title: Cognitive Processing in Non-Communicative Patients: What Can Event-Related Potentials Tell Us?
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.
authors.affiliation: 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.
authors.forename: Zulay R
authors.initials: ZR
authors.lastname: Lugo
authors.affiliation: Neuroelectrical Imaging and BCI Laboratory, Fondazione Santa Lucia, IRCCSRome, Italy; School of Life and Health Sciences, Aston Brain Centre, Aston UniversityBirmingham, UK.
authors.forename: Lucia R
authors.initials: LR
authors.lastname: Quitadamo
authors.affiliation: Department of Civil Engineering and Computer Science, University of Rome Tor Vergata Rome, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Bianchi
authors.affiliation: French Association of Locked-in Syndrome (ALIS)Paris, France; Coma Arousal Unit - PMR Department, Nîmes University HospitalNîmes, France.
authors.forename: Fréderic
authors.initials: F
authors.lastname: Pellas
authors.affiliation: Institute for Medical Psychology and Behavioural Neurobiology, University of Tübingen Tübingen, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Veser
authors.affiliation: Coma Science Group, University and University Hospital of Liège, GIGA Liège, Belgium.
authors.forename: Damien
authors.initials: D
authors.lastname: Lesenfants
authors.affiliation: Institute of Psychology, University of Würzburg Würzburg, Germany.
authors.forename: Ruben G L
authors.initials: RG
authors.lastname: Real
authors.affiliation: Institute of Psychology, University of WürzburgWürzburg, Germany; Department of Psychiatry, University of TübingenTübingen, Germany; Department of Biomedical Resonance, University of TübingenTübingen, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Herbert
authors.affiliation: G.Tec Medical Engineering GmbH/Guger Technologies OG Graz, Austria.
authors.forename: Christoph
authors.initials: C
authors.lastname: Guger
authors.affiliation: Institute for Medical Psychology and Behavioural Neurobiology, University of Tübingen Tübingen, Germany.
authors.forename: Boris
authors.initials: B
authors.lastname: Kotchoubey
authors.affiliation: Neuroelectrical Imaging and BCI Laboratory, Fondazione Santa Lucia, IRCCS Rome, Italy.
authors.forename: Donatella
authors.initials: D
authors.lastname: Mattia
authors.affiliation: Institute of Psychology, University of Würzburg Würzburg, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Kübler
authors.affiliation: Coma Science Group, University and University Hospital of Liège, GIGA Liège, Belgium.
authors.forename: Steven
authors.initials: S
authors.lastname: Laureys
authors.affiliation: Coma Science Group, University and University Hospital of Liège, GIGALiège, Belgium; Department of Cognitive Neuroscience, Maastricht UniversityMaastricht, Netherlands; Brain Innovation B.V.Maastricht, Netherlands.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Noirhomme
keywords: P300; event-related potentials; locked-in syndrome; minimally conscious state; unresponsive wakefulness syndrome; vegetative state