CRS-R score in disorders of consciousness is strongly related to spectral EEG at rest

Abstract

Patients suffering from disorders of consciousness still present a diagnostic challenge due to the fact that their assessment is mainly based on behavioral scales with their motor responses often being strongly impaired. We therefore focused on resting electroencephalography (EEG) in order to reveal potential alternative measures of the patient's current state independent of rather complex abilities (e.g., language comprehension). Resting EEG was recorded in nine minimally conscious state (MCS) and eight vegetative state/unresponsive wakefulness syndrome (VS/UWS) patients. Behavioral assessments were conducted using the Coma-Recovery Scale-Revised (CRS-R). The signal was analyzed in the frequency domain and association between resting EEG and CRS-R score as well as clinical diagnosis were calculated using Pearson correlation and repeated-measures ANOVAs. The analyses revealed robust positive correlations between CRS-R score and ratios between frequencies above 8 Hz and frequencies below 8 Hz. Furthermore, the frequency of the spectral peak was also highly indicative of the patient's CRS-R score. Concerning differences between clinical diagnosis and healthy controls, it could be revealed that while VS/UWS patients showed higher delta and theta activity than controls, MCS did not differ from controls in this frequency range. Alpha activity, on the other hand, was strongly decreased in both patient groups as compared to controls. The strong relationship between various resting EEG parameters and CRS-R score provides significant clinical relevance. Not only is resting activity easily acquired at bedside, but furthermore, it does not depend on explicit cooperation of the patient. Especially in cases where behavioral assessment is difficult or ambiguous, spectral analysis of resting EEG can therefore complement clinical diagnosis.

EEG predictors of outcome in patients with disorders of consciousness admitted for intensive rehabilitation

“…In general, an increasing score indicates a trend toward an improvement in the level of consciousness, but it cannot be unequivocally associated to a particular level of consciousness. The total CRS-R score, which ranges from 0 (comatose state) to 23 (E-MCS), has been recently associated with some EEG parameters (Lechinger et al, 2013). Patients were included in the study if their level of consciousness (i.e., UWS or MCS) and CRS-R total score did not change through the 3-day evaluation period.…”

Brain networks predict metabolism, diagnosis and prognosis at the bedside in disorders of consciousness

“…To help address the diagnostic and prognostic challenge in disorders of consciousness, a range of neuroimaging technologies have been proposed for assessing ongoing brain activity with sophisticated analytical techniques. These include MRI (Demertzi et al, 2015), PET (Thibaut et al, 2012;Stender et al, 2014) and high density EEG (Lehembre et al, 2012;King et al, 2013;Lechinger et al, 2013;Chennu et al, 2014;Sitt et al, 2014). EEG in particular is an attractive option in this context as it is portable, cost-effective, and relatively feasible to deploy at the patient's bedside.…”

Detection of Consciousness in the Severely Injured Brain

“…Neuronal activity elicits electrical signatures that can be recorded from the scalp with electroencephalography (EEG). The amplitude of specific EEG frequency bands has been shown to correlate strongly with CRS-R scores, with UWS patients showing dominance of slow wave delta activity, whereas MCS patients show higher amplitudes in higher frequency alpha and theta [27]. A recent investigation used support-vector-based machine-learning to identify specific characteristics of high-density EEG recordings in 181 MCS and UWS patients.…”