With the discovery of streptomycin (SM), the mortality of pulmonary tuberculosis declined markedly in Japan. The incidence of hearing loss, however, as an important adverse effect of the drug, has been increasing steadily year by year. Hearing loss induced by SM is sometimes familial, when it is referred to as “familial SM deafness”. Analysis of the pedigrees of patients with familial SM hearing loss has suggested that familial SM deafness may be related to a genetic predisposition to hearing loss of cochlear origin. It has been suggested that familial SM hearing loss may be inherited via a 1555 mutation of the mitochondria DNA. Two patients with pedigrees are presented and discussed.
Recently, it has been recognized that the number of multiply handicapped children, especially those with pervasive developmental disorders, who are also hard of hearing, has been gradually increasing. To estimate the hearing threshold, in principle, behavioral observation audiometry (BOA) and/or conditioned orientation response audiometry (COR) with auditory brain responses (ABR) can also be used for multiply handicapped children as for hearing-impaired children with normal development. Periodic assessment of the hearing threshold, however, should be performed because there are cases in which the ABR threshold and the COR minimum reaction level improve with development. The auditory steady-state response (ASSR) can be expected to complement weak points of the COR and ABR, because ASSR thresholds provide objective and reliable estimations of frequency-specific hearing levels in both ears. It would seem that the primary goal of the fitting of hearing aids and of cochlear implants, particularly for multiply handicapped children, has changed nowadays. That is, interventions are thought to be successful even if the children cannot develop language skills, if they become capable of utilizing other communication media. Therefore, the purpose and efficacy of cochlear implants, which are more or less invasive, must be adequately explained to parents so as to avoid unrealistic expectations.
Developmental delay should be included in the differential diagnosis of speech delay as well as hearing loss. Accurate hearing evaluations are difficult in children with disabilities, and reliable assessments of the effectiveness of hearing aids are also difficult. The purpose of this study was to retrospectively review the data of 61 children with hearing impairment referred to our clinic from Niigata Prefecture Hamagumi Rehabilitation Center for Children with Disabilities between 1999 and 2008. Four cases were diagnosed as having severe hearing loss (>70dBHL) and eight as having moderately severe hearing loss (40-70dBHL). Hearing impairment was more likely to be diagnosed in children with mental retardation than in children with pervasive developmental disorder. We recommended hearing aids to the 12 children with hearing impairment. Seven cases who were always could be fitted with hearing aids showed improvement in their auditory behaviors and development. On the other hand, some cases with hearing impairment could not be fitted with hearing aids, and some could not be followed up at our clinic. It is necessary for medical professionals to attempt to improve the parents' acceptance of disabilities, including hearing impairment.
We conducted this study to evaluate the final hearing levels in sudden deafness. Patients with sudden deafness treated at the Kitasato University Hospital between 1995 and 2004 were analyzed. The treatment effects were evaluated and compared with the results of the National Epidemiological Survey of the same patient group in Japan. The final hearing status of both the involved and uninvolved ears after the treatment were also analyzed. Complete recovery of hearing was noted in 44.1%, and persistent hearing loss in the involved ear was noted in 55.9% of the 646 patients; hearing loss of the uninvolved ear was also noted in 21.7% of the patients. 2.2% of the patients showed bilateral hearing loss by more than 40dB. After 1973, the hearing recovery rate in patients with deafness of sudden onset in Japan has gradually improved. However, even now, incomplete hearing recovery is observed in over 50% of patients with sudden deafness. In the 2001 National Epidemiological Survey, an estimated 35000 patients developed sudden deafness each year, of which 20000 are estimated to fall in the category of hearing handicapped. Sudden deafness predominantly involves subjects in their 50's; the patients can generally be expected to live for another 30 years or more years, which suggests that a significant number will suffer additional hearing loss.
A developmental checklist of auditory functions (Tanaka and Shindo) after newborn hearing screening was examined. The checklist was made from the developmental growth chart of a normal hearing group. The development of the unilateral hearing impairment group was within the range of the mean ±1SD of the normal growth chart. Development in the mild hearing impairment group was within the range of the mean ±2SD of the normal growth chart. Development in the severe and profound bilateral hearing impairment cases was outside the range of the mean ±2SD of the normal growth chart. Development in moderately severe hearing impairment cases was outside the range of the normal growth chart, whereas that in cases of psychomotor retardation associated with moderately severe hearing impairment was within the range of the mean ±2SD of the normal growth chart.
Tinnitus retraining therapy (TRT), which is adaptation therapy for tinnitus based on the neurophysiological model proposed by Jastreboff, consists of directive counseling and acoustic therapy with a sound generator (SG). The recommended treatment for patients with tinnitus associated with moderate to severe hearing loss is to provide TRT and to introduce noise from the outside to assist the patients in adapting to tinnitus, thus reducing the annoying buzzing sensation in the ear. It was considered that TRT with an SG-equipped hearing aid, which provides not only noise from the outside through the hearing aid, but also therapeutic sounds generated by the SG, may be more effective in improving tinnitus symptoms. Of 183 patients (102 males and 81 females) who presented at our outpatient clinic for the treatment of tinnitus and hearing loss during the five-year period from April 2004 to March 2009 and received TRT, two patients improvement in tinnitus after TRT with an SG-equipped hearing aid.