Audiology : official organ of the International Society of Audiology最新文献

Permanent childhood hearing impairment is a significant public health issue in the United Kingdom and elsewhere. It has effects on the hearing-impaired individual's linguistic, psychological, educational, and vocational development. Data on prevalence are an essential prerequisite for efficient service planning and development. This paper reports the first study to be undertaken in Cyprus to investigate the prevalence and the age at identification of permanent bilateral (congenital or acquired/late-onset) childhood hearing impairment of 50 dB HL or greater. The study was based upon a case ascertainment approach for children born between 1979 and 1996. Two methods were employed for the data collection: interrogation of case records and questionnaires administered to parents. The results for those years in which most cases are likely to have been identified showed an estimated prevalence of 1.19/1,000 live births (congenital) and 0.40/1,000 live births (acquired/late onset), with a mean identification age of 44.0 months for congenital cases. These findings are discussed with reference to the service development needs in Cyprus.

The Bangkok Otological Center (ISA-HI-lFOS/World Health Organization Collaborating Center) carried out a series of prevalence studies of hearing impairment throughout Thailand. This report includes background information for Thailand and its medical personnel and the results of five studies in different regions from 1988 to the present. This report emphasises sensorineural hearing loss (SNHL). Study I in three Thai provinces showed SNHL at 18.6 per cent. These results were considered abnormally high due to a number of extraneous reasons. Study 2 was conducted in 17 provinces in 5 regions and in Bangkok. Results showed that 8.3 per cent of those tested had a SNHL. Study 3, The Crown Prince Project, involved 21 Crown Prince Hospitals and showed an overall SNHL of 4.6 per cent. Study 4 was the Thai-Swedish project, where SNHL was reported at 22.7 per cent. Study 5 involved school children aged 6 to 15 in both rural Thailand and Bangkok. Results showed SNHL in Bangkok children at 3.5 per cent compared to 3.6 per cent in the rural children. After a careful review of the various studies, the overall results have been interpreted to suggest that the prevalence of SNHL in Thailand is between 3.5 and 5 per cent.

This paper describes a retrospective study of permanent childhood hearing impairment (PCHI) > or = 40 dB HL in the better ear in children born between 1985 and 1990 and resident in Estonia. The prevalence rate of all permanent hearing impairment for the birth cohort 1985-1990 was 172 (95 per cent (CI 151-194) per 100,000 live births and that of congenital impairment was 152 (CI 134-170) per 100,000. For the congenitally-impaired children, 11 per cent had stayed in a neonatal intensive care unit for 48 hours or more, 2 per cent had a craniofacial abnormality, and 31 per cent had a family history of PCHI. As for aetiology, hereditary causes were stated most frequently in 36 per cent of all of the cases of PCHI. The aetiology remained unknown in 34 per cent of cases. Additional disabilities were found in 23 per cent of all cases. Specific syndromes were recognized in 2 per cent of hereditary cases. The mean age at the confirmation of hearing impairment was 46.4 months and at hearing aid fitting 57.0 months. The results were compared with other European studies, particularly the Trent study.

A questionnaire to determine the status of cochlear implant programs was sent to 11 countries in Latin America and Spain. General data were collected based on the population of each country (1996), estimate of population with hearing disorders based on the 10 per cent figure of the World Health Organization. number of people with congenital or acquired sensorineural hearing loss, and candidates for implantation (children and adults). The survey reports the number of people from each country who have been implanted, the cost with respect to per capita annual income (PCAI), and how many people with respect to PCAI would cover the cost of a country's entire program. Also reported are the number who were implanted pre- or post-lingually and the estimate of future new candidates for implantation per year. In conclusion, the paper discusses the ethical and socio-economic issues for cochlear implantation in so-called third world developing countries.

The aim of this paper is to provide an overview of the field of clinical and rehabilitative audiology for children and adults in Brazil, while simultaneously offering some data and results from several different research studies within the country. The theme will address seven main topics: (1) the status of services and assistance for the hearing impaired; (2) the results of five different institutional research studies showing the main causes of hearing impairment in children in the city of Săo Paulo; (3) a review of subjective and objective methods for early diagnosis and audiological habilitation of children, including parent counseling, hearing aids, and cochlear implants; (4) a discussion of hearing conservation in different settings; (5) a brief consideration of audiological rehabilitation for hearing-impaired elderly adults in the country; (6) the main results of the First and Second Brazilian National Campaigns of Deafness Prevention; and (7) conclusions.

The objective of the study was to investigate childhood hearing impairment in a population-based sample from a genetic perspective. Participants included 82 families with hearing-impaired children (aged 4-13) previously ascertained in the Trent Health Region. A questionnaire was mailed to all families, followed by a home visit and Connexin-26 35delG mutation screen. The Connexin-26 35delG mutation was identified in seven families (approximately 10 per cent of non-syndromal hearing impairment). Children of these families were significantly more likely than children with other modes of inheritance to have a profound hearing loss with a flat audiogram profile. The families of children with a significant admission to a neonatal intensive care unit were significantly less likely to have had genetic counselling. Eight families visited were found to have features suggestive of a genetic syndrome that had not been previously assigned a specific diagnosis. The study concluded that hearing-impaired children should be investigated systematically according to an agreed-upon protocol, which should include Connexin-26 35delG mutation analysis at least for those with severe-to-profound hearing loss.

Various anecdotal reports have been presented about attitudes to hearing loss and deafness in less developed countries but few studies have addressed this matter systematically. In the present study, we have applied a standardised questionnaire to 357 teachers from as uniform a sample as possible within 20 countries in Africa, Latin America, and Asia and compared the results with those obtained from 107 teachers in Western Europe. The questions tapped into their responses toward developing hearing loss themselves, hearing loss in children they encountered. and which group of children with disabilities they would prefer to teach. The geographical origins of the teachers influenced all measures except their view of the contribution that deaf children could make to society. This was influenced solely by the age of the responding teacher.

Conventional pure-tone thresholds were collected as determined at ages between 4 and 8 years from a group of 163 infants, tested by auditory brainstem response (ABR) in the age range between 1 and 3 years old for objective hearing assessment. The subjects suffered from a variety of degrees and types of sensorineural hearing impairment. The prognostic value of the ABR peak V thresholds in response to 0.1 ms clicks with respect to the behavioural thresholds at octave frequencies from 125 to 8,000 Hz obtained later is evaluated. Correlation between ABR and behavioural thresholds is largest in the 1,000- to 8,000-Hz frequency range. Predicted pure-tone audiograms (mean and SD) were determined for each 10-dB class of ABR thresholds. SDs are in the order of 15 to 18 dB in the 500- to 4,000-Hz range and slightly higher at adjacent frequencies (i.e., somewhat larger than in comparable adult studies). Mean pure-tone thresholds in the 1,000- to 8,000-Hz frequency range are up to 20 dB worse than ABR thresholds, which is opposite to findings in normally-hearing subjects. Thus, with an increasing degree of sensorineural hearing impairment, pure-tone thresholds increase at a significantly higher rate than ABR thresholds. The observation is explained in terms of reduced temporal integration in cochlear hearing loss. ABR thresholds worse than 80 dB nHL are demonstrated to have very limited predictive value with respect to the amount of residual hearing, not only in the low- but also in the high-frequency range. The presence of otitis media during ABR testing is shown to make estimation errors increase to more than 25 dB (SD).

We have developed a procedure to measure the averaged stapedius muscle reflex in response to electrical stimulation (AESR) with a cochlear implant. The AESR, as activated by ipsilateral stimulation with a cochlear implant, was investigated intra-operatively in a series of 12 children. After the cochlear implant was placed into the cochlea and secured by the surgeon, an electromyographic (EMG) needle electrode was gently placed into the stapedius muscle. During stimulation of the cochlear implant, the stapedius reflex was monitored visually (VESR) and as an averaged EMG response (AESR). Consistent AESRs were obtained in 7 of the 12 children. These measures provide a method to obtain stapedius muscle responses that may be helpful in the programming of young children with cochlear implants. Comparative post-operative measures were also obtained, including behavioral threshold levels, behavioral comfort levels, and the contralateral stapedius reflex threshold (ESR) on selected electrodes.

This paper presents experimental data on the evaluation of middle ear resonances by multifrequency tympanometry. Multifrequency tympanograms (MFTs) of 18 normally-hearing subjects were recorded with a frequency resolution of 15 Hz. The fine structure found in the MFT patterns was compared with findings in literature. A first approach for the evaluation of this fine structure was made explaining the great variability of the main ossicular resonance frequencies described in previous publications. The consequence of the present investigation is that the concept of the main ossicular resonance has to be revised critically.