The effect of the changes of interstimulus interval (ISI) was compared among the four groups consiting of normal hearing subjects sensorineural deafness due to hair cells damage, due to endolymphatic hydrops and cerebello-pontine angle lesion. The click sound stimulation was used for measurement of the auditory whole nerve action potential (AP), using the transtympanic technique in electrocochleography. A moderate decrease in similar manner was shown in two groups of normal hearing subjects and sensorineural hearing loss with hair cells damage. On the other hand, a remarkable decrease was shown in order two groups of sensorineural hearing loss with endolymphatic hydrops and with cerebello-pontine angle lesion. It is suggested that a remarkable decrease in amplitude of AP with shortening of ISI is due to abnormal function in synaptic junction between the cochlear hair cell and the first auditory neuron and/or abnormal function in the post synaps.
Brain electrical activity mappings of ABR components by two methods were studied in cats. One is so-called “Peak to Peak” method, in which the amplitude is measured from a positive peak to the succesive negative peak of ABR component. Another is so-called “Baseline to Peak” method, in which the amplitude is measured from the baseline to a positive peak of ABR component. The differences on the scalp topography in these methods were as follows: 1) Wave I: Mappings by “Peak to Peak” method were more stable and reliable than “Baseline to Peak” method on the scalp topography. 2) WaveIII, waveIV: On the highest electrical ratio area, mappings by “Peak to Peak” method were similar to those by “Baseline to Peak” method, but as for the electrical ratio slope, “Peak to Peak” method showed more steep than “Baseline to Peak” method. 3) Wave V: Mappings by “Baseline to Peak” method were greatly influenced by slow component of ABR.
Intravenous injection of xylocaine was performed in 61 patients with tinnitus. Most cases of tinnitus were inner ear deafness (85.5%). Xylocaine dose was 60mg in men, 40mg in women. Injections were repeated five times and the effects were evaluated in three stage (short, middle, long) by subjective sensation, pitch match and loudness balance test. The results were as follows. 1) Short effect was oftained in 57 cases (81.4%), moderate in 28 cases (44.4%), and long were in 13 cases (52.0%). 2) In presbyacusis, sudden deafness, tinnitus without hearing loss, and chronic otitis media, the therapy were continuously effective. 3) Age and hearing type were related with effects of the therapy. 4) Sufferring duration, hearing level, pitch and loudness were not related with effects of the therapy. 5) All of the side effects were transient.
The Auditory brainstem responses (ABRs) of 606 ears were evaluated from 425 profoundly deaf patients. A potential with negative deflection was found at the latency 3msec in 48 ears of 37 patiants above the intensity of 80dBnHL. As intensity was increased, the amplitude was larger and latency decreased. The response reappered in retesting, and did not disappeared with masking contralateral ear to click stimulation. We speculated the response to be the physiological potential evoked by acoustic stimulation, neither electrical artifact nor shadow response from the good ear, and we concluded the response is one type of ABR wavefrom recorded only in periherally profound deafness, since a few of low frequency threshold remained and none of central disorder wes found.