The middle components of the auditory evoked response during sleep were investigated in 9 normal adults. As the stage of sleep became deeper, the latency of each peak except Po-peak was slightly increased and the amplitude of those was slightly decreased. Nb- and Pb-peak had a tendency to disappear in the deep sleep stage. The detectability of Po-, Na- and Pa-peak during sleep was not lower or higher than that of those during waking. Na-peak usually consisted of double peaks, and Na2 was dominant in the awake stage, but Na1 sometimes became dominant during sleep. From these results, it was concluded that the effect of the depth of sleep on the middle components was not so large in adults as in children.
Pathophysiology and prognosis of hearing acuity in 16 ears of 10 cases with inner ear syphilis were studied by the transtympanic electrode technique of electrocochleography. The results were obtained as follows: The improvement of hearing acuity after steroid therapy was obtained at low frequency range on audiogram. These cases showed a well defined AP, a dominant-SP and remarkable CM response at 0.5kHz. It was speculated that there may be endolymphatic hydrops and the reversible change of hair cells at low frequency area of the cochlea. On the other hand, in the cases showing slight improvement of hearing acuity, both AP and CM responses shwed a low out-put potential which suggests a reversible change or organic damage of the hair cells or cochlear nevre.
Wave I is not always recorded clearly in ABR, and it is effective to record AP simultaneously to identify wave I. If the results of AP are taken into account, no misinter-pretation can be cccured. The simultaneous recordings of AP and ABR are averaged with same stimuli, and it is easy to place the electrodes for recording of AP and ABR Testing time can be shortened by the use of simultaneous recording, and the simultaneous AP and ABR recordings are useful for the detecion of cochlear nerve and the brain stem disorders.