[The influence of reference electrode position on auditory evoked potentials in the brainstem].

INTRODUCTION

In view of the discrepancy in the placement of electrodes and their effects on the auditory evoked potentials of the brainstem (PEAT), we made a statistical study of these potentials using four different sites for the reference electrode to determine the best position for it.

SUBJECTS AND METHODS

The study was done in 30 healthy volunteers aged between 17 and 22 years, 15 men and 15 women. In each person successive measurements were made of the PEAT, with the reference electrode on the vertex (Cz), high frontal (Fz), ear lobe of the opposite side to that of the ear being stimulated and the spinal apophysis of the 7th cervical vertebra (CV). In all cases the active electrode was placed on the ipsilateral ear lobe of the ear being stimulated. After obtaining tables of the normal values for the latency and wave amplitude of waves I to VII in each electrode montage used, we made a study of sex differences and results from the other ear using Student's t test for paired data.

RESULTS

No statistically significant differences were found between the latencies and amplitudes of the waves I to VII for the PEAT obtained with the montage used.

CONCLUSIONS

From our results, we may conclude that the position of the reference electrode does not seem to be a major factor when obtaining PEAT. However, in view of the recordings made, we prefer the reference electrode to be at Cz or Fz when obtaining PEAT, since a clearer recording is obtained when these positions are used. Influence of the reference electrode on PEAT.