Molecular diagnosis has become increasingly important for more accurate diagnosis, prediction of severity of future hearing loss, estimation of associated abnormalities, selection of appropriate habilitation options, prevention of hearing loss, and better genetic counseling. Despite advances in the discovery of deafness genes, clinical application still entails difficulties because of the genetic heterogeneity of deafness. Our series of mutation screenings has revealed that mutations in GJB2, SLC26A4 and CDH23, and the 1555A>G mutation in the mitochondrial 12S rRNA, are major causes of hearing loss in Japanese patients. Interestingly, the spectrums of GJB2, SLC26A4 and CDH23 mutations found in the Japanese population were quite different from those reported in populations with European ancestry. Our simultaneous screening of multiple deafness mutations was based on the mutation spectrum in the corresponding population. The multicenter trial for this assay using an Invader panel revealed that approximately 40% of subjects with congenital hearing loss could be diagnosed. This assay will enable us to detect deafness mutations in an efficient and practical manner in the clinical setting.
The Research group on idiopathic sudden deafness of the Japanese Ministry of Health and Welfare (RGISD) established a grading system of sudden deafness, in which patients with sudden deafness are classified into 4 groups according to the average of initial hearing level. We evaluated the clinical features of 74 cases of sudden deafness with an average hearing level of less than 40 dB (grade1). As hearing loss in grade1 cases was not so profound, various diagnoses, for example, acute hearing loss, sudden deafness and low-tone deafness were made. In the evaluation system of hearing recovery established by the RGISD, recovery is classified into 4 groups: complete recovery, marked recovery, slight recovery and no change. Marked recovery is defined as recovery by more than 30dB of the average of hearing level. There were no cases of marked recovery in our grade 1 group. This is considered to be attributable to the marked recovery cases in grade 1 possibly overlapping with the complete recovery ones. It is necessary to establish a grading system and a recovery evaluation system for sudden deafness according to the initial hearing level.
Until recently, grants for hearing aids by the welfare section of the Tochigi prefectural government were not offered to children with moderate hearing impairment, because those children did not meet the necessary requirements to obtain a certificate of physically disability. At our outpatient clinic, we have encountered many cases where the parents had difficulty in buying hearing aids. Since the children were in obvious need of hearing aids, we requested that the city and prefectural welfare office provide grants for these children. As a result, in accordance with guidelines and requirements similar to those laid out in the Services And Supports For People With Disabilities Act, both the city and prefecture began issuing grants in 2007. Thus far, 13 children out of 14 candidates (between March 2007 and May 2009) have been able to receive financial aid for buying hearing aids. However, some issues remain in the issuing of grants for hearing aids for moderately hearing-impaired children. First, the grants system is being run independently on a trial basis in Tochigi prefecture only, therefore, it is dependent on the limits of the city's budget, leaving its future uncertain. It is our hope that we can maintain active dialogue with the independent body overseeing the trials, and that this measure enacted by Tochigi will ultimately be adopted at the national level in the near future.
It is well known that fraudulent applications are sometimes made for workers' compensation disability benefits, and often involve exaggerated claims of hearing loss. In addition to conventional methods, our department used Auditory Steady-State Response (ASSR) testing to evaluate the hearing thresholds in 14 workers who filed for benefits due to occupational noise-induced hearing loss during the four-year period from January 2006 to December 2009. Seven of the 14 cases (50%) were found to be falsely exaggerating the degree of their hearing loss. Of those seven, the conventional assessment method also suggested exaggeration of hearing loss in six of the 7 cases, in line with the results of the ASSR. In the past, we have experienced difficulty in accurately confirming the hearing loss levels related to workers' compensation benefit claims, however, use of ASSR is expected to make more precise evaluation possible.
We evaluated the transition patterns from written language and manual to the auditory modality and the related factors in 11 hearing-impaired children with a cochlear implant placed between 1 and 5 years of age, trained by the Kanazawa Method. Four types of transition patterns were observed by the age of 6 years: (1) written language acquisition was preceded by other language modalities; (2) oral language acquisition was preceded by other modalities; (3) manual was preceded by other modality, but transfer to oral language was not achieved; (4) written language preceded by other modality, but transfer to oral language was not achieved. The period until acquisition of transition to oral language took a mean of 12 months. We found transfer from manual to the auditory modality in 7 of the subjects by the age of 6. Moreover, we found that these subjects could have accomplished the transition to auditory-oral language to learn about 350 written/manual comprehension words if they had received the cochlear implant by the age of about 2, about 700 words if they had received the implant by the age of 3 years, and about 1000 words if they had received the implant by the age of 3 years 5 months.
We investigated the effectiveness of cochlear implantation (CI) by using a self-rated quality of life questionnaire and a speech perception test. Thirty-two adults with postlingual deafness who had received a CI more than 1 year previously were enrolled. The disease-specific QOL measure, Nijmegen Cochlear Implant Questionnaire (NCIQ), was translated into Japanese. The pre-and postoperative scores on the NCIQ were compared. The satisfaction level with the CI was also evaluated after the surgery. In the NCIQ, the largest postoperative improvement was found in the score for basic sound perception subdomain, followed by that in those for advanced sound perception, social interaction, activity, and self-esteem. A strong correlation was found between the overall QOL score and the phoneme recognition performance. Personal attributes did not influence the QOL score. The satisfaction level with the CI was affected by the speech perception score, social interaction and the activity subdomains of QOL. To study the effect of CI, comprehensive assessment, including the results of objective evaluation of speech perception and self-rated QOL, was important. NCIQ was found to be useful to evaluate the subjective outcome and QOL change in adult users of CI.
We analyzed 168 patients (168 ears) who were diagnosed as having grade 3 or grade 4 idiopathic sensorineural hearing loss. All patients were hospitalized between 2002 and 2009 at our hospital. Ninety-five patients had grade 3 initial hearing level loss, and seventy-three patients had grade 4 initial hearing level loss. The patients were divided into three groups according to the treatment method employed. The first group was treated with 60mg prednisolone (group PSL 60), the second group with 8∼12mg betamethasone (group BT), and the third group with 120mg prednisolone (group PSL120). Each group was treated with a tapering dose of steroids over a week and prostaglandin E1 for 5 to 10 days. The effect of the treatment was evaluated by ascertaining the average of five frequencies from 250 Hz to 4 kHz in the final audiogram. Cure was obtained in 19.4% of all patients. The percentage of cured patients among those presenting with a grade 3 initial hearing level loss was 27.7%, and that of patients presenting with grade 4 initial hearing level loss was 8.5%, with a significant difference between the two groups. Multiple logistic regression analysis revealed no significant difference in the effect of treatment between the PSL120 and PSL 60 groups.