Objective: We analyze a slow electrographic pattern, Macroperiodic Oscillations (MOs), in the EEG from a cohort of young critical care patients (n = 43) with continuous EEG monitoring. We construct novel quantitative methods to quantify and understand MOs. Methods: We applied a nonparametric bilevel spectral analysis to identify MOs, a millihertz (0.004–0.01 Hz) modulation of 5–15 Hz activity in two separate ICU patient cohorts (n = 195 total). We also developed a rigorous measure to quantify MOs strength and spatial expression, which was validated against surrogate noise data. Results: Strong or spatially widespread MOs appear in both high clinical suspicion and a general ICU population. In the former, patients with strong or spatially widespread MOs tended to have worse clinical outcomes. Intracranial pressure and heart rate data from one patient provide insight into a potential broader physiological mechanism for MOs. Conclusions: We quantified millihertz EEG modulation (MOs) in cohorts of critically ill pediatric patients. We demonstrated high incidence in two patient populations. In a high suspicion cohort, MOs are associated with poor outcome, suggesting future potential as a diagnostic and prognostic aid. Significance: These results support the existence of EEG dynamics across disparate time-scales and may provide insight into brain injury physiology in young children.

Original languageEnglish
Pages (from-to)84-91
Number of pages8
JournalClinical Neurophysiology
StatePublished - May 2022


  • Brain monitoring
  • EEG oscillations
  • Pediatric neurology
  • Spectral analysis
  • quantitative EEG


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