[Tables of normal values of average and long latency auditory potentials].
INTRODUCTION AND OBJECTIVE: In view of the disparity of data and methodology concerning medium (MAEP) and long latency (LAEP) acoustic evoked potentials, we have obtained tables of normal values using a reliable method and statistical study of these potentials in 30 healthy persons, in order to serve as a basis for clinical reference and for possible further studies. MATERIAL AND METHODS: In the MAEP we used the two types of stimuli most commonly employed, first a click and then a rising-plateau-falling tone (2-6-2). We observed that this did not affect the latency or amplitude of the different waves, although the best defined waves are obtained with tones. In the LAEP we always used a tone with rise-plateau-fall of 10-50-10, as recommended by the American Electroneurophysiological Society. In all cases the intensity was of 70 db, with rarefaction and masking of the contralateral ear with an intensity of 50 db. Self-adhesive electrodes were used for captation; the active one was placed on the ipsilateral ear lobe and the reference electrode in Cz for the LAEP. For the LAEP the lower filter was of 1 Hz and the higher of 70 Hz. In view of the variety of filters recommended, 10 Hz at the lower level and 500, 1000 and 2000 at the higher level were used successively for the MAEP. We observed that these did not affect the latency or amplitude of the waves, so these three values may all be used equally well. RESULTS AND CONCLUSIONS: In the inter-sexual study, no differences were seen between men and women. Nor were there significant differences between the acoustic evoked potentials on the right and left sides of the same person.