Article (Scientific journals)
Recovery of cortical effective connectivity and recovery of consciousness in vegetative patients.
Rosanova, Mario; Gosseries, Olivia; Casarotto, Silvia et al.
2012In Brain: a Journal of Neurology, 135 (Pt 4), p. 1308-20
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Keywords :
Adult; Aged; Brain Mapping; Brain Waves/physiology; Cerebral Cortex/physiopathology/radiography; Consciousness/physiology; Electroencephalography; Female; Humans; Longitudinal Studies; Male; Middle Aged; Neural Pathways/physiology; Persistent Vegetative State/pathology/physiopathology; Recovery of Function/physiology; Spectrum Analysis; Tomography, X-Ray Computed; Transcranial Magnetic Stimulation
Abstract :
[en] Patients surviving severe brain injury may regain consciousness without recovering their ability to understand, move and communicate. Recently, electrophysiological and neuroimaging approaches, employing simple sensory stimulations or verbal commands, have proven useful in detecting higher order processing and, in some cases, in establishing some degree of communication in brain-injured subjects with severe impairment of motor function. To complement these approaches, it would be useful to develop methods to detect recovery of consciousness in ways that do not depend on the integrity of sensory pathways or on the subject's ability to comprehend or carry out instructions. As suggested by theoretical and experimental work, a key requirement for consciousness is that multiple, specialized cortical areas can engage in rapid causal interactions (effective connectivity). Here, we employ transcranial magnetic stimulation together with high-density electroencephalography to evaluate effective connectivity at the bedside of severely brain injured, non-communicating subjects. In patients in a vegetative state, who were open-eyed, behaviourally awake but unresponsive, transcranial magnetic stimulation triggered a simple, local response indicating a breakdown of effective connectivity, similar to the one previously observed in unconscious sleeping or anaesthetized subjects. In contrast, in minimally conscious patients, who showed fluctuating signs of non-reflexive behaviour, transcranial magnetic stimulation invariably triggered complex activations that sequentially involved distant cortical areas ipsi- and contralateral to the site of stimulation, similar to activations we recorded in locked-in, conscious patients. Longitudinal measurements performed in patients who gradually recovered consciousness revealed that this clear-cut change in effective connectivity could occur at an early stage, before reliable communication was established with the subject and before the spontaneous electroencephalogram showed significant modifications. Measurements of effective connectivity by means of transcranial magnetic stimulation combined with electroencephalography can be performed at the bedside while by-passing subcortical afferent and efferent pathways, and without requiring active participation of subjects or language comprehension; hence, they offer an effective way to detect and track recovery of consciousness in brain-injured patients who are unable to exchange information with the external environment.
Disciplines :
Neurology
Anesthesia & intensive care
Author, co-author :
Rosanova, Mario 
Gosseries, Olivia   ;  Université de Liège - ULiège > Centre de recherches du cyclotron
Casarotto, Silvia
Boly, Mélanie ;  Coma Science Group, Centre de Recherches du Cyclotron, Université de Liège & Département de Neurologie, CHU Sart Tilman
Casali, Adenauer G.
Bruno, Marie-Aurélie ;  Coma Science Group, Centre de Recherches du Cyclotron, Université de Liège & Département de Neurologie, CHU Sart Tilman
Mariotti, Maurizio
BOVEROUX, Pierre ;  Centre Hospitalier Universitaire de Liège - CHU > Anesthésie et réanimation
Tononi, Giulio
Laureys, Steven  ;  Coma Science Group, Centre de Recherches du Cyclotron, Université de Liège & Département de Neurologie, CHU Sart Tilman
Massimini, Marcello
 These authors have contributed equally to this work.
Language :
English
Title :
Recovery of cortical effective connectivity and recovery of consciousness in vegetative patients.
Publication date :
2012
Journal title :
Brain: a Journal of Neurology
ISSN :
0006-8950
eISSN :
1460-2156
Publisher :
Oxford University Press, Oxford, United Kingdom
Volume :
135
Issue :
Pt 4
Pages :
1308-20
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 05 March 2012

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