Identification of Perinatal Risk Factors for Auditory Neuropathy Spectrum Disorder

Impact of Prematurity on Auditory Processing in Children

Prematurity is one of the most crucial risk factors negatively affecting the maturation of the auditory system. Children born preterm demonstrate high rates of hearing impairments. Auditory processing difficulties in preterm children might be a result of disturbances in the central auditory system development and/or sensory deprivation due to peripheral hearing loss. To investigate auditory processing in preterm children, we utilized a set of psychoacoustic tests to assess temporal processing and speech intelligibility. A total of 241 children aged 6-11 years old (136 born preterm and 105 healthy full-term children forming the control group) were assessed. The preterm children were divided into three groups based on their peripheral hearing status: 74 normal hearing (NH group); 30 children with bilateral permanent sensorineural hearing loss (SNHL group) and 32 children with bilateral auditory neuropathy spectrum disorder (ANSD group). The results showed significantly worse performance in all tests in premature children compared with full-term children. NH and SNHL groups showed significant age-related improvement in speech recognition thresholds in noise that might signify a "bottom-up" auditory processing maturation effect. Overall, all premature children had signs of auditory processing disorders of varying degrees. Analyzing and understanding the auditory processing specificity in preterm children can positively contribute to the more effective implementation of rehabilitation programs.

Implementing hearing screening among children aged 0-59 months at established immunization clinics in Uganda: A multi-center study

OBJECTIVE

The prevalence of childhood hearing loss (HL) is high in low and middle income countries (LMICs), with many of the affected children facing communication delays and poor opportunities for education. Despite the increased advocacy for childhood hearing screening globally, Uganda has no established childhood hearing screening programs. This study set out to introduce hearing screening services by non-specialist health workers at routine immunization clinics among children aged 0-59 months and describe the prevalence and factors associated with failed hearing screening (HS) in these children.

METHODS

A cross-sectional multi-center study was conducted at immunization clinics at three regional referral hospitals (RRHs). A semi structured questionnaire was used to capture data on socio-demographic, clinical factors and the two stage Transient Evoked Oto-acoustic emissions (TEOAEs) screening performed on children aged 0-59 months. A child that failed two stage screening was considered to have failed HS. Logistic regression was used to calculate odds ratios (OR) for factors associated with failed HS.

RESULTS

1217 children were recruited at three RRHs, with a median age of 2 months (range: 0 to 59), half were male 52% (n = 633). Overall 45 children failed two staged TEOAE screening giving a prevalence of failed HS of 3.7%, of these 27 (2.2%) and 18 (1.5%) failed unilaterally and bilaterally respectively. Children of rural residence (aOR = 2.18, p = 0.027), of low birth weight (aOR = 0.42, p = 0.045), with relatives having hearing loss (aOR = 4.64, p= <0.001), who were admitted in hospital after birth (aOR = 3.72, p = 0.012) and a history of a childhood suppurative otitis media (aOR = 9.53, p = 0.015) all had increased odds of failed HS.

CONCLUSIONS

The prevalence of failed screening is high. Implementation of childhood hearing screening by non-specialist health workers at immunization clinics using TEOAEs is possible and may be a necessary initial step in starting countrywide hearing screening in Uganda.

Auditory neuropathy: from etiology to management

PURPOSE OF REVIEW

Auditory neuropathy is a disorder of auditory dysfunction characterized by the normal function of the outer hair cells and malfunction of the inner hair cells, synapses, postsynapses and/or auditory afferent nervous system. This review summarizes the process of discovery and naming of auditory neuropathy and describes the acquired, associated genetic disorders and management available.

RECENT FINDINGS

In the last 40 years, auditory neuropathy has undergone a process of discovery, naming and progressive elucidation of its complex pathological mechanisms. Recent studies have revealed numerous acquired and inherited causative factors associated with auditory neuropathy. Studies have analyzed the pathogenic mechanisms of various genes and the outcomes of cochlear implantation. New therapeutic approaches, such as stem cell therapy and gene therapy are the future trends in the treatment of auditory neuropathy.

SUMMARY

A comprehensive understanding of the pathogenic mechanisms is crucial in illustrating auditory neuropathy and assist in developing future management strategies.

Cochlear nerve deficiency is an important cause of auditory neuropathy spectrum disorder at a population level in children

OBJECTIVES

To determine the incidence, prevalence and describe risk factors and etiology for childhood Auditory Neuropathy Spectrum Disorder using population level data from a statewide universal newborn hearing program.

METHODS

A retrospective statewide universal newborn hearing screening database review and descriptive analysis from 2012 to 2019 of demographic, risk factors and hearing loss etiology for babies with sensorineural hearing loss and ANSD was completed. A 2 stage aABR protocol was used and ANSD was classified when click evoked ABR were absent or grossly abnormal but otoacoustic emissions and or cochlear microphonics were present. Medical evaluation and investigation by a pediatrician or otolaryngologist was performed and etiology was assigned using a coding scheme. Next generation genetic sequencing was not available.

RESULTS

From 2012 to 2019, 487 636 babies were screened for congenital hearing loss (99.1%) and 1150 were confirmed to have permanent SNHL, 80 of whom were diagnosed with ANSD (52 unilateral and 28 bilateral). The prevalence of ANSD was 7.0% and population prevalence was 0.16 per 1000 live births. The only demographic or risk factor significantly more likely to be associated with ANSD than SNHL was hyperbilirubinemia. The most common etiology for ANSD was hypoplasia or absence of the cochlear nerve with 37 cases (46.3%), and it was significantly more likely with unilateral than bilateral ANSD.

CONCLUSION

At a population level, ANSD was more likely to be unilateral and the only perinatal risk factor significantly associated was hyperbilirubinemia. Cochlear nerve deficiency was the most common etiology. Given that this can occur in well babies, this provides further evidence for aABR as a preferred mode for newborn hearing screening.