EEG ultradian rhythmicity differences in disorders of consciousness during wakefulness.
Temporal fluctuations of cognitively-mediated behaviors in minimally conscious state (MCS) have been linked to changes of awareness, but the time-pattern of these variations remains ill-described. We analyzed 4-h EEG recordings from 12 patients with disorders of consciousness (6 MCS and 6 vegetative state/unresponsive wakefulness syndrome, VS/UWS). Relative powers (delta, theta, alpha, beta1 and beta2 bands) and spectral entropy were estimated (Fz, Cz and Pz derivations). Spectral entropy time-courses were then analyzed. MCS patients had higher theta and alpha and lower delta power when compared to VS/UWS. They showed higher spectral entropy mean value and higher time variability. MCS patients were characterized by spectral entropy fluctuations with periodicities of 70 min (range 57-80 min). Notably, these periodicities closely resemble those described in awake healthy subjects, which were hypothesized to be related to fluctuation in vigilance/attention. No significant periodicity was observed for VS/UWS. The spectral entropy periodicity found in MCS patients could reflect the fluctuation of awareness responsible for the inconsistency of MCS manifestation of cognitively-mediated behaviors. The presence of a 70 min periodicity in spectral entropy could permit clinicians to better choose their time-window when performing a clinical assessment of consciousness. It could also permit to monitor fluctuations in cognitive performance (i.e., response to command) during complementary testing by passive or active electrophysiological or functional neuroimaging paradigms or in resting state conditions.
Coma Science Group, GIGA-Research B34, University and University Hospital of Liége, Avenue de l'Hôpital 1, B-4000, Liége, Belgium. a.piarulli@sssup.it.|Perceptual Robotics Laboratory, TECIP Institute, Scuola Superiore Sant'Anna, Via Alamanni 13D, 56010, Pisa, Italy. a.piarulli@sssup.it.
Andrea
http://orcid.org/0000-0003-4516-2671
A
Piarulli
Perceptual Robotics Laboratory, TECIP Institute, Scuola Superiore Sant'Anna, Via Alamanni 13D, 56010, Pisa, Italy.
Massimo
M
Bergamasco
Coma Science Group, GIGA-Research B34, University and University Hospital of Liége, Avenue de l'Hôpital 1, B-4000, Liége, Belgium.
Aurore
A
Thibaut
Innovation and Research Management, University Hospital of Toulouse (Hôtel-Dieu Saint-Jacques), 31059, Toulouse, France.
Victor
V
Cologan
Coma Science Group, GIGA-Research B34, University and University Hospital of Liége, Avenue de l'Hôpital 1, B-4000, Liége, Belgium.|Department of Psychiatry and Psychology, University of Wisconsin, Madison, WI, 53706, USA.
Olivia
O
Gosseries
Coma Science Group, GIGA-Research B34, University and University Hospital of Liége, Avenue de l'Hôpital 1, B-4000, Liége, Belgium.
Steven
S
Laureys
D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000503:physiopathology*; D004569:Electroencephalography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018458:Persistent Vegetative State / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D012727:Sex Characteristics; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology*; D058067:Wavelet Analysis
Awareness temporal fluctuations; Disorders of consciousness, DOC; EEG spectral entropy; Minimally conscious state, MCS; Vegetative state/unresponsive wakefulness syndrome, VS/UWS