Caffeine, nicotine, and alcohol are not allowed for at least 48 hours before EEG.
EEG recordings (to be performed in all centers)
Quantitative EEGs are recorded from 21 scalp derivations. Ag/AgCl disk scalp electrodes (19) are placed according to the international 10-20 system, EEG is recorded from Fp1, Fp2, Fz, F3, F4, F7, F8, Cz, C3, C4, Pz, P3, P4, T3, T 4, T5, T6, O1, and O2. Two additional electrodes are placed on A1 and A2. EEG activity is analyzed from single leads.
Recordings are obtained with subjects resting comfortably, with their eyes closed. Patients’ wakefulness is ascertained every 2 minutes inviting the patients to open their eyes and checking block reactions. A simultaneous electrooculogram needs to be recorded and muscular or tremor artefacts should be controlled with supplementary derivations. Two pairs of bipolar recording channels for respiration and electrocardiogram are also applied. EEG is acquired as a continuous signal for 30 minutes and visually inspected for current clinical interpretation or detection of artefacts and stored to be epoched in off-analysis setting as series of 2 seconds-long epochs.
The computer should collect 10 minutes of EEG recorded with closed eyes, digitized at 1024 Hz with a low filter at 0.1 Hz and high filter at
70 Hz (decay constant 12 dB) with a 50 Hz notch filter in each channel. Blocks of artefact-free 2-second long epochs appearing consecutively for 20-40 seconds will be selected off-line by visual inspection after preprogrammed automatic blink reduction and muscle and tremor artefact rejection system and were compared with the remaining artefact-free epochs to avoid possible discrepancies among acquired sets.
Transfer of data from the different centers to the Chieti center will be performed, after anonymization of the files, through a dropbox secured with a password .