We compared 5 children wearing a cochlear implant plus hearing aid (CI+HA) with 5 children wearing a cochlear implant alone (CI) in terms of the hearing acuity of the non-implanted ear, the hearing threshold, and the speech intelligibility. The following differences were observed between the CI+HA group and the CI group. It was found that in the CI+HA group, the average pure-tone hearing level of the non-implanted ear was about 90dBHL; therefore, the average speech intelligibility of the CI+HA group was better than that of the CI group. It was also found that the children in the CI+HA group realized that their hearing improved with the wearing of the cochlear implant and hearing aid, whereas the children in the CI group were unwilling to wear a hearing aid in the non-implanted ear because they did not realize the effectiveness of a hearing aid. Therefore, it is important to evaluate the hearing acuity of the non-implanted ear and the binaural hearing effectiveness with the wearing of a cochlear implant and hearing aid. Furthermore, we should consider the necessity of a hearing aid for the non-implanted ear through observation of the auditory responses in children, and perform counseling for the children.
Speech perception is known to deteriorate in subjects with sensorineural hearing impairment, due to the increased spectral and temporal masking effects in the peripheral auditory system. As a hearing enhancement technique to deal with this issue, dichotic hearing appears promising. This technique splits speech signals into two complementary parts and presents them dichotically. In the present study, in order to verify the efficacy of this method for dealing with the masking of consonants by the preceding vowels, a listening test was conducted in 27 subjects with mild to moderate high-frequency sensorineural impairment. Forty VCV syllables were divided into two bands taking into account the formant frequency of the preceding vowels. The changes in clarity were analyzed by selecting the dividing frequency and by interchanging the conditions for presenting the high- and low-frequency components. The following results were obtained: 1) irrespective of the dividing frequency, the dichotic listening enhancement effects were observed. However, there were differences in the degree of improvement in the proportion of correct answers among the consonants; 2) intelligibility of the preceding vowels, /u/, /i/ and /e/, improved; 3) the intelligibility could be further improved when a better combination was chosen based on the sum of the hearing acuity for the low-frequency band presenting the low-frequency components and the hearing acuity for the high-frequency band presenting the high-frequency components rather than the sum of the hearing acuity for their complementary bands or vice versa.
Auditory localization and the cocktail party effect are examples of the advantages of dichotic hearing. Bilateral cochlear implants have already begun to be used in many countries, and been reported to enable good performances of the patients in speech recognition tasks. In Japan, cochlear implant users generally use a hearing aid for the opposite ear, because the benefits of use of a hearing aid for contralateral ears have been reported by many studies from other countries. We examined the benefits of use of a hearing aid for the contralateral ear in Japanese patients under silent and noisy conditions. Under the silent condition, there was no significant difference in the hearing ability between subjects with unilateral cochlear implants and those with unilateral cochlear implants with a hearing aid for the contralateral ear. According to further analyses taking into consideration other components, such as the period of wearing, hearing ability of the contralateral ear and that of the cochlear implant, no benefits were observed. Under the noisy condition also, no significant difference in the hearing ability was observed between the two groups. Some causes are suggested for the absence of the benefits of contralateral hearing aids in the present study: stringent criteria for the fitting of cochlear implants; the small number of cases in the study; the phonemic features of Japanese. To improve the hearing ability in cochlear implant users, we suggest aggressive use of the contralateral ears, using bilateral cochlear implants if necessary.
We evaluated the binaural advantage in users of bilateral hearing aids at our clinic. From June 2001 to June 2008, 924 patients visiting our clinic wore hearing aids. Among them, 286 (31%) wore bilateral hearing aids, while the remaining 638 (69%) patients were unilateral hearing aid users. The percentage of individuals wearing bilateral hearing aids was higher among children than among the elderly. In our evaluation of the speech discrimination score (SDS), subjects with moderate hearing loss (51-70dB), severe hearing loss (71-90dB) and profound hearing loss (over 91dB) wearing bilateral hearing aids showed better performance in terms of the rate of recovery than those wearing unilateral hearing aids. In terms of the SDS under the noise (S/N ratio=80/70, +10dB), a better recovery rate (35.2%) was noted in the severe hearing loss group (71-90dB). The difference in the SDS (70dBSPL) between the right-side speaker (SP) and left side SP was smaller in the bilateral hearing aid users (8%) than in the unilateral hearing aid users (13.8%). For subjects with moderate to severe hearing loss, we consider that bilateral hearing aids may offer greater binaural advantage.
We investigated the clinical differences between a group of IBSH patients with rapidly progressive hearing loss and a group of these patients with slowly progressive hearing loss. A total of 107 patients of IBSH followed up at the hearing clinic in our department for more than 10 years were enrolled. Of the 107 patients, 51 were classified into the rapidly progressive deafness group and 56 into the slowly progressive group. In regard to the age distribution, a high incidence in the 40-49 years age group was seen in the rapidly progressive deafness group and a high incidence in the 0-9 years and over 40 years age groups was found in the slowly progressive deafness group. The number of patients with vertigo in the rapidly progressive deafness group was 27 (52%), and that in the slowly progressive deafness group was 17 (30%). Next, we investigated 19 patients of the rapidly progressive deafness group who presented with recurrent episodes of vertigo. In regard to the type of audiograms at the first visit, 28 ears (74%) showed a high-tone hearing loss pattern. When the cases were classified according to the frequency area of rapid deterioration in the audiograms, deterioration in the all-frequencies (250Hz-8kHz) area was found to be the most frequent. We considered that in many cases in this study, recurrent vertigo were needed to be differentiated from Meniere's disease.
The purpose of this retrospective study was to evaluate the clinical features of solitary and familial cases of idiopathic bilateral sensorineural hearing loss (IBSH), after exclusion of patients suspected to have hereditary hearing loss . We enrolled 31 patients (definite group) who were diagnosed to have IBSH by pure-tone audiometry and had been followed up for more than 3 years, and 159 patients (suspected group) who were suspected to have IBSH based on subjective symptoms. No significant differences were found in relation to the gender, age of onset, ratio of symmetric configuration in audiometry, or results of pure-tone average between the solitary and familial cases. The percentage of patients showing high-frequency or flat hearing loss in audiometric configurations was significantly higher in the familial group than in the solitary group . The hearing loss tended to progress bilaterally while keeping the same audiometric configuration in the familial cases. In the genetic analysis of GJB2, mitochondrial DNA 1555A>G and 3243A>G mutations, both mitochondrial mutations, were detected only in the familial cases. The characteristics of conventional IBSH may reflect those of the familial cases. The clinical features of solitary cases of IBSH should be evaluated to clearly elucidate the nature of IBSH.
The epidemiology and the clinical features were examined in 107 patients with idiopathic bilateral sensorineural hearing loss who could be followed up for ten years or more. The peak age of incidence existed a past neither report nor change and was in one's forties with less than ten years old. These cases were divided into the adult-onset from and the young appearance of disease type. As for the young appearance of disease type, there were a lot of people who have family medical histories of hard hearing, and were advanced auditory disorder. There was a case who repeated dizziness and was difficult to discriminate with Meniere's disease. Grade1 and Grade2 accounted for 95% at the first medical examination, but finally examination, the half was Grade3 or Grade4. So, it was a result of showing that this disease social influence was large.
Enlargement of the vestibular aqueduct (EVA) is an inner ear malformation associated with both non-syndromic and syndromic forms of sensorinural hearing loss and dizziness, including Pendred's syndrome. Mutation of SLC26A4 has been found in many patients with EVA, although the mechanism by which this mutation gives rise to the malformation is still unclear. In this study, we subclassified fifteen patients with bilateral EVA into an ‘enlarged’ or ‘borderline’ group based on axial CT imaging, and examined the correlation of the SLC26A4 genotype with the clinical features. Two mutant SLC26A4 alleles were found in 89% of the ‘enlarged’ cases and 33% of the ‘borderline’ cases. Mondini's dysplasia was detected in 67% of the ‘enlarged’ cases and 33% of the ‘borderline’ cases. Episodes of dizziness occurred in 33% of the ‘enlarged’ cases and 17% of the ‘borderline’ cases, and goiter was present in 22% of the ‘enlarged’ cases and 17% of the ‘borderline’ cases. Serum thyroglobulin levels were elevated in 50% of patients with either mutant allele. Mutational analysis of SLC26A4 may facilitate the diagnosis of Pendred's syndrome and non-syndromic recessive deafness in patients with EVA.