Electroencephalographic (EEG) Stages in Patients With Cerebral Edema Following Cardiac Arrest.

Objective: To describe electroencephalographic (EEG) changes in pediatric patients with cerebral edema after cardiac arrest.
Methods: A retrospective study of patients admitted to the pediatric intensive care unit from July 2021 to January 2023. We included patients with cardiac arrest and changes in EEG background with clinical changes and/or neuroimaging consistent with cerebral edema. We excluded patients with electrographic seizures. We applied American Clinical Neurophysiology Society standardized critical care EEG terminology to classify EEG background, noting timing of the change in background classification. Clinical variables included age, sex, and neuroimaging findings and were described with descriptive statistics.
Results: Nine patients met inclusion criteria, with median age 24 months (interquartile range 21-49), and 89% were male. There were 5 common EEG stages: stage 1, burst suppression/burst attenuation; stage 2, continuous/discontinuous ± multifocal sporadic epileptiform discharges ± rhythmic or periodic patterns; stage 3, discontinuous/burst suppression/burst attenuation ± rhythmic or periodic patterns; stage 4, gradual voltage suppression; and stage 5, diffuse suppression. The ranges for each stage were as follows: stage 1, 2-10 hours; stage 2, 2.5-15.5 hours; stage 3, 0.5-6.24 hours; and stage 4, 0.5-11 hours. We could not calculate the duration of stage 5 given no uniform time to EEG discontinuation. One patient had a clinical change in stage 3. Remaining patients presented with fixed and dilated pupils with global anoxic injury.
Conclusions: EEG stages of cerebral edema have not been described after pediatric cardiac arrest. These stages may be relevant to other patient populations. Early stages may be a therapeutic target for intracranial pressure-lowering medications and/or neuroprotective strategies to minimize sequalae of cerebral edema.