1.3 Resting EEG shows a severe background
disorganization
During week 2, a
comprehensive neurophysiological battery including visual and spectral
analysis of spontaneous EEG (Figure 3) was performed to complement the
behavioral evaluation. 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).