Supplemental Table 1. Discontinuous EEG Activity in Neonates
PMA*
EEG Features
Term Clinical Correlate Suppression
Periods Length
Suppression Amplitude (Voltage)
Burst Period Length
Burst Amplitude
(Voltage) Reactivity
> 30 weeks >10 seconds <5 μV 1-2 seconds
Theta and delta waves 75 to 250 μV
Not reactive to
external stimuli Burst Suppression
Associated with poor outcomes such as encephalitis and hypoxemic injury
30-35 weeks > 2 seconds 5-25 μV
(often <10 μV) - up to 300 μV Reactive to external stimuli
Discontinuous EEG activity
Normal discontinuous tracing of the very immature premature infant
> 36 weeks 3-15 seconds >25 μV
(25–50 μV) -
Slow waves 100 to 200 μV (50-150)
Reactive to external
stimuli Tracé alternant Quiet sleep of the infant. May persist up to 4 weeks after birth
*Postmenstrual Age (PMA). In older neurological literature the term “postconceptional age,” defined as gestational age (in weeks) plus the number of weeks since birth, is used instead of PMA.
Reactivity: A phenomena in which the EEG pattern clearly and reproducibly changes with sensory (visual, auditory, or noxious) stimulation. Clinical response includes active movements and respiratory pattern changes. EEG response may include changes in frequency, morphology, and/or amplitude, including attenuation of activity after stimulus and increased continuity.
Supplemental Figure 1. Example of EEG Reactivity.
Example of EEG reactivity: Spectrogram of electroencephalogram of a 9-week-old premature infant (GA 29, PMA 38; ASA status III) under spinal anesthesia for inguinal herniorrhaphy. The spectrogram above shows discontinuous activity (~50-52 minutes) characterized by an alternating pattern of burst events lasting a few seconds followed by periods of suppression of variable duration and amplitude. At ~52 and ~56 minutes high-power activity across all the frequencies appears consistent with muscle activity from patient movement induced by clinically annotated “chin-lift.” After these events the EEG activity regains continuity.