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Kotchoubey B. Evoked and event-related potentials in disorders of consciousness: A quantitative review. Conscious Cogn 2017; 54:155-167. [DOI: 10.1016/j.concog.2017.05.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 04/18/2017] [Accepted: 05/10/2017] [Indexed: 11/25/2022]
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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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Lugo ZR, Quitadamo LR, Bianchi L, Pellas F, Veser S, Lesenfants D, Real RGL, Herbert C, Guger C, Kotchoubey B, Mattia D, Kübler A, Laureys S, Noirhomme Q. Cognitive Processing in Non-Communicative Patients: What Can Event-Related Potentials Tell Us? Front Hum Neurosci 2016; 10:569. [PMID: 27895567 PMCID: PMC5107572 DOI: 10.3389/fnhum.2016.00569] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/26/2016] [Indexed: 12/03/2022] Open
Abstract
Event-related potentials (ERP) have been proposed to improve the differential diagnosis of non-responsive patients. We investigated the potential of the P300 as a reliable marker of conscious processing in patients with locked-in syndrome (LIS). Eleven chronic LIS patients and 10 healthy subjects (HS) listened to a complex-tone auditory oddball paradigm, first in a passive condition (listen to the sounds) and then in an active condition (counting the deviant tones). Seven out of nine HS displayed a P300 waveform in the passive condition and all in the active condition. HS showed statistically significant changes in peak and area amplitude between conditions. Three out of seven LIS patients showed the P3 waveform in the passive condition and five of seven in the active condition. No changes in peak amplitude and only a significant difference at one electrode in area amplitude were observed in this group between conditions. We conclude that, in spite of keeping full consciousness and intact or nearly intact cortical functions, compared to HS, LIS patients present less reliable results when testing with ERP, specifically in the passive condition. We thus strongly recommend applying ERP paradigms in an active condition when evaluating consciousness in non-responsive patients.
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Affiliation(s)
- Zulay R Lugo
- Coma Science Group, University and University Hospital of Liège, GIGALiège, Belgium; Institute of Psychology, University of WürzburgWürzburg, Germany; French Association of Locked-in Syndrome (ALIS)Paris, France
| | - Lucia R Quitadamo
- Neuroelectrical Imaging and BCI Laboratory, Fondazione Santa Lucia, IRCCSRome, Italy; School of Life and Health Sciences, Aston Brain Centre, Aston UniversityBirmingham, UK
| | - Luigi Bianchi
- Department of Civil Engineering and Computer Science, University of Rome Tor Vergata Rome, Italy
| | - Fréderic Pellas
- French Association of Locked-in Syndrome (ALIS)Paris, France; Coma Arousal Unit - PMR Department, Nîmes University HospitalNîmes, France
| | - Sandra Veser
- Institute for Medical Psychology and Behavioural Neurobiology, University of Tübingen Tübingen, Germany
| | - Damien Lesenfants
- Coma Science Group, University and University Hospital of Liège, GIGA Liège, Belgium
| | - Ruben G L Real
- Institute of Psychology, University of Würzburg Würzburg, Germany
| | - Cornelia Herbert
- Institute of Psychology, University of WürzburgWürzburg, Germany; Department of Psychiatry, University of TübingenTübingen, Germany; Department of Biomedical Resonance, University of TübingenTübingen, Germany
| | - Christoph Guger
- G.Tec Medical Engineering GmbH/Guger Technologies OG Graz, Austria
| | - Boris Kotchoubey
- Institute for Medical Psychology and Behavioural Neurobiology, University of Tübingen Tübingen, Germany
| | - Donatella Mattia
- Neuroelectrical Imaging and BCI Laboratory, Fondazione Santa Lucia, IRCCS Rome, Italy
| | - Andrea Kübler
- Institute of Psychology, University of Würzburg Würzburg, Germany
| | - Steven Laureys
- Coma Science Group, University and University Hospital of Liège, GIGA Liège, Belgium
| | - Quentin Noirhomme
- Coma Science Group, University and University Hospital of Liège, GIGALiège, Belgium; Department of Cognitive Neuroscience, Maastricht UniversityMaastricht, Netherlands; Brain Innovation B.V.Maastricht, Netherlands
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Kotchoubey B, Pavlov YG, Kleber B. Music in Research and Rehabilitation of Disorders of Consciousness: Psychological and Neurophysiological Foundations. Front Psychol 2015; 6:1763. [PMID: 26640445 PMCID: PMC4661237 DOI: 10.3389/fpsyg.2015.01763] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 11/03/2015] [Indexed: 01/18/2023] Open
Abstract
According to a prevailing view, the visual system works by dissecting stimuli into primitives, whereas the auditory system processes simple and complex stimuli with their corresponding features in parallel. This makes musical stimulation particularly suitable for patients with disorders of consciousness (DoC), because the processing pathways related to complex stimulus features can be preserved even when those related to simple features are no longer available. An additional factor speaking in favor of musical stimulation in DoC is the low efficiency of visual stimulation due to prevalent maladies of vision or gaze fixation in DoC patients. Hearing disorders, in contrast, are much less frequent in DoC, which allows us to use auditory stimulation at various levels of complexity. The current paper overviews empirical data concerning the four main domains of brain functioning in DoC patients that musical stimulation can address: perception (e.g., pitch, timbre, and harmony), cognition (e.g., musical syntax and meaning), emotions, and motor functions. Music can approach basic levels of patients' self-consciousness, which may even exist when all higher-level cognitions are lost, whereas music induced emotions and rhythmic stimulation can affect the dopaminergic reward-system and activity in the motor system respectively, thus serving as a starting point for rehabilitation.
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Affiliation(s)
- Boris Kotchoubey
- Institute for Medical Psychology and Behavioural Neurobiology, University of Tübingen, Tübingen, Germany
| | - Yuri G. Pavlov
- Institute for Medical Psychology and Behavioural Neurobiology, University of Tübingen, Tübingen, Germany
- Department of Psychology, Ural Federal University, Yekaterinburg, Russia
| | - Boris Kleber
- Institute for Medical Psychology and Behavioural Neurobiology, University of Tübingen, Tübingen, Germany
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Kirschner A, Cruse D, Chennu S, Owen AM, Hampshire A. A P300-based cognitive assessment battery. Brain Behav 2015; 5:e00336. [PMID: 26085962 PMCID: PMC4467771 DOI: 10.1002/brb3.336] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 02/15/2015] [Accepted: 02/25/2015] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND It is well established that some patients who are diagnosed as being in a vegetative state or a minimally conscious state show reliable signs of volition that may only be detected by measuring neural responses. A pertinent question is whether these patients are capable of higher cognitive processes. METHODS Here, we develop a series of EEG paradigms that probe several core aspects of cognition at the bedside without the need for motor responses and explore the sensitivity of this approach in a group of healthy controls. RESULTS Using analysis of ERPs alone, this method can determine with high reliability whether individual participants are able to attend a stimulus stream, maintain items in working memory, or solve complex grammatical reasoning problems. CONCLUSION We suggest that this approach could form the basis of a brain-based battery for assessing higher cognition in patients with severe motor impairments or disorders of consciousness.
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Affiliation(s)
- Aaron Kirschner
- The Brain and Mind Institute, University of Western OntarioLondon, Ontario, Canada
| | - Damian Cruse
- The Brain and Mind Institute, University of Western OntarioLondon, Ontario, Canada
| | - Srivas Chennu
- Department of Clinical Neurosciences, The University of CambridgeCambridge, UK
| | - Adrian M Owen
- The Brain and Mind Institute, University of Western OntarioLondon, Ontario, Canada
| | - Adam Hampshire
- The Computational, Cognitive and Clinical Neuroimaging Laboratory, Division of Brain Sciences, Imperial College LondonLondon, UK
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Visual processing during recovery from vegetative state to consciousness: Comparing behavioral indices to brain responses. Neurophysiol Clin 2014; 44:457-69. [DOI: 10.1016/j.neucli.2014.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 08/19/2014] [Accepted: 08/23/2014] [Indexed: 11/19/2022] Open
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Repeated Measurements of the Auditory Oddball Paradigm Is Related to Recovery From the Vegetative State. J Clin Neurophysiol 2014; 31:65-80. [DOI: 10.1097/01.wnp.0000436894.17749.0c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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Halder S, Ruf CA, Furdea A, Pasqualotto E, De Massari D, van der Heiden L, Bogdan M, Rosenstiel W, Birbaumer N, Kübler A, Matuz T. Prediction of P300 BCI aptitude in severe motor impairment. PLoS One 2013; 8:e76148. [PMID: 24204597 PMCID: PMC3799852 DOI: 10.1371/journal.pone.0076148] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 08/20/2013] [Indexed: 12/14/2022] Open
Abstract
Brain-computer interfaces (BCIs) provide a non-muscular communication channel for persons with severe motor impairments. Previous studies have shown that the aptitude with which a BCI can be controlled varies from person to person. A reliable predictor of performance could facilitate selection of a suitable BCI paradigm. Eleven severely motor impaired participants performed three sessions of a P300 BCI web browsing task. Before each session auditory oddball data were collected to predict the BCI aptitude of the participants exhibited in the current session. We found a strong relationship of early positive and negative potentials around 200 ms (elicited with the auditory oddball task) with performance. The amplitude of the P2 (r = −0.77) and of the N2 (r = −0.86) had the strongest correlations. Aptitude prediction using an auditory oddball was successful. The finding that the N2 amplitude is a stronger predictor of performance than P3 amplitude was reproduced after initially showing this effect with a healthy sample of BCI users. This will reduce strain on the end-users by minimizing the time needed to find suitable paradigms and inspire new approaches to improve performance.
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Affiliation(s)
- Sebastian Halder
- Institute of Psychology, University of Würzburg, Würzburg, Germany
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- Department of Computer Engineering, University of Tübingen, Tübingen, Germany
- * E-mail:
| | - Carolin Anne Ruf
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
| | - Adrian Furdea
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
| | - Emanuele Pasqualotto
- Psychological Sciences Research Institute, Université catholique de Louvain, Louvain-la-neuve, Belgium
| | - Daniele De Massari
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- Ospedale San Camillo, Istituto Di Ricovero e Cura a Carattere Scientifico Fondazione, Venezia-Lido, Italy
- Graduate Training Centre of Neuroscience, International Max Planck Research School, Tübingen, Germany
| | - Linda van der Heiden
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- Department of Cognitive Psychology, University of Finance and Management, Warsaw, Poland
| | - Martin Bogdan
- Department of Computer Engineering, University of Tübingen, Tübingen, Germany
- Computer Engineering, University of Leipzig, Leipzig, Germany
| | - Wolfgang Rosenstiel
- Department of Computer Engineering, University of Tübingen, Tübingen, Germany
| | - Niels Birbaumer
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- Ospedale San Camillo, Istituto Di Ricovero e Cura a Carattere Scientifico Fondazione, Venezia-Lido, Italy
| | - Andrea Kübler
- Institute of Psychology, University of Würzburg, Würzburg, Germany
| | - Tamara Matuz
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
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Chennu S, Finoia P, Kamau E, Monti MM, Allanson J, Pickard JD, Owen AM, Bekinschtein TA. Dissociable endogenous and exogenous attention in disorders of consciousness. NEUROIMAGE-CLINICAL 2013; 3:450-61. [PMID: 24273727 PMCID: PMC3830059 DOI: 10.1016/j.nicl.2013.10.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 09/23/2013] [Accepted: 10/09/2013] [Indexed: 01/19/2023]
Abstract
Recent research suggests that despite the seeming inability of patients in vegetative and minimally conscious states to generate consistent behaviour, some might possess covert awareness detectable with functional neuroimaging. These findings motivate further research into the cognitive mechanisms that might support the existence of consciousness in these states of profound neurological dysfunction. One of the key questions in this regard relates to the nature and capabilities of attention in patients, known to be related to but distinct from consciousness. Previous assays of the electroencephalographic P300 marker of attention have demonstrated its presence and potential clinical value. Here we analysed data from 21 patients and 8 healthy volunteers collected during an experimental task designed to engender exogenous or endogenous attention, indexed by the P3a and P3b components, respectively, in response to a pair of word stimuli presented amongst distractors. Remarkably, we found that the early, bottom-up P3a and the late, top-down P3b could in fact be dissociated in a patient who fitted the behavioural criteria for the vegetative state. In juxtaposition with healthy volunteers, the patient's responses suggested the presence of a relatively high level of attentional abilities despite the absence of any behavioural indications thereof. Furthermore, we found independent evidence of covert command following in the patient, as measured by functional neuroimaging during tennis imagery. Three other minimally conscious patients evidenced non-discriminatory bottom-up orienting, but no top-down engagement of selective attentional control. Our findings present a persuasive case for dissociable attentional processing in behaviourally unresponsive patients, adding to our understanding of the possible levels and applications of consequent conscious awareness. We dissociated endogenous and exogenous attention in disorders of consciousness. 21 vegetative (VS) and minimally conscious (MCS) patients tested with EEG task Exogenous bottom-up P3a found in 3 minimally conscious and 1 vegetative patient Endogenous top-down P3b found in one VS patient who performed fMRI tennis imagery Discriminative attention can be preserved in disorders of consciousness.
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Affiliation(s)
- Srivas Chennu
- Division of Neurosurgery, University of Cambridge, Box 167, Level 4, A Block, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK ; Medical Research Council, Cognition and Brain Sciences Unit, 15 Chaucer Road, Cambridge CB2 7EF, UK
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Halder S, Hammer EM, Kleih SC, Bogdan M, Rosenstiel W, Birbaumer N, Kübler A. Prediction of auditory and visual p300 brain-computer interface aptitude. PLoS One 2013; 8:e53513. [PMID: 23457444 PMCID: PMC3573031 DOI: 10.1371/journal.pone.0053513] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 11/30/2012] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE Brain-computer interfaces (BCIs) provide a non-muscular communication channel for patients with late-stage motoneuron disease (e.g., amyotrophic lateral sclerosis (ALS)) or otherwise motor impaired people and are also used for motor rehabilitation in chronic stroke. Differences in the ability to use a BCI vary from person to person and from session to session. A reliable predictor of aptitude would allow for the selection of suitable BCI paradigms. For this reason, we investigated whether P300 BCI aptitude could be predicted from a short experiment with a standard auditory oddball. METHODS Forty healthy participants performed an electroencephalography (EEG) based visual and auditory P300-BCI spelling task in a single session. In addition, prior to each session an auditory oddball was presented. Features extracted from the auditory oddball were analyzed with respect to predictive power for BCI aptitude. RESULTS Correlation between auditory oddball response and P300 BCI accuracy revealed a strong relationship between accuracy and N2 amplitude and the amplitude of a late ERP component between 400 and 600 ms. Interestingly, the P3 amplitude of the auditory oddball response was not correlated with accuracy. CONCLUSIONS Event-related potentials recorded during a standard auditory oddball session moderately predict aptitude in an audiory and highly in a visual P300 BCI. The predictor will allow for faster paradigm selection. SIGNIFICANCE Our method will reduce strain on patients because unsuccessful training may be avoided, provided the results can be generalized to the patient population.
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Affiliation(s)
- Sebastian Halder
- Institute of Psychology, University of Würzburg, Würzburg, Germany.
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Chennu S, Bekinschtein TA. Arousal modulates auditory attention and awareness: insights from sleep, sedation, and disorders of consciousness. Front Psychol 2012; 3:65. [PMID: 22403565 PMCID: PMC3293189 DOI: 10.3389/fpsyg.2012.00065] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 02/18/2012] [Indexed: 11/13/2022] Open
Abstract
The interplay between attention and consciousness is frequently tested in altered states of consciousness, including transitions between stages of sleep and sedation, and in pathological disorders of consciousness (DoC; the vegetative and minimally conscious states; VS and MCS). One of the most widely used tasks to assess cognitive processing in this context is the auditory oddball paradigm, where an infrequent change in a sequence of sounds elicits, in awake subjects, a characteristic EEG event-related potential called the mismatch negativity, followed by the classic P300 wave. The latter is further separable into the slightly earlier, anterior P3a and the later, posterior P3b, thought to be linked to task-irrelevant "bottom-up" and task-oriented "top-down" attention, respectively. We discuss here the putative dissociations between attention and awareness in DoC, sedation and sleep, bearing in mind the recently emerging evidence from healthy volunteers and patients. These findings highlight the neurophysiological and cognitive parallels (and differences) across these three distinct variations in levels of consciousness, and inform the theoretical framework for interpreting the role of attention therein.
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Affiliation(s)
- Srivas Chennu
- Department of Clinical Neurosciences, University of CambridgeCambridge, UK
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Cavinato M, Volpato C, Silvoni S, Sacchetto M, Merico A, Piccione F. Event-related brain potential modulation in patients with severe brain damage. Clin Neurophysiol 2011; 122:719-24. [DOI: 10.1016/j.clinph.2010.08.024] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 07/05/2010] [Accepted: 08/03/2010] [Indexed: 10/18/2022]
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Abstract
The diagnosis and management of patients with persistent vegetative (PVS) and minimally conscious (MCS) states entail powerful medical, ethical and legal debates. The recent description of the MCS highlights the crucial role of unexpected and well-documented recoveries of cognitive functions. Functional neuroimaging has provided new insights for assessing neuropathology and cerebral activity in these patients, providing information on the presence, degree, and location of any residual brain function in patients with PVS or MCS. We present a review on this topic, emphasizing the clinical and neuroimaging assessment of these states, with some of our recent results in this area. We conclude that the development of rehabilitation techniques for patients with PVS and others suffering long-lasting effects of brain injury is a crucial challenge for actual and future generations of neuroscientists.
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Abstract
Vegetative state (VS) is a clinical condition in the severely brain damaged, characterized by wakefulness but unaccompanied by any evidence of awareness of self or environment, voluntary or purposeful behavioral responses to external stimuli, and communication. A metabolic dysfunction of the frontal-parietal network is thought to be responsible for the “functional disconnection” underlying it. Most subjects recover with or without residual disabilities depending on the extent of brain damage. However, VS persists for over 1 year in about 15% of all cases, with exceptional later recovery; prolonged observation has thus become possible and our perspectives have expanded substantially. In recent years, brain activation in response to painful or emotional stimuli (e.g., the mother’s voice or presence) or under stimulus conditions implying processing at varying levels of functional complexity (including learning and semantic functions) has been documented in unambiguously diagnosed VS subjects by advanced electrophysiological and neuroimaging techniques. Methods, experimental conditions, and the results of studies published in years 2002–2008 are summarized. The extent to which brain activation concomitant to external events reflect brain function remains to be investigated. Today, VS nevertheless appears neither static nor homogeneous. An updated characterization also taking the evidence of residual brain responsiveness into account is due. Research with advanced technologies and sophisticated paradigms of brain activation in VS may help us to understand the basic neural processes underlying human consciousness.
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Affiliation(s)
- Francesco Riganello
- Semi-intensive Care Unit, S. Anna Institute – RAN (Research in Advanced Neurorehabilitation), Crotone, Italy
| | - Walter G. Sannita
- Department of Motor Science and Rehabilitation, University of Genova, Italy
- Department of Psychiatry, State University of New York, Stony Brook, NY, USA
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Liu Z, Liu L, Fan Z, Chen X, Zhao X, Zhang L, Rao G, Li H. Correlations between event-related potentials with pictures recognition and WMS-RC scores in patients with memory disorder caused by severe traumatic brain injury. ACTA ACUST UNITED AC 2008; 28:700-5. [PMID: 19107371 DOI: 10.1007/s11596-008-0620-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Indexed: 10/19/2022]
Abstract
This study explored the possibility of using event-related potentials (ERP) for the measurement of picture-recognition memory and examined its correlation with the Chinese Wechsler Memory Scale-revised (WMS-RC) in patients with memory disorder caused by severe traumatic brain injury (sTBI). The subjects included 20 sTBI patients with memory disorder and 22 healthy individuals. Memory function was measured by using WMS-RC. Behavioral and ERP responses were recorded on-line during performance on a battery of picture recognition and the responses were analyzed off-line for recognition memory effects. Mean memory quotient (MQ) of patients with sTBI was significantly lower than that of the control group. Mean reaction time (RT) was significantly longer and the mean correctness rate (CR) of picture recognition was significantly lower in sTBI group than that of the controls. In controls, the main components of average ERP of picture recognition includes two positive-going waves, designated as P(170) and P(500), that appear 170 ms and 500 ms after stimulation when the subject could later successfully recall and recognize the pictures. P(500) amplitude of target stimulus was significantly higher than that of non-target stimulus. Compared to controls, P(500) responses of sTBI group were significantly delayed in latency (P<0.001) and lower in amplitude (P<0.001). P(500) latency showed significant negative correlation with MQ and the scores of "addition", "visual recognition", "picture recall", "visual reproduction" and "tactile memory" in WMS-RC. ERP of picture recognition provides a neurophysiological approach to directly assess memory impairment, and P(500) may serve as a helpful index for memory disorder caused by sTBI in forensic practice.
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Affiliation(s)
- Zilong Liu
- Faculty of Forensic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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Guidelines for Quality Management of Apallic Syndrome / Vegetative State. Eur J Trauma Emerg Surg 2007; 33:268-92. [PMID: 26814491 DOI: 10.1007/s00068-007-6138-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Accepted: 08/13/2006] [Indexed: 01/02/2023]
Abstract
INTRODUCTION Epidemiology in Europe shows constantly increasing figures for the apallic syndrome (AS)/vegetative state (VS) as a consequence of advanced rescue, emergency services, intensive care treatment after acute brain damage and high-standard activating home nursing for completely dependent end-stage cases secondary to progressive neurological disease. Management of patients in irreversible permanent AS/VS has been the subject of sustained scientific and moral-legal debate over the past decade. METHODS A task force on guidelines for quality management of AS/VS was set up under the auspices of the Scientific Panel Neurotraumatology of the European Federation of Neurological Societies to address key issues relating to AS/VS prevalence and quality management. Collection and analysis of scientific data on class II (III) evidence from the literature and recommendations based on the best practice as resulting from the task force members' expertise are in accordance with EFNS Guidance regulations. FINDINGS The overall incidence of new AS/VS full stage cases all etiology is 0.5-2/100.000 population per year. About one third are traumatic and two thirds non traumatic cases. Increasing figures for hypoxic brain damage and progressive neurological disease have been noticed. The main conceptual criticism is based on the assessment and diagnosis of all different AS/VS stages based solely on behavioural findings without knowing the exact or uniform pathogenesis or neuropathological findings and the uncertainty of clinical assessment due to varying inclusion criteria. No special diagnostics, no specific medical management can be recommended for class II or III AS treatment and rehabilitation. This is why sine qua non diagnostics of the clinical features and appropriate treatment of AS/VS patients of "AS full, remission, defect and end stages" require further professional training and expertise for doctors and rehabilitation personnel. INTERPRETATION Management of AS aims at the social reintegration of patients or has to guarantee humanistic active nursing if treatment fails. Outcome depends on the cause and duration of AS/VS as well as patient's age. There is no single AS/VS specific laboratory investigation, no specific regimen or stimulating intervention to be recommended for improving higher cerebral functioning. Quality management requires at least 3 years of advanced training and permanent education to gain approval of qualification for AS/VS treatment and expertise. Sine qua non areas covering AS/VS institutions for early and long-term rehabilitation are required on a population base (prevalence of 2/100.000/year) to quicken functional restoration and to prevent or treat complications. Caring homes are needed for respectful humane nursing including basal sensor-motor stimulating techniques. Passive euthanasia is considered an act of mercy by physicians in terms of withholding treatment; however, ethical and legal issues with regard to withdrawal of nutrition and hydration and end of life discussions raise deep concerns. The aim of the guideline is to provide management guidance (on the best medical evidence class II and III or task force expertise) for neurologists, neurosurgeons, other physicians working with AS/VS patients, neurorehabilitation personnel, patients, next-of-kin, and health authorities.
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Wijnen VJM, van Boxtel GJM, Eilander HJ, de Gelder B. Mismatch negativity predicts recovery from the vegetative state. Clin Neurophysiol 2007; 118:597-605. [PMID: 17239656 DOI: 10.1016/j.clinph.2006.11.020] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Revised: 11/03/2006] [Accepted: 11/08/2006] [Indexed: 11/15/2022]
Abstract
OBJECTIVE Mismatch negativity (MMN) is an automatic event related brain response, well investigated in the acute phase after severe brain injury: the presence of a MMN is often found to predict the emergence from coma, and the exclusion of shifting into a vegetative state (VS). In the present study MMN was examined during recovery from VS. METHODS Ten vegetative patients were repeatedly examined every 2 weeks for an average period of 3.5 months. Amplitudes and latencies were related to the patients' recovery from VS to consciousness, and to a healthy norm group. In addition, MMN was examined on its prognostic value in VS patients, in predicting recovery to consciousness and long-term functional outcome. RESULTS With recovery to consciousness MMN-amplitudes increased. A sudden increase was seen in MMN amplitude when patients started to show inconsistent behavioural responses to simple commands. At this level MMN resembled the MMN response as was seen in the norm group. In addition, the MMN-amplitude and latency during the first measurement predicted the patients' outcome on recovery to consciousness. CONCLUSIONS With recovery from VS to consciousness the ability to process auditory stimulus deviance increases. A sudden enhancement in MMN-amplitude preceded overt communication with the environment. This might be indicative of the consolidation of neural networks underlying overt communication. Moreover, MMN can be helpful in identifying the ability to recover from VS. SIGNIFICANCE MMN can be used to track recovery from the vegetative state in the post-acute phase after severe brain injury. In addition, MMN can be used to predict the ability to recover from the vegetative state.
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Affiliation(s)
- V J M Wijnen
- Tilburg University, Department of Psychology and Health, Cognitive and Affective Neuroscience Laboratory, Warandelaan 2, 5000 LE Tilburg, The Netherlands
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Abstract
Initial conceptualisation about the nature of vegetative state (VS) assumed at least temporary loss of the entire cortical functioning. Since a broad range of stimulus-related cortical activations was demonstrated in VS patients, this simplified idea is not tenable any longer, but no alternative concept emerges instead. Two recent hypotheses, empirically testable and well grounded, could fill this vacuum: (1) In VS, isolated cortical areas may work, but their integration into a distributed network is lacking. (2) In VS, complex stimulus processing is limited to primary sensory and motor areas; the co-ordination between them and the secondary and tertiary areas is lacking. To test these hypotheses, we estimated the frequency of occurrence of late event-related potential components P3 and N400, presumably indicating activity of complex distributed networks including high-level sensory and associative areas. Both components occurred in VS with above-chance frequencies, but less frequently than in two control groups. Besides these frequent normal brain activations, some VS patients exhibit highly significant but abnormal activations, whose functional meaning remains unclear. A methodological analysis leads to the conclusion that any neurophysiological assessment of VS patients is biased toward under-, rather than over-estimation, of their remaining information processing abilities.
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Affiliation(s)
- Boris Kotchoubey
- Institute of Medical Psychology and Behavioural Neurobiology, Eberhardt-Karls-University of Tübingen, Germany.
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20
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Abstract
This paper reviews the possible usefulness of electroencephalogram (EEG) and evoked potential (EP) recording in vegetative and poorly-responsive patients. There is a marked inter-individual EEG and EP variability, which reflects the state heterogeneity. Four clinical applications are described: (1) the identification of primary midbrain dysfunction--and, therefore, a possible reversibility--in post-traumatic states; (2) the identification of the permeability of sensory channels; (3) quantitative follow-up; and (4) individual assessment of cognitive functions and/or consciousness. Regarding this last issue, the loss of primary cortical EPs, although rarely observed, constitutes one major argument against consciousness. Conversely, cognitive EPs definitely proved the persistence of cognitive functions in several vegetative patients. Whether these cognitive functions are conscious or not remains a matter of debate.
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Affiliation(s)
- Jean-Michel Guérit
- St Luc Hospital, Catholic University of Louvain, and CHIREC, Brussels, Belgium.
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Kotchoubey B, Lang S, Mezger G, Schmalohr D, Schneck M, Semmler A, Bostanov V, Birbaumer N. Information processing in severe disorders of consciousness: Vegetative state and minimally conscious state. Clin Neurophysiol 2005; 116:2441-53. [PMID: 16002333 DOI: 10.1016/j.clinph.2005.03.028] [Citation(s) in RCA: 217] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2004] [Revised: 03/17/2005] [Accepted: 03/17/2005] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To study the presence of electrophysiological indicators of remaining cortical functions in patients with persistent vegetative state (PVS) and minimally conscious state (MCS). Previous electrophysiological and PET data indicated that some PVS patients have partially intact cortical processing functions. However, it remains unclear whether the reported patients were representative for PVS population or just some exceptional cases. METHODS Event-related brain responses to stimuli of different complexity levels, recorded in 98 patients with extremely severe diffuse brain injuries, 50 of which in PVS. Four main indicators of cortical functions were: (i) N1-P2 complex as an index of simple, undifferentiated cortical processing; (ii) mismatch negativity as an index of pre-attentive, probably unconscious, cortical orientation; (iii) P3 wave as an index of deep cortical analysis of physical stimuli, and (iv) brain responses to semantic stimuli. RESULTS Cortical responses were found in all PVS patients with a background EEG activity > 4 Hz. All responses investigated, including those to semantic stimuli that indicated comprehension of meaning, occurred significantly above chance, though less frequently than in patients with severe brain injuries who were conscious. CONCLUSIONS Cortical responses were lacking in most patients with severe EEG slowing (< 4 Hz). Follow-up data revealed that the presence of a mismatch negativity, a short disease duration, and the traumatic etiology were related to a better outcome. SIGNIFICANCE The data show that in a subpopulation of PVS patients with preserved thalamocortical feedback connections, remaining cortical information processing is a consistent finding and may even involve semantic levels of processing.
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Affiliation(s)
- B Kotchoubey
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Gartenstrasse 29, 72074 Tübingen, Germany.
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22
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Lefebvre CD, Marchand Y, Eskes GA, Connolly JF. Assessment of working memory abilities using an event-related brain potential (ERP)-compatible digit span backward task. Clin Neurophysiol 2005; 116:1665-80. [PMID: 15908268 DOI: 10.1016/j.clinph.2005.03.015] [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] [Received: 08/26/2004] [Revised: 03/20/2005] [Accepted: 03/23/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVE This study investigated the effectiveness of an ERP-compatible Digit Span Backward (ERP-DB) task to determine working memory abilities in healthy participants. METHODS Participants were administered both the standard digit span backward and ERP-DB tasks. The ERP-DB task was divided into two sections, consisting of 2, 4, 6 and 8 (Group 1) and 3, 5, and 7 (Group 2) set sizes. A set of digits was aurally presented, followed by a second set that either corresponded to the reverse order of the first set (correct condition) or had one digit in the sequence replaced by an incorrect digit (incorrect condition). RESULTS Two posterior positive components were found to distinguish the two conditions; an earlier positive component (P200/P300) was elicited in the correct condition, whereas a comparatively robust and prolonged positive slow wave (PSW) was elicited in the incorrect condition. Furthermore, the PSW and the difference in PSW amplitude between incorrect and correct conditions (dPSW) dissipated as working memory load increased and were related to working memory capacity. CONCLUSIONS The PSW, dPSW and P200/P300 components were found to be associated with working memory abilities and may have the potential to act as neurophysiological markers for the assessment of working memory capacity. SIGNIFICANCE This research lends support for the utility of the ERP-DB task as a means of assessing working memory abilities, which may have implications for testing patients with expressive communication impairments.
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Affiliation(s)
- Celeste D Lefebvre
- Department of Psychology, Dalhousie University, Life Sciences Centre, Halifax NS, Canada B3H 4J1.
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Guérit JM. [Evoked potentials and post-traumatic evolution]. ANNALES FRANCAISES D'ANESTHESIE ET DE REANIMATION 2005; 24:673-8. [PMID: 15950115 DOI: 10.1016/j.annfar.2005.03.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Visual, somatosensory, and brainstem auditory evoked potentials provide functional quantitative assessment of the cerebral cortex and brainstem. Their contribution at the acute stage of coma concerns diagnosis, prognosis, and follow-up. Four patterns are observed in traumatic coma: pattern 1=dysfunction of the cerebral cortex, brainstem integrity: good prognosis in more than 80% of cases; pattern 2=midbrain dysfunction: prognosis depends on both the reversibility of midbrain dysfunction and the extent of associated axonal lesions in the hemispheric white matter; pattern 3=pontine dysfunction due to transtentorial herniation: ominous prognosis, this pattern must be early detected by continuous monitoring; pattern 4=brain death: we currently use evoked potentials at the only brain-death confirmatory test, even in sedated patients. The contribution of evoked potentials in vegetative or minimally responsive states concerns the identification of these patients whose state is determined by midbrain dysfunction and the evaluation of persisting cognitive abilities in individual cases.
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Affiliation(s)
- J-M Guérit
- Clinique Edith Cavell, service de neurologie, rue Edith Cavell 32, 1180 Bruxelles, Belgique.
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Vaitl D, Birbaumer N, Gruzelier J, Jamieson GA, Kotchoubey B, Kübler A, Lehmann D, Miltner WHR, Ott U, Pütz P, Sammer G, Strauch I, Strehl U, Wackermann J, Weiss T. Psychobiology of altered states of consciousness. Psychol Bull 2005; 131:98-127. [PMID: 15631555 DOI: 10.1037/0033-2909.131.1.98] [Citation(s) in RCA: 220] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The article reviews the current knowledge regarding altered states of consciousness (ASC) (a) occurring spontaneously, (b) evoked by physical and physiological stimulation, (c) induced by psychological means, and (d) caused by diseases. The emphasis is laid on psychological and neurobiological approaches. The phenomenological analysis of the multiple ASC resulted in 4 dimensions by which they can be characterized: activation, awareness span, self-awareness, and sensory dynamics. The neurophysiological approach revealed that the different states of consciousness are mainly brought about by a compromised brain structure, transient changes in brain dynamics (disconnectivity), and neurochemical and metabolic processes. Besides these severe alterations, environmental stimuli, mental practices, and techniques of self-control can also temporarily alter brain functioning and conscious experience.
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Affiliation(s)
- Dieter Vaitl
- Center for Psychobiology and Behavioral Medicine, Department of Psychology, University of Giessen, Giessen, Germany.
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Hinterberger T, Wilhelm B, Mellinger J, Kotchoubey B, Birbaumer N. A Device for the Detection of Cognitive Brain Functions in Completely Paralyzed or Unresponsive Patients. IEEE Trans Biomed Eng 2005; 52:211-20. [PMID: 15709658 DOI: 10.1109/tbme.2004.840190] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Unresponsive patients with remaining cognitive abilities may be able to communicate with a brain-computer interface (BCI) such as the Thought Translation Device (TTD). Before initiating TTD learning, which may imply considerable effort, it is important to classify the patients' state of awareness and their remaining cognitive abilities. A tool for detection of cognitive activity (DCA) in the completely paralyzed was developed and integrated into the TTD which is a psychophysiological system for direct brain communication. In the present version, DCA entails five event-related brain-potential (ERP) experiments and investigates the capability of a patient to discriminate, e.g., between semantically related and unrelated concepts and categories. ERPs serve as an indicator of the patients' cortical information processing. Data from five severely brain-injured patients in persistent vegetative state diagnosed as unresponsive and five healthy controls are presented to illustrate the methodology. Two patients showing the highest responsiveness were selected for TTD training. The DCA integrated in the TTD allows screening of cognitive abilities and direct brain communication in the patients' home.
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Affiliation(s)
- Thilo Hinterberger
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen 72074, Germany.
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26
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Kotchoubey B. Event-related potential measures of consciousness: two equations with three unknowns. PROGRESS IN BRAIN RESEARCH 2005; 150:427-44. [PMID: 16186040 DOI: 10.1016/s0079-6123(05)50030-x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This is a brief review of event-related brain potentials (ERPs) as indices of cortical information processing in conditions in which conscious perception of stimuli is supposed to be absent: sleep, coma, vegetative state, general anesthesia, neglect as well as presentation of subliminal or masked stimuli. Exogenous ERP components such as N1 and P2 are much more likely to remain in all these conditions than endogenous components. Further, all varieties of the late posterior positive ERP waves (e.g., P3b, P600, late positive complex) are most difficult to be elicited in such conditions, indicating that the cortical activity underlying the late posterior positivity may have a particularly close relationship to brain mechanisms of conscious perception. Contrary to what might be expected, reliable ERP effects indicating complex analysis of semantic stimulus features (i.e., meaning) can be recorded without conscious awareness, generally, as easy as (in some conditions, even easier than) ERP components related to rather simple physical stimulus features. It should be emphasized, however, that we never should overestimate our confidence about the degree of subjects' unawareness. Particularly in the conditions in which no behavioral response can be obtained (e.g., sleep, coma, anesthesia), residual conscious processing, at least in some subjects and on some trials, cannot be ruled out.
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Affiliation(s)
- Boris Kotchoubey
- Institute of Medical Psychology and Behavioral Neurobiology, Eberhard-Karls-University of Tübingen, Gartenstr. 29, 72074 Tübingen, Germany.
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27
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Owen AM, Coleman MR, Menon DK, Berry EL, Johnsrude IS, Rodd JM, Davis MH, Pickard JD. Using a hierarchical approach to investigate residual auditory cognition in persistent vegetative state. PROGRESS IN BRAIN RESEARCH 2005; 150:457-71. [PMID: 16186042 DOI: 10.1016/s0079-6123(05)50032-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Persistent vegetative state is arguably one of the least understood and most ethically troublesome neurological conditions in modern medicine. The term describes a rare disorder in which patients who emerge from coma appear to be awake, but show no signs of awareness. In recent years, a number of studies have demonstrated an important role for functional neuroimaging in the identification of residual cognitive function in patients meeting the clinical criteria for persistent vegetative state. Such studies, when successful, may be particularly useful where there is a concern about the accuracy of the diagnosis and the possibility that residual cognitive function has remained undetected. Unfortunately, functional neuroimaging in persistent vegetative state is extremely complex and subject to numerous methodological, clinical and theoretical difficulties. In this chapter, we argue that in order to most effectively define the degree and extent of preserved cognitive function in persistent vegetative state, a hierarchical approach to cognition is required. To illustrate this point, a series of functional neuroimaging paradigms in the auditory domain are described, which systematically increase in complexity in terms of the auditory and/or linguistic processes required and, therefore, the degree of preserved cognition that can be inferred from "normal" patterns of activation in persistent vegetative patients. Preliminary results in a small series of patients provide a strong basis for the systematic study of possible residual cognitive function in persistent vegetative state.
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Affiliation(s)
- Adrian M Owen
- MRC Cognition and Brain Sciences Unit, 15 Chaucer Road, Cambridge CB2 2EF, UK.
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Neumann N, Kotchoubey B. Assessment of cognitive functions in severely paralysed and severely brain-damaged patients: neuropsychological and electrophysiological methods. ACTA ACUST UNITED AC 2004; 14:25-36. [PMID: 15519949 DOI: 10.1016/j.brainresprot.2004.09.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2004] [Indexed: 11/18/2022]
Abstract
A systematic neuropsychological assessment technique is described for use with severely physically disabled individuals, possibly with combined motor and cognitive disorders. Target neurological conditions may be, e.g., an incomplete locked-in state, a minimally conscious state, or severe combinations of paralysis, agnosia, and apraxia. Neuropsychological assessment in these patients is difficult, because standard neuropsychological tests require fast motor responses, which can be manual, verbal, or both. To assess the cognitive status of patients with residual motor function, tests have been applied that can be answered by a binary (yes/no) signal and whose outcomes were not based on reaction times. Further, a battery of neurophysiological examination procedures based on event-related brain potentials has been developed. These procedures can be performed directly at a patient's bedside (at home or in a hospital) and applied for assessment of cognitive functions even in patients without residual motor function.
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Affiliation(s)
- Nicola Neumann
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tuebingen, D-72074 Tuebingen, Germany
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Naccache L, Obadia M, Crozier S, Detante O, Guillerm C, Bonneville F, Dormont D, Willer JC, Samson Y. Preserved auditory cognitive ERPs in severe akinetic mutism: a case report. ACTA ACUST UNITED AC 2004; 19:202-5. [PMID: 15019716 DOI: 10.1016/j.cogbrainres.2003.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2003] [Indexed: 11/16/2022]
Abstract
kinetic mustism is a dramatic deficit in spontaneous initiation of voluntary motor and speech acts, usually secondary to bilateral lesions of the anterior cingulate cortices and supplementary motor areas [Principles of Neurology, McGraw-Hill, New York, 1989]. Given the obvious limitations of traditional neuropsychological testing in this clinical context, the use of neurophysiological tools such as bedside auditory cognitive event-related potentials (ERPs), recently proven to be relevant to evaluate comatose and vegetative patients [Clin. Neurophysiol. 110 (9) (1999) 1601; News Physiol. Sci. 17 (2002) 38], may constitute an interesting alternative. Here, we present the ERPs of a 38-year-old right-handed woman with severe akinetic mutism recorded in a passive auditory odd-ball paradigm. In spite of this severe clinical state, we could observe the presence of a "Mismatch Negativity", and of a larger P300 in rare trials than in frequent ones. By revealing a high level of cognitive integration of environmental auditory information, our study emphasizes the potential clinical relevance of MMN and P300 recordings in akinetic mutism to assess patient cognitive functioning.
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Affiliation(s)
- Lionel Naccache
- Fédération de Neurophysiologie Clinique, Hôpital de la Pitié-Salpêtrière 47-83 Bd de l'Hôpital, 75013 Paris, France.
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30
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Grapperon J, Vidal F, Bruschera D, Cantais E, Salinier L, Costes O, Palmier B. Les potentiels évoqués cognitifs, auditifs et somesthésiques dans les comas : valeur pronostique pour l’éveil et la réintégration socioprofessionnelle. ACTA ACUST UNITED AC 2004; 23:102-8. [PMID: 15030858 DOI: 10.1016/j.annfar.2003.12.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2003] [Revised: 12/10/2003] [Accepted: 12/10/2003] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To appreciate prognostical value of event-related potentials in comatose states and the influence of the stimulation's modality. PATIENTS AND METHODS Thirty-five patients were recorded with the auditory modality whose thirteen were also recorded with the somesthetic modality. They were free of sedation except for five. For 21 patients out of coma, it was possible to get information about their social readaptation 14 months later. RESULTS When present, cognitive components predict awakening in 100 % of the cases, but only 50 % of the patients who awake had these components. The somesthetic modality seemed to enlarge their detection, but did not improve short-term forecasts. We could not confirm their absence could hamper social reinstatement. CONCLUSION Event-related potentials are strengthened as having excellent positive prognostic value. Further studies should clarify the interest of the somesthetic modality, and the possibility to get remote prognostic.
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Affiliation(s)
- J Grapperon
- Laboratoire de neurophysiologie clinique, HIA Sainte-Anne, BP 600, 83800 Toulon Naval, France.
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Abstract
ERPs may extend the battery of neurophysiologic tests currently available for determining the functional integrity of the central nervous system and the capacity of cognition in patients with brain injury. The use of stimuli relevant for the patient can enhance the probability to record these waves in unconscious patients and in patients with cognitive impairment and enhance the predictive value on outcome. The experimental data in these patients still are not sufficient, however, to standardize the indications of ERPs in clinical practice. Their limitations, mainly the variability also present in normal individuals and the limited standardization and validation, must be considered, and they must be judged cautiously as a prognostic index. Nevertheless, ERPs might be applied as a useful supplement to neuropsychologic assessment.
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Affiliation(s)
- Letizia Mazzini
- Department of Neurology, San Giovanni Bosco Hospital, Hospital Largo Donatori di Sangue 3, 10154 Torino, Italy.
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32
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Kotchoubey B, Lang S, Herb E, Maurer P, Schmalohr D, Bostanov V, Birbaumer N. Stimulus complexity enhances auditory discrimination in patients with extremely severe brain injuries. Neurosci Lett 2004; 352:129-32. [PMID: 14625040 DOI: 10.1016/j.neulet.2003.08.045] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
There is controversy as to what extent the processing of spectrally rich sounds in the human auditory cortex is related to the processing of singular frequencies. An informative index of the function of the auditory cortex, particularly important in neurological patients, is the mismatch negativity (MMN), a component of auditory event-related potentials. In the present study the MMN was recorded in 79 patients with extremely severe diffuse brain injuries, most of them in persistent vegetative state or minimal consciousness state. Both sinusoidal ('pure') and complex musical tones were used. Different statistical approaches converged in that musical tones elicited an MMN significantly more frequently, and of a larger amplitude, than simple sine tones. This implies that using simple stimuli in clinical populations may lead to a severe underestimation of the functional state of a patient's auditory system. The findings are also in line with behavioral and physiological data indicating independent processing of complex sounds in the auditory cortex.
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Braverman ER, Blum K. P300 (Latency) Event-Related Potential: An Accurate Predictor of Memory Impairment. ACTA ACUST UNITED AC 2003; 34:124-39. [PMID: 14521274 DOI: 10.1177/155005940303400306] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
To determine if P300 latency changes precede and correlate with memory and mental status, patients (N=1506 aged 20–100 years) who received medical and psychiatric diagnoses (from 1997 to 2002), were assessed for P300 (N=1496), WMS-III (N=694), and MMSE (N=456). Patient and control groups included, a) normal WMS-III on all 4 subscales (N=36), b) normal WMS-III and MMSE (N=189) with subjective memory/mental status complaints, and c) medical patients with normal WMS-III and no memory complaints (N=205), and d) P300 control group without medical, psychiatric or memory problems for ROC. Patients with impaired/borderline memory had a prolonged P300 latency (P<0.02) compared to age matched non-impaired controls; in patients with normal WMS-III/MMSE, with subjective mild memory/mental status impairment, P300 latency was prolonged compared to controls (P=0.0004). The P300 latency increased by 0.72ms per year (P=7.9×10−65) and voltage decreased by 0.03dV per year (P=6.7×10−10), and both parameters were linearly correlated with the age of the subjects. Male subjects had an average voltage of 6.1dV and female 6.8dV(P=0.00009). Statistically, prolonged latency began at age range 41–50 (P=0.0002); reduced P300 voltage began at age range 51–60 (P=0.003). WMS-III memory decline for all measures began in females at age range 61–70 (P value at least=0.02) and for males at age range 61–80 (P=0.02). Prolonged P300 latency (P≤0.0001) and memory impairment (at least <0.02) were greater for females than males. MMSE memory decline, male and female, began at age range 81–90 (P value of at least 0.00007). In our logistic regression model P300 latency was more predictive of WMS-III impairment than MMSE >24. In patients whose WMS-III score is impaired ≤69, or borderline ≤79 (P at least =0.004), a P300 latency more prolonged than the norm (≥300 + 30 + Age) identifies these patients, whereas a MMSE >24 failed. With the ROC curve, we confirmed that P300 latency could accurately identify borderline/impaired memory.
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Affiliation(s)
- Eric R Braverman
- Path Medical Clinics and Research Foundation, New York, NY 10016, USA.
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Fischer C, Mutschler V. [Traumatic brain injuries in adults: from coma to wakefulness. Neurophysiological data]. ANNALES DE READAPTATION ET DE MEDECINE PHYSIQUE : REVUE SCIENTIFIQUE DE LA SOCIETE FRANCAISE DE REEDUCATION FONCTIONNELLE DE READAPTATION ET DE MEDECINE PHYSIQUE 2002; 45:448-55. [PMID: 12490333 DOI: 10.1016/s0168-6054(02)00295-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
OBJECTIVE To analyse relevant literature and to express an expert point of view concerning the interest of electroencephalography and evoked potentials recordings in the evaluation of severe head trauma in adults in the context of a consensus conference. MATERIAL AND METHODS Scientific databases have been checked on the Internet using key-words. The summaries of 340 papers have checked out. Consequently 94 papers have been thoroughly analysed. Fifty-nine of them are cited in the text of this paper. RESULTS Electroencephalography (EEG) and evoked potentials (Eps) evaluate the functional status of the brain. They augment the clinical examination. They are non invasive and easy to perform at patient's bedside. The EEG evaluate globally the functional status of the brain but it is very sensitive to sedative and anaesthetic drugs. It can disclose subclinical or electroclinical epileptic seizures. When reactivity to sensory stimulations can be elicited, this can be considered a prognostic indicator for a good outcome. Evoked potentials are less influenced by sedative drugs. There are several types of evoked potentials, each one with a different localizing value. Brainstem auditory evoked potentials (or short-latency Eps) evaluate the auditory nerve and brainstem. When normal they have no specificity. When abnormal they are an indicator of a poor or bad outcome. Somatosensory and auditory middle-latency Eps evaluate the primary cortex. In coma due to traumatic brain injury the presence of primary cortex components is an indicator of a good outcome and its absence is an indicator of a poor outcome at least when there is no focal brain lesion as to have the primary cortex component to be absent. Event-related potentials evaluate associative brain areas. When they are present in a comatose patient they favor the idea that some cognitive processes are active and they have a high positive predictive value for a return to consciousness. The electrophysiological evaluation can help to identify atypical situations and pathologies close to coma, disclose nonconvulsive seizures and localize certain complications or dysfunctions in atypical cases.
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Affiliation(s)
- C Fischer
- Service de neurologie fonctionnelle et épileptologie, hôpital neurologique, 59, boulevard Pinel, 69003 cedex, Lyon, France.
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35
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Kotchoubey B, Lang S, Bostanov V, Birbaumer N. Is there a mind? Electrophysiology of unconscious patients. Physiology (Bethesda) 2002; 17:38-42. [PMID: 11821535 DOI: 10.1152/physiologyonline.2002.17.1.38] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Event related brain potentials (ERPs) provide information about cortical processing in severe neurological patients whose cognitive abilities cannot be expressed in their behavior. In coma, ERPs contribute to the prediction of the outcome. In a vegetative state, ERPs uncover the functional state of cortical processes. The significance of ERPs in the neurophysiological study of consciousness is discussed.
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Affiliation(s)
- Boris Kotchoubey
- Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, 72074 Tübingen, Germany
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