Duration of EEG monitoring needed to ensure a low risk of seizure recurrence in hospitalized patients

BACKGROUND: Continuous EEG (cEEG) monitoring is critical for detecting seizures in hospitalized patients, but optimal durations of EEG monitoring remain unclear, particularly after a seizure has been detected on monitoring. METHODS: We conducted survival analysis on 117 patients with electrographic or electroclinical seizures who underwent cEEG at the University of Wisconsin Hospital (UWH) between 2018 and 2022. Time from the end of seizure-to-seizure recurrence or cEEG termination was analyzed using Cox regression. RESULTS: In univariate analysis, status epilepticus (SE) was the only clinical feature significantly associated with increased risk of seizure recurrence (P = 0.022). The estimated EEG duration required to reduce seizure recurrence risk below 5% was 36.8 h in patients with SE and 21.2 h in those without SE. Numerous other clinical variables, including coma, antiseizure medications addition, use of anesthetic infusions, history of epilepsy, and epileptiform discharges, were not significant. CONCLUSION: Our findings support current clinical practices of at least 24 h of EEG monitoring following seizure cessation and highlight that patients with a history of status epilepticus may require longer monitoring. These data reinforce the value of individualized, risk-based approaches to EEG monitoring strategies.