In order to study hearing changes caused by Kendo (Japanese fencing), we examined 33 students, aged between 15 and 18 years old, who were active members of a Kendo team at a senior high school in Miyazaki. The pure tone audiometry revealed that 10 out of 33 (30%) students had a various degrees of sensorineural hearing impairment. In paricular, abnormal audiograms with dips shown at 2kHz or at 4kHz seemed to feature the early audiometric changes caused by Kendo. Ears with a 2kHz-dip were found more frequently than those with a 4kHz-dip, and it was suggested that hearing impairment was caused by Kendo with some strong mechanisms, such as head contusion, in addition to acoustic trauma.
In a 5-year-old girl with tinnitus in her right ear, pure tone audiogram at first visit showed a right hearing impairment of 60-80dB HL at 1-8kHz range. It was found that she blew a toy trumpet very closely to her ear several times. From these history and findings, diagnosis of acute acoustic trauma was made. Intravenous administration of ATP, vitamin B complex and steroids was employed immediately. Hearing was partially recovered but hearing impairment remained at 2 and 4kHz and tinnitus also persisted. Intensity measurement of the trumpet sound revealed very high value over 130dB (A) at 5cm distance which would be loud enough to produce acoustic trauma.
A study of tinnitus due to abnormal contraction of the stapedial muscle in eight patients with hemifacial spasm was done. The electromyographic response of the orbicularis oculi and the orbicularis oris muscles and the non-acoustic stapedial reflex were simultaneously recorded during hemifacial spasm before microvascular decompression. During hemifacial spasm, the electromyographic response revealed the recurrence of action potentials and the non-acoustic stapedial reflex showed the decrease of compliance. The decrease of compliance was found to be 0.54±0.36cc (n=8). The microvascular decompression was performed in 6 of 8 patients. In all the patients, the tinnitus disappeared without any complication after operation. The seventh cranial nerve was compressed by a loop of the anterior inferior cerebellar artery in 4 of 6 patients and by a loop of the posterior inferior cerebellar artery in 2 of 6. There findings suggested that the non-acoustic stapedial reflex could be a useful tool for evaluation of tinnitus due to abnormal contraction of the stapedial muscle in the patients with hemifacial spasm and the microvascular decompression could be effective treatment.
It is well known that quinine gives rise to reversible sensorineural hearing loss. But there was very few reports about it in Japan, because malaria is infrequent. We reported the clinical details of 3 cases with hearing loss caused by quinine. The drug has also therapeutic effect against arrhythmia. Three patients were suffered from arrhythmia that other drugs were not effective and treated by quinine. Their hearing threshold was shifted about 10-30dB in pure tone audiometry. They showed recruitment phenomenon in SISI test, Bekesy audiometry and Metz test. The hearing loss improved following discontinuation of the drug.
Endolymphatic hydrops (ELH) have been reported to occur in some individuals exposed to acoustic trauma, such as a military related noise or other intense sound. In this paper we studied effect of acoustic trauma in human inner ear by means of an electro-cochleography (ECochG). The subjects consist of 32 defense force personnel whose ears have been affected with acoustic insult by repeated shooting practice or exposure to other intense noise in their military training. Of the 32 men studied for ECochG, 30 percent of the ears showed either broad type AP or increased negative SP, suggesting a possible development of ELH. Although only two of these subjects demonstrated what appeared to be Meniere's like clinical symptoms or repetitive acoustico-equilibrium disorders, a detailed and longterm follow-up seem to promise a more concrete data as to the relationship between the intense noise exposure and the development of ELH.
The purpose of this study is to investigate whether the auditory sustained potential elicited by a sustained toneburst is a sensory response or a endogenous potential associated with attention to the auditory stimulus. We designed two paradigms each of which consisted of three experiments. In both paradigms, only the third experiment required the subjects to pay their attention to duration of the auditory stimulus. As a result, in both paradigms, the first and second experiments failed in eliciting the auditory sustained potentials, on the other hand, only the third experiment succeeded in eliciting the auditory sustained potentials. Based on these results, we suggested that the auditory sustained potential is a endogenous potential associated with sustained attention to the auditory stimulus, rather than a sensory response.
The characteristics of combination tones produced by complex sounds and frequency modulated complex sounds were investigated by using a masking technique in five ears of normal hearing listeners and twenty-two ears of sensory-neural hearing impaired in order to analyze the auditory nonlinearity. From the experimental results, it was found that the masking phenomena produced by the exisitence of combination tones appeared only in seven ears of the hearing impaired different from the normal hearing listeners. The masking level increased at the frequency corresponding to the combination tone by using frequency modulated complex sounds than the frequency constant complex sounds in the normal listeners. This phenomenon did not appear in most of the hearing impaired.
Since Auditory Screening Test was cutrobuced to the group examintion of three-year-old-children in kyoto in 1991, three years have passed. 468 cases who had hearing test in our clinic for the past six years were studied and the results were compared before and after screening. The results were as follows: (1) Number of cases increased after screening but number of cases who were found hearing impariment were as many as befor screening. Cases introduced by pediatricians and health centers were increased. (2) In 216 children with hearing impariment 116 had bilateral sensorineural hearing loss (bSNH), 33 OME or others. Average age to be found their hearing loss were 1 year and 5 months (severe bSNH), 3 years and 8 months (moderate bSNH). The age was lower after screening than before, mainly for high-risk infants were tested earlier. (3) One third of the cases with severe bSNH were found late. A few cases with moderate bSNH were found late for their little symptoms and it is hoped screening would play an important role in finding such cases. (4) About 70% cases were found to have speech retardation or disarthria, while only 17% were found of suspicion of hearing loss. Children with suspicion of hearing loss should be examined in de tail by some other hearing tests such as, whispered voice test.
Auditory evoked responses (ABR, MLR, SVR, ECochG) were recorded in five patients with pontine glioma. The aims were to examine possible mechanisms by which the disease causes response abnormalities and to evaluate the diagnostic potential of auditory evoked responses for detecting pontine glioma. 1. Abnormalities of the ABR were recorded in all cases. 2. Only wave I of the ABR was observed in three of the five sides in which the infiltrating tumor edge was in contact with the cerebellopontine angle cistern. 3. Results of ECochG in three cases provided evidence that functions of the cochlea were not impaired. In two of 3 cases, the AP thresholds were better than subjective thresholds at 4kHz. 4. Even in the sides with only wave I of the ABR, MLRs and/or SVRs were recorded in some cases. The ABR examination is of excellent clinical value in detecting functional abnormalities resulting from infiltration by pontine glioma. The dominant effect of pontine glioma causing hearing disturbance is on the brainstem, probably as a result of direct invasion. Physiologically, it can be surmised that impaired synchronization of firing is an important mechanism causing abnormalities of auditory evoked responses.
Using dipole tracing method, we investigated P2 component of slow vertex response. In 24 adults with normal hearing 18 subjects achieved reasonable results. The dipole located in the fairly rear of the midline, and directed to upper-front. The dipole was considered to exist single. Although the kind of stimuli, stimulating duration, stimulating frequency were varied no remarkable change in the location and direction of the dipole was recognized. The dipole was considered to be stable. We examined the dipole related to the digital-filtered waves. The location and direction of the dipole were stable unless we cut the bands from 2 to 6Hz. We considered that the dipole tracing method is reliable and can be used without failure of the essential qualities of P2 component, and can be useful in fature clinical examination.