A 40-year-old woman showed cortical deafness following bilateral temporal lobe infarct. The lesions were demonstrated by the radiological and neurophysiological investigation and the peripheral and brainstem auditory pathways were confirmed intact. Results of auditory examinations were as follows; 1. Pure tone audiometry revealed bilateral mild hearing loss but the thresholds were unstable. 2. Bekesy audiometry was extremely unstable but it did not show any temporary threshold shift or recruitment prenomenon. 3. Speech audiometry revealed poor discrimination rate. 4. Results of acoustic reflex test showed normal AR function. 5. Auditory brainstem responses obtained by click sounds showed normal pattern. 6. Middle latency responses obtained from the right ear stimulation was normal but Nb latency of left MLR was prolonged. In conclusion, the auditory dysfunction of this case was thought to be produced from bilateral temporal lobe infarction and there may be functional difference between pure tone hearing and speech sound processing.
A 52-year-old man with central auditory disturbance due to bilateral putamen hemorrhage was presentel. Pure tone audiometry showed no hearing loss, but speech audiometry revealed that he was unable to discriminate monosyllabic words. Neuropsychiatry tests revealed that he comprehended written language and spoken polysyllabic words or sentences, therefore, aphasia was denied. We observed his perceptive ability of environmental sounds was considerably recovered for more than 2 years after putamen hemorrhage. We thought his auditory disturbance should be considered “word deafness”, in particular, “word-sound deafness”. Auditory brainstem response showed no peripheral or brainstem damage. Soon after brain hemorrhage, middle latency response showed no response, but almost normal configurations appeared in proportion to improvement of his perceptive ability of environmental sounds. The lesion of bilateral auditory radiation was detected by MRI, therefore it was conclusioned that word-sound deafness of this patient was due to partial damage of bilateral auditory radiation.
The three-steps auditory screening system for 6-month-old infants has been performed. The questionaire, that was used as the first step procedure, was distributed with the test paper for neuroblastoma at 3 or 4-month-old infants health examination. The parents answered the questionaire when their infant was 6 months old, and the questionaire was collected with the test paper of neuroblastoma. The second step procedure was behavioral audiometry, and third step procedure was conditioned orientation response and auditory brainstem response. This system has been performed in about 18, 000 infants, and 4 infants with bilateral sensor-ineural hearing loss were found. It was confirmed that this system is effective to find the infants with hearing loss, but it is difficult to find all of infants with hearing loss by this system. We failed to find 3 infants with bilateral sensorineural hearing loss. It is necessary to create the system to find the infants with moderate or profound hearing loss at 6-month-old health examination, and those with mild or moderate hearing loss at 1-year-6-month-old health examination in the future. The role of auditory screening at 3-year-old health examination is to find the infants with hearing loss that failed to find by that time.
Using dipole tracing method, we investigated N1 component of slow vertex response. In 24 adults with normal hearing, 78 waveform showed reasonable results. We classified the location of the dipoles into 5 patterns and examined the tendency where these dipoles existed. 96.2% of the dipoles existed in the midline or lateral portion. The dipole of N1 component mainly located in the lateral portion. Hewever, some results showed that the dipoles of N1 located in around the midline. We considered that the origins of N1 component are in three or more portions, and two of them exist in the bilateral auditory cortex.
The auditory and linguistic abilities of 4 children was examined after they received the multichannel cochlear implant. Three children were post lingual profound deafness resulting from meningitis and one was congenital profound deafness, ranging between 37 and 51 months of age. The mean hearing level at the first visit was 130dB or more in all children. Improvements in speech perception and vocabulary were found after postoperative rehabilitation in all children. Verbal imitation of 5 Japanese vowels was almost completely achieved 9 months after implantation in all children. Achievement of verbal imitation of consonants tended to be delayed in the congenital case and the acquired case with a longer deaf period, compared with another 2 children who underwent surgery after a short period of time since meningitis.
The dipole tracing method (DT method) is a technique which estimates the approximate generator of brain electrical activity three-dimensionally and noninvasively. We studied N2 component of the slow vertex response (SVR). Twenty adult healthy volunteers were employed for this study. Tone bursts (duration: 40msec, rise and decay: 10msec, 1kHz, 70dBHL) were used as stimuli. SVR was recorded with 21-leads and analyzed by DT method. The dipoles of N2 showed the tendency to locate in the frontal region of brain. But dipoles other than those found in the frontal region were varied in both position and direction. With the dipoles in the frontal region, the direction was irregular. So classifying them by type was difficult. The dipoles found in the frontal region were divided on the stimulation side. Variations of positions due to the difference of the stimulation side were not found. It is possible that there are too many dipoles to be expressed by the 2-dipole model. And one of them might possibly be in the frontal region. The latter half component of SVR is said to be susceptible to the different stages of sleep. How to record it steadily will be the subject of future study.
This study presents 20 selected patients with acute acoustic trauma (AAT) who visited us during the disease course, and followed up for a certain period of time. The patients were tested pure-tone audiogram (at 0.125, 0.25, 0.5, 1, 2, 4, and 8kHz) after the acoustic accident. All patients were men, with ages varying between 18 and 48 years. The patients who recovered rapidly after AAT were followed until the hearing threshold was normalized. The patients with remaining hearing loss were followed up for months. The initial audiogram after AAT demonstrated that the most affected frequency was 4kHz, followed by 8kHz and 2kHz. The hearing recovery after the acoustic accident showed the complete recovery of hearing in 5 patients (5 ears), partial improvement after the first post-accidental audiogram, but not complete recovery in 10 patients (13 ears) and unchanged hearing in 5 patients (6 ears). And the hearing recovery was poor at 4kHz, followed by 8kHz and 2kHz. These findings suggest that the audiometric follow-up at 4kHz is useful to predict the prognosis of AAT.
During 1990-1995, 329 infants in the neonatal intensive care unit (NICU) of Nara Medical University were screened by auditory brainstem response (ABR). Thirty-three infants out of 329 (10.0%) were judged to be abnormal because either or both ABR threshold was higher than 60dBnHL. Significant predictors of ABR abnormality in the high risk infants were (1) long-term respiratory care for longer than 10days, (2) brain damage due to hypoxia, (3) head and neck anomalies, (4) syndromes due to chromosome aberration or dysbolism, (5) persistent pulmonary hypertension of the newborn (PPHN), (6) non-bacterial infection during pregnancy and (7) very low birth weight, less than 1, 000g. Four infants developed bilateral profound hearing loss, although they had shown normal ABR at discharge from the NICU. Three of them had long-term respiratory care using high frequency oxygenation (HFO) and 2 of them also had PPHN. We propose a new time-saving protocol for the delayed hearing disturbance. The screening consisted of two tents as follows: 1) ABR-test to the infants who have above (1) to (7) neonatal predictors, with careful follow-up, 2) COR-test at age of 12 months to all the infants who discharged from the NICU.
Averaged Electrode Voltages (AEVs) data were collected in the bipolar+1 (BP+1) mode and the variable mode from 4 adult Nucleus cochlear implant patients. These four patients had a full insertion of the active electrode array. AEVs data were also obtained from a case whose electrodes had been in trouble, and another case who had an incomplete insertion of the electrode array into the middle turn because of the ossification of the basal turn of the cochlear. The AEVs data from the patients with well functioned implant were very stable, and almost had no change for six months. The AEVs data from the case with malfunction of the implant reflected the state of each electrode correctly and were very effective for re-programming. The AEVs data from the case with insertion of only 12 electrodes also responded the state of each electrode correctly and coincided with the sound feeling of the patient. We concluded that measuring AEVs is very stable and effective, and AEVs will be useful especially for children because this test is completely objective and produces no pain.
Fifteen children with mild or mild-moderate sensorineural hearing loss were assessed for the fitting of hearing aids. All of the subjects had not been wearing hearing aids until the time of their first consultation with us. We evaluated the development of their language and speech discrimination ability by analysis of the followings: (1) Clinical history, (2) Speech discrimination test results, (3) Misunderstanding of Japanese consonant sounds, and (4) language development assessed by the WISC-R test. The subjects who showed a deficiency in even one of these four items were fitted with hearing aids. As the result, hearing aids were fitted in 12 of the 15 children. With hearing aids fitted, the average speech discrimination score was 79.7% (1SD=±12.9) when 55dBSPL test sound was used. This was markedly better than the score of 48.5% (1SD=±21.4) obtained when they were not fitted with hearing aids. We concluded that hearing aids were effective for children with mild or mild-moderate sensorineural hearing loss.
The reliability of the clinical application of 80-Hz amplitude-modulation following response (80-Hz AMFR) was examined at different carrier frequencies, and the threshold pattern was compared between the pure-tone audiograms in 27 affected ears of 26 children with various patterns of audiogram. 80-Hz AMFR was also clinically examined as an objective audiometry in 2 young children with otitis media with effusion before and after the insertion of ventilation tube and in 2 children with psychogenic hearing loss. The threshold patterns of 80-Hz AMFR clearly followed the corresponding audiogram patterns in all types of hearing impairment. The thresholds of 80-Hz AMFR were improved after the insertion of ventilation tube and aggravated after remission of OME. In the cases of psychogenic hearing loss, evoked response audiometry, including 80-Hz AMFR and ABR evoked by clicks, revealed almost normal hearing. The measurement of 80-Hz AMFR thus appears to be accurate in hearing assessment and to have good frequency specificity in children during sleep.
We examined 251 children with sensorineural hearing loss (SNH) at Kyoto City juvenile welfare center from 1986 to 1995. The ages of children with severe SNH (>70dB) were 4 months to 5 years and 2 months old (average: 1 year and 6 months). 39% of all received hearing tests after 1 year and 6 months. Children with moderate SNH (40dB≤, <70dB) received test in 6 months to 16 years (average: 4 years and 5 months), and half of them after 3 years and 6 months. In the group of severe SNH, a child was delayed to be discovered and underwent medical treatment in spite of having risk factor for SNH. Auditory screening test for 1-year-6-month-old children at a health center is useful.
We developed an experimental “binaural supremental telephone communication system” at 1993 for patients with profound hearing impairment. After 1 year training with this system, 21 of 31 patients were evaluated. 1) The features of this system are: (1) Binaural hearing (2) External input terminal of hearing aids 2) 8 of 31 patients were using telephone, and 2 of them had over 100dB hearing level. 3) After training with the system, 16 of 21 patients obtained communication by telephone.