Mutations in the mitochondrial DNA have been shown to be one of the most important causes of sensorineural hearing loss. Here, we report the characterization of a large Chinese family (507 members in six generations) with maternally inherited non-syndromic hearing loss. Members of this family showed variable severity and age-of-onset of hearing impairment. In particular, the average age at onset of hearing loss in this family changed from 49 years (generation III) to 3 years (generation VI). Sequence analysis of the complete mitochondrial genome in this pedigree revealed the presence of a homoplasmic A1555G mutation in the 12S rRNA gene and other nucleotide changes. Of these changes, a C insertion at position 961 in the 12S rRNA gene is of special interest as mutations at this position have been found to be associated with aminoglycoside induced deafness in several genetically unrelated families. These data imply that the C insertion at position 961 in the 12S rRNA gene, acting as a secondary factor, could play a role in the phenotypic expression of the deafness associated A1555G mutation.
Recent prevalence estimates indicate that in 2015 almost half a billion people—about 6.8% of the world’s population—had disabling hearing loss and that prevalence numbers will further increase. The World Health Organization (WHO) currently estimates that at least 34 million children under the age of 15 have disabling hearing loss. Based on a 2012 WHO report, approximately 7.5 million of these children were under the age of 5 years. This review article focuses on the importance of high-quality newborn and infant hearing screening (NIHS) programs as one strategy to ameliorate disabling hearing loss as a global health problem. Two WHO resolutions regarding the prevention of deafness and hearing loss have been adopted urging member states to implement screening programs for early identification of ear diseases and hearing loss in babies and young children. The effectiveness of these programs depends on factors such as governmental mandates and guidance; presence of a national committee with involvement of professionals, industries, and stakeholders; central oversight of hearing screening; clear definition of target parameters; presence of tracking systems with bi-directional data transfer from screening devices to screening centers; accessibility of pediatric audiological services and rehabilitation programs; using telemedicine where connectivity is available; and the opportunity for case discussions in professional excellence circles with boards of experts. There is a lack of such programs in middle- and low-income countries, but even in high-income countries there is potential for improvement. Facing the still growing burden of disabling hearing loss around the world, there is a need to invest in national, high-quality NIHS programs.
The lack of an appropriately trained global hearing-care workforce is recognized as a barrier to developing and implementing services to treat ear and hearing disorders. In this article we examine some of the published literature on the current global workforce for ear and hearing care. We outline the status of both the primary-care workforce, including community health workers, and specialist services, including audiologists, ear, nose and throat specialists, speech and language therapists, and teachers of the deaf. We discuss models of training health workers in ear and hearing care, including the role of task-sharing and the challenges of training in low and middle-income countries. We structure the article by the components of ear and hearing care that may be delivered in isolation or in integrated models of care: primary care assessment and intervention; screening; hearing tests; hearing rehabilitation; middle-ear surgery; deaf services; and cochlear implant programmes. We highlight important knowledge gaps and areas for future research and reporting.
Tinnitus is a common problem in the population. With the aging of the population, the prevalence of tinnitus will increase. The prevention of tinnitus should focus on hearing impairment screening, otitis media treatment, and noise exposure reduction. Health services in rural areas should emphasize prevention more.
Hearing loss is the most common of all disabilities in China, with three million of the 1.4 billion population affected. Recently, the release of an official neonatal hearing screening consensus has drawn attention to the importance of continued surveillance throughout childhood and the need for a system that is suited to the Chinese situation. The current research aimed to develop and evaluate a questionnaire for mass screening of school children in China. In Jiangsu Province, 317 rural students were screened using the Chinese Hearing Questionnaire for School Children (CHQS) and otoacoustic emissions (OAE). Test performance measures for the questionnaire method revealed average overall accuracy (A' = 0.54), while higher system accuracy was obtained for the OAEs (A' = 0.85). The OAE screening also produced very high efficiency and specificity values with reasonable sensitivity. Unlike the OAE protocol, the CHQS will require substantial modification to improve its sensitivity prior to utilization as a mass screening tool.
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