Auditory Event-Related "Global Effect" Predicts Recovery of Overt Consciousness.

Pauline Perez,Bertrand Hermann,Frédéric Faugeras,Benjamin Rohaut,Sophie Demeret,Lionel Naccache,Jacobo Sitt,Mélanie Valente

doi:10.3389/fneur.2020.588233

Abstract

Objective: To explore whether the presence of an event-related potential (ERP) “global effect” (GE+)—that corresponds to a correlate of conscious processing in the local–global auditory task—predicts behaviorally overt consciousness recovery in a large cohort of patients suffering from disorders of consciousness (DOC).Methods: We conducted a prospective study on all DOC patients evaluated during the 2009–2018 period. Behavioral examination included Coma Recovery Scale-Revised (CRS-R) scores and bedside high-density EEG recordings. Consciousness recovery was evaluated at 6 months by a structured phone interview. The predictive value of a GE+ was calculated both on survivors and on all patients.Results: A total of 236 patients with a documented outcome and technically valid EEG recordings could be included. Among them, 66 patients had a GE+ status (28%). Presence of GE+ predicted behaviorally overt consciousness recovery in survivors with high specificity (Sp = 84%) and high positive predictive value (PPV = 80%) but with low sensitivity (Se = 35%) and low negative predictive value (NPV = 42%). Positive likelihood ratio (LR+) of GE+ was superior to LR+ of initial clinical status and of ERP effect indexing unconscious auditory processing [local effect (LE)].Interpretation: Our results demonstrate that the presence of a bedside ERP GE+ is highly predictive of behaviorally overt consciousness recovery in DOC patients, regardless of the delay, of behavioral status, and of the etiology of brain dysfunction. However, the absence of this effect is not a reliable predictor of negative outcome. This study provides Class III evidence that the presence of an ERP “global effect” predicts consciousness recovery in DOC patients.

Highlights

The ability to predict consciousness recovery in patients suffering from disorders of consciousness constitutes a major clinical and neuroscientific challenge
Behavioral labeling of these patients was based on the best Coma Recovery Scale-Revised (CRS-R) scores and revealed that while most of them were either in minimally conscious state (MCS) (N = 141) or in vegetative state/unresponsive wakefulness syndrome (VS/UWS) (N = 138), some of them were in a conscious exit-MCS (EMCS) state (N = 30)
The main result of our study reveals the presence of an event-related potential (ERP) global effect (GE) as a specific predictor of behavioral recovery of consciousness

Summary

Introduction

The ability to predict consciousness recovery in patients suffering from disorders of consciousness constitutes a major clinical and neuroscientific challenge. Recordings of brain activity with PET-glucose imaging, functional MRI (fMRI), or EEG during cognitively passive or active conditions invariably revealed that around 15% of DOC patients diagnosed by CRS-R experts as being in a non-conscious VS/UWS show neural evidence in favor of an MCS or of a fully conscious state [7,8,9,10,11,12,13,14,15,16] All these limitations call for the use of additional diagnostic specific markers derived from brain activity that may be useful to predict consciousness recovery

Methods

Results

Conclusion