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A 45-year-old house wife with hemifacial spasm developed a profound sensorineural deafness after neuro-vascular decompression operation of the facial nerve at cerebellopontine angle.Electrocochleography was performed using the transtympanic electrode technique.The results obtained were as follows:The wave form of action potential (AP) showed a broad pattern and a low amplitude, but AP threshold was remarkably lower than that of pure tone audiogram.The cochlear microphonics showed the well-developed responses.The above findings seem to indicate that the organ of Corti was found to be functioning because of the preservation of blood supply, but the first neuron region or spiral ganglion cell region was impaired partially and retrogradely, by the surgical procedure on the eighth cranial nerve.

AP and SP responses were investigated by the single electrode technique.The recording sites were the round window, mid-portion of the bony wall of cochlea, the apical portion of the cochlea and bony wall of the hypotympanum.One cycle of sound stimuli at 8kHz, 4kHz, 1kHz and 0.5kHz was used and the sounds were given from 50cm lateral to the tested ear.The tone bursts with duration of 30msec were used as measurement of SP.The results obtained were as follows:The highest value of AP out-put potential was obtained by the round window recording. The highest value of AP out-put potential was obtained by the stimulation of one cycle of 4kHz and 8kHz.The positive SP as seen in the round window recording changed to a decreased positive SP or negative SP at the recording sites except the round window.The SP induced by a tone burst from the round window showed the positive SP at high frequency and the negative SP at low frequency.These results will contribute to the research on the single electrode recording of AP and SP responses in these animals.

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.

In experiments using rabbits, the pupil on the side of irritative inner ear lesion showed dilatation, and that on the side of paretic lesion showed constriction. In the clinical observation of patients with unilateral inner ear diseases (134 cases), anisocoria was recognized in 54.5%. In 68.5% of these, anisocoria was induced after applying a drop of neosynephrine. The size of the pupil on the healthy side was smaller in 65.8% than the pupil on the healthy side. Anisocoria in inner ear lesions is believed to be due to vestibulo-sympathetic imbalance through the superior cervical sympathetic ganglion.

The changes of the action potential (AP), the summating potential (SP) and cochlear microphonics (CM) were investigated in reference to the grade of endolymphatic hydrops produced by endolymphatic sac obliteration in guinea pigs. In a few cases with minimum endolymphatic hydrops, super-normal AP was obtained. With an increase of endolymphatic hydrops, CM responses were reduced although AP responses at intensive stimulation were maintained relatively well. It is thought that the polarity of positive SP, as observed in control, was influenced to deflect towards negative SP by an interaction between the increased degree of endolymphatic hydrops and the changes of the biochemical components of the inner ear fluids.