Evaluation of a novel EEG preamplifier

The authors performed initial clinical testing of a novel EEG transduction module (ETM), designed to record EEG signals from electrodes with high and unbalanced contact impedances. Twenty patients underwent two consecutive EEG studies. In the first, experimental study, electrodes were applied to an unprepared scalp, and the ETM performed initial signal transduction and pre-amplification. The second, routine EEG was acquired in the standard manner, with electrode contact impedances of 5 k Omega or less. Power spectral analysis was performed on all electrode signals from three experimental studies, and all studies were interpreted by three board-certified electro-encephalographers. Individual electrode impedances in the experimental studies ranged from 10 to 560 k Omega (mean 129 k Omega). Power spectra on 54 of 57 electrode signals analyzed were free of 60-Hz noise. The majority of experimental studies were technically adequate, and technical limitations were unrelated to the ETM. Interrater reliability of preparation-free and standard EEG interpretation was high. The ETM device is an effective preparation-free technology in the setting of a clinical EEG laboratory. It provided easily interpretable EEG signals free of 60-Hz noise, recorded from electrodes with high and unbalanced impedances placed on completely unprepared scalp with minimal electrode paste