Clinical value of subclinical seizures in children with focal epilepsy

SummaryPurposeSubclinical seizures (SCSs) are ictal electrographic discharges lacking clinical seizure signs or subjective symptoms. In this study, frequency, characteristics and diagnostic relevance of SCSs recorded by scalp-EEG were analyzed in a large population of children with focal epilepsy.MethodsLong-term monitoring (LTM) database of 322 consecutive patients <18 years with focal epilepsy were assessed. Video-EEG data of all children with SCS were re-analyzed.ResultsFifty-nine of 322 (18%) children showed SCS on scalp-EEG, nine (15%) of them had no clinical seizures during LTM. Duration of epilepsy (5.2 vs. 6.9 years; p = 0.019) as well as length of LTM (2.8 vs. 3.6 days; p < 0.001) were longer in children with SCS. Neither sex, age at onset, age at LTM, nor focus localization showed significant difference. In 85% of cases the presence of SCS had supplementary value during the diagnostic process. It assisted localizing the seizure onset zone in 53%, suggested multiple seizure onset zones in 20% and influenced antiepileptic drug therapy in 12% of cases.DiscussionScalp-EEG SCS in children with focal epilepsy is a frequent and important phenomenon. Although our therapeutic decisions are usually based on interictal and ictal EEG data and clinical symptoms, SCS is also suggested to be considered during the epilepsy evaluation process. This is the first study assessing SCSs recorded by scalp-EEG.