In sudden deafness, the central nervous system is rarely involved. We report a case with a sudden sensorineural hearing loss caused by an infarction of the vertebral basilar system. A 62-year-old male presented with a sudden onset of hearing loss and tinnitus in the left ear and dizziness. Audiogram showed a left-sided moderate loss of hearing which is greater in the high frequencies. Spontaneous nystagmus toward the right side was found and caloric test showed CP on the left car. Neurological examination demonstrated staggering gate, diminution in left corneal reflex and facial sensation and disability of heel-knee test indicating disorder in the cetral nervous system. ABR showed mild elongation of wave III and V latencies. He was urgently subjected to MRI, showing an infarction localized in the pons and the cerebellar peduncle. The present case indicates that neurootological examinations should be performed in initial examinations of sudden deafness patients not to overlook any retrocochlear lesions.
We evaluated a complete in the canal hearing aid (CIC) in 8 patients with moderate hearing loss. Speech discrimination test, pure tone audiometry and subjective assessment were performed in all patients. Advantages of the hearing aid were almost undiscerning, no acoustic fead back and no autophony due to occulsion effect. The hearing aid was suitable for the patients whose pure tone threshold is within 60dB and whose external ear is not narrow. Cooperation of otolaryngologists and hearing aid dealers was essential to make this type of hearing aid.
It is very important but difficult to estimate subjectively the characteristics of tinnitus for the appropriate treatment because loudness or pitch level of tinnitus has objective characteristics. The standardized tinnitus test promoted by Tinnitus Study Group in 1993 presented 16 onomatopoias, their objective expression of tinnitus, pitch match test, loudness balance test and masking test corresponding frequency areas of pure tones or band noise of pure tone audiometer as an indicator to evaluate the characteristics of tinnitus. The purpose of this study was to investigate the clinical efficacy of the standardized test 1993 to the patients with various types of tinnitus. Subjects were 107 patients with tinnitus and the classification was performed according to the hearing type. Results obtained were as follows: 1) The standardization of the estimation method of tinnitus was sufficiently performed with this test. 2) In not only same institution but also other institution, the information about the patient with tinnitus was able to communicate about the subjective and objective symptoms. 3) If the classification according to the hearing type was performed at first, it was supposed to promote a better mutual understanding between patient and doctor.
The cochlear microphonic (CM) is an AC receptor potential that is derived from the cochlea. Recently a new component of CM that emerges at the threshold level and has longer latency than the conventional CM has been reported. It is tentatively called as a “delayed CM”. To investigate the origin of the delayed CM, a mathematical model of the cochlea was constructed and simulation of the phenomenon was done using a computer. The result of the simulation suggested that the delayed CM had most probably the same origin as evoked otoacoustic emissions (EOAEs). Consequently the delayed CM seemed to be clinically useful phenomenon related to the most delicate function of the cochlea at the threshold level in the same way as EOAEs.
Masking performance with three types of broad band noise, white noise, speech noise, and weighted noise, was measured for 67-S speech audiometric test lists which comprise numeral and monosyllable lists. Twenty otologically normal subjects for each noise participated in the study. Rounded reference sound pressure levels corresponding to 0dB of the effective masking level for the numeral list, were measured to be 23dB for speech noise, 30dB for white noise, and 35dB for weighted noise. For the monosyllable list, the levels at which 95% of the list were masked out, were 5 to 10dB higher than the above effective masking levels. Inter-subject and inter-item variations of maskability for the monosyllable list were somewhat larger in white noise than in the other two noises. Masking performance showed a marked difference in recognition thresholds of monosyllables containing fricative consonants between white noise and speech noise, corresponding to the difference in the high frequency spectrum of the two noises. Considering the above results, speech noise was confirmed to be preferable for masking 67-S speech audiometric test list.
The questionnaires sent to each family before the auditory screening for three-year-old children were filled out by all parents. Auditory tests using a whispering voice test and a finger friction test were administered by 96% of the parents at home. The auditory tests were effective in detecting bilateral moderate hearing-impaired children. While on the other hand, the questionnaire showed poor test sensitivity. However the implementation of this questionnaire is still necessary for hearing-impaired children with language or mental retardation. It is recommended that the auditory tests become standardized by using videotapes that show how to perform the tests properly.
Objective: The main objective of this study was to evaluate differences in performance associated with changing assignment of frequency bands to electrodes of cochlear implant. Design: Seven subjects with cochlear implant identified recorded vowels, consonant and sentences with changing seven frequency allocations. Evaluation was conducted immediately after changing frequency allocation. Results: 1) Assignment to the upper frequency bands between 4500 and 6700Hz was found to be most suitable for speech identification. 2) Assignments to frequencies above 9000Hz was not effective for improvements. 3) Consonant's performance was not enhanced with any frequency boundaries. Conclusions: 1) Considering of features in cochlear implants, the range of frequency allocation should not be applied to assign for speech frequency range. 2) It would be more effective for programing to decrease frequency bands above 6700Hz and to narrow frequency range of assignments to an electrode. 3) Increase of stimulus speed would make more improvement of consonant performance.
As middle ear diseases affect the vibration mode of the tympanic membrane, it is necessary for a correct diagnosis to measure the tympanic membrane vibration precisely. Although some techniques for the measurement of the tympanic membrane vibration has already been developed, they need high SPL for measurement, and the phase information is not obtainable by those techniques. Therefore, in this study, using the time-averaged electronic speckle pattern interferometry and sinusoidal phase modulation technique, an attempt is made to develop a system for measuring a small vibration sensitively. Then, the vibratory responses of guinea pigs' tympanic membranes are measured by this system. The results of this study indicate that the vibration amplitude is detectable in nanometer order even when the stimulus level is small, e. g. 70dB SPL and phase information is also obtainable. Consequently, the system developed in this study has a potential for clinical application.
As well as pure tone audiometry, highfrequency audiometry has been conducted for early detection of hearing loss caused by cisplatin administration. The high-frequency audiometry was conducted at range of 2 to 16kHz in 25 ears of 14 patients with gynecologic cancer, before and after the administration of Cisplatin. In seven ears, over 20dB increase of hearing level were detected by high-frequency audiometry. On the other hand, by pure tone audiometry hearing loss was found in only one ear of them after high-frequency audiometry was performed. High-frequency audiometry disclosed hearing loss in the patients at the time when 140 to 560mg/m2 of cisplatin administration was completed. Although the patients in this study received a high-does of Cisplatin administration, pure tone audiometry failed to detect their hearing losses. We proposed clinical application of the high-frequency audiometry for early detection of cisplatin ototoxicity.
Pinealoma occasionally causes midbrain deafness. We had evaluated two cases of pinealoma. Case 1 suffered from difficulty of speech perception after the removal of the tumor, and Case 2 developed tinnitus after administration of cisplatine. Audiological examinations disclosed normal pure tone thresholds only in Case 1, and normal ABRs and normal ability of detecting sound localization in both cases. Low speech discrimination score was noted in Case 1. Case 2 showed a slight high tone sensorinural hearing loss, while the speech discrimination score was normal. In Case 1, MRI (T2) revealed high signal level at the bilateral cortices of the inferior colloculi. Brain MRI of Case 2 showed no abnormality. It has been postulated that the central nucleus of the inferior colliculus is passing a pure tone to the upper auditory pathway, and concerning to sound localization and generating the ABRs wave IV and V. However, the function of cortex of inferior colliculus is not clear. From the audiological findings and MRI, we would suggest that the cortex of the inferior colliculus plays the important role in speech discrimination.
Twenty five children with profound hearing impairment underwent telephon-communication training from 1992 or 1997. Twenty of 25 children were enable to establish telephon-communication, and the training results were evaluated in regard to the following fuctors; 1) hearing level, 2) age of start, 3) duration of training, 4) educational environment. The results were as follows: 1) The children with hearing level under 100dBHL were more effectively trained than those with over 100dBHL. Children who discontinued training were found in both groups. 2) All cases who discontinued the training started it after the upper grades in an elementary school. 3) It was suggested that their mother's attitude and the patient's desire were affecting the results of training.
Although objective audiometry as ABR is now widely used for early detection of hearing impairment in children, various methods of subjective audiometry are still indispensable to diagnose the nature and degree of hearing loss. To investigate the applicable ages of different audiological examinations for children, we reviewed the results of 817 children who underwent audiological tests in Kanariya Gakuen (Auditory Center for Hearing Impaired Children in Okayama). Combinations of various procedures and number of each test required for determination of the hearing level in a child were analyzed. The different indications between the children with and without developmental retardation were also reported. 1) In the group without developmental retardation, behavioral observation audiometry (BOA), conditioned orientation reflex audiometry (COR), peep show test with a loudspeaker, peep show test with headphone, and play audiometry with Barr method (PA) were most applicable, respectively, to ages 0-1: 11 years old, ages 1:0-2:5, ages 2:0-3:5, ages 3:0-4:5, and ages 3:6-5:5. In retarded group, the age suitable for each procedure was generally delayed and the length of each period uaried widely. 2) ABR, BOA, peep show test with loudspeaker, COR, peep show test with headphone, PA and standard audiometry were used respectively in decreasing frequency. Audiometry with headphone was more frequently used in the children without developmental delay than those with delay and was not able to be used for the retarded children except for peep show test with headphone. 3) The combination of ABR and sound field audiometry was best employed for the diagnosis of hearing level of the children with or without developmental retardation, while a single procedure was more frequently adequate for the children without developmental retardation.
Tinnitus associated with intracranial lesions has rarely been reported. This report describes a case of pineal tumor, suffering from left-sided tinnitus and subjective hearing loss. An audiogram revealed symmetrical mild sensorineural hearing loss in both ears. In the left ear, auditory brainstem response (ABR) showed an increased I-III inter-peak latency, and the threshold of 80Hz amplitude modulation following response (80Hz AMFR) was obviously higher than that in the right ear. These findings implied disorder in the auditory pathway of the brainstem. Gamma knife radiosurgery was performed as treatment for the pineal tumor. MR images taken prior to gamma knife treatment showed a compression of the pineal tumor against the brainstem. However, this compression was reduced after the gamma knife treatment. One month after the irradiation, the patient was relieved of tinnitus and hearing loss. The threshold of 80Hz AMFR in the left ear improved remarkably, while the abnormality on the ABR was not changed. Since the generator of the 80Hz AMFR was reported to be the inferior colliculus, these findings suggested that the cause of tinnitus in this patient was the inferior colliculus which was damaged by the tumor compression.