brain regions, elucidating the mechanism of recovery requires tracking cortical activity in spatio-temporal dimensions. METHODS We tracked the cortical activities of 40 patients (mean age: 54.38 years; 28 males; 21 patients with minimally conscious states) with disorders of consciousness, and collected a total of 156 electroencephalographic signals. We investigated the longitudinal changes in EEG nonlinear dynamic features (i.e., approximate entropy, sample entropy, and Lempel-Ziv complexity) and relative wavelet energy along with consciousness recovery. RESULTS Global EEG features showed a non-monotonic trend during consciousness recovery (P < 0.05). When the level of consciousness of patients was transferred to a minimally conscious state from an unresponsive wakefulness syndrome/ vegetative state, an inflection point appeared in the EEG features. The EEG feature change trends between the injured and uninjured areas were dissimilar (P < 0.05). Importantly, the degree of dissimilarity increased non-monotonically across the levels of consciousness (P < 0.05). CONCLUSIONS EEG recovery was non-monotonic and dissimilar in spatio-temporal dimensions, with an inflection point. SIGNIFICANCE These findings further clarify the process of consciousness recovery and provide assistance in exploring the mechanism of consciousness recovery.
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Affiliation(s)
- Ling Lei
- College of Automation, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018, China
| | - Kehong Liu
- Wu Jing Hospital, Rehabilitation Center, Hangzhou, Zhejiang 310051, China
| | - Yong Yang
- College of Automation, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018, China.
| | - Alice Doubliez
- Paris Descartes University, 45 rue des Saints-Peres, Paris 75006, France
| | - Xiaohua Hu
- Wu Jing Hospital, Rehabilitation Center, Hangzhou, Zhejiang 310051, China
| | - Ying Xu
- College of Automation, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018, China
| | - Yixing Zhou
- First People's Hospital of Zhaoqing City, No. 9 Donggang East Road, Duanzhou District, Zhaoqing 526060, China.
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11
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Li D, He W, Guo Y. Why AI still doesn’t have consciousness? CAAI TRANSACTIONS ON INTELLIGENCE TECHNOLOGY 2021. [DOI: 10.1049/cit2.12035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Deyi Li
- Department of Computer Science and Technology Tsinghua University Beijing China
| | - Wen He
- Institute of Systems Engineering Academy of Military Sciences PLA Beijing China
| | - Yike Guo
- Data Science Institute Imperial College London UK
- Hongkong Baptist University Hong Kong China
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12
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Bender Pape TL, Livengood SL, Kletzel SL, Blabas B, Guernon A, Bhaumik DK, Bhaumik R, Mallinson T, Weaver JA, Higgins JP, Wang X, Herrold AA, Rosenow JM, Parrish T. Neural Connectivity Changes Facilitated by Familiar Auditory Sensory Training in Disordered Consciousness: A TBI Pilot Study. Front Neurol 2020; 11:1027. [PMID: 33132997 PMCID: PMC7578344 DOI: 10.3389/fneur.2020.01027] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 08/06/2020] [Indexed: 12/19/2022] Open
Abstract
For people with disordered consciousness (DoC) after traumatic brain injury (TBI), relationships between treatment-induced changes in neural connectivity and neurobehavioral recovery have not been explored. To begin building a body of evidence regarding the unique contributions of treatments to changes in neural network connectivity relative to neurobehavioral recovery, we conducted a pilot study to identify relationships meriting additional examination in future research. To address this objective, we examined previously unpublished neural connectivity data derived from a randomized clinical trial (RCT). We leveraged these data because treatment efficacy, in the RCT, was based on a comparison of a placebo control with a specific intervention, the familiar auditory sensory training (FAST) intervention, consisting of autobiographical auditory-linguistic stimuli. We selected a subgroup of RCT participants with high-quality imaging data (FAST n = 4 and placebo n = 4) to examine treatment-related changes in brain network connectivity and how and if these changes relate to neurobehavioral recovery. To discover promising relationships among the FAST intervention, changes in neural connectivity, and neurobehavioral recovery, we examined 26 brain regions and 19 white matter tracts associated with default mode, salience, attention, and language networks, as well as three neurobehavioral measures. Of the relationships discovered, the systematic filtering process yielded evidence supporting further investigation of the relationship among the FAST intervention, connectivity of the left inferior longitudinal fasciculus, and auditory-language skills. Evidence also suggests that future mechanistic research should focus on examining the possibility that the FAST supports connectivity changes by facilitating redistribution of brain resources. For a patient population with limited treatment options, the reported findings suggest that a simple, yet targeted, passive sensory stimulation treatment may have altered functional and structural connectivity. If replicated in future research, then these findings provide the foundation for characterizing the unique contributions of the FAST intervention and could inform development of new treatment strategies. For persons with severely damaged brain networks, this report represents a first step toward advancing understanding of the unique contributions of treatments to changing brain network connectivity and how these changes relate to neurobehavioral recovery for persons with DoC after TBI. Clinical Trial Registry: NCT00557076, The Efficacy of Familiar Voice Stimulation During Coma Recovery (http://www.clinicaltrials.gov).
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Affiliation(s)
- Theresa L Bender Pape
- The Department of Veterans Affairs (VA), Center for Innovation in Complex Chronic Healthcare & Research Service, Edward Hines Jr. VA Hospital, Hines, IL, United States.,Department of Physical Medicine and Rehabilitation, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Sherri L Livengood
- The Department of Veterans Affairs (VA), Center for Innovation in Complex Chronic Healthcare & Research Service, Edward Hines Jr. VA Hospital, Hines, IL, United States.,Department of Physical Medicine and Rehabilitation, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Sandra L Kletzel
- The Department of Veterans Affairs (VA), Center for Innovation in Complex Chronic Healthcare & Research Service, Edward Hines Jr. VA Hospital, Hines, IL, United States
| | - Brett Blabas
- The Department of Veterans Affairs (VA), Center for Innovation in Complex Chronic Healthcare & Research Service, Edward Hines Jr. VA Hospital, Hines, IL, United States
| | - Ann Guernon
- The Department of Veterans Affairs (VA), Center for Innovation in Complex Chronic Healthcare & Research Service, Edward Hines Jr. VA Hospital, Hines, IL, United States.,Marianjoy Rehabilitation Hospital Part of Northwestern Medicine, Wheaton, IL, United States
| | - Dulal K Bhaumik
- Division of Epidemiology and Biostatistics, Department of Psychiatry, Biostatistical Research Center, University of Illinois at Chicago, Chicago, IL, United States.,Research Service, Cooperative Studies Program Coordinating Center, Edward Hines Jr. VA Hospital, Hines, IL, United States
| | - Runa Bhaumik
- Division of Epidemiology and Biostatistics, Department of Psychiatry, Biostatistical Research Center, University of Illinois at Chicago, Chicago, IL, United States
| | - Trudy Mallinson
- Department of Clinical Research and Leadership, School of Medicine and Health Sciences, The George Washington University, Washington, DC, United States
| | - Jennifer A Weaver
- Department of Clinical Research and Leadership, School of Medicine and Health Sciences, The George Washington University, Washington, DC, United States
| | - James P Higgins
- Department of Radiology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Xue Wang
- Department of Radiology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Amy A Herrold
- The Department of Veterans Affairs (VA), Center for Innovation in Complex Chronic Healthcare & Research Service, Edward Hines Jr. VA Hospital, Hines, IL, United States.,Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Joshua M Rosenow
- Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, United States.,Northwestern Memorial Hospital, Chicago, IL, United States
| | - Todd Parrish
- Department of Radiology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
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13
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Cortical Function in Acute Severe Traumatic Brain Injury and at Recovery: A Longitudinal fMRI Case Study. Brain Sci 2020; 10:brainsci10090604. [PMID: 32899145 PMCID: PMC7563151 DOI: 10.3390/brainsci10090604] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 08/22/2020] [Accepted: 09/01/2020] [Indexed: 11/17/2022] Open
Abstract
Differences in the functional integrity of the brain from acute severe brain injury to subsequent recovery of consciousness have not been well documented. Functional magnetic resonance imaging (fMRI) may elucidate this issue as it allows for the objective measurement of brain function both at rest and in response to stimuli. Here, we report the cortical function of a patient with a severe traumatic brain injury (TBI) in a critically ill state and at subsequent functional recovery 9-months post injury. A series of fMRI paradigms were employed to assess sound and speech perception, command following, and resting state connectivity. The patient retained sound perception and speech perception acutely, as indexed by his fMRI responses. Command following was absent acutely, but was present at recovery. Increases in functional connectivity across multiple resting state networks were observed at recovery. We demonstrate the clinical utility of fMRI in assessing cortical function in a patient with severe TBI. We suggest that hallmarks of the recovery of consciousness are associated with neural activity to higher-order cognitive tasks and increased resting state connectivity.
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14
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Machado C, Rodríguez-Rojas R, Leisman G. Partial recovery of vegetative state after a massive ischaemic stroke in a child with sickle cell anaemia. BMJ Case Rep 2020; 13:13/5/e233737. [PMID: 32376659 DOI: 10.1136/bcr-2019-233737] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
A 15-year-old patient with sickle cell disease with recessive homozygous haemoglobin S/HbSS suffered several crises developmentally after the last of which the patient fell into coma. CT scan then revealed a large infarct of the right cerebral hemisphere. Three weeks after the event, the patient began to demonstrate spontaneous eye opening and spastic quadriparesis with no evidence of command-following, gestural or verbal communication, visual pursuit or purposeful motor behaviour. Our case was in an 'unresponsive wakefulness syndrome' with atrophy of lateral and frontal regions of both hemispheres, demonstrated by MRI and preservation of circulation in the posterior arterial system, documented by MR angiography. Currently observed are spontaneous eye opening, preserved visual and auditory startle reflexes, normal brainstem reflexes, and grasp, palmomental and sucking reflexes. Our case demonstrates partial recovery of awareness with significant brain lesions, reflecting preserved brain activity as an indication of the modular nature of functional networks.
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Affiliation(s)
- Calixto Machado
- Department of Clinical Neurophysiology, Instituto de Neurología y Neurocirugía, La Habana, Cuba
| | - Rafael Rodríguez-Rojas
- CINAC (Centro Integral de Neurociencias), University Hospital CEU-San Pablo University, Madrid, Spain
| | - Gerry Leisman
- Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel .,Department of Clinical Elelctrophysiology, Universidad de Ciencias Médicas, Instituto de Neurología y Neurocirugía, Neurofisiología Cliníca, Ciudad de La Habana, Cuba
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15
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Mashour GA, Roelfsema P, Changeux JP, Dehaene S. Conscious Processing and the Global Neuronal Workspace Hypothesis. Neuron 2020; 105:776-798. [PMID: 32135090 PMCID: PMC8770991 DOI: 10.1016/j.neuron.2020.01.026] [Citation(s) in RCA: 364] [Impact Index Per Article: 91.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 10/31/2019] [Accepted: 01/22/2020] [Indexed: 10/24/2022]
Abstract
We review the central tenets and neuroanatomical basis of the global neuronal workspace (GNW) hypothesis, which attempts to account for the main scientific observations regarding the elementary mechanisms of conscious processing in the human brain. The GNW hypothesis proposes that, in the conscious state, a non-linear network ignition associated with recurrent processing amplifies and sustains a neural representation, allowing the corresponding information to be globally accessed by local processors. We examine this hypothesis in light of recent data that contrast brain activity evoked by either conscious or non-conscious contents, as well as during conscious or non-conscious states, particularly general anesthesia. We also discuss the relationship between the intertwined concepts of conscious processing, attention, and working memory.
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Affiliation(s)
- George A Mashour
- Center for Consciousness Science, Neuroscience Graduate Program, and Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA
| | - Pieter Roelfsema
- Department of Vision & Cognition, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA, Amsterdam, the Netherlands; Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU University, Amsterdam, the Netherlands; Department of Psychiatry, Academic Medical Center, Amsterdam, the Netherlands
| | - Jean-Pierre Changeux
- CNRS UMR 3571, Institut Pasteur, 75724 Paris, France; Collège de France, 11 Place Marcelin Berthelot, 75005 Paris, France; Kavli Institute for Brain & Mind, University of California, San Diego, La Jolla, CA, USA.
| | - Stanislas Dehaene
- Collège de France, 11 Place Marcelin Berthelot, 75005 Paris, France; Cognitive Neuroimaging Unit, CEA, INSERM, Université Paris-Sud, Université Paris-Saclay, NeuroSpin Center, 91191 Gif/Yvette, France.
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16
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Bayne T, Seth AK, Massimini M. Are There Islands of Awareness? Trends Neurosci 2020; 43:6-16. [DOI: 10.1016/j.tins.2019.11.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 10/30/2019] [Accepted: 11/08/2019] [Indexed: 12/26/2022]
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17
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Rosanova M, Fecchio M, Casarotto S, Sarasso S, Casali AG, Pigorini A, Comanducci A, Seregni F, Devalle G, Citerio G, Bodart O, Boly M, Gosseries O, Laureys S, Massimini M. Sleep-like cortical OFF-periods disrupt causality and complexity in the brain of unresponsive wakefulness syndrome patients. Nat Commun 2018; 9:4427. [PMID: 30356042 PMCID: PMC6200777 DOI: 10.1038/s41467-018-06871-1] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 10/01/2018] [Indexed: 12/21/2022] Open
Abstract
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. Many brain-injured patients retain large cortical islands that are intact, active and reactive but blocked in a state of low complexity, leading to unconsciousness. Here, the authors show that this loss of complexity is due to the pathological engagement of sleep-like neuronal mechanisms.
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Affiliation(s)
- M Rosanova
- Department of Biomedical and Clinical Sciences "L. Sacco", University of Milan, Milan, 20157, Italy.,Fondazione Europea per la Ricerca Biomedica Onlus, Milan, 20063, Italy.,Neurointensive Care Unit, ASTT Grande Ospedale Metropolitano Niguarda, Milan, 20162, Italy
| | - M Fecchio
- Department of Biomedical and Clinical Sciences "L. Sacco", University of Milan, Milan, 20157, Italy
| | - S Casarotto
- Department of Biomedical and Clinical Sciences "L. Sacco", University of Milan, Milan, 20157, Italy.,IRCCS Fondazione Don Gnocchi, Milan, 20149, Italy
| | - S Sarasso
- Department of Biomedical and Clinical Sciences "L. Sacco", University of Milan, Milan, 20157, Italy
| | - A G Casali
- Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo, Sao Jose dos Campos, 12231-280, Brazil
| | - A Pigorini
- Department of Biomedical and Clinical Sciences "L. Sacco", University of Milan, Milan, 20157, Italy
| | - A Comanducci
- Department of Biomedical and Clinical Sciences "L. Sacco", University of Milan, Milan, 20157, Italy
| | - F Seregni
- Department of Paediatrics, Cambridge University Hospital NHS Foundation Trust, Cambridge, CB2 0QQ, UK
| | - G Devalle
- IRCCS Fondazione Don Gnocchi, Milan, 20149, Italy
| | - G Citerio
- Scuola di Medicina e Chirurgia, University of Milan Bicocca, Milan, 20126, Italy
| | - O Bodart
- GIGA-consciousness, Coma Science Group, University and University Hospital of Liège, Liège, 4000, Belgium
| | - M Boly
- Department of Neurology, University of Wisconsin, Madison, WI, 53705, USA.,Department of Psychiatry, University of Wisconsin, Madison, WI, 53719, USA
| | - O Gosseries
- GIGA-consciousness, Coma Science Group, University and University Hospital of Liège, Liège, 4000, Belgium
| | - S Laureys
- GIGA-consciousness, Coma Science Group, University and University Hospital of Liège, Liège, 4000, Belgium
| | - M Massimini
- Department of Biomedical and Clinical Sciences "L. Sacco", University of Milan, Milan, 20157, Italy. .,IRCCS Fondazione Don Gnocchi, Milan, 20149, Italy.
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18
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Wade DT. Using best interests meetings for people in a prolonged disorder of consciousness to improve clinical and ethical management. JOURNAL OF MEDICAL ETHICS 2018; 44:336-342. [PMID: 28912289 DOI: 10.1136/medethics-2017-104244] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 07/14/2017] [Accepted: 07/18/2017] [Indexed: 06/07/2023]
Abstract
Current management of people with prolonged disorders of consciousness is failing patients, families and society. The causes include a general lack of concern, knowledge and expertise; a legal and professional framework which impedes timely and appropriate decision-making and/or enactment of the decision; and the exclusive focus on the patient, with no legitimate means to consider the broader consequences of healthcare decisions. This article argues that a clinical pathway based on the principles of (a) the English Mental Capacity Act 2005 and (b) using time-limited treatment trials could greatly improve patient management and reduce stress on families. There needs to be early and continuing use of formal best interests meetings, starting between 7 and 21 days after onset of unconsciousness (from any cause, including progressive disorders). The treatment options need to evolve as the clinical state and prognosis becomes more certain. A formal discussion of treatment withdrawal should occur when the upper bound of predicted recovery falls below a level the patient would have considered acceptable, and it should always be discussed when the condition is considered permanent. Any decision to stop treatment should be contingent on a formal second opinion from an independent expert who should review the clinical situation and expected prognosis, but not the best interests decision. The article also asks how, if at all, the adverse effects on the family and the resource implications of long-term care of people left in a prolonged state of unconsciousness should be incorporated in the process.
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Tobaldini E, Toschi-Dias E, Trimarchi PD, Brena N, Comanducci A, Casarotto S, Montano N, Devalle G. Cardiac autonomic responses to nociceptive stimuli in patients with chronic disorders of consciousness. Clin Neurophysiol 2018; 129:1083-1089. [DOI: 10.1016/j.clinph.2018.01.068] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 12/07/2017] [Accepted: 01/06/2018] [Indexed: 11/15/2022]
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20
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Farisco M, Kotaleski JH, Evers K. Large-Scale Brain Simulation and Disorders of Consciousness. Mapping Technical and Conceptual Issues. Front Psychol 2018; 9:585. [PMID: 29740372 PMCID: PMC5928391 DOI: 10.3389/fpsyg.2018.00585] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 04/06/2018] [Indexed: 11/15/2022] Open
Abstract
Modeling and simulations have gained a leading position in contemporary attempts to describe, explain, and quantitatively predict the human brain's operations. Computer models are highly sophisticated tools developed to achieve an integrated knowledge of the brain with the aim of overcoming the actual fragmentation resulting from different neuroscientific approaches. In this paper we investigate the plausibility of simulation technologies for emulation of consciousness and the potential clinical impact of large-scale brain simulation on the assessment and care of disorders of consciousness (DOCs), e.g., Coma, Vegetative State/Unresponsive Wakefulness Syndrome, Minimally Conscious State. Notwithstanding their technical limitations, we suggest that simulation technologies may offer new solutions to old practical problems, particularly in clinical contexts. We take DOCs as an illustrative case, arguing that the simulation of neural correlates of consciousness is potentially useful for improving treatments of patients with DOCs.
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Affiliation(s)
- Michele Farisco
- Centre for Research Ethics and Bioethics, Uppsala University, Uppsala, Sweden
- Science and Society Unit, Biogem Genetic Research Centre, Ariano Irpino (AV), Italy
| | - Jeanette H. Kotaleski
- Science for Life Laboratory, School of Computer Science and Communication, KTH Royal Institute of Technology, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institute, Solna, Sweden
| | - Kathinka Evers
- Centre for Research Ethics and Bioethics, Uppsala University, Uppsala, Sweden
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21
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Annen J, Frasso G, Crone JS, Heine L, Di Perri C, Martial C, Cassol H, Demertzi A, Naccache L, Laureys S. Regional brain volumetry and brain function in severely brain-injured patients. Ann Neurol 2018; 83:842-853. [PMID: 29572926 DOI: 10.1002/ana.25214] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 03/15/2018] [Accepted: 03/16/2018] [Indexed: 11/07/2022]
Abstract
OBJECTIVE The relationship between residual brain tissue in patients with disorders of consciousness (DOC) and the clinical condition is unclear. This observational study aimed to quantify gray (GM) and white matter (WM) atrophy in states of (altered) consciousness. METHODS Structural T1-weighted magnetic resonance images were processed for 102 severely brain-injured and 52 healthy subjects. Regional brain volume was quantified for 158 (sub)cortical regions using Freesurfer. The relationship between regional brain volume and clinical characteristics of patients with DOC and conscious brain-injured patients was assessed using a linear mixed-effects model. Classification of patients with unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS) using regional volumetric information was performed and compared to classification using cerebral glucose uptake from fluorodeoxyglucose positron emission tomography. For validation, the T1-based classifier was tested on independent datasets. RESULTS Patients were characterized by smaller regional brain volumes than healthy subjects. Atrophy occurred faster in UWS compared to MCS (GM) and conscious (GM and WM) patients. Classification was successful (misclassification with leave-one-out cross-validation between 2% and 13%) and generalized to the independent data set with an area under the receiver operator curve of 79% (95% confidence interval [CI; 67-91.5]) for GM and 70% (95% CI [55.6-85.4]) for WM. INTERPRETATION Brain volumetry at the single-subject level reveals that regions in the default mode network and subcortical gray matter regions, as well as white matter regions involved in long range connectivity, are most important to distinguish levels of consciousness. Our findings suggest that changes of brain structure provide information in addition to the assessment of functional neuroimaging and thus should be evaluated as well. Ann Neurol 2018;83:842-853.
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Affiliation(s)
- Jitka Annen
- Coma Science Group, GIGA Consciousness, University of Liège, Liège, Belgium.,University Hospital of Liège, Liège, Belgium
| | - Gianluca Frasso
- Faculty of Social Sciences, Quantitative Methods for Social Sciences, University of Liège, Liège, Belgium
| | | | - Lizette Heine
- Coma Science Group, GIGA Consciousness, University of Liège, Liège, Belgium.,Auditory Cognition and Psychoacoustics Team, Lyon Neuroscience Research Center, Lyon, France
| | - Carol Di Perri
- Coma Science Group, GIGA Consciousness, University of Liège, Liège, Belgium.,University Hospital of Liège, Liège, Belgium.,Centre for Clinical Brain Sciences UK Dementia Research Institute, Centre for Dementia Prevention, University of Edinburgh, Edinburgh, United Kingdom
| | - Charlotte Martial
- Coma Science Group, GIGA Consciousness, University of Liège, Liège, Belgium.,University Hospital of Liège, Liège, Belgium
| | - Helena Cassol
- Coma Science Group, GIGA Consciousness, University of Liège, Liège, Belgium.,University Hospital of Liège, Liège, Belgium
| | - Athena Demertzi
- Coma Science Group, GIGA Consciousness, University of Liège, Liège, Belgium.,INSERM, U 1127, F-75013, Paris, France; Institut du Cerveau et de la Moelle épinière, Hôpital Pitié-Salpêtrière, 47 bd de l'Hôpital, 75013, Paris, France
| | - Lionel Naccache
- INSERM, U 1127, F-75013, Paris, France; Institut du Cerveau et de la Moelle épinière, Hôpital Pitié-Salpêtrière, 47 bd de l'Hôpital, 75013, Paris, France
| | - Steven Laureys
- Coma Science Group, GIGA Consciousness, University of Liège, Liège, Belgium.,University Hospital of Liège, Liège, Belgium
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22
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Naccache L. Minimally conscious state or cortically mediated state? Brain 2018; 141:949-960. [PMID: 29206895 PMCID: PMC5888986 DOI: 10.1093/brain/awx324] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/07/2017] [Accepted: 09/27/2017] [Indexed: 01/04/2023] Open
Abstract
Durable impairments of consciousness are currently classified in three main neurological categories: comatose state, vegetative state (also recently coined unresponsive wakefulness syndrome) and minimally conscious state. While the introduction of minimally conscious state, in 2002, was a major progress to help clinicians recognize complex non-reflexive behaviours in the absence of functional communication, it raises several problems. The most important issue related to minimally conscious state lies in its criteria: while behavioural definition of minimally conscious state lacks any direct evidence of patient's conscious content or conscious state, it includes the adjective 'conscious'. I discuss this major problem in this review and propose a novel interpretation of minimally conscious state: its criteria do not inform us about the potential residual consciousness of patients, but they do inform us with certainty about the presence of a cortically mediated state. Based on this constructive criticism review, I suggest three proposals aiming at improving the way we describe the subjective and cognitive state of non-communicating patients. In particular, I present a tentative new classification of impairments of consciousness that combines behavioural evidence with functional brain imaging data, in order to probe directly and univocally residual conscious processes.
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Affiliation(s)
- Lionel Naccache
- AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurology, 75013, Paris, France
- AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurophysiology, 75013, Paris, France
- INSERM, U 1127, F-75013, Paris, France
- Institut du Cerveau et de la Moelle épinière, ICM, PICNIC Lab, F-75013, Paris, France
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23
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Wade DT. How often is the diagnosis of the permanent vegetative state incorrect? A review of the evidence. Eur J Neurol 2018; 25:619-625. [DOI: 10.1111/ene.13572] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 01/08/2018] [Indexed: 12/11/2022]
Affiliation(s)
- D. T. Wade
- OxINMAHR, and Movement Science Group; Faculty of Health and Life Sciences; Oxford Brookes University; Oxford UK
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24
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Naro A, Chillura A, Portaro S, Bramanti A, De Luca R, Bramanti P, Calabrò RS. Novel Approaches to the Diagnosis of Chronic Disorders of Consciousness: Detecting Peripersonal Space by Using Ultrasonics. Front Neurol 2018; 9:47. [PMID: 29459847 PMCID: PMC5807342 DOI: 10.3389/fneur.2018.00047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 01/18/2018] [Indexed: 01/17/2023] Open
Abstract
The assessment of behavioral responsiveness in patients suffering from chronic disorders of consciousness (DoC), including Unresponsive Wakefulness Syndrome (UWS) and Minimally Conscious State (MCS), is challenging. Even if a patient is unresponsive, he/she may be covertly aware in reason of a cognitive-motor dissociation, i.e., a preservation of cognitive functions despite a solely reflexive behavioral responsiveness. The approach of an external stimulus to the peripersonal space (PPS) modifies some biological measures (e.g., hand-blink reflex amplitude) to the purpose of defensive responses from threats. Such modulation depends on a top-down control of subcortical neural circuits, which can be explored through changes in cerebral blood flow velocity (CBFV), using functional transcranial Doppler (fTCD) and, thus, gaining useful, indirect information on brain connectivity. These data may be used for the DoC differential diagnosis. We evaluated the changes in CBFV by measuring the pulsatility index (PI) in 21 patients with DoC (10 patients with MCS and 11 with UWS) and 25 healthy controls (HC) during a passive movement and motor imagery (MI) task in which the hand of the subject approached and, then, moved away from the subject’s face. In the passive movement task, the PI increased progressively in the HCs when the hand was moved toward the face and, then, it decreased when the hand was removed from the face. The PI increased when the hand was moved toward the face in patients with DoC, but then, it remained high when the hand was removed from the face and up to 30 s after the end of the movement in the patients with MCS (both MCS+ and MCS−) and 1 min in those with UWS, thus differentiating between patients with MCS and UWS. In the MI task, all the HCs, three out of four patients with MCS+, and one out of six patients with MCS− showed an increase–decrease PI change, whereas the remaining patients with MCS and all the patients with UWS showed no PI changes. Even though there is the possibility that our findings will not be replicated in all patients with DoC, we propose fTCD as a rapid and very easy tool to differentiate between patients with MCS and UWS, by identifying residual top-down modulation processes from higher-order cortical areas to sensory-motor integration networks related to the PPS, when using passive movement tasks.
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Affiliation(s)
- Antonino Naro
- IRCCS centro Neurolesi Bonino-Pulejo, Messina, Italy
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25
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Global structural integrity and effective connectivity in patients with disorders of consciousness. Brain Stimul 2017; 11:358-365. [PMID: 29162503 DOI: 10.1016/j.brs.2017.11.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 10/07/2017] [Accepted: 11/08/2017] [Indexed: 12/17/2022] Open
Abstract
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.
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26
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Abstract
This article addresses questions surrounding the minimally conscious state (MCS) from the perspective of adult clinical ethics. It describes the background of the MCS diagnosis, analyzes phenomenological ambiguities inherent in the nature of MCS, and raises epistemological concerns surrounding its diagnosis. It argues that in many cases, the burdens of prolonging treatment for people who have sustained certain severe brain injuries (SBI) outweigh the benefits, even if they are in or have the prospect of entering into MCS. It also argues that often such long-term measures are problematic from the perspective of patient preferences and stewardship of resources. Consequently, it suggests that the delineation of MCS as a distinct neurological state, along with research that seeks to expand how MCS is diagnosed, poses ethical difficulties for families and providers making decisions for affected patients.
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27
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Ragazzoni A, Cincotta M, Giovannelli F, Cruse D, Young GB, Miniussi C, Rossi S. Clinical neurophysiology of prolonged disorders of consciousness: From diagnostic stimulation to therapeutic neuromodulation. Clin Neurophysiol 2017; 128:1629-1646. [DOI: 10.1016/j.clinph.2017.06.037] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 05/17/2017] [Accepted: 06/15/2017] [Indexed: 10/19/2022]
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28
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Wade D. Back to the bedside? Making clinical decisions in patients with prolonged unconsciousness. JOURNAL OF MEDICAL ETHICS 2017; 43:457-458. [PMID: 27501786 DOI: 10.1136/medethics-2015-103140] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 07/07/2016] [Accepted: 07/17/2016] [Indexed: 05/11/2023]
Abstract
In 1993, the UK High Court decided that Tony Bland was unaware of himself and his environment, had no interest in medical treatment and allowed withdrawal of treatment. Subsequently, the court has reviewed all cases of stopping feeding and hydration in people with a prolonged disorder of consciousness. Their focus has been on determining whether the person is in the permanent vegetative state, because this avoids considering what is in a person's Best Interests. Consequently, much resource is spent distinguishing the vegetative state from the minimally conscious state and often clinical decisions are delayed or not made because of the requirement to go to court. In this paper, I argue that the neurophysiological basis of consciousness is unknown, and one cannot test whether the necessary structures are functioning. Unconscious people have responsiveness which varies; they may even have brief behaviours suggestive of awareness. No single clinical sign or investigation nor assessment battery can prove the presence (or absence) of consciousness or its permanence. The diagnosis of consciousness is clinical. Furthermore, awareness varies across a spectrum. There is no separate vegetative state. People simply have very limited or absent awareness. Even if there were such a state, it cannot be identified. The ethical and legal issues associated with decisions on treatment of unconscious people are no different from similar decisions in other patients. All decisions should be taken within the Best Interests framework and process. There should be no requirement to take any particular decision to court in this patient group.
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29
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Basic discriminative and semantic processing in patients in the vegetative and minimally conscious state. Int J Psychophysiol 2017; 113:8-16. [DOI: 10.1016/j.ijpsycho.2016.12.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 12/03/2016] [Accepted: 12/28/2016] [Indexed: 11/20/2022]
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30
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40Hz auditory steady-state responses in patients with disorders of consciousness: Correlation between phase-locking index and Coma Recovery Scale-Revised score. Clin Neurophysiol 2017; 128:799-806. [PMID: 28319881 DOI: 10.1016/j.clinph.2017.02.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 01/23/2017] [Accepted: 02/16/2017] [Indexed: 11/22/2022]
Abstract
OBJECTIVE We aimed to elucidate whether 40Hz auditory steady-state response (ASSR) could be sensitive to the state of patients with disorders of consciousness (DOC) as estimated with Coma Recovery Scale-Revised (CRS-R) diagnostic tool. METHODS Fifteen DOC patients and 24 healthy controls took part in the study. The 40Hz click trains were used to evoke ASSRs. Mean evoked amplitude (EA) and phase-locking index (PLI) within 38-42Hz window were calculated for 100ms bins, starting from -200 to 700ms relative to stimulus onset. RESULTS The PLI values from the patient group in the period of 200-500ms after the stimulus onset positively correlated with the CRS-R total score and with the scores of the Auditory and Visual subscales. CONCLUSIONS The phase-locking index of 40Hz auditory steady-state responses can be an indicator of the level of dysfunction of the central nervous system in DOC. SIGNIFICANCE Our results emphasize the role of central auditory system integrity in determining the level of functioning of DOC patients and suggest the possibility to use the ASSR protocol as an objective diagnostic method in DOC patients.
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Canadian perspectives on the clinical actionability of neuroimaging in disorders of consciousness. Can J Neurol Sci 2016; 42:96-105. [PMID: 25804248 DOI: 10.1017/cjn.2015.8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Acquired brain injury is a critical public health and socioeconomic problem in Canada, leaving many patients in vegetative, minimally conscious, or locked-in states, unresponsive and unable to communicate. Recent advances in neuroimaging research have demonstrated residual consciousness in a few exemplary patients with acquired brain injury, suggesting potential misdiagnosis and changes in prognosis. Such progress, in parallel with research using multimodal brain imaging technologies in recent years, has promising implications for clinical translation, notwithstanding the many challenges that impact health care and policy development. This study explored the perspectives of Canadian professionals with expertise either in neuroimaging research, disorders of consciousness, or both, on the potential clinical applications and implications of imaging technology. METHODS Twenty-two professionals from designated communities of neuroimaging researchers, ethicists, lawyers, and practitioners participated in semistructured interviews. Data were analyzed for emergent themes. RESULTS The five most dominant themes were: (1) validation and calibration of the methods; (2) informed consent; (3) burdens on the health care system; (4) implications for the Canadian health care system; and (5) possibilities for improved prognosis. CONCLUSIONS Movement of neuroimaging from research into clinical care for acquired brain injury will require careful consideration of legal and ethical issues alongside research reliability, responsible distribution of health care resources, and the interaction of technological capabilities with patient outcome.
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De Pasquale F, Caravasso CF, Péran P, Catani S, Tuovinen N, Sabatini U, Formisano R. Functional magnetic resonance imaging in disorders of consciousness: preliminary results of an innovative analysis of brain connectivity. FUNCTIONAL NEUROLOGY 2016; 30:193-201. [PMID: 26910178 DOI: 10.11138/fneur/2015.30.3.193] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The aim of this preliminary study was to present a new approach for connectivity analysis in patients with severe acquired brain injury (ABI) that overcomes some of the difficulties created by anatomical abnormalities due to the brain injury. Using a data-driven approach, resting-state structural MRI (sMRI) and functional MRI (fMRI) data from three severe ABI patients - two with disorders of consciousness (DOC) and one who had recovered consciousness (non-DOC) - were integrated and analyzed. Parameters extracted from the distribution of the connectivity values, such as mean, standard deviation and skeweness, were considered. The distribution parameters estimated seem to provide an accurate multivariate classification of the considered cases that can be summarized as follows: connectivity in the severe ABI patients with DOC was on average lower than in the severe ABI non-DOC patient and healthy subjects. The dispersion of connectivity values of the severe ABI patients, non-DOC and DOC, was comparable, however the shape of the distribution was different in the non-DOC patient. Eventually, seed-based connectivity maps of the default mode Functional magnetic resonance imaging in disorders of consciousness: preliminary results of an innovative analysis of brain connectivity network show a pattern of increasing disruption of this network from the healthy subjects to non-DOC and DOC patients. Consistent results are obtained using an ICA-based approach..
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Keller I, Garbacenkaite R. Neurofeedback in three patients in the state of unresponsive wakefulness. Appl Psychophysiol Biofeedback 2016; 40:349-56. [PMID: 26159769 DOI: 10.1007/s10484-015-9296-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Some severely brain injured patients remain unresponsive, only showing reflex movements without any response to command. This syndrome has been named unresponsive wakefulness syndrome (UWS). The objective of the present study was to determine whether UWS patients are able to alter their brain activity using neurofeedback (NFB) technique. A small sample of three patients received a daily session of NFB for 3 weeks. We applied the ratio of theta and beta amplitudes as a feedback variable. Using an automatic threshold function, patients heard their favourite music whenever their theta/beta ratio dropped below the threshold. Changes in awareness were assessed weekly with the JFK Coma Recovery Scale-Revised for each treatment week, as well as 3 weeks before and after NFB. Two patients showed a decrease in their theta/beta ratio and theta-amplitudes during this period. The third patient showed no systematic changes in his EEG activity. The results of our study provide the first evidence that NFB can be used in patients in a state of unresponsive wakefulness.
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Affiliation(s)
- Ingo Keller
- Schoen Klinik Bad Aibling, Kolbermoorer Strasse 72, 83043, Bad Aibling, Germany.
| | - Ruta Garbacenkaite
- Clinical Neuropsychology Unit and Outpatient Service, Saarland University, Saarbruecken, Germany
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Geluing L. Researching patients in the vegetative state: Difficulties of studying this patient group. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/136140960400900103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
It is now generally accepted that all patient groups should benefit from the potential advances in knowledge and understanding that result from clinical research. Despite this principle, patients in the vegetative state remain a group that has been chronically under-researched by neuroscientists because complex ethical questions and logistical dilemmas are raised by such research. The vegetative state is one of the best known but least understood of neurological conditions. It affects a small but significant number of people who make a poor recovery after sustaining a brain injury and has been brought to public attention through high profile cases in the UK and the USA. This paper defines the vegetative state and explores four important issues that should be considered when planning clinical research in this field. It is demonstrated that not only is it possible to undertake such research but also that there needs to be more of it so that greater numbers of patients and their families will benefit.
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Affiliation(s)
- Leslie Geluing
- School of Community Health & Social Studies Anglia Polytechnic University, Cambridge,
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Towards a method to differentiate chronic disorder of consciousness patients' awareness: The Low-Resolution Brain Electromagnetic Tomography Analysis. J Neurol Sci 2016; 368:178-83. [PMID: 27538628 DOI: 10.1016/j.jns.2016.07.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 07/01/2016] [Accepted: 07/08/2016] [Indexed: 01/18/2023]
Abstract
Assessing residual signs of awareness in patients suffering from chronic disorders of consciousness (DOC) is a challenging issue. DOC patient behavioral assessment is often doubtful since some individuals may retain covert traces of awareness; thus, some Unresponsive Wakefulness Syndrome (UWS) patients may be misdiagnosed. The aim of our study was to explore possible differences between the source powers within poly-modal cortices to differentiate Minimally Conscious State (MCS) from UWS. To this end, we recorded an electroencephalogram (EEG) during awake resting state and performed a Low-Resolution Brain Electromagnetic Tomography (LORETA), which is a 3D source localization method allowing the visualization of the most probable neuroanatomical generators of EEG differences. MCS and UWS patients showed significant variations concerning the frontal source power of delta-band, frontal and parietal of theta, parietal and occipital of alpha, central of beta, and parietal of gamma, in correlation with the Coma Recovery Scale-Revised (CRS-R) score. The alpha-band was the most significant LORETA data correlating with the consciousness level. In addition, we observed a significant correlation between central beta-peaks and the motor abilities and a dissociation between theta and gamma bands within parietal regions. Our findings suggest that LORETA analysis may be useful in DOC differential diagnosis since distinct neurophysiological correlates in some UWS patients could be used to assess deeper the residual cerebral activity of brain areas responsible for covert awareness.
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Koch C, Massimini M, Boly M, Tononi G. Neural correlates of consciousness: progress and problems. Nat Rev Neurosci 2016; 17:307-21. [DOI: 10.1038/nrn.2016.22] [Citation(s) in RCA: 731] [Impact Index Per Article: 91.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Naro A, Bramanti P, Leo A, Russo M, Calabrò RS. Transcranial Alternating Current Stimulation in Patients with Chronic Disorder of Consciousness: A Possible Way to Cut the Diagnostic Gordian Knot? Brain Topogr 2016; 29:623-44. [PMID: 27062669 DOI: 10.1007/s10548-016-0489-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 04/04/2016] [Indexed: 01/10/2023]
Abstract
Unresponsive wakefulness syndrome (UWS) is a chronic disorder of consciousness (DOC) characterized by a lack of awareness and purposeful motor behaviors, owing to an extensive brain connectivity impairment. Nevertheless, some UWS patients may retain residual brain connectivity patterns, which may sustain a covert awareness, namely functional locked-in syndrome (fLIS). We evaluated the possibility of bringing to light such residual neural networks using a non-invasive neurostimulation protocol. To this end, we enrolled 15 healthy individuals and 26 DOC patients (minimally conscious state-MCS- and UWS), who underwent a γ-band transcranial alternating current stimulation (tACS) over the right dorsolateral prefrontal cortex. We measured the effects of tACS on power and partial-directed coherence within local and long-range cortical networks, before and after the protocol application. tACS was able to specifically modulate large-scale cortical effective connectivity and excitability in all the MCS participants and some UWS patients, who could be, therefore, considered as suffering from fLIS. Hence, tACS could be a useful approach in supporting a DOC differential diagnosis, depending on the level of preservation of the cortical large-scale effective connectivity.
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Affiliation(s)
- Antonino Naro
- IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, S.S.113, Contrada Casazza, 98124, Messina, Italy
| | - Placido Bramanti
- IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, S.S.113, Contrada Casazza, 98124, Messina, Italy
| | - Antonino Leo
- IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, S.S.113, Contrada Casazza, 98124, Messina, Italy
| | - Margherita Russo
- IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, S.S.113, Contrada Casazza, 98124, Messina, Italy
| | - Rocco Salvatore Calabrò
- IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, S.S.113, Contrada Casazza, 98124, Messina, Italy.
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Naro A, Leo A, Cannavò A, Buda A, Bramanti P, Calabrò RS. Do unresponsive wakefulness syndrome patients feel pain? Role of laser-evoked potential-induced gamma-band oscillations in detecting cortical pain processing. Neuroscience 2016; 317:141-8. [PMID: 26791527 DOI: 10.1016/j.neuroscience.2016.01.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 01/04/2016] [Accepted: 01/07/2016] [Indexed: 01/18/2023]
Affiliation(s)
- A Naro
- IRCCS Centro Neurolesi Bonino-Pulejo, Messina, Italy
| | - A Leo
- IRCCS Centro Neurolesi Bonino-Pulejo, Messina, Italy
| | - A Cannavò
- IRCCS Centro Neurolesi Bonino-Pulejo, Messina, Italy
| | - A Buda
- IRCCS Centro Neurolesi Bonino-Pulejo, Messina, Italy
| | - P Bramanti
- IRCCS Centro Neurolesi Bonino-Pulejo, Messina, Italy
| | - R S Calabrò
- IRCCS Centro Neurolesi Bonino-Pulejo, Messina, Italy.
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Abstract
The science of consciousness has made great strides by focusing on the behavioural and neuronal correlates of experience. However, while such correlates are important for progress to occur, they are not enough if we are to understand even basic facts, for example, why the cerebral cortex gives rise to consciousness but the cerebellum does not, though it has even more neurons and appears to be just as complicated. Moreover, correlates are of little help in many instances where we would like to know if consciousness is present: patients with a few remaining islands of functioning cortex, preterm infants, non-mammalian species and machines that are rapidly outperforming people at driving, recognizing faces and objects, and answering difficult questions. To address these issues, we need not only more data but also a theory of consciousness—one that says what experience is and what type of physical systems can have it. Integrated information theory (IIT) does so by starting from experience itself via five phenomenological axioms: intrinsic existence, composition, information, integration and exclusion. From these it derives five postulates about the properties required of physical mechanisms to support consciousness. The theory provides a principled account of both the quantity and the quality of an individual experience (a quale), and a calculus to evaluate whether or not a particular physical system is conscious and of what. Moreover, IIT can explain a range of clinical and laboratory findings, makes a number of testable predictions and extrapolates to a number of problematic conditions. The theory holds that consciousness is a fundamental property possessed by physical systems having specific causal properties. It predicts that consciousness is graded, is common among biological organisms and can occur in some very simple systems. Conversely, it predicts that feed-forward networks, even complex ones, are not conscious, nor are aggregates such as groups of individuals or heaps of sand. Also, in sharp contrast to widespread functionalist beliefs, IIT implies that digital computers, even if their behaviour were to be functionally equivalent to ours, and even if they were to run faithful simulations of the human brain, would experience next to nothing.
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Affiliation(s)
- Giulio Tononi
- Department of Psychiatry, University of Wisconsin, Madison WI, USA
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Thul A, Lechinger J, Donis J, Michitsch G, Pichler G, Kochs EF, Jordan D, Ilg R, Schabus M. EEG entropy measures indicate decrease of cortical information processing in Disorders of Consciousness. Clin Neurophysiol 2015; 127:1419-1427. [PMID: 26480834 DOI: 10.1016/j.clinph.2015.07.039] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Revised: 07/21/2015] [Accepted: 07/24/2015] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Clinical assessments that rely on behavioral responses to differentiate Disorders of Consciousness are at times inapt because of some patients' motor disabilities. To objectify patients' conditions of reduced consciousness the present study evaluated the use of electroencephalography to measure residual brain activity. METHODS We analyzed entropy values of 18 scalp EEG channels of 15 severely brain-damaged patients with clinically diagnosed Minimally-Conscious-State (MCS) or Unresponsive-Wakefulness-Syndrome (UWS) and compared the results to a sample of 24 control subjects. Permutation entropy (PeEn) and symbolic transfer entropy (STEn), reflecting information processes in the EEG, were calculated for all subjects. Participants were tested on a modified active own-name paradigm to identify correlates of active instruction following. RESULTS PeEn showed reduced local information content in the EEG in patients, that was most pronounced in UWS. STEn analysis revealed altered directed information flow in the EEG of patients, indicating impaired feed-backward connectivity. Responses to auditory stimulation yielded differences in entropy measures, indicating reduced information processing in MCS and UWS. CONCLUSIONS Local EEG information content and information flow are affected in Disorders of Consciousness. This suggests local cortical information capacity and feedback information transfer as neural correlates of consciousness. SIGNIFICANCE The utilized EEG entropy analyses were able to relate to patient groups with different Disorders of Consciousness.
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Affiliation(s)
- Alexander Thul
- Department of Neurology, Klinikum rechts der Isar, Technische Universität München, Germany; Department of Anesthesiology, Klinikum rechts der Isar, Technische Universität München, Germany.
| | - Julia Lechinger
- Department of Psychology, Laboratory for Sleep, Cognition and Consciousness Research, University of Salzburg, Austria
| | - Johann Donis
- Apallic Care Unit, Neurological Division, Geriatriezentrum am Wienerwald, Vienna, Austria
| | - Gabriele Michitsch
- Apallic Care Unit, Neurological Division, Geriatriezentrum am Wienerwald, Vienna, Austria
| | - Gerald Pichler
- Apallic Care Unit, Neurological Division, Albert-Schweitzer-Klinik, Graz, Austria
| | - Eberhard F Kochs
- Department of Anesthesiology, Klinikum rechts der Isar, Technische Universität München, Germany
| | - Denis Jordan
- Department of Anesthesiology, Klinikum rechts der Isar, Technische Universität München, Germany
| | - Rüdiger Ilg
- Department of Neurology, Klinikum rechts der Isar, Technische Universität München, Germany
| | - Manuel Schabus
- Department of Psychology, Laboratory for Sleep, Cognition and Consciousness Research, University of Salzburg, Austria; Centre for Cognitive Neuroscience Salzburg (CCNS), Salzburg, Austria
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Magee WL, O'Kelly J. Music therapy with disorders of consciousness: current evidence and emergent evidence-based practice. Ann N Y Acad Sci 2015; 1337:256-62. [PMID: 25773642 DOI: 10.1111/nyas.12633] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Patients with prolonged disorders of consciousness (PDOC) stemming from acquired brain injury present one of the most challenging clinical populations in neurological rehabilitation. Because of the complex clinical presentation of PDOC patients, treatment teams are confronted with many medicolegal, ethical, philosophical, moral, and religious issues in day-to-day care. Accurate diagnosis is of central concern, relying on creative approaches from skilled clinical professionals using combined behavioral and neurophysiological measures. This paper presents the latest evidence for using music as a diagnostic tool with PDOC, including recent developments in music therapy interventions and measurement. We outline standardized clinical protocols and behavioral measures to produce diagnostic outcomes and examine recent research illustrating a range of benefits of music-based methods at behavioral, cardiorespiratory, and cortical levels using video, electrocardiography, and electroencephalography methods. These latest developments are discussed in the context of evidence-based practice in rehabilitation with clinical populations.
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Affiliation(s)
- Wendy L Magee
- Boyer College of Music and Dance, Temple University, Philadelphia, Pennsylvania
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Japaridze N, Muthuraman M, Reinicke C, Moeller F, Anwar AR, Mideksa KG, Pressler R, Deuschl G, Stephani U, Siniatchkin M. Neuronal Networks during Burst Suppression as Revealed by Source Analysis. PLoS One 2015; 10:e0123807. [PMID: 25927439 PMCID: PMC4415810 DOI: 10.1371/journal.pone.0123807] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 03/06/2015] [Indexed: 12/04/2022] Open
Abstract
Introduction Burst-suppression (BS) is an electroencephalography (EEG) pattern consisting of alternant periods of slow waves of high amplitude (burst) and periods of so called flat EEG (suppression). It is generally associated with coma of various etiologies (hypoxia, drug-related intoxication, hypothermia, and childhood encephalopathies, but also anesthesia). Animal studies suggest that both the cortex and the thalamus are involved in the generation of BS. However, very little is known about mechanisms of BS in humans. The aim of this study was to identify the neuronal network underlying both burst and suppression phases using source reconstruction and analysis of functional and effective connectivity in EEG. Material/Methods Dynamic imaging of coherent sources (DICS) was applied to EEG segments of 13 neonates and infants with burst and suppression EEG pattern. The brain area with the strongest power in the analyzed frequency (1–4 Hz) range was defined as the reference region. DICS was used to compute the coherence between this reference region and the entire brain. The renormalized partial directed coherence (RPDC) was used to describe the informational flow between the identified sources. Results/Conclusion Delta activity during the burst phases was associated with coherent sources in the thalamus and brainstem as well as bilateral sources in cortical regions mainly frontal and parietal, whereas suppression phases were associated with coherent sources only in cortical regions. Results of the RPDC analyses showed an upwards informational flow from the brainstem towards the thalamus and from the thalamus to cortical regions, which was absent during the suppression phases. These findings may support the theory that a “cortical deafferentiation” between the cortex and sub-cortical structures exists especially in suppression phases compared to burst phases in burst suppression EEGs. Such a deafferentiation may play a role in the poor neurological outcome of children with these encephalopathies.
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Affiliation(s)
- Natia Japaridze
- Department of Neuropediatrics, Christian-Albrechts-University, Kiel, Germany
- * E-mail:
| | | | - Christine Reinicke
- Department of Neuropediatrics, Christian-Albrechts-University, Kiel, Germany
| | - Friederike Moeller
- Department of Neurophysiology, Great Ormond Street Hospital for Children, London, United Kingdom
| | - Abdul Rauf Anwar
- Department of Neurology, Christian-Albrechts-University, Kiel, Germany
| | | | - Ronit Pressler
- Department of Neurophysiology, Great Ormond Street Hospital for Children, London, United Kingdom
| | - Günther Deuschl
- Department of Neurophysiology, Great Ormond Street Hospital for Children, London, United Kingdom
| | - Ulrich Stephani
- Department of Neuropediatrics, Christian-Albrechts-University, Kiel, Germany
| | - Michael Siniatchkin
- Institute of Medical Psychology and Medical Sociology, Christian-Albrechts-University of Kiel, Kiel, Germany
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Haupt WF, Hansen HC, Janzen RWC, Firsching R, Galldiks N. Coma and cerebral imaging. SPRINGERPLUS 2015; 4:180. [PMID: 25984436 PMCID: PMC4424227 DOI: 10.1186/s40064-015-0869-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 02/03/2015] [Indexed: 01/20/2023]
Abstract
The clinical sign of coma is a common feature in critical care medicine. However, little information has been put forth on the correlations between coma and cerebral imaging methods. The purpose of the article is to compile the available information derived from various imaging methods and placing it in a context of clinical knowledge of coma and related states. The definition of coma and the cerebral structures responsible for consciousness are described; the mechanisms of cerebral lesions leading to impaired consciousness and coma are explained. Cerebral imaging methods provide a large array of information on the structural changes of brain tissue in the various diseases leading to coma. Circumscript lesions produce space-occupying masses that displace the brain, ultimately leading to various types of herniation. Generalized disease of the brain usually leads to diffuse brain swelling which also can cause herniation. Epileptic states, however, rarely are detectable by imaging methods and mandate EEG examinations. Another important aspect of imaging in coma is the increasing use of functional imaging methods, which can detect the function of loss of function in various areas of the brain and render information on the extent and severity of brain damage as well as on the prognosis of disease. The MRI methods of 1H-spectroscopy and diffusion tensor imaging may provide more functional information in the future.
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Affiliation(s)
- Walter F Haupt
- Department of Neurology, University of Cologne, Kerpener St. 62, 50937 Cologne, Germany
| | - Hans Christian Hansen
- Department of Neurology and Psychiatry, Friedrich-Ebert Krankenhaus, Friesenstr. 11, 24534 Neumünster, Germany
| | | | - Raimund Firsching
- Department of Neurosurgery, Otto-von-Guericke University Magdeburg, Leipzigerstr 44, 39120 Magdeburg, Germany
| | - Norbert Galldiks
- Department of Neurology, University of Cologne, Kerpener St. 62, 50937 Cologne, Germany ; Research Center Juelich, 52425 Juelich, Germany
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Cortically projecting basal forebrain parvalbumin neurons regulate cortical gamma band oscillations. Proc Natl Acad Sci U S A 2015; 112:3535-40. [PMID: 25733878 DOI: 10.1073/pnas.1413625112] [Citation(s) in RCA: 190] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Cortical gamma band oscillations (GBO, 30-80 Hz, typically ∼40 Hz) are involved in higher cognitive functions such as feature binding, attention, and working memory. GBO abnormalities are a feature of several neuropsychiatric disorders associated with dysfunction of cortical fast-spiking interneurons containing the calcium-binding protein parvalbumin (PV). GBO vary according to the state of arousal, are modulated by attention, and are correlated with conscious awareness. However, the subcortical cell types underlying the state-dependent control of GBO are not well understood. Here we tested the role of one cell type in the wakefulness-promoting basal forebrain (BF) region, cortically projecting GABAergic neurons containing PV, whose virally transduced fibers we found apposed cortical PV interneurons involved in generating GBO. Optogenetic stimulation of BF PV neurons in mice preferentially increased cortical GBO power by entraining a cortical oscillator with a resonant frequency of ∼40 Hz, as revealed by analysis of both rhythmic and nonrhythmic BF PV stimulation. Selective saporin lesions of BF cholinergic neurons did not alter the enhancement of cortical GBO power induced by BF PV stimulation. Importantly, bilateral optogenetic inhibition of BF PV neurons decreased the power of the 40-Hz auditory steady-state response, a read-out of the ability of the cortex to generate GBO used in clinical studies. Our results are surprising and novel in indicating that this presumptively inhibitory BF PV input controls cortical GBO, likely by synchronizing the activity of cortical PV interneurons. BF PV neurons may represent a previously unidentified therapeutic target to treat disorders involving abnormal GBO, such as schizophrenia.
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Stender J, Kupers R, Rodell A, Thibaut A, Chatelle C, Bruno MA, Gejl M, Bernard C, Hustinx R, Laureys S, Gjedde A. Quantitative rates of brain glucose metabolism distinguish minimally conscious from vegetative state patients. J Cereb Blood Flow Metab 2015; 35:58-65. [PMID: 25294128 PMCID: PMC4294395 DOI: 10.1038/jcbfm.2014.169] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 08/11/2014] [Accepted: 09/03/2014] [Indexed: 12/20/2022]
Abstract
The differentiation of the vegetative or unresponsive wakefulness syndrome (VS/UWS) from the minimally conscious state (MCS) is an important clinical issue. The cerebral metabolic rate of glucose (CMRglc) declines when consciousness is lost, and may reveal the residual cognitive function of these patients. However, no quantitative comparisons of cerebral glucose metabolism in VS/UWS and MCS have yet been reported. We calculated the regional and whole-brain CMRglc of 41 patients in the states of VS/UWS (n=14), MCS (n=21) or emergence from MCS (EMCS, n=6), and healthy volunteers (n=29). Global cortical CMRglc in VS/UWS and MCS averaged 42% and 55% of normal, respectively. Differences between VS/UWS and MCS were most pronounced in the frontoparietal cortex, at 42% and 60% of normal. In brainstem and thalamus, metabolism declined equally in the two conditions. In EMCS, metabolic rates were indistinguishable from those of MCS. Ordinal logistic regression predicted that patients are likely to emerge into MCS at CMRglc above 45% of normal. Receiver-operating characteristics showed that patients in MCS and VS/UWS can be differentiated with 82% accuracy, based on cortical metabolism. Together these results reveal a significant correlation between whole-brain energy metabolism and level of consciousness, suggesting that quantitative values of CMRglc reveal consciousness in severely brain-injured patients.
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Affiliation(s)
- Johan Stender
- 1] Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark [2] Cyclotron Research Centre and Neurology Department, University and University Hospital of Liège, Liège, Belgium
| | - Ron Kupers
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Anders Rodell
- 1] Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark [2] Centre for Advanced Imaging, University of Queensland, Brisbane, Australia
| | - Aurore Thibaut
- Cyclotron Research Centre and Neurology Department, University and University Hospital of Liège, Liège, Belgium
| | - Camille Chatelle
- Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Marie-Aurélie Bruno
- Cyclotron Research Centre and Neurology Department, University and University Hospital of Liège, Liège, Belgium
| | - Michael Gejl
- 1] Centre for Advanced Imaging, University of Queensland, Brisbane, Australia [2] Department of Biomedicine-Pharmacology, Aarhus University, Aarhus, Denmark
| | - Claire Bernard
- Department of Nuclear Medicine, University Hospital of Liège, Liège, Belgium
| | - Roland Hustinx
- Department of Nuclear Medicine, University Hospital of Liège, Liège, Belgium
| | - Steven Laureys
- Cyclotron Research Centre and Neurology Department, University and University Hospital of Liège, Liège, Belgium
| | - Albert Gjedde
- 1] Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark [2] Department of Neurology, McGill University, Montréal, Québec, Canada [3] Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
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Liberati G, Hünefeldt T, Olivetti Belardinelli M. Questioning the dichotomy between vegetative state and minimally conscious state: a review of the statistical evidence. Front Hum Neurosci 2014; 8:865. [PMID: 25404905 PMCID: PMC4217390 DOI: 10.3389/fnhum.2014.00865] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 10/07/2014] [Indexed: 01/24/2023] Open
Abstract
Given the enormous consequences that the diagnosis of vegetative state (VS) vs. minimally conscious state (MCS) may have for the treatment of patients with disorders of consciousness, it is particularly important to empirically legitimate the distinction between these two discrete levels of consciousness. Therefore, the aim of this contribution is to review all the articles reporting statistical evidence concerning the performance of patients in VS vs. patients in MCS, on behavioral or neurophysiological measures. Twenty-three articles matched these inclusion criteria, and comprised behavioral, electroencephalographic (EEG), positron emission tomography (PET) and magnetic resonance imaging (MRI) measures. The analysis of these articles yielded 47 different statistical findings. More than half of these findings (n = 24) did not reveal any statistically significant difference between VS and MCS. Overall, there was no combination of variables that allowed reliably discriminating between VS and MCS. This pattern of results casts doubt on the empirical validity of the distinction between VS and MCS.
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Affiliation(s)
- Giulia Liberati
- Institute of Neuroscience, Université Catholique de Louvain Brussels, Belgium
| | - Thomas Hünefeldt
- ECONA - Interuniversity Centre for Research on Cognitive Processing in Natural and Artificial Systems, "Sapienza" University of Rome Rome, Italy ; Department of Philosophy, Catholic University of Eichstätt-Ingolstadt Eichstätt, Germany
| | - Marta Olivetti Belardinelli
- ECONA - Interuniversity Centre for Research on Cognitive Processing in Natural and Artificial Systems, "Sapienza" University of Rome Rome, Italy ; Department of Psychology, Sapienza, University of Rome Rome, Italy
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Abbate C, Trimarchi PD, Basile I, Mazzucchi A, Devalle G. Sensory stimulation for patients with disorders of consciousness: from stimulation to rehabilitation. Front Hum Neurosci 2014; 8:616. [PMID: 25157226 PMCID: PMC4127462 DOI: 10.3389/fnhum.2014.00616] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 07/23/2014] [Indexed: 11/05/2022] Open
Affiliation(s)
- Carlo Abbate
- Unità Operativa Complessa di Geriatria, Fondazione I.R.C.C.S. Ca' Granda, Ospedale Maggiore Policlinico Milan, Italy
| | - Pietro D Trimarchi
- Nucleo di Accoglienza per Persone in Stato Vegetativo, Fondazione I.R.C.C.S. Don Carlo Gnocchi ONLUS, Milan, Italy
| | - Isabella Basile
- Nucleo di Accoglienza per Persone in Stato Vegetativo, Fondazione I.R.C.C.S. Don Carlo Gnocchi ONLUS, Milan, Italy
| | - Anna Mazzucchi
- Nucleo di Accoglienza per Persone in Stato Vegetativo, Fondazione I.R.C.C.S. Don Carlo Gnocchi ONLUS, Milan, Italy
| | - Guya Devalle
- Nucleo di Accoglienza per Persone in Stato Vegetativo, Fondazione I.R.C.C.S. Don Carlo Gnocchi ONLUS, Milan, Italy
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48
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Napolitani M, Bodart O, Canali P, Seregni F, Casali A, Laureys S, Rosanova M, Massimini M, Gosseries O. Transcranial magnetic stimulation combined with high-density EEG in altered states of consciousness. Brain Inj 2014; 28:1180-9. [DOI: 10.3109/02699052.2014.920524] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Cavinato M, Genna C, Manganotti P, Formaggio E, Storti SF, Campostrini S, Arcaro C, Casanova E, Petrone V, Piperno R, Piccione F. Coherence and Consciousness: Study of Fronto-Parietal Gamma Synchrony in Patients with Disorders of Consciousness. Brain Topogr 2014; 28:570-9. [PMID: 25070585 DOI: 10.1007/s10548-014-0383-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 07/07/2014] [Indexed: 12/25/2022]
Abstract
Evaluation of consciousness needs to be supported by the evidence of brain activation during external stimulation in patients with unresponsive wakefulness syndrome (UWS). Assessment of patients should include techniques that do not depend on overt motor responses and allow an objective investigation of the spontaneous patterns of brain activity. In particular, electroencephalography (EEG) coherence allows to easily measure functional relationships between pairs of neocortical regions and seems to be closely correlated with cognitive or behavioral measures. Here, we show the contribution of higher order associative cortices of patients with disorder of consciousness (N = 26) in response to simple sensory stimuli, such as visual, auditory and noxious stimulation. In all stimulus modalities an increase of short-range parietal and long-range fronto-parietal coherences in gamma frequencies were seen in the controls and minimally conscious patients. By contrast, UWS patients showed no significant modifications in the EEG patterns after stimulation. Our results suggest that UWS patients can not activate associative cortical networks, suggesting a lack of information integration. In fact, fronto-parietal circuits result to be connectively disrupted, conversely to patients that exhibit some form of consciousness. In the light of this, EEG coherence can be considered a powerful tool to quantify the involvement of cognitive processing giving information about the integrity of fronto-parietal network. This measure can represent a new neurophysiological marker of unconsciousness and help in determining an accurate diagnosis and rehabilitative intervention in each patient.
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Affiliation(s)
- Marianna Cavinato
- Neurophysiology Department, San Camillo Foundation, Institute of Care and Research, Via Alberoni, 70, 30126, Venice, Italy,
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Brisson CD, Hsieh YT, Kim D, Jin AY, Andrew RD. Brainstem neurons survive the identical ischemic stress that kills higher neurons: insight to the persistent vegetative state. PLoS One 2014; 9:e96585. [PMID: 24802253 PMCID: PMC4011844 DOI: 10.1371/journal.pone.0096585] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 04/08/2014] [Indexed: 11/19/2022] Open
Abstract
Global ischemia caused by heart attack, pulmonary failure, near-drowning or traumatic brain injury often damages the higher brain but not the brainstem, leading to a ‘persistent vegetative state’ where the patient is awake but not aware. Approximately 30,000 U.S. patients are held captive in this condition but not a single research study has addressed how the lower brain is preferentially protected in these people. In the higher brain, ischemia elicits a profound anoxic depolarization (AD) causing neuronal dysfunction and vasoconstriction within minutes. Might brainstem nuclei generate less damaging AD and so be more resilient? Here we compared resistance to acute injury induced from simulated ischemia by ‘higher’ hippocampal and striatal neurons versus brainstem neurons in live slices from rat and mouse. Light transmittance (LT) imaging in response to 10 minutes of oxygen/glucose deprivation (OGD) revealed immediate and acutely damaging AD propagating through gray matter of neocortex, hippocampus, striatum, thalamus and cerebellar cortex. In adjacent brainstem nuclei, OGD-evoked AD caused little tissue injury. Whole-cell patch recordings from hippocampal and striatal neurons under OGD revealed sudden membrane potential loss that did not recover. In contrast brainstem neurons from locus ceruleus and mesencephalic nucleus as well as from sensory and motor nuclei only slowly depolarized and then repolarized post-OGD. Two-photon microscopy confirmed non-recoverable swelling and dendritic beading of hippocampal neurons during OGD, while mesencephalic neurons in midbrain appeared uninjured. All of the above responses were mimicked by bath exposure to 100 µM ouabain which inhibits the Na+/K+ pump or to 1–10 nM palytoxin which converts the pump into an open cationic channel. Therefore during ischemia the Na+/K+ pump of higher neurons fails quickly and extensively compared to naturally resilient hypothalamic and brainstem neurons. The selective survival of lower brain regions that maintain vital functions will support the persistent vegetative state.
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Affiliation(s)
- C. Devin Brisson
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Yi-Ting Hsieh
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Danielle Kim
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Albert Y. Jin
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - R. David Andrew
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
- * E-mail:
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