Incidence of auditory neuropathy among the deaf school students

New-born Hearing Screening Programmes in 2020: CODEPEH Recommendations

Programmes for early detection of congenital hearing loss have been successfully implemented mainly in developed countries, after overcoming some conceptual errors argued against their implementation and some criticism of their efficacy. However, some difficulties and weaknesses are still identified in these programmes: the detection of late-onset hearing loss and the percentage of children who did not pass the screening and did not complete the process of diagnosis and treatment, these being cases that are lost in the process. The purpose of this Document is to analyse these problems to determine areas for improvement and to emphasize one of the basic principles for the success of the programmes: continuous training for the interdisciplinary team. The result of the review process carried out by CODEPEH has been drafted as Recommendations for updating the Programmes with the evidence of the last decade, including advances in screening technology, the impact of the present knowledge on congenital infection by cytomegalovirus, genetic hearing loss research and control systems of lost to follow-up cases, treatment and follow up.

Auditory dyssynchrony or auditory neuropathy: understanding the pathophysiology and exploring methods of treatment

OBJECTIVE

To review the literature on auditory dyssynchrony (AD) or neuropathy which is characterized by absent auditory brainstem responses, normal otoacoustic emissions, and word discrimination disproportional to the pure tone audiogram.

RESULTS

Several papers attempt to estimate the prevalence of AD that seems to range between 0.23 and 2% in infants "at risk" for hearing impairment and it is considered to be responsible for approximately 8% of newly diagnosed cases of hearing loss in children per year. The prevalence gets even higher, reaching 10% in children with permanent hearing loss. It seems that AD is not a single disease but a spectrum of pathologies that affect the auditory pathway at the level of the inner hair cells, the synapses, or the auditory nerve. Many predisposing or contribution factors have been reported, including prematurity, hyperbilirubinemia, hypoxia, low-birth weight, immunological conditions, infectious diseases, etc. Before proposing any method of management, parents should be informed about the variation among patients and the changes that may appear in some children's audition over time. Sigh language, speech and language therapy, hearing-aids, and cochlear implantation have been used in the treatment of AD. In general, AD is rather refractory to conventional amplification and cochlear implantation has been found an effective method of management in young implanted children with severe/profound deafness and AD. However, the situation is more complicated and challenging in milder hearing losses.

CONCLUSION

The selected and proposed 30 related articles published in the International Journal of Pediatric Otorhinolaryngology aim to stimulate the related research in order to further explore the etiology, pathophysiology, and management of AD.

Prevalence of auditory neuropathy spectrum disorder in an auditory health care service

Auditory neuropathy spectrum disorder (ANSD) is characterized by impairment of the auditory nerve associated with preservation of outer hair cell function.

Objective

To establish the prevalence of ANSD in subjects with sensorineural hearing loss (SNHL).

Method

This retrospective study was carried out between 2010 and 2012 and included the charts of 2,292 individuals with SNHL. Data from otolaryngological and audiological examinations based on pure-tone and speech audiometry, impedance tests, otoacoustic emissions (OAEs), and brainstem auditory evoked potentials (BAEPs) were collected. Inclusion criteria: presence of OAEs and/or cochlear microphonic (CM); absent or altered BAEPs, and normal MRI scans of the brain.

Results

Twenty-seven (1.2%) of the 2,292 subjects with SNHL had ANSD (37% males; 63% females). Mild SNHL was seen in 29.6% of the individuals with ANSD; 55.5% had moderate SNHL; 7.4% had severe SNHL; and 7.5% had profound SNHL. In terms of age, 14.8% were aged between zero and 20 years, 44.1% were 41 to 60 years old, and 7.4% were above the age of 60.

Conclusion

ANSD was seen in 1.2% of the individuals with SNHL included in this study.

The performance of distortion product otoacoustic emissions and automated auditory brainstem response in the same ear of the babies in neonatal unit

OBJECTIVE

To identify the outcomes of hearing screening using different protocols of both Distortion Product Otoacoustic Emissions (DPOAE) and Automated Auditory Brainstem Response (AABR) tests in the same ear of the babies in a neonatal unit population.

METHODS

A cross-sectional study was carried out on babies who were admitted into a neonatal unit. By using a formula of single proportion and considering 20% drop out, the number of sample required was 114. The subjects were chosen by using a systematic random sampling. The infants selected were subjected to DPOAE followed by AABR tests screening at the same setting before discharge.

RESULTS

There were 73 newborns (61.6% male and 38.4% female) participated in this study with a total of 146 ears screened. Ototoxic medication was the most common risk factor followed by hyperbilirubinaemia and low birth weight. AABR had higher passing rate (82.9%) as compared to DPOAE (77.4%). The highest passing rate was achieved if the protocol of either passed DPOAE or AABR was used (90.4%). The rate was lower when auditory neuropathy spectrum disorder (ANSD) has been considered (82.9%). Hyperbilirubinaemia, prematurity, craniofacial malformation and ototoxic drugs seem to be the high risk factors for auditory neuropathy.

CONCLUSION

AABR has a higher passing rate as compared to DPOAE. However, the use of both instruments in the screening process especially in NICU will be useful to determine the infants with ANSD who may need different approach to management. Therefore, a protocol in which newborns are tested with AABR first and then followed by DPOAE on those who fail the AABR is recommended.

Prevalence of auditory neuropathy (AN) among infants and young children with severe to profound hearing loss

Auditory neuropathy is a challenging disorder and needs special habilitative/rehabilitative approach. This study aimed to detect its prevalence among infants and young children with severe to profound hearing loss. 112 infants and young children with age ranged 6-32 months were examined and diagnosed as having severe to profound hearing loss and were referred for hearing aid fitting. Those infants were reassessed in our centers for detecting cases with auditory neuropathy. The study group was subjected to immittancemetry, behavioral observation audiometry, ABR and cochlear microphonics.

RESULTS

15 patients were found to have auditory neuropathy according to our criteria for diagnosis.

CONCLUSIONS

The prevalence of AN in the study group was 13.4%. CM were recommended to be tested routinely during ABR assessment whenever abnormal results are obtained.