2.2. EEG Assessments

Routine awake and sleep 60-minute-EEG or both were performed with a Medicid-5 digital EEG system (Neuronic SA, Cuba), with 32 channels. Monopolar leads were employed, using Fpz electrodes as reference. Moreover, electrodes placed over the superior and inferior rim were used in order to record eye movement artifacts for easing their detection in the EEG records. EEG technical parameters were: gain 20,000, pass-band filters 0.1–70 Hz, “notch” filter at 60 Hz, noise level of 2 lV(root mean square), sampling frequency 200 Hz, and electrode–skin impedance never higher than 5 KX. EEG analyses were performed by two board-certified electroencephalographers.

Type and localization of EEG epileptiform abnormalities in awake/sleep-EEG recordings were evaluated. EEG studies were classified as epileptiform if spikes, sharp waves, or spike/slow waves complexes were recorded. Abnormalities such as slowing of the background or other non-epileptic pattern were not considered. All activity regarded as artefactual was excluded.