Requirements for recording the EEG at high sensitivity in suspected brain death

Abstract The requirements for recording the EEG at high sensitivity and for its evaluation in suspected brain death are described, including: (i) precautions to reduce electrical interference from outside and from the measuring circuit (noise); and (ii) measures to identify and subtract bio-potentials of extracerebral origin which are unavoidably present in the EEG recorded at increased gain. The resolution of the high gain record was determined by a noise level of up to 2 μV peak-to-peak; consequently, the EEG was considered without detectable cortical activity when there was no activity above 2 μV. Since cortical low voltage activity could appear at intervals of up to 20 min, the recording time necessary to establish the absence of detectable cortical activity was set to 30 min. including 10 min of recording during stimulation of visual, auditory and cutaneous receptors.