Cost of waiting: association of EEG delay and poor functional outcome in adult status epilepticus

BACKGROUND: Status epilepticus (SE) is associated with substantial mortality and morbidity that increase with seizure duration. Prompt diagnosis is essential, but access to electroencephalography (EEG) is often limited outside regular working hours. We examined whether EEG delay due to prolonged waiting times for EEG is associated with worse outcomes. METHODS: This retrospective cohort study comprised adults (≥18 years; n=163) with first-time, non-anoxic, EEG-verified non-convulsive SE treated at Odense University Hospital, Denmark (2008-2017). EEG delay was defined as the time from last antiseizure treatment or clinical suspicion of SE to EEG confirmation. Outcomes were new neurological deficit at discharge and 2-year all-cause mortality. External validation used two retrospective German cohorts (n=906) differing in weekend EEG availability. RESULTS: Median EEG delay was 11.7 hours (IQR 3.5-22.6) and correlated with SE duration (r=0.2, p