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Arciniegas DB, Gurin LJ, Zhang B. Structural and Functional Neuroanatomy of Core Consciousness: A Primer for Disorders of Consciousness Clinicians. Phys Med Rehabil Clin N Am 2024; 35:35-50. [PMID: 37993192 DOI: 10.1016/j.pmr.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2023]
Abstract
Understanding the structural and functional neuroanatomy of core consciousness (ie, wakefulness and awareness) is an asset to clinicians caring for persons with disorders of consciousness. This article provides a primer on the structural and functional neuroanatomy of wakefulness and awareness. The neuroanatomical structures supporting these elements of core consciousness functions are reviewed first, after which brief description of the clinically evaluable relationships between disruption of these structures and disorders of consciousness (ie, brain-behavior relationships) are outlined. Consideration of neuroanatomy at the mesoscale (ie, the mesocircuit hypothesis) as well as in relation to several large-scale neural networks is offered.
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Affiliation(s)
- David B Arciniegas
- Marcus Institute for Brain Health, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Department of Neurology, University of Colorado School of Medicine, Aurora, CO 80045, USA; Department of Psychiatry, University of Colorado School of Medicine, Aurora, CO 80045, USA; Department of Psychiatry and Behavioral Sciences, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA.
| | - Lindsey J Gurin
- Department of Neurology, NYU Grossman School of Medicine, New York, NY 10017, USA; Department of Psychiatry, NYU Grossman School of Medicine, New York, NY 10016, USA; Department of Physical Medicine & Rehabilitation, NYU Grossman School of Medicine, New York, NY 10016, USA
| | - Bei Zhang
- Division of Physical Medicine and Rehabilitation, Department of Neurology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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Claar LD, Rembado I, Kuyat JR, Russo S, Marks LC, Olsen SR, Koch C. Cortico-thalamo-cortical interactions modulate electrically evoked EEG responses in mice. eLife 2023; 12:RP84630. [PMID: 37358562 DOI: 10.7554/elife.84630] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023] Open
Abstract
Perturbational complexity analysis predicts the presence of consciousness in volunteers and patients by stimulating the brain with brief pulses, recording EEG responses, and computing their spatiotemporal complexity. We examined the underlying neural circuits in mice by directly stimulating cortex while recording with EEG and Neuropixels probes during wakefulness and isoflurane anesthesia. When mice are awake, stimulation of deep cortical layers reliably evokes locally a brief pulse of excitation, followed by a biphasic sequence of 120 ms profound off period and a rebound excitation. A similar pattern, partially attributed to burst spiking, is seen in thalamic nuclei and is associated with a pronounced late component in the evoked EEG. We infer that cortico-thalamo-cortical interactions drive the long-lasting evoked EEG signals elicited by deep cortical stimulation during the awake state. The cortical and thalamic off period and rebound excitation, and the late component in the EEG, are reduced during running and absent during anesthesia.
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Affiliation(s)
- Leslie D Claar
- MindScope Program, Allen Institute, Seattle, United States
| | - Irene Rembado
- MindScope Program, Allen Institute, Seattle, United States
| | | | - Simone Russo
- MindScope Program, Allen Institute, Seattle, United States
- Department of Biomedical and Clinical Sciences "L. Sacco", University of Milan, Milan, Italy
| | - Lydia C Marks
- MindScope Program, Allen Institute, Seattle, United States
| | - Shawn R Olsen
- MindScope Program, Allen Institute, Seattle, United States
| | - Christof Koch
- MindScope Program, Allen Institute, Seattle, United States
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Curley WH, Comanducci A, Fecchio M. Conventional and Investigational Approaches Leveraging Clinical EEG for Prognosis in Acute Disorders of Consciousness. Semin Neurol 2022; 42:309-324. [PMID: 36100227 DOI: 10.1055/s-0042-1755220] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
Prediction of recovery of consciousness after severe brain injury is difficult and limited by a lack of reliable, standardized biomarkers. Multiple approaches for analysis of clinical electroencephalography (EEG) that shed light on prognosis in acute severe brain injury have emerged in recent years. These approaches fall into two major categories: conventional characterization of EEG background and quantitative measurement of resting state or stimulus-induced EEG activity. Additionally, a small number of studies have associated the presence of electrophysiologic sleep features with prognosis in the acute phase of severe brain injury. In this review, we focus on approaches for the analysis of clinical EEG that have prognostic significance and that could be readily implemented with minimal additional equipment in clinical settings, such as intensive care and intensive rehabilitation units, for patients with acute disorders of consciousness.
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Affiliation(s)
- William H Curley
- Harvard Medical School, Boston, Massachusetts.,Department of Neurology, Center for Neurotechnology and Neurorecovery, Massachusetts General Hospital, Boston, Massachusetts
| | - Angela Comanducci
- IRCSS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy.,Università Campus Bio-Medico di Roma, Rome, Italy
| | - Matteo Fecchio
- Department of Neurology, Center for Neurotechnology and Neurorecovery, Massachusetts General Hospital, Boston, Massachusetts
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Shin TJ, Kim PJ, Choi B. How general anesthetics work: from the perspective of reorganized connections within the brain. Korean J Anesthesiol 2022; 75:124-138. [PMID: 35130674 PMCID: PMC8980288 DOI: 10.4097/kja.22078] [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: 02/03/2022] [Accepted: 02/06/2022] [Indexed: 11/24/2022] Open
Abstract
General anesthesia is critical for various procedures and surgeries. Despite the widespread use of anesthetics, their precise mechanisms remain poorly understood. Anesthetics inevitably act on the brain, primarily through the modulation of target receptors. Even if the action is specific to an individual neuron, however, long-range effects can occur due to the tremendous interconnectedness of neuronal activity. The strength of this connectivity can be understood using mathematical models that allow for the study of neuronal connectivity dynamics. These models also allow researchers to develop hypotheses on the candidate mechanisms of action of different types of anesthesia. This review highlights the theoretical background associated with the study of the mechanisms of action of anesthetics. We propose a candidate framework that describes how anesthetics act on the brain and consciousness in general.
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Porcaro C, Nemirovsky IE, Riganello F, Mansour Z, Cerasa A, Tonin P, Stojanoski B, Soddu A. Diagnostic Developments in Differentiating Unresponsive Wakefulness Syndrome and the Minimally Conscious State. Front Neurol 2022; 12:778951. [PMID: 35095725 PMCID: PMC8793804 DOI: 10.3389/fneur.2021.778951] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 12/08/2021] [Indexed: 12/12/2022] Open
Abstract
When treating patients with a disorder of consciousness (DOC), it is essential to obtain an accurate diagnosis as soon as possible to generate individualized treatment programs. However, accurately diagnosing patients with DOCs is challenging and prone to errors when differentiating patients in a Vegetative State/Unresponsive Wakefulness Syndrome (VS/UWS) from those in a Minimally Conscious State (MCS). Upwards of ~40% of patients with a DOC can be misdiagnosed when specifically designed behavioral scales are not employed or improperly administered. To improve diagnostic accuracy for these patients, several important neuroimaging and electrophysiological technologies have been proposed. These include Positron Emission Tomography (PET), functional Magnetic Resonance Imaging (fMRI), Electroencephalography (EEG), and Transcranial Magnetic Stimulation (TMS). Here, we review the different ways in which these techniques can improve diagnostic differentiation between VS/UWS and MCS patients. We do so by referring to studies that were conducted within the last 10 years, which were extracted from the PubMed database. In total, 55 studies met our criteria (clinical diagnoses of VS/UWS from MCS as made by PET, fMRI, EEG and TMS- EEG tools) and were included in this review. By summarizing the promising results achieved in understanding and diagnosing these conditions, we aim to emphasize the need for more such tools to be incorporated in standard clinical practice, as well as the importance of data sharing to incentivize the community to meet these goals.
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Affiliation(s)
- Camillo Porcaro
- Department of Neuroscience and Padova Neuroscience Center (PNC), University of Padova, Padova, Italy
- Institute of Cognitive Sciences and Technologies (ISTC)–National Research Council (CNR), Rome, Italy
- Department of Information Engineering, Università Politecnica delle Marche, Ancona, Italy
- Centre for Human Brain Health, School of Psychology, University of Birmingham, Birmingham, United Kingdom
- *Correspondence: Camillo Porcaro ; orcid.org/0000-0003-4847-163X
| | - Idan Efim Nemirovsky
- Department of Physics and Astronomy, Brain and Mind Institute, University of Western Ontario, London, ON, Canada
| | - Francesco Riganello
- Sant'Anna Institute and Research in Advanced Neurorehabilitation (RAN), Crotone, Italy
| | - Zahra Mansour
- Department of Information Engineering, Università Politecnica delle Marche, Ancona, Italy
| | - Antonio Cerasa
- Sant'Anna Institute and Research in Advanced Neurorehabilitation (RAN), Crotone, Italy
- Institute for Biomedical Research and Innovation (IRIB), National Research Council, Messina, Italy
- Pharmacotechnology Documentation and Transfer Unit, Preclinical and Translational Pharmacology, Department of Pharmacy, Health Science and Nutrition, University of Calabria, Rende, Italy
| | - Paolo Tonin
- Sant'Anna Institute and Research in Advanced Neurorehabilitation (RAN), Crotone, Italy
| | - Bobby Stojanoski
- Faculty of Social Science and Humanities, University of Ontario Institute of Technology, Oshawa, ON, Canada
- Department of Psychology, Brain and Mind Institute, University of Western Ontario, London, ON, Canada
| | - Andrea Soddu
- Department of Physics and Astronomy, Brain and Mind Institute, University of Western Ontario, London, ON, Canada
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Straudi S, Bonsangue V, Mele S, Craighero L, Montis A, Fregni F, Lavezzi S, Basaglia N. Bilateral M1 anodal transcranial direct current stimulation in post traumatic chronic minimally conscious state: a pilot EEG-tDCS study. Brain Inj 2019; 33:490-495. [PMID: 30632807 DOI: 10.1080/02699052.2019.1565894] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVE We tested the preliminary effects of bilateral anodal transcranial direct current stimulation (tDCS) in patients with disorders of consciousness. DESIGN Open label pilot study. SUBJECTS Ten chronic (greater than 12 months) patients in a minimally conscious state (MCS) following severe traumatic brain injury. METHODS The patients received 10 sessions of bilateral M1 anodal tDCS. Behavioural changes were assessed with the Coma Recovery Scale-Revised (CRS-R) before stimulation (T-1, T0), after five sessions (T1), at the end of the stimulation (T2), after two weeks (T3) and after three months (T4). Moreover, an EEG assessment was conducted. RESULTS Eight out of 10 patients showed new clinical signs of consciousness; specifically, a 2-point CRS-R improvement was detected in the last follow-up (p = 0.004). EEG upper α bandwidth was greater in the parietal site at T1 (p < 0.034). In addition, we found a significant correlation between behavioral and EEG indices at T1 (r = 0.89; p = 0.001). CONCLUSION This preliminary study presents several limitations (small sample size and no control group). However, it provides important initial data that can be used to design randomized clinical trials testing this novel approach in MCS and to further explore EEG as a neural marker for the effects of tDCS.
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Affiliation(s)
- Sofia Straudi
- a Neuroscience and Rehabilitation Department , Ferrara University Hospital , Ferrara , Italy
| | - Valentina Bonsangue
- a Neuroscience and Rehabilitation Department , Ferrara University Hospital , Ferrara , Italy
| | - Sonia Mele
- b Biomedical and Specialty Surgical Sciences Department , Ferrara University , Ferrara , Italy
| | - Laila Craighero
- b Biomedical and Specialty Surgical Sciences Department , Ferrara University , Ferrara , Italy
| | - Andrea Montis
- c Sardinian Health Trust , Neurorehabilitation Unit, San Martino Hospital , Oristano , Italy
| | - Felipe Fregni
- d Department of Physical Medicine and Rehabilitation, Harvard Medical School , Neuromodulation Center, Spaulding Rehabilitation Hospital , Boston , MA , USA
| | - Susanna Lavezzi
- a Neuroscience and Rehabilitation Department , Ferrara University Hospital , Ferrara , Italy
| | - Nino Basaglia
- a Neuroscience and Rehabilitation Department , Ferrara University Hospital , Ferrara , Italy
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Greco A, Carboncini MC, Virgillito A, Lanata A, Valenza G, Scilingo EP. Quantitative EEG analysis in minimally conscious state patients during postural changes. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2013:6313-6. [PMID: 24111184 DOI: 10.1109/embc.2013.6610997] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mobilization and postural changes of patients with cognitive impairment are standard clinical practices useful for both psychic and physical rehabilitation process. During this process, several physiological signals, such as Electroen-cephalogram (EEG), Electrocardiogram (ECG), Photopletysmography (PPG), Respiration activity (RESP), Electrodermal activity (EDA), are monitored and processed. In this paper we investigated how quantitative EEG (qEEG) changes with postural modifications in minimally conscious state patients. This study is quite novel and no similar experimental data can be found in the current literature, therefore, although results are very encouraging, a quantitative analysis of the cortical area activated in such postural changes still needs to be deeply investigated. More specifically, this paper shows EEG power spectra and brain symmetry index modifications during a verticalization procedure, from 0 to 60 degrees, of three patients in Minimally Consciousness State (MCS) with focused region of impairment. Experimental results show a significant increase of the power in β band (12 - 30 Hz), commonly associated to human alertness process, thus suggesting that mobilization and postural changes can have beneficial effects in MCS patients.
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Rosenbaum AM, Giacino JT. Clinical management of the minimally conscious state. HANDBOOK OF CLINICAL NEUROLOGY 2015; 127:395-410. [PMID: 25702230 DOI: 10.1016/b978-0-444-52892-6.00025-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The minimally conscious state (MCS) was defined as a disorder of consciousness (DoC) distinct from the vegetative state more than a decade ago. While this condition has become widely recognized, there are still no guidelines to steer the approach to assessment and treatment. The development of evidence-based practice guidelines for MCS has been hampered by ambiguity around the concept of consciousness, the lack of accurate methods of assessment, and the dearth of well-designed clinical trials. This chapter provides a critical review of existing assessment procedures, critically reviews available treatment options and identifies knowledge gaps. We close with practice-based recommendations for a rational approach to clinical management of this challenging population.
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Affiliation(s)
| | - Joseph T Giacino
- Department of Physical Medicine and Rehabilitation, Harvard Medical School and Spaulding Rehabilitation Hospital, Boston, MA, USA.
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9
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Disorders of consciousness after acquired brain injury: the state of the science. Nat Rev Neurol 2014; 10:99-114. [PMID: 24468878 DOI: 10.1038/nrneurol.2013.279] [Citation(s) in RCA: 463] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The concept of consciousness continues to defy definition and elude the grasp of philosophical and scientific efforts to formulate a testable construct that maps to human experience. Severe acquired brain injury results in the dissolution of consciousness, providing a natural model from which key insights about consciousness may be drawn. In the clinical setting, neurologists and neurorehabilitation specialists are called on to discern the level of consciousness in patients who are unable to communicate through word or gesture, and to project outcomes and recommend approaches to treatment. Standards of care are not available to guide clinical decision-making for this population, often leading to inconsistent, inaccurate and inappropriate care. In this Review, we describe the state of the science with regard to clinical management of patients with prolonged disorders of consciousness. We review consciousness-altering pathophysiological mechanisms, specific clinical syndromes, and novel diagnostic and prognostic applications of advanced neuroimaging and electrophysiological procedures. We conclude with a provocative discussion of bioethical and medicolegal issues that are unique to this population and have a profound impact on care, as well as raising questions of broad societal interest.
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10
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CRS-R score in disorders of consciousness is strongly related to spectral EEG at rest. J Neurol 2013; 260:2348-56. [PMID: 23765089 DOI: 10.1007/s00415-013-6982-3] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 05/23/2013] [Accepted: 05/25/2013] [Indexed: 10/26/2022]
Abstract
Patients suffering from disorders of consciousness still present a diagnostic challenge due to the fact that their assessment is mainly based on behavioral scales with their motor responses often being strongly impaired. We therefore focused on resting electroencephalography (EEG) in order to reveal potential alternative measures of the patient's current state independent of rather complex abilities (e.g., language comprehension). Resting EEG was recorded in nine minimally conscious state (MCS) and eight vegetative state/unresponsive wakefulness syndrome (VS/UWS) patients. Behavioral assessments were conducted using the Coma-Recovery Scale-Revised (CRS-R). The signal was analyzed in the frequency domain and association between resting EEG and CRS-R score as well as clinical diagnosis were calculated using Pearson correlation and repeated-measures ANOVAs. The analyses revealed robust positive correlations between CRS-R score and ratios between frequencies above 8 Hz and frequencies below 8 Hz. Furthermore, the frequency of the spectral peak was also highly indicative of the patient's CRS-R score. Concerning differences between clinical diagnosis and healthy controls, it could be revealed that while VS/UWS patients showed higher delta and theta activity than controls, MCS did not differ from controls in this frequency range. Alpha activity, on the other hand, was strongly decreased in both patient groups as compared to controls. The strong relationship between various resting EEG parameters and CRS-R score provides significant clinical relevance. Not only is resting activity easily acquired at bedside, but furthermore, it does not depend on explicit cooperation of the patient. Especially in cases where behavioral assessment is difficult or ambiguous, spectral analysis of resting EEG can therefore complement clinical diagnosis.
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11
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Michelagnoli G, Zamidei L, Consales G. Organ failure and central nervous system. TRENDS IN ANAESTHESIA AND CRITICAL CARE 2013. [DOI: 10.1016/j.tacc.2013.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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12
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Valenza G, Carboncini MC, Virgillito A, Creatini I, Bonfiglio L, Rossi B, Lanatà A, Scilingo EP. EEG complexity drug-induced changes in disorders of consciousness: a preliminary report. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2012; 2011:3724-7. [PMID: 22255149 DOI: 10.1109/iembs.2011.6090633] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The goal of this work is to investigate EEG (ElectroEncephaloGram) dynamics after drug intake in patients being in states of Disorders Of Consciousness (DOC) after brain injury. Four patients were involved in the study. All the patients exhibit cerebral lesions located in the same anatomical region. Two nonlinear indexes, such as Lempel-Ziv Complexity (LZC) and Approximate Entropy (ApEn), along with power spectra, were calculated for EEG signals gathered from electrodes placed on both injured and non-injured regions. Experimental results show that after drug administration the two nonlinear indexes calculated from EEG taken from injured regions increase (p < 0.001) while power spectra decrease or remain unchanged. These results do not pretend to draw conclusions about consciousness level either suggest promising therapeutical treatments, but represent only an experimental evidence about the change in the EEG complexity after drug administration.
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Affiliation(s)
- G Valenza
- Department of Information Engineering and Interdepartmental Research Center E Piaggio, Faculty of Engineering, University of Pisa, Via G Caruso 16, 56122 Pisa, Italy.
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Boly M, Massimini M, Garrido MI, Gosseries O, Noirhomme Q, Laureys S, Soddu A. Brain connectivity in disorders of consciousness. Brain Connect 2012; 2:1-10. [PMID: 22512333 DOI: 10.1089/brain.2011.0049] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The last 10 years witnessed a considerable increase in our knowledge of brain function in survivors to severe brain injuries with disorders of consciousness (DOC). At the same time, a growing interest developed for the use of functional neuroimaging as a new diagnostic tool in these patients. In this context, particular attention has been devoted to connectivity studies-as these, more than measures of brain metabolism, may be more appropriate to capture the dynamics of large populations of neurons. Here, we will review the pros and cons of various connectivity methods as potential diagnostic tools in brain-damaged patients with DOC. We will also discuss the relevance of the study of the level versus the contents of consciousness in this context.
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Affiliation(s)
- Mélanie Boly
- Coma Science Group, Cyclotron Research Centre and Neurology Department, University of Liège and CHU Sart Tilman Hospital, Liège, Belgium.
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Fellinger R, Klimesch W, Schnakers C, Perrin F, Freunberger R, Gruber W, Laureys S, Schabus M. Cognitive processes in disorders of consciousness as revealed by EEG time–frequency analyses. Clin Neurophysiol 2011; 122:2177-84. [PMID: 21511524 DOI: 10.1016/j.clinph.2011.03.004] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 02/04/2011] [Accepted: 03/06/2011] [Indexed: 11/19/2022]
Affiliation(s)
- R Fellinger
- Department of Psychology, Laboratory for Sleep and Consciousness Research and Division of Physiological Psychology, University of Salzburg, Hellbrunnerstraße 34, 5020 Salzburg, Austria
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15
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Goldfine AM, Schiff ND. Consciousness: its neurobiology and the major classes of impairment. Neurol Clin 2011; 29:723-37. [PMID: 22032656 DOI: 10.1016/j.ncl.2011.08.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Human consciousness requires brainstem, basal forebrain, and diencephalic areas to support generalized arousal, and functioning thalamocortical networks to respond to environmental and internal stimuli. Disconnection of these interconnected systems, typically from cardiac arrest and traumatic brain injury, can result in disorders of consciousness. Brain injuries can also result in loss of motor output out of proportion to consciousness, resulting in misdiagnoses. The authors review pathology and imaging studies and derive mechanistic models for each of these conditions. Such models may guide the development of target-based treatment algorithms to enhance recovery of consciousness in many of these patients.
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Affiliation(s)
- Andrew M Goldfine
- Department of Neurology and Neuroscience, Weill Cornell Medical College, LC 803, 1300 York Avenue, New York, NY 10065, USA.
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Oliveira L, Fregni F. Pharmacological and electrical stimulation in chronic disorders of consciousness: New insights and future directions. Brain Inj 2011; 25:315-27. [DOI: 10.3109/02699052.2011.556103] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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17
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Piccione F, Cavinato M, Manganotti P, Formaggio E, Storti SF, Battistin L, Cagnin A, Tonin P, Dam M. Behavioral and neurophysiological effects of repetitive transcranial magnetic stimulation on the minimally conscious state: a case study. Neurorehabil Neural Repair 2010; 25:98-102. [PMID: 20647501 DOI: 10.1177/1545968310369802] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND In 2007, Schiff et al reported a patient in a minimally conscious state (MCS) who responded to deep brain stimulation (DBS), but clinicians cannot predict which patients might respond prior to the implantation of electrodes. METHODS A patient in a MCS for 5 years participated in an ABA design alternating between repetitive transcranial magnetic stimulation (rTMS) and peripheral nerve stimulation. rTMS (condition A) involved the delivery of 10 trains of 100 stimuli at 20 Hz using a stimulator with a 70-mm figure-of-eight coil to elicit a contraction of the abductor pollicis brevis. Condition B used median nerve electrical stimulation. RESULTS After peripheral stimulation, the patient did not exhibit clinical, behavioral, or electroencephalographic (EEG) changes. The frequency of specific and meaningful behaviors increased after rTMS, along with the absolute and relative power of the EEG δ, β, and α bands. CONCLUSION These results suggest that rTMS may improve awareness and arousal in MCS. If these results are reproducible, rTMS may identify subgroups of MCS patients who might benefit from DBS.
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Gutiérrez J, Machado C, Estévez M, Olivares A, Hernández H, Perez J, Beltrán C, Leisman G. Heart rate variability changes induced by auditory stimulation in persistent vegetative state. ACTA ACUST UNITED AC 2010. [DOI: 10.1515/ijdhd.2010.041] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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19
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Schiff ND. Recovery of consciousness after brain injury: a mesocircuit hypothesis. Trends Neurosci 2009; 33:1-9. [PMID: 19954851 DOI: 10.1016/j.tins.2009.11.002] [Citation(s) in RCA: 386] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Revised: 10/13/2009] [Accepted: 11/03/2009] [Indexed: 11/29/2022]
Abstract
Recovery of consciousness following severe brain injuries can occur over long time intervals. Importantly, evolving cognitive recovery can be strongly dissociated from motor recovery in some individuals, resulting in underestimation of cognitive capacities. Common mechanisms of cerebral dysfunction that arise at the neuronal population level may explain slow functional recoveries from severe brain injuries. This review proposes a "mesocircuit" model that predicts specific roles for different structural and dynamic changes that may occur gradually during recovery. Recent functional neuroimaging studies that operationally identify varying levels of awareness, memory and other higher brain functions in patients with no behavioral evidence of these cognitive capacities are discussed. Measuring evolving changes in underlying brain function and dynamics post-injury and post-treatment frames future investigative work.
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Affiliation(s)
- Nicholas D Schiff
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, NY, USA.
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Demertzi A, Vanhaudenhuyse A, Bruno MA, Schnakers C, Boly M, Boveroux P, Maquet P, Moonen G, Laureys S. Is there anybody in there? Detecting awareness in disorders of consciousness. Expert Rev Neurother 2009; 8:1719-30. [PMID: 18986242 DOI: 10.1586/14737175.8.11.1719] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The bedside detection of awareness in disorders of consciousness (DOC) caused by acquired brain injury is not an easy task. For this reason, differential diagnosis using neuroimaging and electrophysiological tools in search for objective markers of consciousness is being employed. However, such tools cannot be considered as diagnostic per se, but as assistants to the clinical evaluation, which, at present, remains the gold standard. Regarding therapeutic management in DOC, no evidence-based recommendations can be made in favor of a specific treatment. The present review summarizes clinical and paraclinical studies that have been conducted with neuroimaging and electrophysiological techniques in search of residual awareness in DOC. We discuss the medical, scientific and ethical implications that derive from these studies and we argue that, in the future, the role of neuroimaging and electrophysiology will be important not only for the diagnosis and prognosis of DOC but also in establishing communication with these challenging patients.
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Affiliation(s)
- Athena Demertzi
- Coma Science Group, Neurology Department, Cyclotron Research Centre, University of Liège, Liège, Belgium
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23
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Leon-Carrion J, Martin-Rodriguez JF, Damas-Lopez J, Barroso y Martin JM, Dominguez-Morales MR. Brain function in the minimally conscious state: a quantitative neurophysiological study. Clin Neurophysiol 2008; 119:1506-14. [PMID: 18486547 DOI: 10.1016/j.clinph.2008.03.030] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Revised: 02/22/2008] [Accepted: 03/19/2008] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To explore possible EEG power spectrum and coherence differences between patients in minimally conscious state (MCS) and patients with severe neurocognitive disorders (SND), who show signs of awareness. We also try to find EEG cortical sources that differentiate between both conditions using LORETA source analysis. METHODS We studied 16 patients with traumatic brain injury (7 MCS, 9 SND; aged 18-49) and compared EEG power spectra, coherence, and LORETA sources at rest for both groups. RESULTS EEG power spectra revealed significant differences in the delta range of both conditions. Patients in MCS showed a notably increased power in this band, compared to SND patients. LORETA analysis showed that posterior sources of delta and theta frequencies had higher amplitude in MCS patients than in SND patients. Regarding fast frequencies, lower source magnitudes in temporal and frontal lobes were found for MCS patients. CONCLUSIONS Our results stress the importance of fronto-temporal-parietal associative cortices within the "awareness-regions" model. Our results also suggest a relation between excess of slow wave activity and diminished level of awareness in brain injury population. SIGNIFICANCE Neurophysiological correlates in brain damaged patients who are severely impaired could be used to assess the integrity of brain areas responsible for awareness.
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Affiliation(s)
- J Leon-Carrion
- Human Neuropsychology Laboratory, School of Psychology, Department of Experimental Psychology, C/Camilo José Cela s/n, University of Seville, Seville, Spain.
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24
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Boly M, Owen AM, Laureys S. To be or not to be ... Vegetative. Intensive Care Med 2007. [DOI: 10.1007/978-0-387-49518-7_83] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Giacino JT, Hirsch J, Schiff N, Laureys S. Functional neuroimaging applications for assessment and rehabilitation planning in patients with disorders of consciousness. Arch Phys Med Rehabil 2007; 87:S67-76. [PMID: 17140882 DOI: 10.1016/j.apmr.2006.07.272] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 07/24/2006] [Accepted: 07/24/2006] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To describe the theoretic framework, design, and potential clinical applications of functional neuroimaging protocols in patients with disorders of consciousness. DATA SOURCES Recent published literature and authors' own work. STUDY SELECTION Studies using functional neuroimaging techniques to investigate cognitive processing in patients diagnosed with vegetative and minimally conscious state. DATA EXTRACTION Not applicable. DATA SYNTHESIS Positron-emission tomography activation studies suggest that the vegetative state represents a global disconnection syndrome in which higher order association cortices are functionally disconnected from primary cortical areas. In contrast, patterns of activation in functional magnetic resonance imaging studies of patients in the minimally conscious state show preservation of large-scale cortical networks associated with language and visual processing. CONCLUSIONS Novel applications of functional neuroimaging in patients with disorders of consciousness may aid in differential diagnosis, prognostic assessment and identification of pathophysiologic mechanisms. Improvements in patient characterization may, in turn, provide new opportunities for restoration of function through interventional neuromodulation.
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Affiliation(s)
- Joseph T Giacino
- JFK Johnson Rehabilitation Institute, and New Jersey Neuroscience Institute, JFK Medical Center, Edison, NJ 08818, USA.
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26
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Abstract
Advances in neuroimaging techniques hold significant promise for improving understanding of disorders of consciousness arising from severe brain injuries. We review neuroimaging studies of the vegetative state (VS) and minimally conscious state (MCS), and findings in an unusual case of late emergence from MCS. Multimodal neuroimaging studies using positron emission tomography techniques, functional magnetic resonance imaging, and quantitative electroencephalography and magnetoencephalography quantify variations of residual cerebral activity across these patient populations. The results suggest models to distinguish the pathophysiologic basis of VS and MCS. Less clear are potential brain mechanisms underlying late recovery of communication in rare MCS patients. Diffusion tensor magnetic resonance imaging studies and recent experimental findings suggest that structural remodeling of the brain following severe injury may play a role in late functional recoveries. More generally, relatively long time courses of recovery following severe brain injury emphasize the need to develop markers for identifying patients who may harbor potential for further meaningful recovery. Introduction of neuroimaging into the clinical evaluation process will require developing frameworks for longitudinal assessments of cerebral function. Although limited in number, available studies already provide important insights into underlying brain mechanisms that may help guide development of such assessment strategies.
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Affiliation(s)
- Nicholas D Schiff
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY 10021, USA.
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27
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Abstract
We review the emerging applications of functional and structural neuroimaging techniques for the assessment of patients with disorders of consciousness. Measurements of brain function from patients in the vegetative state (VS) and minimally conscious state (MCS) are compared, and a conceptual organization is developed that suggests models of brain mechanisms associated with different functional levels of recovery. We emphasize developing strategies to place complex brain injuries on a more equal footing using global and regional quantification of resting or activated brain activity using functional imaging techniques alongside more detailed structural assessments of neuronal integrity and axonal connectivity now available. Preliminary studies from several investigative groups suggest that some MCS patients may harbor a functional reserve in the form of recruitable cerebral networks. These findings support developing systematic characterizations of the severely injured brain and suggest that some patients may benefit from improved diagnostic assessments.
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Affiliation(s)
- Nicholas D Schiff
- Laboratory of Cognitive Neuromodulation, Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, New York 10021, USA.
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28
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Fins JJ. Affirming the right to care, preserving the right to die: disorders of consciousness and neuroethics after Schiavo. Palliat Support Care 2006; 4:169-78. [PMID: 16903588 DOI: 10.1017/s1478951506060238] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In this article, I attempt to untangle some of the cultural, philosophical, and ethical currents that informed the Schiavo case. My objective is to better apprehend what the Schiavo case means for end-of-life care in general and to assert that our discourse about the ethical issues attendant to brain injury will be impoverished if we limit our discussions about disorders of consciousness solely to the vegetative state. If we ignore emerging developments in neuroscience that are helping to elucidate the nature of these disorders and fail to broaden the conversation about brain injury, beyond the unmitigated futility of the permanent vegetative state, we will imperil others who might improve and be helped. Through such efforts we can help mitigate the tragedy of the Schiavo case and overcome the rhetoric that marked the national discourse in March 2005. Once the complexity of disorders of consciousness is appreciated, rhetorical statements about a right to die or a right to life are exposed as being incompatible with the challenge of providing care to such patients. This is especially true as neuroscience brings greater diagnostic refinement to their assessment and management, a topic addressed in this article, which specifically focuses on the clinical and ethical implications of the recently described minimally conscious state. Instead of staking out ideological positions that do not meet the needs of patients or families, we should strive to both preserve the right to die for those who are beyond hope while affirming the right to care to those who might benefit from coming advances in neuroscience. If we can achieve that delicate balance, we will be able to transcend the partisan debate that shrouded the life and death of Theresa Marie Schiavo and begin to articulate a palliative neuroethics of care for those touched by severe brain injury and disorders of consciousness.
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Affiliation(s)
- Joseph J Fins
- Division of Medical Ethics, New York Presbyterian-Weill Cornell Medical Center, 435 East 70th Street, Suite 4-J, New York, NY 10021, USA.
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29
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Laureys S, Giacino JT, Schiff ND, Schabus M, Owen AM. How should functional imaging of patients with disorders of consciousness contribute to their clinical rehabilitation needs? Curr Opin Neurol 2006; 19:520-7. [PMID: 17102688 PMCID: PMC2858870 DOI: 10.1097/wco.0b013e3280106ba9] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
PURPOSE OF REVIEW We discuss the problems of evidence-based neurorehabilitation in disorders of consciousness, and recent functional neuroimaging data obtained in the vegetative state and minimally conscious state. RECENT FINDINGS Published data are insufficient to make recommendations for or against any of the neurorehabilitative treatments in vegetative state and minimally conscious state patients. Electrophysiological and functional imaging studies have been shown to be useful in measuring residual brain function in noncommunicative brain-damaged patients. Despite the fact that such studies could in principle allow an objective quantification of the putative cerebral effect of rehabilitative treatment in the vegetative state and minimally conscious state, they have so far not been used in this context. SUMMARY Without controlled studies and careful patient selection criteria it will not be possible to evaluate the potential of therapeutic interventions in disorders of consciousness. There also is a need to elucidate the neurophysiological effects of such treatments. Integration of multimodal neuroimaging techniques should eventually improve our ability to disentangle differences in outcome on the basis of underlying mechanisms and better guide our therapeutic options in the challenging patient populations encountered following severe acute brain damage.
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Affiliation(s)
- Steven Laureys
- Cyclotron Research Center and Neurology Department, University of Liège, Liège, Belgium.
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30
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Zasler ND. Neurorehabilitation issues in states of disordered consciousness following traumatic brain injury. FUTURE NEUROLOGY 2006. [DOI: 10.2217/14796708.1.4.439] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The assessment and care of persons with disorders of consciousness (DOC) following catastrophic traumatic brain injury is often difficult and filled with both challenges and potential controversies. Rates of misdiagnosis of low-level neurological state (LLNS) patients with signs of awareness as being vegetative have been noted to be unacceptably high and call for better education and training regarding the assessment methodologies of individuals with DOC. Clinician knowledge regarding prognostication and neural recovery from LLNSs following traumatic brain injury is often lacking, as is awareness of the neurorehabilitative interventions that can potentially facilitate recovery, as well as minimize morbidity and mortality in this unique population of neurological patients.
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Affiliation(s)
- Nathan D Zasler
- Concussion Care Centre of Virginia, Ltd., Tree of Life Services, 10120 West Broad Street, Suite G & H, Glen Allen, VA 23060, USA
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Laureys S, Perrin F, Schnakers C, Boly M, Majerus S. Residual cognitive function in comatose, vegetative and minimally conscious states. Curr Opin Neurol 2005; 18:726-33. [PMID: 16280686 DOI: 10.1097/01.wco.0000189874.92362.12] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
PURPOSE OF REVIEW The clinical evaluation of cognition in non-communicative severely brain-damaged patients is inherently difficult. In addition to novel behavioural 'consciousness-scales', the role of para-clinical markers of consciousness, such as event related potentials and functional neuroimaging is reviewed. RECENT FINDINGS New behavioural scales for vegetative and minimally conscious patients have been shown to reduce diagnostic error but regrettably remain underused in clinical routine. Electrophysiological studies have confirmed their role in estimating outcome and possibly cognition. Several recent functional neuroimaging studies have shown residual cortical function in undeniably vegetative patients. This cortical activation, however, seems limited to primary 'low-level' areas and does not imply 'higher-order' integration, considered necessary for conscious perception. Minimally conscious patients show large-scale high-order cerebral activation, apparently dependent upon the emotional relevance of the stimulation. SUMMARY Careful clinical assessment of putative 'conscious behaviour' in vegetative and minimally conscious patients is the first requirement for their proper diagnosis and management. Complementary functional neuroimaging and electrophysiological studies will have a major impact on future clinical decision making and may guide selective therapeutic options. At present, more experimental evidence and the elucidation of methodological and ethical controversies are awaited prior to their routine clinical use.
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Affiliation(s)
- Steven Laureys
- Cyclotron Research Centre, University of Liège, Belgium.
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