Elimination of EKG artifacts from EEGs recorded with balanced non-cephalic reference electrode method

The EKG artifacts contaminating EEGs recorded by the balanced non-cephalic reference electrode system were removed from EEGs by using a device composed of a one channel averager and simple hardware. This device has the following advantages to the others which have been previously proposed: (1) it is possible by averaging of a few (i.e., 5) EKG artifacts in EEG records successfully with only one channel averaged EEG derived from an earlobe; (2) the averaged EKG pattern is able to follow rapid EKG pattern change due to altered body position; (3) the possibility of being affected by another kind of artifact was decreased, because the time of averaging process to obtain averaged EKG became shorter. A remaining problem in achieving a complete removal of EKG artifacts (maximally of 100 micro V) was beat-by-beat small changes in EKG wave forms due to the respiratory cycle. Therefore, it was felt that our method was sufficiently accurate for clinical examination of EEG.