Prevalence, behavioural, and management outcomes of infants with auditory neuropathy spectrum disorder

Analysis of audiological outcomes of children referred from a universal newborn hearing screening program over 9 years in Beijing, China

Universal newborn hearing screening (UNHS) and audiological diagnosis are crucial for children with congenital hearing loss (HL). The objective of this study was to analyze hearing screening techniques, audiological outcomes and risk factors among children referred from a UNHS program in Beijing. A retrospective analysis was performed in children who were referred to our hospital after failing UNHS during a 9-year period. A series of audiological diagnostic tests were administered to each case, to confirm and determine the type and degree of HL. Risk factors for HL were collected. Of 1839 cases, 53.0% were referred after only transient evoked otoacoustic emission (TEOAE) testing, 46.1% were screened by a combination of TEOAE and automatic auditory brainstem response (AABR) testing, and 1.0% were referred after only AABR testing. HL was confirmed in 55.7% of cases. Ears with screening results that led to referral experienced a more severe degree of HL than those with results that passed. Risk factors for HL were identified in 113 (6.1%) cases. The main risk factors included craniofacial anomalies (2.7%), length of stay in the neonatal intensive care unit longer than 5 days (2.4%) and birth weight less than 1500 g (0.8%). The statistical data showed that age (P < 0.001) and risk factors, including craniofacial anomalies (P < 0.001) and low birth weight (P = 0.048), were associated with the presence of HL. This study suggested that hearing screening plays an important role in the early detection of HL and that children with risk factors should be closely monitored.

Systematic Literature Review and Early Benefit of Cochlear Implantation in Two Pediatric Auditory Neuropathy Cases

Approximately 1 in 10 children with hearing loss is affected by auditory neuropathy spectrum disorder (ANSD). People who have ANSD usually have great difficulty understanding speech or communicating. However, it is possible for these patients to have audiograms that may indicate profound hearing loss up to normal hearing. This disorder is prognosed with positive, intact or present otoacoustic emissions (OAE) and/or cochlear microphonics (CM) as well as abnormal or absent auditory brainstem responses (ABR). Treatment methods include conventional hearing aids as well as cochlear implants. Cochlear implants (CI) usually promise better speech understanding for ANSD patients. We performed a systematic literature review aiming to show what improvements can effectively be achieved with cochlear implants in children with ANSD and compare this with our experience with two cases of ANSD implanted at our clinic. The retrospective review of two young CI patients diagnosed with ANSD during infancy demonstrated improvements over time in speech development communicated by their parents.

The audiological characteristics of infant auditory neuropathy patients without otoacoustic emission

Objective

To explore the audiological characteristics of infant auditory neuropathy (AN) patients with cochlear microphonic (CM) recorded but absent otoacoustic emission (OAE), clinically reducing the rate of missed diagnosis of AN.

Methods

We retrospectively analyzed the audiological characteristics of infant AN patients in our medical center between 2003 and 2020. A total of 18 infant AN patients were OAE absent group, with CM present and distortion product otoacoustic emission (DPOAE) absent in both ears. A total of 44 infant AN patients were OAE present group, with CM and DPOAE present in both ears.

Results

(1) The found age in OAE absent group was 0.9 (0.02) years old, which was younger than 1.11 (1.63) years old in OAE present group (p = .041). (2) The CM threshold of OAE absent group was 80 (10) dB nHL, which was significantly higher (p < .001) than OAE present group. CM amplitude were smaller (p < .05), and CM duration were shorter (p < .05) in OAE absent group. (3) The thresholds of auditory steady-state response (ASSR) at 0.5, 1, 2, and 4 kHz were 94 (10), 94 (10), 87 (20), and 81 (10) dB HL cg, respectively in OAE absent group, which were higher than those in OAE present group (p < .01).

Conclusions

Infant AN patients with CM present and OAE absent showed earlier detection and different audiological performance, which was manifested in ASSR thresholds, audiometric configurations and CM performance. CM thresholds were increased, amplitude and duration were decreased, non-linearity of I/O function was reduced.

Level of Evidence

4.

Impacts of impaired mitochondrial dynamics in hearing loss: Potential therapeutic targets

Mitochondria are the powerhouse of the cells. Under physiological conditions, mitochondrial fission and fusion maintain a dynamic equilibrium in the cytoplasm, which is referred to as mitochondrial dynamics. As an important approach to regulating mitochondrial function and quantity, the role of mitochondrial dynamics has been demonstrated in the pathogenesis of various disease models, including brain damage, neurodegeneration, and stress. As the vital organ of the peripheral auditory system, the cochlea consumes a significant amount of energy, and the maintenance of mitochondrial homeostasis is essential for the cochlear auditory capacity. OPA1 functions as both a necessary gene regulating mitochondrial fusion and a pathogenic gene responsible for auditory neuropathy, suggesting that an imbalance in mitochondrial dynamics may play a critical role in hearing loss, but relevant studies are few. In this review, we summarize recent evidence regarding the role of mitochondrial dynamics in the pathogenesis of noise-induced hearing loss (NIHL), drug-induced hearing loss, hereditary hearing loss, and age-related hearing loss. The impacts of impaired mitochondrial dynamics on hearing loss are discussed, and the potential of mitochondrial dynamics for the prevention and treatment of hearing loss is considered.