title: Assessing consciousness in coma and related states using transcranial magnetic stimulation combined with electroencephalography.
abstract: Thanks to advances in medical care, an increased number of patients recover from coma. However, some remain in vegetative/unresponsive wakefulness syndrome or in a minimally conscious state. Detection of awareness in severely brain-injured patients is challenging because it relies on behavioral assessments, which can be affected by motor, sensory and cognitive impairments of the patients. Other means of evaluation are needed to improve the accuracy of the diagnosis in this challenging population. We will here review the different altered states of consciousness occurring after severe brain damage, and explain the difficulties associated with behavioral assessment of consciousness. We will then describe a non-invasive technique, transcranial magnetic stimulation combined with high-density electroencephalography (TMS-EEG), which has allowed us to detect the presence or absence of consciousness in different physiological, pathological and pharmacological states. Some potential underlying mechanisms of the loss of consciousness will then be discussed. In conclusion, TMS-EEG is highly promising in identifying markers of consciousness at the individual level and might be of great value for clinicians in the assessment of consciousness.
authors.affiliation: Coma Science Group, Cyclotron Research Center and Neurology Department, University of Liège and University Hospital of Liège, Sart Tilman B30, allée du 6-Août-n(o) 8, 4031 Liège, Belgium; Center for Sleep and Consciousness, Department of Psychiatry, University of Wisconsin, Madison, WI, USA; Postle Laboratory, Department of Psychology and Psychiatry, University of Wisconsin, Madison, WI, USA. Electronic address: ogosseries@ulg.ac.be.
authors.forename: O
authors.initials: O
authors.lastname: Gosseries
authors.affiliation: Coma Science Group, Cyclotron Research Center and Neurology Department, University of Liège and University Hospital of Liège, Sart Tilman B30, allée du 6-Août-n(o) 8, 4031 Liège, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Thibaut
authors.affiliation: Coma Science Group, Cyclotron Research Center and Neurology Department, University of Liège and University Hospital of Liège, Sart Tilman B30, allée du 6-Août-n(o) 8, 4031 Liège, Belgium; Center for Sleep and Consciousness, Department of Psychiatry, University of Wisconsin, Madison, WI, USA; Department of Neurology, University of Wisconsin, Madison, WI, USA.
authors.forename: M
authors.initials: M
authors.lastname: Boly
authors.affiliation: Department of Biomedical and Clinical Sciences "Luigi Sacco", University of Milan, Milan, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Rosanova
authors.affiliation: Department of Biomedical and Clinical Sciences "Luigi Sacco", University of Milan, Milan, Italy; Istituto Di Ricovero e Cura a Carattere Scientifico, Fondazione Don Carlo Gnocchi, 20148 Milan, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Massimini
authors.affiliation: Coma Science Group, Cyclotron Research Center and Neurology Department, University of Liège and University Hospital of Liège, Sart Tilman B30, allée du 6-Août-n(o) 8, 4031 Liège, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Laureys
mesh_terms: D000768:Anesthesia, General; D001930:Brain Injuries / Q000150:complications / Q000523:psychology; D003128:Coma / Q000175:diagnosis / Q000503:physiopathology; D003244:Consciousness Disorders / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D004569:Electroencephalography / Q000379:methods*; D006801:Humans; D018458:Persistent Vegetative State / Q000175:diagnosis; D011379:Prognosis; D011782:Quadriplegia / Q000175:diagnosis; D012890:Sleep / Q000502:physiology; D012895:Sleep, REM / Q000502:physiology; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D014851:Wakefulness / Q000502:physiology
keywords: Anesthesia; Anesthésie; Brain stimulation; Disorders of consciousness; Electroencephalography; Locked-in syndrome; Minimally conscious state; Sleep; Sommeil; Stimulation cérébrale; Stimulation magnétique transcrânienne; Syndrome d’éveil non-répondant; Transcranial magnetic stimulation; Troubles de la conscience; Unresponsive wakefulness syndrome; Vegetative state; Électroencéphalographie; État de conscience minimale; État végétatif