Altered brain dynamics index levels of arousal in complete locked-in syndrome

Federico Zilio, Javier Gomez-Pilar, Ujwal Chaudhary, Stuart Fogel, Tatiana Fomina, Matthis Synofzik, Ludger Schöls, Shumei Cao, Jun Zhang, Zirui Huang, Niels Birbaumer, Georg Northoff

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Complete locked-in syndrome (CLIS) resulting from late-stage amyotrophic lateral sclerosis (ALS) is characterised by loss of motor function and eye movements. The absence of behavioural indicators of consciousness makes the search for neuronal correlates as possible biomarkers clinically and ethically urgent. EEG-based measures of brain dynamics such as power-law exponent (PLE) and Lempel-Ziv complexity (LZC) have been shown to have explanatory power for consciousness and may provide such neuronal indices for patients with CLIS. Here, we validated PLE and LZC (calculated in a dynamic way) as benchmarks of a wide range of arousal states across different reference states of consciousness (e.g., awake, sleep stages, ketamine, sevoflurane). We show a tendency toward high PLE and low LZC, with high intra-subject fluctuations and inter-subject variability in a cohort of CLIS patients with values graded along different arousal states as in our reference data sets. In conclusion, changes in brain dynamics indicate altered arousal in CLIS. Specifically, PLE and LZC are potentially relevant biomarkers to identify or diagnose the arousal level in CLIS and to determine the optimal time point for treatment, including communication attempts.

Original languageEnglish
Article number757
JournalCommunications Biology
Issue number1
Publication statusPublished - Dec 2023

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)


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