Conventional and Investigational Approaches Leveraging Clinical EEG for Prognosis in Acute Disorders of Consciousness

Abstract

Prediction of recovery of consciousness after severe brain injury is difficult and limited by a lack of reliable, standardized biomarkers. Multiple approaches for analysis of clinical electroencephalography (EEG) that shed light on prognosis in acute severe brain injury have emerged in recent years. These approaches fall into two major categories: conventional characterization of EEG background and quantitative measurement of resting state or stimulus-induced EEG activity. Additionally, a small number of studies have associated the presence of electrophysiologic sleep features with prognosis in the acute phase of severe brain injury. In this review, we focus on approaches for the analysis of clinical EEG that have prognostic significance and that could be readily implemented with minimal additional equipment in clinical settings, such as intensive care and intensive rehabilitation units, for patients with acute disorders of consciousness.

Unconsciousness or unresponsiveness in akinetic mutism? Insights from a multimodal longitudinal exploration

“…The visual analysis of clinical standard EEG demonstrated a diffuse slowing of the background activity with high‐amplitude frontally dominant slow‐waves (>75 μV) without a reproducible reactivity to stimuli (Figure 3, upper left panel). In accordance with recent review and specific recommendations (Curley et al, 2022), these findings were interpreted as a severely abnormal EEG, a pattern more often found in VS/UWS patients and not suggestive of covert consciousness (Curley et al, 2018; Forgacs et al, 2014). The severity of EEG slowing was confirmed by the quantification of Delta‐Alpha Ratio spectral power (Bai et al, 2021; Leon‐Carrion et al, 2008; Wutzl et al, 2021) showing values above the 95th percentiles of the distribution previously obtained in a reference population of 40 patients with a minimally conscious state (MCS) (Figure 3, upper right panel).…”

Unconsciousness or unresponsiveness in Akinetic Mutism? Insights from a multimodal longitudinal exploration

“…The visual analysis of clinical standard EEG demonstrated a diffuse slowing of the background activity with high-amplitude frontally-dominant slow-waves (>75μV) and sporadic lateralized epileptiform discharges on the left parietal sites, without a reproducible reactivity to exogenous stimuli (Figure 3, upper left panel). In accordance with recent review and specific recommendations (Curley et al , 2022), these findings were interpreted as a severely abnormal EEG, a pattern more often found in VS/UWS patients and not suggestive of covert consciousness (Forgacset al , 2014;Curley et al , 2018). The severity of EEG slowing was confirmed by the quantification of Delta-Alpha Ratio (DAR) spectral power (Leon-Carrion et al , 2008;Bai et al , 2021;Wutzl et al , 2021) showing values above the 95th percentiles of the distribution previously obtained in a reference population of 40 patients with a minimally conscious state (MCS) (Figure 3, upper right panel).…”