Detection Rates of Interictal Epileptiform Discharges in Epilepsy Patients: A Comparison of Routine, 1-3 Hours Daytime, and Whole-night EEG Recordings

METHODSEEG recordings of patients who were followed up in the epilepsy outpatient clinic of Dokuz Eyll University Hospital between 2006 and 2024 were reviewed retrospectively.Adult patients (18 years) who underwent at least one routine EEG, one 1-3 hours daytime vEEG, AbstractObjective: The detection rate of interictal epileptiform discharges (IEDs) varies among electroencephalography (EEG) recordings in patients with epilepsy.This study aimed to compare the yield of IED detection across three recording protocols of varying durations routinely used at our center: routine 20-30 minutes EEG, 1-3 hours daytime video-EEG (vEEG), and whole-night (8-12 hours) vEEG.Methods: The EEG reports of adult patients treated at the Dokuz Eyll University Hospital epilepsy outpatient clinic between 2006 and 2024 were retrospectively reviewed.Patients older than 18 years who had undergone at least one routine EEG, one 1-3 hours daytime vEEG, and one whole-night vEEG on separate occasions were included.The detection rates of IEDs across the three modalities, along with patients' clinical characteristics, were analyzed.Results: Seventy-three patients (43 women and 30 men) were included in the study.For the initial EEG, the IED detection rate was 17.8% for routine EEG, 45.2% for 1-3 hours daytime vEEG, and 46.6% for whole-night vEEG.The routine EEG detection rate was significantly lower (p=0.001).With repeated examinations, the yield of routine EEG increased to 41.1%, daytime vEEG to 52.1%, and whole night vEEG to 56.2%; with no significant difference between the modalities (p=0.099).Conclusion: Although IED detection was highest with whole-night vEEG, daytime 1-3 hours vEEG recordings that included sleep achieved a comparable yield and may be preferred to reduce laboratory workload.The recording duration can be individualized according to the laboratory resources and patient preferences.