Introduction and objective:
Febrile seizures (FS) are the most common type of seizures in childhood. Depending on focality, duration and possible recurrence FS are divided into simple (SFS), complex (CFS) and simple plus (SFS+). Simple FS are considered not to require detailed diagnostics nor electroencephalographic (EEG) studies, even though some cases present EEG abnormalities that may affect the initial diagnosis and long-term prognosis. The aim of the study was to assess the usefulness of EEG as a potential prognostic neuromarker of FS.

Material and methods:
103 FS children aged 5–55 months (SFS – 62 cases (60%); SFS+ – 15 cases (15%); CFS – 26 cases (25%) were retrospectively analyzed. EEG was performed in all cases after the resolution of fever (3rd-7th day). The clinical characteristics (seizure morphology, episode duration and recurrence) were confronted with EEG findings (normal vs. epileptiform pattern: generalized or focal). The results were analyzed statistically to look for prognostically useful correlations.

Results:
Abnormal EEG pattern was recorded in 29% of patients (SFS 27%; SFS+ 40%; CFS 27%). Generalized epileptiform discharges were noted in 18 cases (SFS 21%; SFS+ 27%; CFS 4%) while focal EEG discharges were seen in 12 cases (SFS 6%; SFS+ 13%; CFS 23%). Generalized FS in 30% were associated with generalized (19%) or focal (11%) EEG discharges.

Conclusions:
The current protocol of FS management does not warrant further diagnostics in 27–40% of FS children with abnormal EEG. SFS+ children are be the most underdiagnosed group, with a greater number of EEG abnormalities compared to SFS and CFS. It seems reasonable to extend the routine EEG diagnostics into this group of FS patients.