Bedside Evaluation of the Functional Organization of the Auditory Cortex in Patients with Disorders of Consciousness

Abstract

To measure the level of residual cognitive function in patients with disorders of consciousness, the use of electrophysiological and neuroimaging protocols of increasing complexity is recommended. This work presents an EEG-based method capable of assessing at an individual level the integrity of the auditory cortex at the bedside of patients and can be seen as the first cortical stage of this hierarchical approach. The method is based on two features: first, the possibility of automatically detecting the presence of a N100 wave and second, in showing evidence of frequency processing in the auditory cortex with a machine learning based classification of the EEG signals associated with different frequencies and auditory stimulation modalities. In the control group of twelve healthy volunteers, cortical frequency processing was clearly demonstrated. EEG recordings from two patients with disorders of consciousness showed evidence of partially preserved cortical processing in the first patient and none in the second patient. From these results, it appears that the classification method presented here reliably detects signal differences in the encoding of frequencies and is a useful tool in the evaluation of the integrity of the auditory cortex. Even though the classification method presented in this work was designed for patients with disorders of consciousness, it can also be applied to other pathological populations.

Electrophysiological and Neuroimaging Studies – During Resting State and Sensory Stimulation in Disorders of Consciousness: A Review

“…Among the different modalities in sensory stimulation, auditory modality has been extensively explored. Most of the studies ( Bekinschtein et al, 2004 , 2009 ; Di et al, 2007 ; Qin et al, 2008 , 2010 ; Höller et al, 2011 ; Varotto et al, 2012 ; Chennu et al, 2013 ; Sitt et al, 2014 ; Castro et al, 2015 ; Schorr et al, 2015 ; Beukema et al, 2016 ; Henriques et al, 2016 ; Zhang et al, 2017 ; Kempny et al, 2018 ; Stefan et al, 2018 ; Agoiz Badia et al, 2019 ; Formisano et al, 2019 ; Portnova and Atanov, 2019 ) have used auditory stimulation, since it is much easier to conduct for the DOC patients, than visual and tactile stimulations.…”

tDCS-EEG for Predicting Outcome in Patients With Unresponsive Wakefulness Syndrome

“…Event-related potential (ERP; including N100, MMN, P300 and N400) is currently the most effective method for evaluating prognosis in patients with DOC. Previous findings revealed that ERP has a good predictive value regarding the outcome of patients with MCS (Morlet and Fischer, 2014;Salvo et al, 2015;Henriques et al, 2016;Zhang et al, 2017a).…”