225 cases with sensori-neural hearing loss were observed for one year or more clinically and audiometrically. 25 cases (31 ears) among them showed the more than one paroxysmal recovery or fluctuation in the hearing level of 15dB or more in a long term observation. The recovery or fluctuation in the hearing level occured predominantly at the range of low frequencies. This phenomenon was occured in various kinds of diseases; 6 cases of Meniere's disease, 4 of sudden deafness, 3 of cerebello-pontine angle tumor, 2 of each labyrinthine syphilis, Hunt's syndrome and each one of acoustic trauma, acoustic neuritis, Lermoyez's syndrome, circular disturbance in basilar artery and unknown etiology. 18 cases among them were of unilateral sensorineural hearing loss, and 7 cases were of bilateral. There were many processes in the recovery or fluctuation of the hearing loss, but any characteristics in the processes were not observed.
Fluctuating hearing loss presumed to be caused by endolymphatic hydrops without vertigo, according to Williams et al (1950), was reported. A 39-year-old woman had a fluctuating hearing loss in her right ear and sever perceptive hearing loss in her left ear. The right ear showed recurrent perceptive hearing loss of 50-60dB in low frequencies with almost complete recovery in each occasion. The onset of the hearing loss was gradual, accompanied with tinnitus, fullness in the ear and sometimes slight dizziness. All three symptoms, however, did not always occur in each attack. There was no complain of true turning vertigo. Four attacks were occurred with remissions of one to two months. Treatment with steroid was effective to each attack, but because of appearance of its side effect, treatment was switched to stellate ganglion block and hyperbaric oxygen and these prevented further attacks. The literature was reviewed in brief and the possible mechanisms to explain the fluctuation on hearing were discussed.
The cases suffering from a fluctuating hearing impairment were reported. Most of all these patients had tinnitus and fullness prior to a loss of hearing acuity, however, vestibular imbalance such as vertigo seemed much less than cochlear symptoms. Apparently these clinical manifestations differed from Meniere's disease or sudden deafness. Hearing loss of these patients, which showed a low tone deafness in most cases, were a sensorineural in type an fluctuating hearing loss were observed in clinical course. Audiometric evaluations revealed that lesions of this type of deafness might be inner ear. Moreover, a pathogenesis for fluctuating deafness was discussed.
1) Ten cases (fourteen ears) with fluctuant hearing loss without vertigo were clinically investigated. 2) Hearing loss was seen in low and middle frequencies with positive recruitment. Degree of hearing fluctuation was, in most cases, between 20 and 40dB. Durations between the shift of hearing loss were various in each case, and there was no relation of fluctuating hearing loss to a particular season. 3) Four cases of fluctuant hearing loss without vertigo were firstly diagnosed as Ménière's disease. 4) Though vertigo was not observed in these cases with fluctuant hearing loss, most casès showed abnormal findings in equilibrium examinations. In caloric test unilateral hypofunction was observed in 60%. While in damped pendular rotationtest, 57% showed abnormal findings suggesting dysfunction or circulatory disturbances in the brainstem. 5) Serum lipids, total cholesterol, and glucose torelance test were within normal limits. In two cases abnormal values of serum protein fraction (increase of γ- and α2-globuline) were obtained. It is noteworthy that in these two cases sensorineural hearing losses were improved by administration of steroid (predonine). One of these cases were proved to be aortitis syndrome by aortography. 6) Fluctuant hearing loss in these series is a syndrome which include sensori-neural hearingloss due to endolymphatic hydrops (Williams type) or local manifestation of systemic vascular disorders and psychogenic deafness. Therefore, examinations should include not only audiological and vestibular tests but also systemic examinations (BSR, serological tests, endocrine tests, etc.) and studies from psychosomatic standpoint.
The pathogenesis of fluctuating sensory-neural hearing loss was classified into two types. In the first type, both hair cells and nerve cells are normal and the auxiliary tissues of the inner ear only are reversibly involved. By contrast, in the second type, hair cells and/or nerve cells themseles are involved by reversible degeneration but the auxiliary tissues are normal. In the former, especially the stria vascularis was thought to play an important role. Cochlear potentials, Preyer's reflex and post-rotatory nystagmus in guinea pigs were recorded under application of anoxia and intravenous administration of furosemide. The 8th nerve action potential of the Ménière's disease was also examined and analysed by means of an anlog averaging computor. These experimental results induced the conclusion that vascular or metabolic insufficiency of the stria vascularis caused a reversible hearing threshold elavation of 30-35dB for all frequencies, and then change of ion composition and volume of endolymph resulted in a reversible inner ear conductive deafness.
The authors reported a 60 years old man who had reccurent attacks of bilateral sensori-neural hearing loss concurrent with impaired visual acuities and narrowing of visual fields. The attacks occured four times during two years. The severity of the attack became reduced following to each one. Observing the clinical course, auditory and ophthalmologic findings in this patient, it is reasonable to assume that cochlear and retrobulbar neuritis due to a viral infection had subsided gradually showing the repeated remission for two years, and the neuritis caused the coexistent auditory and visual disturbances.
Application of the operating microscope to neurosurgery has been making a significant technical advance. Especially it brings a tremendous merits in the operation for acoustic tumor and cerebellopontine angle tumor. And many investigators have reported a good recovery of hearing in these patients after the operation. These patients generally exhibited variable symptoms and clinical data according to intracranial edema, circulatory disturbance or compression by tumor. Even in audiometry, it also exhibited various results depending on the location or the size of the tumor. From this point of view, 2 cases of the cerebellopontine angle tumor were studied audiometrically on the relationship between the audiometric changes and the development of the tumor. One deaf patient recovered audiometrically his hearing to normal range in 6 months after the operation of the tumor. Another patient showed progressive and fluctuating deafness of a few days' duration accompanied with nausea, vomitting and tinnitus. He died of subarachnoidal bleeding after the third severe attack of deafness. Authopsy revealed a thin wall cyst covering cerebellum, pons and medulla. The changes of audiometrical findings were discussed with the pathological data of the tumor.
Five cases of cerebello-pontine angle and brain-stem tumors with fluctuating hearing loss were reported. They were consisted of two cases of acoustic neurinomas, one of cerebello-pontine angle meningioma, one of hemangioblastoma of brain-stem, and one of supra- and sub-tentorial dumb-bell type astrocytoma. Their fluctuating hearing losses occurred predominantly on the range of low frequencies. They were observed paroxysmal fluctuation in the hearing losses during their clinical courses. In two cases of them, deafness occurred and improved abruptly, and we found a cyst in a part of these tumors. The mechanisms of the fluctuating phenomenon were explored from the operative and audiological findings, and following causes were presumed. The first, in the courses of growths of the tumors, it may act as reversible invasion to acoustic nerve or acoustic tracts in the brain-stem, within a certain period of time. The second, as a result of that cerebello-pontine angle tumor may exert pressure upon the labyrinthine artery, it may cause the reversible of the inner ear function to make change in some instances. The third, the rapid increase or decrease in cerebro-spinal fluid pressure may cause the change of pressure of the tumor on acoustic nerve or brain-stem.
Auditory variability were measured on normal adults and several hearing disorders, and its bioinformative analysis was performed. It was recognized that high variability meant unsteady physiological function and also high potentiality of recovery. Normal adult auditory variability showed about 3dB. From the results of measurement on Meniere's disease and sudden deafness, it was clarified that auditory variability were 14-20dB in the period of attack of hearing loss, 5-7dB in the intermittent period and about 3dB in the steady period.
One hundred and eighty-two cases of occupational deafness were selected as subjects of this study, and variation of hearing threshold of air conduction were statistically observed mainly with the left side ears. The results of the experiments are as follows: 1) No clear correlation was noticed between the average hearing loss and variation of hearing threshold. 2) As to tinnitus and variation of hearing threshold, no significant difference was found between continuous tinnitus, intermittent tinnitus and no tinnitus. 3) As to variations of hearing threshold obtained by comparing hearing threshold of the first test with that of the second, and the second with the third, etc., significant differences were noticed only at 1, 000Hz, 2, 000Hz and 4, 000Hz. 4) When variations of hearing threshold were examined at various frequencies, no significant differences were found. 5) Mention was also made of qualifications of technicians who measures auditory acuity.