Gamma frequency SSVEP components differentiate children with febrile seizures from normal controls.

Gamma band electroencephalography (EEG) abnormalities have been reported in patients with epilepsy. We aimed to investigate whether patients with febrile seizures (FS) show abnormalities of the gamma frequency steady-state visual evoked potential (SSVEP) components evoked by intermittent photic stimulation (IPS). We analyzed the magnitude and phase alignment of the 50-100 Hz SSVEP components elicited by IPS from 12 FS patients, 5 siblings of FS patients, and 15 control children between 6 and 36 months of age. Patients with FS showed significantly higher SSVEP magnitude and phase alignment values when compared to both the siblings and control groups. Detected abnormalities could either represent the direct consequence of seizures or indicate a preexisting tendency to hypersynchrony in FS patients. Future prospective studies could assess whether SSVEP abnormalities are associated with complex rather than simple FS, or have a prognostic value for the development of epilepsy following FS.