Incidence of auditory neuropathy among the deaf school students

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• 作者：Kü ; r&#x15f ; at Duman ; Abdullah Ayç ; iç ; ek ; Ramazan Sargı ; n ; Fethullah Kenar ; Mustafa Deniz Yı ; lmaz ; F. Sefa Derekö ; y
• 关键词：Auditory neuropathy ; ABR ; TEOAE
• 刊名：International Journal of Pediatric Otorhinolaryngology
• 出版年：2008
• 出版时间：July 2008
• 年：2008
• 卷：72
• 期：7
• 页码：1091-1095
• 全文大小：462 K

文摘

From 1997 until 2004, 5190 children, aged 1–15 years, whose hearing ability was uncertain or who had risk factors for hearing impairment were investigated with subjective and objective hearing tests. Three thousand four hundred and fifteen from these children were screened for AN/AS using pure-tone audiometry, impedance measurement, transient evoked otoacoustic emissions (TEOAE) and click-evoked auditory brainstem responses (ABR).

Results

From 3415 patients who participated in an ABR and TEOAE assessment, 379 children showed absent or elevated (≥80 dB nHL) ABR thresholds. Within this group we found 32 cases with evidence of AN/AS via visible TEOAE and/or cochlear microphonics (CM) coupled with absent ABR. In the remaining 3036 children, AN/AS, could be ruled out by means of detectable ABR-thresholds and coherent findings in pure-tone audiometry and TEOAE assessment. This results in a prevalence of AN/AS of 0.94 % within the group at risk for hearing loss, compared to 8.44 % among profoundly hearing impaired children.

Conclusion

This study shows that AN/AS is a common finding in the population of hearing impaired infants. In the majority of our AN/AS children (50 % , n = 16), an early audiological diagnosis was made under the age of 12 months. Therefore, clinicians and other health care professionals should generally be sensitised for AN/AS in infants, so that an appropriate treatment can promptly be initiated. Further research on clinical and pathophysiological aspects is necessary to better identify and manage patients suffering from AN/AS.

Summary

The implementation of neonatal hearing screening has enabled early detection and intervention in hearing loss. The use of otoacoustic emissions (OAE) and auditory brainstem response testing in universal screening has led to the recognition of this recently described disorder called auditory neuropathy/auditory dys-synchrony (AN/AD). This diagnosis indicates that the infant has significant hearing loss despite having normal outer hair cells in the cochlea. We reviewed the characteristics and natural history of nine infants detected to have AN/AD from universal newborn hearing screening in a national pediatric hospital. Fifty-two cases of hearing loss were detected from 14,807 consecutively screened cases. Of the 52 cases, 9 had electrophysiological test results consistent with AN/AD. They include both premature infants who had major neonatal complications and term infants with no perinatal complications. Six cases had bilateral and three cases had unilateral findings. We suggest that AN/AD can occur in low-risk infants and hence screening of high-risk cases alone is insufficient. Our findings are discussed with reference to the current literature.

We report two siblings with a family history of Waardenburg's syndrome (WS) for whom the audiological profile corresponds to auditory neuropathy (AN). They have; (1) bilateral severe to profound hearing loss, (2) robust oto-acoustic emissions (OAEs) in both ears, and (3) no auditory evoked responses at 95 dBnHL bilaterally. Electrocochleography (ECochG) and auditory middle and late latency potentials were performed in one of the children. Results showed cochlear and neural activities in both ears. Central auditory responses were not conclusive. These children did not have any history of neonatal illness and one child was diagnosed with AN at the age of 3 weeks and the other at the age of 11 months.