The varieties of auditory neuropathy

A Consolidated Understanding of the Contribution of Redox Dysregulation in the Development of Hearing Impairment

The etiology of hearing impairment is multifactorial, with contributions from both genetic and environmental factors. Although genetic studies have yielded valuable insights into the development and function of the auditory system, the contribution of gene products and their interaction with alternate environmental factors for the maintenance and development of auditory function requires further elaboration. In this review, we provide an overview of the current knowledge on the role of redox dysregulation as the converging factor between genetic and environmental factor-dependent development of hearing loss, with a focus on understanding the interaction of oxidative stress with the physical components of the peripheral auditory system in auditory disfunction. The potential involvement of molecular factors linked to auditory function in driving redox imbalance is an important promoter of the development of hearing loss over time.

Clinical and genetic architecture of a large cohort with auditory neuropathy

Auditory neuropathy (AN) is a unique type of language developmental disorder, with no precise rate of genetic contribution that has been deciphered in a large cohort. In a retrospective cohort of 311 patients with AN, pathogenic and likely pathogenic variants of 23 genes were identified in 98 patients (31.5% in 311 patients), and 14 genes were mutated in two or more patients. Among subgroups of patients with AN, the prevalence of pathogenic and likely pathogenic variants was 54.4% and 56.2% in trios and families, while 22.9% in the cases with proband-only; 45.7% and 25.6% in the infant and non-infant group; and 33.7% and 0% in the bilateral and unilateral AN cases. Most of the OTOF gene (96.6%, 28/29) could only be identified in the infant group, while the AIFM1 gene could only be identified in the non-infant group; other genes such as ATP1A3 and OPA1 were identified in both infant and non-infant groups. In conclusion, genes distribution of AN, with the most common genes being OTOF and AIFM1, is totally different from other sensorineural hearing loss. The subgroups with different onset ages showed different genetic spectrums, so did bilateral and unilateral groups and sporadic and familial or trio groups.

Cochlear implantation in children with auditory neuropathy spectrum disorder: an updated systematic review

BACKGROUND

The goal of managing auditory neuropathy spectrum disorder (ANSD) is to restore the children's ability to discriminate auditory information. Children who are not making sufficient progress in speech comprehension, and speech and language development after receiving adequate auditory re/habilitation and/or acoustic amplification may be candidates for cochlear implantation (CI). Despite the growing number of published literature on CI outcomes in children with ANSD, the current evidence is primarily based on case reports or retrospective chart reviews some of which had a limited number of children. In addition, the outcomes of CI seem to vary between children with ANSD. Thus, compelling evidence is lacking. This updated systematic review evaluated the speech perception, language, and speech intelligibility outcomes of children with ANSD post-CI.

METHODS

An online bibliographic search was conducted in PubMed, Scopus, Web of Science, and CENTRAL databases. We included both interventional and observational studies that assessed the outcomes of the CI in  children with ANSD.

RESULTS

Thirty-three studies were included in this systematic review. Several tests were used to assess speech perception following CI in children with ANSD. The findings of this study revealed that  children with ANSD had mean Categories of Auditory Performance scores ranging from 4.3 to 7 post-operatively, this result was better than the pre-operative scores which ranged between 0.4 to 2.5. Likewise, the Infant-Toddler Meaningful Auditory Integration Scale, Phonetically Balanced Kindergarten, and multisyllabic lexical neighborhood test showed clinically relevant improvement after CI. The same findings were reported for language and speech intelligibility scores. One study investigated the quality of life/children satisfaction after CI and showed overall good satisfaction with the outcomes.

CONCLUSIONS

The present systematic review suggests that CI is a feasible and effective hearing  rehabilitation modality for children with ANSD.

REGISTRATION AND PROTOCOL

PROSPERO ID: CRD42021279140.

NADH improves AIF dimerization and inhibits apoptosis in iPSCs-derived neurons from patients with auditory neuropathy spectrum disorder

Auditory neuropathy spectrum disorder (ANSD) is a hearing impairment involving disruptions to inner hair cells (IHCs), ribbon synapses, spiral ganglion neurons (SGNs), and/or the auditory nerve itself. The outcomes of cochlear implants (CI) for ANSD are variable and dependent on the location of lesion sites. Discovering a potential therapeutic agent for ANSD remains an urgent requirement. Here, 293T stable transfection cell lines and patient induced pluripotent stem cells (iPSCs)-derived auditory neurons carrying the apoptosis inducing factor (AIF) p.R422Q variant were used to pursue a therapeutic regent for ANSD. Nicotinamide adenine dinucleotide (NADH) is a main electron donor in the electron transport chain (ETC). In 293T stable transfection cells with the p.R422Q variant, NADH treatment improved AIF dimerization, rescued mitochondrial dysfunctions, and decreased cell apoptosis. The effects of NADH were further confirmed in patient iPSCs-derived neurons. The relative level of AIF dimers was increased to 150.7 % (P = 0.026) from 59.2 % in patient-neurons upon NADH treatment. Such increased AIF dimerization promoted the mitochondrial import of coiled-coil-helix-coiled-coil-helix domain-containing protein 4 (CHCHD4), which further restored mitochondrial functions. Similarly, the content of mitochondrial calcium (mCa2+) was downregulated from 136.7 % to 102.3 % (P = 0.0024) in patient-neurons upon NADH treatment. Such decreased mCa2+ levels inhibited calpain activity, ultimately reducing the percentage of apoptotic cells from 30.5 % to 21.1 % (P = 0.021). We also compared the therapeutic effects of gene correction and NADH treatment on hereditary ANSD. NADH treatment had comparable restorative effects on functions of ANSD patient-specific cells to that of gene correction. Our findings offer evidence of the molecular mechanisms of ANSD and introduce NADH as a potential therapeutic agent for ANSD therapy.

Cortical Auditory Evoked Potential Testing in Children With Auditory Neuropathy Spectrum Disorder

PURPOSE

In the present report, we reviewed the role of cortical auditory evoked potentials (CAEPs) as an objective measure during the evaluation and management process in children with auditory neuropathy spectrum disorder (ANSD).

METHOD

We reviewed the results of CAEP recordings in 66 patients with ANSD aged between 2 months and 12 years and assessed the relationship between their characteristics (prevalence, morphology, latencies, and amplitudes) and various clinical features, including the mode of medical management.

RESULTS

Overall, the CAEPs were present in 85.2% of the ears tested. Factors such as prematurity, medical complexity, neuronal issues, or presence of syndromes did not have an effect on the presence or absence of CAEPs. CAEP latencies were significantly shorter in ears with cochlear nerve deficiency than in ears with a normal caliber nerve. Three different patterns of CAEP responses were observed in patients with bilateral ANSD and present cochlear nerves: (a) responses with normal morphology and presence of both P1-P2complex and N2 components, (b) responses with abnormal morphology and presence of the N2 component but undefined P1-P2complex peak, and (c) entirely absent responses. None of the patients with normal, mild, or moderate degree of hearing loss had a complete absence of CAEP responses. No significant differences were uncovered when comparing the latencies across unaided and aided children and children who later received cochlear implants.

CONCLUSIONS

The CAEP protocol used in our ANSD program did inform about the presence or absence of central auditory stimulation. Absent responses typically fit into an overall picture of complete auditory deprivation and all of these children were ultimately offered cochlear implants after failing to develop oral language. Present responses, on the other hand, were acknowledged as a sign of some degree of auditory stimulation but always interpreted with caution given that prognostic implications remain unclear.

Prevalence and Auditory Characteristics of Auditory Neuropathy Spectrum Disorder in Adult Population with Sensory Neural Hearing Loss: A Hospital Based Study in South India

Auditory neuropathy spectrum disorder (ANSD) is a heterogenous group of disorder characterized by abnormalities in auditory brainstem responses (ABR) with preserved otoacoustic emissions and/or cochlear microphonics. The aim of the study is to estimate the prevalence and evaluate the audiological characteristics of ANSD in adult population with sensory neural hearing loss. A prospective study was conducted on the adult population (≥ 18 years) attending ENT outpatients clinic at Rajiv Gandhi Government General Hospital, Chennai. All patients reported to the department with auditory and vestibular symptoms underwent case history, otoscopic examination, and routine audiological evaluation (pure tone audiometry, speech audiometry and immittance audiometry). Patients with indications of ANSD in case history and routine audiological evaluation were further evaluated using distortion product otoacoustic emissions and ABR. A total of 8682 adult population was evaluated during the period of 2017 to 2018. Out of 8682 patients, 1343 (15.46%) of them had sensory neural hearing loss of varying degrees. Out of 1343 adults with sensory neural hearing loss, 24 (1.78%) adults were diagnosed as ANSD. The prevalence of ANSD in adult population with sensory neural hearing loss in our study is 1.32% per 1000 adults. The clinical characteristics of ANSD shows impairment in speech perception irrespective of degree of hearing loss, preserved cochlear functions and abnormal ABR. Hence ANSD is not a rare clinical finding in adults with sensory neural hearing loss, but its prevalence was estimated to be lower in Indian population. Often young females are affected causing significant impairment in speech perception and disability.

A 15-year Review of 260 Children With Auditory Neuropathy Spectrum Disorder: II. Management and Outcomes

OBJECTIVES

Following a review of the demographic and clinical characteristics of all pediatric patients diagnosed with auditory neuropathy spectrum disorder (ANSD) by a pediatric health care system from 2005 to 2020, the present report highlights the type and timing of intervention and outcomes in the same 260 patients with ANSD.

DESIGN

This was a retrospective study reviewing the demographic data, medical history, imaging studies, audiological and speech language data, type of audiological intervention (hearing aids or cochlear implants), and mode of communication in 260 pediatric patients diagnosed with ANSD over a 15-year period.

RESULTS

A significant decrease over time in the age at hearing aid fitting was observed. While a similar reduction in the age at implantation occurred over time, cochlear implantation is still rarely performed by 12 months of age in most ANSD patients. Among bilateral ANSD patients fitted with hearing aids, the majority (89.2%) did not benefit from conventional amplification and most received cochlear implants. Some hearing aid benefit for speech and language development was observed in 5.8%, though communication difficulties were persistent and most used a combination of oral and sign language for communication. Only six patients (5%) received significant benefit from their hearing aids for speech and language development.

CONCLUSIONS

This review of ANSD management over a 15-year period reveals that hearing aids are not a viable option to develop speech and language for most infants and children with ANSD. This finding confirms previous reports and suggest that while hearing aid trials are warranted, children must be tracked closely so as to avoid delays in decision making. Cochlear implantation constitutes the major (if not only) rehabilitative intervention that allows for speech perception in patients who do not benefit from conventional amplification.

Auditory and Speech Outcomes of Cochlear Implantation in Children With Auditory Neuropathy Spectrum Disorder: A Systematic Review and Meta-Analysis

OBJECTIVE

The aim of this meta-analysis was to critically assess the effect of cochlear implantation on auditory and speech performance outcomes of children with auditory neuropathy spectrum disorder (ANSD).

MATERIAL AND METHODS

A systematic literature search was conducted on PubMed, EMbase, and Web of Science. The outcomes included speech recognition score, Categories of Auditory Performance (CAP), Speech Intelligibility Rating (SIR) score, and open-set speech perception. Results were expressed as standardized mean difference (SMD) or risk ratio (RR) with a 95% confidence interval (95% CI).

RESULTS

A total of 15 studies was included in this meta-analysis. Pooled data showed that, there were no significant differences between ANSD and sensorineural hearing loss (SNHL) groups in terms of speech recognition score (SMD = 0.01, 95% CI: -0.45, 0.47; P = .959),CAP (SMD = 0.71, 95% CI: -0.13, 1.54; P = .098), SIR score (SMD = -0.09, 95% CI: -0.49, 0.32; P = .667), and open-set speech perception (RR = 0.85, 95% CI: 0.69, 1.05; P = .142). Sensitivity analysis by removing individual studies one at a time showed that the overall estimate and level of heterogeneity did not change substantially.

CONCLUSION

The current evidence suggested that children with ANSD who underwent cochlear implants achieved comparable effects in auditory and speech performance as children with non-ANSD SNHL.

Is Working Memory Compromised in Individuals with Sensorineural Hearing Loss with Auditory Neural Origin?

The study aimed to investigate the working memory and speech recognition in noise from individuals with Sensori Neural Hearing Loss (SNHL) with and without auditory neuropathy spectrum disorder (ANSD). The purpose of assessing working memory recommends for a potential intervention program to perceive speech. Twenty participants in the age range of 16-44 years, diagnosed as having mild to moderate SNHL were recruited for the study. The participants were divided into two groups based on the presence and absence of ANSD (10 in each group). The visual working memory was assessed in all the participants using the Operation Span Test, Reading Span Test and Visual Backward Test. Speech perception ability was assessed using the SNR 50 test. There was no significant difference between the scores of Operation Span, Reading Span, and Visual Backward Span for individuals with SNHL with and without ANSD. There was a significant difference between the scores of SNR 50 for individuals with SNHL with and without ANSD. The visual working memory in individuals with and without ANSD is similar. Speech perception in noise is significantly affected in ANSD than SNHL without ANSD. Thus, it is recommended to use speech reading, which utilizes visual working memory to interpret the message, as previous studies have reported that individuals with ANSD show limited benefit in auditory mode of rehabilitation alone.

How Craniofacial Anomalies Can Obscure the Diagnosis of Unilateral Auditory Neuropathy Spectrum Disorder: A Case Study

Comorbidities are common with craniofacial anomalies and can include auditory neuropathy spectrum disorder (ANSD). Identification of these comorbidities, such as a diagnosis of ANSD, has increased with expanded multi-disciplinary care teams and the use of auditory objective measures. Patients with craniofacial anomalies often have complex medical histories including extreme prematurity and jaundice, which may lead to the development of additional comorbidities. The 5-year-old boy that is the subject of this case study presented with noted developmental delays and residing in foster care with an unknown family/medical history. Initially presenting with middle ear dysfunction, exacerbated by craniofacial anomalies, the underlying cause of his speech delays was missed. Behavioral audiometry was attempted with inaccurate results. Surgery was performed to correct the craniofacial anomalies, middle ear dysfunction, and was followed with auditory brainstem response (ABR) testing. The boy healed well without complications. The ABR revealed ANSD, hearing aids were fitted for the diagnosis, regular speech therapy was initiated, and the boy continues to make steady progress toward developmental milestones. The purpose of this case study was to highlight the course of identification and treatment of a complex case that may provide insight into determining a differential diagnosis of ANSD when initially obscured by craniofacial anomalies.

Vestibular and radiological characteristics of children affected by unilateral auditory neuropathy spectrum disorder

OBJECTIVE

Auditory neuropathy spectrum disorders (ANSD) are defined by the association of a preserved outer hair cell function and an impaired auditory nerve neural response, and present mostly bilaterally. Unilateral ANSD are consequently only seldom described, and most frequently as isolated cases. This study aims to describe the audiological, vestibular and radiological characteristics of a population of children with unilateral ANSD.

MATERIAL AND METHODS

We isolated 22 patients with unilateral ANSD, 12 boys and 10 girls from 0 to 95 months, in a database of auditory evoked potentials. We reviewed the audiological, radiological and vestibular assessments. The audiological assessment included tympanometry, otoacoustic emission recording and auditory evoked potential. Otolithic function was assessed by performing cervical vestibular evoked myogenic potential. The canal function was determined by video head impulse test and/or caloric test. The radiological evaluation consisted of an MRI of the internal auditory canal.

RESULTS

Many patients with a type A tympanometry had no response to otoacoustic emission (53,8%), in the presence of a cochlear microphonic potential. Vestibular assessment was performed in 9 of the 22 patients. 4 children had impaired otolithic and/or canal function. MRI evaluation of the inner ear was performed in 18 patients. Aplasia or hypoplasia of the cochlear nerve was found in 17 of them. MRI showed additional vestibular or brainstem abnormalities in 7 of the 18 children. All children with impaired vestibular function had vestibular or brainstem radiological alterations in addition to cochlear branch aplasia or hypoplasia.

CONCLUSIONS

Radiological and vestibular abnormalities are common in children with unilateral ANSD and suggest that a radiological and vestibular assessment is required.

Prevalence, risk factors, and audiological characteristics of auditory neuropathy

OBJECTIVE

The objective of this study was to determine the prevalence, risk factors, and audiological characteristics of auditory neuropathy spectrum disorder (ANSD) in the pediatric population.

DESIGN

A retrospective review of medical charts was conducted for children visiting two hospitals in Saudi Arabia.

STUDY SAMPLE

Medical records of 1025 patients with sensorineural hearing loss (SNHL) were reviewed. We analyzed the databases for results of audiological examinations, risk factors, and outcomes of intervention including hearing aid (HA) and cochlear implantation (CI).

RESULTS

Out of 1025 children with SNHL, 101 patients (9.85%) were identified to have ANSD. Audiological characteristics of the ANSD group revealed a severe-to-profound degree of hearing loss, all showed type A tympanogram and absent reflexes, absent auditory brainstem response (ABR) findings with present cochlear microphonic while otoacoustic emissions were absent in 54.5% of patients. The most prevalent risk factors for ANSD in this group were family history of hearing loss, consanguinity, hyperbilirubinemia, and low birth weight. Pure tone and speech detection thresholds improved significantly with CI compared to HA use in this sample of patients with ANSD.

CONCLUSION

This study shows that ANSD is not extremely rare among Saudi children with severe to profound hearing loss, with a prevalence of 9.85%.

Experimental animal models of drug-induced sensorineural hearing loss: a narrative review

Objective

This narrative review describes experimental animal models of sensorineural hearing loss (SNHL) caused by ototoxic agents.

Background

SNHL primarily results from damage to the sensory organ within the inner ear or the vestibulocochlear nerve (cranial nerve VIII). The main etiology of SNHL includes genetic diseases, presbycusis, ototoxic agents, infection, and noise exposure. Animal models with functional and anatomic damage to the sensory organ within the inner ear or the vestibulocochlear nerve mimicking the damage seen in humans are employed to explore the mechanism and potential treatment of SNHL. These animal models of SNHL are commonly established using ototoxic agents.

Methods

A literature search of PubMed, Embase, and Web of Science was performed for research articles on hearing loss and ototoxic agents in animal models of hearing loss.

Conclusions

Common ototoxic medications such as aminoglycoside antibiotics (AABs) and platinum antitumor drugs are extensively used to induce SNHL in experimental animals. The effect of ototoxic agents in vivo is influenced by the chemical mechanisms of the ototoxic agents, the species of animal, routes of administration of the ototoxic agents, and the dosage of ototoxic agents. Animal models of drug-induced SNHL contribute to understanding the hearing mechanism and reveal the function of different parts of the auditory system in humans.

Familial Temperature-Sensitive Auditory Neuropathy: Distinctive Clinical Courses Caused by Variants of the OTOF Gene

Objective: To investigate the clinical course and genetic etiology of familial temperature-sensitive auditory neuropathy (TSAN), which is a very rare subtype of auditory neuropathy (AN) that involves an elevation of hearing thresholds due to an increase in the core body temperature, and to evaluate the genotype-phenotype correlations in a family with TSAN. Methods: Six members of a non-consanguineous Chinese family, including four siblings complaining of communication difficulties when febrile, were enrolled in this study. The clinical and audiological profiles of the four siblings were fully evaluated during both febrile and afebrile episodes, and the genetic etiology of hearing loss (HL) was explored using next-generation sequencing (NGS) technology. Their parents, who had no complaints of fluctuating HL due to body temperature variation, were enrolled for the genetics portion only. Results: Audiological tests during the patients' febrile episodes met the classical diagnostic criteria for AN, including mild HL, poor speech discrimination, preserved cochlear microphonics (CMs), and absent auditory brainstem responses (ABRs). Importantly, unlike the pattern observed in previously reported cases of TSAN, the ABRs and electrocochleography (ECochG) signals of our patients improved to normal during afebrile periods. Genetic analysis identified a compound heterozygous variant of the OTOF gene (which encodes the otoferlin protein), including one previously reported pathogenic variant, c.5098G > C (p.Glu1700Gln), and one novel variant, c.4882C > A (p.Pro1628Thr). Neither of the identified variants affected the C2 domains related to the main function of otoferlin. Both variants faithfully cosegregated with TSAN within the pedigree, suggesting that OTOF is the causative gene of the autosomal recessive trait segregation in this family. Conclusion: The presence of CMs with absent (or markedly abnormal) ABRs is a reliable criterion for diagnosing AN. The severity of the phenotype caused by dysfunctional neurotransmitter release in TSAN may reflect variants that alter the C2 domains of otoferlin. The observations from this study enrich the current understanding of the phenotype and genotype of TSAN and may lay a foundation for further research on its pathogenesis.

Perception of temporally enhanced and hearing aid processed speech in children with late-onset Auditory Neuropathy Spectrum Disorder

OBJECTIVE

To investigate phrase perception and subjective quality preference of temporal enhancement-based speech processing strategies: Deep-band modulation and Stretching, and hearing aid processed speech in adolescents with late-onset Auditory Neuropathy.

METHODS

15 participants with Auditory Neuropathy Spectrum Disorder were involved. Speech perception was assessed using unprocessed, deep-band modulated, stretched, and hearing aid processed conditions. Subjective preference was also assessed using the pair-wise comparison technique. Gap detection test was done using broadband noise to investigate the possible correlation with benefit from processing strategies.

RESULTS

As a group, no significant benefits were found with processed speech. Clinically relevant trends emerged on subdividing the group into good and poor performers. Deep-band modulation processing was significantly better than unprocessed speech in those with poorer speech recognition abilities. There was a trend for those with poorer temporal processing abilities to benefit more with deep-band modulation processing. In those with relatively better speech recognition abilities, processing showed no benefit, and hearing aid processed speech was inferior to unprocessed speech. Quality-wise, the unprocessed speech was preferred by all the participants. Among the processed conditions, deep-band modulation was preferred by most, followed by stretching and hearing aid processed speech.

CONCLUSION

Results indicate that temporal enhancement strategies may be beneficial for a subset of individuals with ANSD with poorer temporal processing and speech perception abilities. However, processing strategies need to take into account the quality aspect and not just intelligibility.

Auditory testing outcomes with hearing aids in patients with auditory neuropathy spectrum disorder

OBJECTIVE

The objective of this study is to evaluate the audiologic outcomes with hearing aids in pediatric patients with auditory neuropathy spectrum disorder (ANSD) using the Infant Toddler-Meaningful Auditory Integration Scale (IT-MAIS), and the Ling 6 Sound Test (Ling 6).

STUDY DESIGN

Case series.

SETTING

Single tertiary care academic medical center.

SUBJECTS AND METHODS

All pediatric patients with a confirmed diagnosis of ANSD on Auditory Brainstem Response (ABR) testing who presented to a single tertiary medical center between September 2008 and September 2018 were included. Only patients that underwent Infant Toddler-Meaningful Auditory Integration Scale (IT-MAIS) and/or Ling 6 Sound Test (Ling 6) were included in the study. Audiologic testing performed after cochlear implantation was excluded.

RESULTS

60 pediatric patients with ANSD were analyzed. There were 10 patients included in the study with documented hearing aid use who underwent IT-MAIS and/or Ling 6 testing. Average IT-MAIS score improved by 20.4% after initial or extended trial of amplification. Similarly, average Ling 6 score improved from 3.6 to 4.8 after initial or extended trial of amplification. The four patients who did not receive amplification had higher average IT-MAIS and Ling 6 scores.

CONCLUSION

In most children with ANSD, IT-MAIS and Ling 6 Sound Test scores improved with initial hearing aid use and over time with extended hearing aid use. Long-term prospective, multi-institutional studies are needed to determine the impact of the natural history of ANSD, comorbidities, and socioeconomic variables on auditory function testing results in children with ANSD using hearing aids.

Determining attributed factors of hearing handicap in individuals with auditory sensory and neural pathology

INTRODUCTION

There is a modest relationship between speech perception skills and perceived hearing handicap in individuals with hearing loss. In this study, an attempt is made at linking psychoacoustic results and speech perception skills to understand the subjective handicap and quality of life.

OBJECTIVE

To investigate how speech perception in noise (signal to noise ratio-50), difference limen frequency, temporal modulation transfer function, hearing handicap inventory for adults, and quality of life in auditory neuropathy spectrum disorder differs from sensorineural hearing loss. Further we attempt to discern attributed factors of hearing handicap in auditory neuropathy spectrum disorder and sensorineural hearing loss.

METHODS

A cross-sectional study with comparative and correlational research designs were utilized. Eighty-four participants were grouped into sensorineural hearing loss (n = 49), and auditory neuropathy spectrum disorder (n = 35) was sub-grouped into mild, moderately severe, and severe. We evaluated signal to noise ratio-50, difference limen frequency, and temporal modulation transfer function. In addition, hearing handicap inventory for adults, and quality of life questionnaires were administered.

RESULTS

Mild auditory neuropathy spectrum disorder showed impairment in speech perception and discriminating frequency, which were similar to the severe sensory neural hearing loss. Temporal resolution impairment in auditory neuropathy spectrum disorder mild was significantly higher than in each sub-groups of sensorineural hearing loss. The severity of the hearing handicap in was similar to severe sensorineural hearing loss, quality of life was equally affected in sensorineural hearing loss and auditory neuropathy spectrum disorder. In sensorineural hearing loss, signal to noise ratio-50 was positively related, and quality of life was negatively related to hearing handicap. In auditory neuropathy spectrum disorder, no contributory factors were related to hearing handicap.

CONCLUSION

Mild auditory neural pathology demonstrates impairment in speech recognition and psychoacoustic skills similar to severe cochlear pathology. In sensorineural hearing loss, hearing handicap is predicted from quality of life and speech perception, but none of the contributory factors predicted hearing handicap in auditory neuropathy spectrum disorder.

Cochlear implantation in auditory neuropathy spectrum disorders: role of transtympanic electrically evoked auditory brainstem responses and serial neural response telemetry

OBJECTIVE

To evaluate the utility of pre-operative transtympanic electrically evoked auditory brainstem responses and post-operative neural response telemetry in auditory neuropathy spectrum disorder patients.

METHODS

Four auditory neuropathy spectrum disorder patients who had undergone cochlear implantation and used it for more than one year were studied. All four patients underwent pre-operative transtympanic electrically evoked auditory brainstem response testing, intra-operative and post-operative (at 3, 6 and 12 months after switch-on) neural response telemetry, and out-patient cochlear implant electrically evoked auditory brainstem response testing (at 12 months).

RESULTS

Patients with better waveforms on transtympanic electrically evoked auditory brainstem response testing showed superior performance after one year of implant use. Neural response telemetry and electrically evoked auditory brainstem response measures improved in all patients.

CONCLUSION

Inferences related to cochlear implantation outcomes can be based on the waveform of transtympanic electrically evoked auditory brainstem responses. Robust transtympanic electrically evoked auditory brainstem responses suggest better performance. Improvements in electrically evoked auditory brainstem responses and neural response telemetry over time indicate that electrical stimulation is favourable in auditory neuropathy spectrum disorder patients. These measures provide an objective way to monitor changes and progress in auditory pathways following cochlear implantation.

Auditory Neuropathy Spectrum Disorder (ANSD)-Clinical Characteristics and Pathogenic Variant Analysis of Three Nonsyndromic Deafness Families

Objective

To analyze the phenotypic features and pathogenic variants of three unrelated families presenting with nonsyndromic auditory neuropathy spectrum disorder (ANSD).

Methods

Three recruited families that were affected by congenital deafness were clinically evaluated, including a detailed family history and audiological and radiological examination. The peripheral blood of all patients and their parents was collected for DNA extraction, and then, the exonic and flanking regions were enriched and sequenced using targeted capture and high-throughput sequencing technology. Bioinformatics analyses and the Sanger sequencing were carried out to screen and validate candidate pathogenic variants. The pathogenicity of candidate variants was evaluated by an approach that was based on the standards and guidelines for interpreting genetic variants as proposed by the American College of Medical Genetics and Genomics (ACMG).

Results

Four patients in three families were diagnosed as nonsyndromic ANSD, and all exhibited OTOF gene mutations. Among them, two individuals in family 1 (i.e., fam 1-II-2 and fam 1-II-3) carried homozygous variants c.[2688del];[2688del] (NM_194248.3). Two individuals from family 2 (fam 2-II-1) and family 3 (fam 3-II-4) carried compound heterozygous variants c.[4960G>A];[1469C>G] and c.[2675A>G];[2977_2978del], respectively.

Conclusions

Three unrelated pedigrees with ANSD were caused by pathogenic variants in the OTOF gene. Five mutations were found and included c.2688del, c.2675A>G, c.2977_2978del, c.4960G>A, and c.1469C>G, of which the first two are novel and expanded mutational spectrum of the OTOF gene, thus having important implications for genetic counseling of the family.

Effect of Quiet and Noise on P300 Response in Individuals with Auditory Neuropathy Spectrum Disorder

Introduction  Auditory neuropathy spectrum disorder (ANSD) is a clinical condition in which individuals have normal cochlear responses and abnormal neural responses. There is a lack of evidence in the literature regarding the neural discrimination skill in individuals with ANSD, especially when the signal is presented in the presence of noise. Objectives  The present study was performed with the aim to investigate auditory discrimination skill, in quiet and in the presence of noise, in individuals with ANSD and to compare the findings with normal-hearing individuals. Methods  A total of 30 individuals with normal hearing sensitivity and 30 individuals with ANSD in the age range of 15 to 55 years old, with the mean age of 27.86 years old, were the participants. P300 response was recorded from both groups using syllable pairs /ba/-/da/ in oddball paradigm and the syllable /da/ in repetitive paradigm in quiet and at +10 dB signal-to-noise ratio (SNR). Results  There was significant prolongation in latency and reaction time, and reduction in amplitude of P300 response and sensitivity in both groups with the addition of noise. The topographic pattern analysis showed activation of the central-parietal-occipital region of the brain in individuals with ANSD, whereas activation of the central-parietal region was observed in individuals with normal hearing. The activation was more diffused in individuals with ANSD compared with that of individuals with normal hearing. Conclusion  The individuals with ANSD showed a significantly more adverse effect of noise on the neural discrimination skill than the normal counterpart.

Pediatric Hearing Thresholds Post-bacterial Meningitis

Introduction: Disabling hearing loss as a sequela of bacterial meningitis results from damage to the auditory system. This study was designed to ascertain the hearing thresholds in survivors of bacterial meningitis and the risk factors of hearing loss in childhood bacterial meningitis.

Methodology: One hundred and two children admitted and treated for bacterial meningitis were recruited prospectively along with 102 age- and sex-matched controls who had auditory evaluation using otoacoustic emission and auditory brain stem response tests 48 h prior to hospital discharge. This was also repeated at the follow-up clinic at 1 month after hospital discharge, irrespective of the initial hearing assessment results.

Result: There were 57 (55.9%) males and 45 (44.1%) females among the cases (mean age, 5.34 ± 4.40 years) and 55 (53.9%) males and 47 (46.1%) females among the controls (mean age, 5.31 ± 3.15 years). The prevalence of hearing loss was 30.4% among the cases, while it was 6.9% among the controls. The risk factors of hearing impairment in this study were the presence of anemia, leukocytosis, and hypoglycorrhachia.

Conclusion: Hearing impairment with varying degrees of severity is a frequent complication of bacterial meningitis in children.

Long-term treatment outcomes in children with auditory neuropathy spectrum disorder (ANSD)

INTRODUCTION

The present article shows long-term results in the hearing and speech development of children with auditory neuropathy spectrum disorder (ANSD). Some children were followed up for nearly 20 years, monitoring their progress through childhood into adulthood.

METHODS

This retrospective study examined data from 10 children who were diagnosed and treated at our tertiary referral center. All children were provided with hearing aids and/or cochlear implants. The children's hearing and speech development and their social and educational development were evaluated.

RESULTS

Seven children were provided with cochlear implants on both sides; three children, one of which had single-sided deafness, received hearing aids. All children with cochlear implants on both sides used their devices full-time. Speech perception ranged between 100% and 0% on one side. Five children attended a school for the hearing impaired; four children attended a regular school. Four children attended vocational training.

CONCLUSIONS

At present, there is a lack of literature on the long-term outcomes of treatment in children with ANSD. The data presented show that the hearing and speech development in children with ANSD are significantly heterogeneous. Regular school education and social integration of children with ANSD can be achieved with intensive and supportive rehabilitative methods.

Impaired frequency selectivity and sensitivity to temporal fine structure, but not envelope cues, in children with mild-to-moderate sensorineural hearing loss

Psychophysical thresholds were measured for 8-16 year-old children with mild-to-moderate sensorineural hearing loss (MMHL; N = 46) on a battery of auditory processing tasks that included measures designed to be dependent upon frequency selectivity and sensitivity to temporal fine structure (TFS) or envelope cues. Children with MMHL who wore hearing aids were tested in both unaided and aided conditions, and all were compared to a group of normally hearing (NH) age-matched controls. Children with MMHL performed more poorly than NH controls on tasks considered to be dependent upon frequency selectivity, sensitivity to TFS, and speech discrimination (/bɑ/-/dɑ/), but not on tasks measuring sensitivity to envelope cues. Auditory processing deficits remained regardless of age, were observed in both unaided and aided conditions, and could not be attributed to differences in nonverbal IQ or attention between groups. However, better auditory processing in children with MMHL was predicted by better audiometric thresholds and, for aided tasks only, higher levels of maternal education. These results suggest that, as for adults with MMHL, children with MMHL may show deficits in frequency selectivity and sensitivity to TFS, but sensitivity to the envelope may remain intact.

Evaluation and therapy outcome in children with auditory neuropathy spectrum disorder (ANSD)

OBJECTIVES

The aims of the present study are to: describe diagnostic findings in patients with auditory neuropathy spectrum disorder (ANSD); and demonstrate the outcomes of different therapies like hearing aids (HAs) or cochlear implantation.

METHODS

32 children were diagnosed and treated at our tertiary referral center and provided with HAs or cochlear implants (CIs). All of them underwent free-field or pure-tone audiometry. Additionally, otoacoustic emissions (OAEs), impedance measurements, auditory brainstem responses (ABRs), auditory steady-state responses (ASSR), electrocochleography, and cranial magnetic resonance imaging (cMRI) were all performed. Some patients also underwent genetic evaluation. Following suitable provision pediatric audiological tests, psychological developmental diagnostic and speech and language assessments were carried out at regular intervals in all the children.

RESULTS

OAEs could initially be recorded in most of the children; 17 had no ABRs. The other eight children had a poor ABR morphology. Most of the children had typical, long-oscillating cochlear microphonics (CMs) in their ABRs, which was also observed in all of those who underwent electrocochleography. Eight children were provided with a HA and 17 received a CI. The functional gain was between 32 and 65 decibel (dB) with HAs and between 32 and 50 dB with CI. A speech discrimination level between 35 and 100% was achieved during open-set monosyllabic word tests in quiet with HA or CI. With the Hochmair-Schulz-Moser (HSM) sentence test at 65 dB SPL (sound pressure level), 75% of the children with a CI achieved a speech discrimination in noise score of at least 60% at a signal to noise ratio (SNR) of 5, and four scored 80% or higher. Most of the children (72%) were full-time users of their devices. All the children with a CI used it on a regular basis.

CONCLUSION

Only a few case reports are available in the literature regarding the long-term outcomes of ANSD therapy. The present study reveals satisfactory outcomes with respect to hearing and speech discrimination in children with CIs or HAs. The nearly permanent use of the devices reflects a subjective benefit for the children. Provision with a suitable hearing device depends on audiological results, the speech and language development of an individual child, and any accompanying disorders. Repeated audiological evaluations, interdisciplinary diagnostics, and intensive hearing and speech therapy are essential for adequate rehabilitation of this group of children.

The audiologic profile of patients with Charcot-Marie Tooth neuropathy can be characterised by both cochlear and neural deficits

Objective: The primary goal of this study was to characterise the cochlear and neural components of hearing loss in a large cohort of people with Charcot-Marie Tooth neuropathy who reported hearing difficulties.Design: A full complement of audiologic measures including behavioral, physiologic and subjective assessments were administered.Study sample: Seventy-nine participants completed the study. Forty-four people had CMT1, 27 had CMT2 and four had CMT-INT.Results: Pure tone average was related to age and the absence of high-frequency DPOAE energy, suggesting a strong cochlear component. Acoustic reflexes were often elevated or absent and many participants exhibited abnormal ABR waveforms, suggesting additional neural hearing loss components. Participants with an abnormal or absent ABR wave V exhibited poorer speech perception abilities. There was an association between a prolonged ABR wave I latency and an abnormal or absent ABR wave V with a higher Charcot-Marie Tooth Neuropathy Score (indicating greater disability).Conclusions: The hearing abilities of people with CMT are highly variable. While there were strong neural hearing loss components, speech perception abilities were not disproportionately affected in most participants. Therefore, a hearing aid trial is recommended. ABR responses may be a useful tool for monitoring the progression of CMT over time.

Crafting Polymeric and Peptidic Hydrogels for Improved Wound Healing

Wound healing is a multifaceted biological process involving the replacement of damaged tissues and cellular structures, restoring the skin barrier's function, and maintaining internal homeostasis. Over the past two decades, numerous approaches are undertaken to improve the quality and healing rate of complex acute and chronic wounds, including synthetic and natural polymeric scaffolds, skin grafts, and supramolecular hydrogels. In this context, this review assesses the advantages and drawbacks of various types of supramolecular hydrogels including both polymeric and peptide-based hydrogels for wound healing applications. The molecular design features of natural and synthetic polymers are examined, as well as therapeutic-based and drug-free peptide hydrogels, and the strategies for each system are analyzed to integrate key elements such as biocompatibility, bioactivity, stimuli-responsiveness, site specificity, biodegradability, and clearance.

Deterioration in Distortion Product Otoacoustic Emissions in Auditory Neuropathy Patients With Distinct Clinical and Genetic Backgrounds

OBJECTIVES

Auditory neuropathy (AN) is a clinical disorder characterized by the absence of auditory brainstem response and presence of otoacoustic emissions. A gradual loss of otoacoustic emissions has been reported for some cases of AN. Such cases could be diagnosed as cochlear hearing loss and lead to misunderstanding of the pathology when patients first visit clinics after the loss of otoacoustic emissions. The purpose of this study was to investigate the time course of changes in distortion product otoacoustic emissions (DPOAEs) in association with patients' genetic and clinical backgrounds, including the use of hearing aids.

DESIGN

DPOAE measurements from 31 patients with AN were assessed. Genetic analyses for GJB2, OTOF, and mitochondrial m.1555A> G and m.3243A> G mutations were conducted for all cases, and the analyses for CDH23 and OPA1 were conducted for the selected cases. Patients who were younger than 10 years of age at the time of AN diagnosis were designated as the pediatric AN group (22 cases), and those who were 18 years of age or older were designated as the adult AN group (9 cases). DPOAE was measured at least twice in all patients. The response rate for DPOAEs was defined and analyzed.

RESULTS

The pediatric AN group comprised 10 patients with OTOF mutations, 1 with GJB2 mutations, 1 with OPA1 mutation, and 10 with indefinite causes. Twelve ears (27%) showed no change in DPOAE, 20 ears (46%) showed a decrease in DPOAE, and 12 ears (27%) lost DPOAE. Loss of DPOAE occurred in one ear (2%) at 0 years of age and four ears (9%) at 1 year of age. The time courses of DPOAEs in patients with OTOF mutations were divided into those with early loss and those with no change, indicating that the mechanism for deterioration of DPOAEs includes not only the OTOF mutations but also other common modifier factors. Most, but not all, AN patients who used hearing aids showed deterioration of DPOAEs after the start of using hearing aids. A few AN patients also showed deterioration of DPOAEs before using hearing aids. The adult AN group comprised 2 patients with OPA1 mutations, 2 with OTOF mutations, and 5 with indefinite causes. Four ears (22%) showed no change in DPOAE, 13 ears (72%) showed a decrease, and one ear (6%) showed a loss of DPOAE. Although the ratio of DPOAE decrease was higher in the adult AN group than in the pediatric AN group, the ratio of DPOAE loss was lower in the adult AN group. DPOAE was not lost in all four ears with OPA1 mutations and in all four ears with OTOF mutations in the adult group.

CONCLUSIONS

DPOAE was decreased or lost in approximately 70% of pediatric and about 80% of adult AN patients. Eleven percent of pediatric AN patients lost DPOAEs by 1 year of age. Genetic factors were thought to have influenced the time course of DPOAEs in the pediatric AN group. In most adult AN patients, DPOAE was rarely lost regardless of the genetic cause.

Effect of acoustic features on discrimination ability in individuals with auditory neuropathy spectrum disorder: an electrophysiological and behavioral study

PURPOSE

The present study aimed to investigate the discrimination ability for acoustic cues in individuals with auditory neuropathy spectrum disorder (ANSD) using both behavioral and neural measures and to compare the result with normal hearing individuals.

METHODS

Four naturally produced syllables /ba/, /da/, /ma/ and /pa/ were used to study discrimination skills. They were combined in pairs such that the two syllables differ in acoustic features, that is place (/ba/-/da/), manner (/ba/-/ma/) and voicing (/ba/-/pa/) cues. Thirty individuals with ANSD and 30 individuals with normal hearing sensitivity were the participants. Syllable discrimination skill was assessed using behavioral (reaction time, sensitivity and D-prime) and neural (P300) measures.

RESULTS

There was prolongation in latency and reduction in amplitude of P300 in individuals with ANSD compared to individuals with normal hearing sensitivity. Individuals with ANSD showed better discrimination skill for stimulus pairs differing in the manner followed by place and the least perceived was voicing information.

CONCLUSION

Discrimination ability of individuals with ANSD is found to be affected as evident on behavioral and neural measures. The discrimination ability varies with acoustic features of speech.

Auditory and speech performance in cochlear implanted ANSD children

BACKGROUND

Auditory neuropathy spectrum disorder (ANSD) is a distinct type of SNHL that is characterized by the presence of otoacoustic emissions and/or cochlear microphonics. Cochlear implantation was initially not recommended for ANSD children, later studies showed variable outcomes among those subjects.

OBJECTIVE

To assess the auditory and speech performance of cochlear implanted children with auditory neuropathy spectrum disorder (ANSD) and to compare these results to those obtained from cochlear implanted children with sensorineural hearing loss (SNHL) Material and methods: 18 cochlear implanted children with ANSD and 40 cochlear implanted children with SNHL were included in this study. Auditory and speech performance results were compared across both subject groups using the Category of Auditory Performance (CAP) and Speech Intelligibility Rate (SIR) tests, with measurements recorded one year post implantation.

RESULTS

Cochlear implanted children with ANSD showed clinically significant improvements that were comparable to those observed from cochlear implanted subjects without ANSD.

CONCLUSIONS

Children with ANSD benefit from early cochlear implantation and can reach similar auditory and speech performance results as that achieved by children without ANSD.

Findings from aetiological investigation of Auditory Neuropathy Spectrum Disorder in children referred to cochlear implant programs

OBJECTIVES

Auditory neuropathy spectrum disorder (ANSD) is an audiological diagnosis characterised by hearing dysfunction in the presence of intact outer hair cell function in the cochlea. ANSD is thought to account for 7-10% of all childhood permanent hearing impairment, and can result from a range of pathological processes. This paper describes the rationale, methods and findings from the aetiological investigation of ANSD.

METHODS

Retrospective audit of four cochlear implant programmes.

RESULTS

97 patients were identified. 79% of patients were identified before the age of one. Prematurity and jaundice were the most frequently identified aetiological factors. 33 patients had cochlear nerve deficiency on imaging. Genetic diagnoses identified included otoferlin, SX010 gene, connexin 26 and A1FM1 gene mutations. ANSD was seen in conjunction with syndromes including Kallman syndrome, CHARGE syndrome, X-linked deafness, SOTOS syndrome, Brown Vieletto Van Laere syndrome, and CAPOS syndrome.

DISCUSSION

We present a two-level system of aetiological investigation that is clinically practical. Patients with ANSD sufficiently severe to consider cochlear implantation are generally identified at an early age. Aetiological investigation is important to guide prognosis and identify comorbidity.

CONCLUSION

Prematurity and jaundice are the most commonly identified aetiological factors in ANSD. Imaging findings identify crucial factors in a significant minority. An important minority may have genetic and syndromic diagnoses that require further management.

Novel OTOF gene mutations identified using a massively parallel DNA sequencing technique in DFNB9 deafness

OBJECTIVES

This study examined the causative genes in patients with early-onset hearing loss from two Chinese families.

METHOD

Massively parallel sequencing, designed to screen all reported genes associated with hearing loss, was performed in a large number of Chinese individuals with hearing loss. This study enrolled patients with the same OTOF mutation and analyzed their phenotype-genotype correlations.

RESULTS

Three novel OTOF mutations (NM_001287489) [c.1550T > C (p.L517P), c.5900_5902delTCA (p.I1967del), and c.4669_4677delCTGACGGTG (p.L1557-V1559del)] were found to be the cause of hearing loss in five patients. In family AH-890, the affected subject homozygous for p.L517P presented with profound hearing loss, while the affected sisters compound heterozygous for p.L517P and p.I1967del had mild-to-moderate hearing loss. The patient with hearing loss in family SD-345 was found to be compound heterozygous for p.L517P and p.L1557-V1559del.

CONCLUSION

Three presumably pathogenic mutations in the OTOF gene were detected for the first time, including the first pathogenic mutation detected in the TM domain. In addition to expanding the spectrum of OTOF mutations resulting in DFNB9, our findings present the diversity of its clinical presentation and indicate that MPS is an efficient approach to identify the causative genes associated with hereditary hearing loss.

An OTOF Frameshift Variant Associated with Auditory Neuropathy Spectrum Disorder

Background:

Auditory Neuropathy Spectrum Disorder (ANSD) is manifested as impairment of auditory nerve activity but preservation of the outer hair cell function.

Objective:

This study was to detect the disease-causing gene and variant(s) in a Chinese ANSD family.

Methods:

A four-generation consanguineous Chinese ANSD family and 200 unrelated healthy controls were enrolled. Exome sequencing and Sanger sequencing were applied to identify the genetic basis for ANSD in this family.

Results:

Exome sequencing detected a c.1236delC variant of the otoferlin gene in an apparently homozygous state. Sanger sequencing confirmed that the variant co-segregating with the phenotype of hearing impairments in this family. The variant was not detected in 200 healthy controls. The c.1236delC alteration may result in a truncated otoferlin missing the C2C-C2F domains and the C-terminal transmembrane domain, and thus severely damages Ca2+-dependent synaptic vesicle fusion and targeting function of the otoferlin.

Conclusion:

Our study suggested that the c.1236delC alteration in the otoferlin gene may be the disease-causing variant in this family, and also shed new light on genetic counseling to this ANSD family.

Dynamics of Speech Perception in the Auditory-Visual Mode: An Empirical Evidence for the Management of Auditory Neuropathy Spectrum Disorders

BACKGROUND AND OBJECTIVES

The present study probed into the relative and combined contribution of auditory and visual modalities in the speech perception of individuals with auditory neuropathy spectrum disorders (ANSD). Specifically, the identification scores of consonantvowel (CV) syllables, visual enhancement (VE), and auditory enhancement in different signal to noise ratios (SNRs) were compared with that of the control group. Subjects and.

METHODS

The study used a repeated measure standard group comparison research design. Two groups of individuals in the age range of 16 to 35 years participated in the study. The clinical group included 35 participants diagnosed as ANSD, while the control group had 35 age and gender matched individuals with typical auditory abilities. The participants were assessed for CV syllable identification in auditory only (A), visual only (V), and auditory-visual (AV) modalities. The syllables were presented in quiet and at 0 dB SNR.

RESULTS

The speech identification score was maximum in AV condition followed by A-condition and least in V condition. This was true in both the groups. The individuals with ANSD were able to make better use of visual cues than the control group, as evident in the VE score.

CONCLUSIONS

The dynamics of speech perception in the AV mode is different between ANSD and control. There is definite benefit of auditory as well as visual cues to individuals with ANSD, suggesting the need to facilitate both the modalities as part of the audiological rehabilitation. Future studies can focus on independently facilitating the two modalities and testing the benefits in the AV mode of speech perception in individuals with ANSD.

A case of auditory neuropathy revealed by OTOF gene mutation analysis in a junior high school girl

Objective

Congenital auditory neuropathy (AN) affects hearing and speech development. The degree of hearing difficulty in congenital AN varies as a function of pathology at the inner ear hair cell (IHC) synapses or the auditory nerve. We report a case of a Chinese girl with AN revealed by OTOF (otoferlin) gene mutation analysis who had only a mild hearing loss.

Patient

A 13-year-old Chinese girl was diagnosed as having congenital AN on the basis of OTOF gene mutation analysis. She manifest a mild sensorineural hearing loss with 50% maximum monosyllable speech discrimination rate, normal DPOAEs (distortion product otoacoustic emissions) beyond ambient noise levels, only SPs (summating potentials) evoked during ECoG (electrocochleography) and absent ABRs (auditory evoked brainstem responses) bilaterally to clicks presented at 100 dBnHL. She was able to effectively communicate with others by speech reading owing to her mild hearing loss. Moreover, bilateral hearing aids helped her to communicate.

Conclusions

Our patient was demonstrated to have a mutation on the OTOF gene. Nevertheless, she was able to communicate using auditory visual speech reading in spite of a mild auditory threshold elevation probably due to partial pathology at the IHC synapses or in the auditory nerve.

Cochlear Gene Therapy for Sensorineural Hearing Loss: Current Status and Major Remaining Hurdles for Translational Success

Sensorineural hearing loss (SNHL) affects millions of people. Genetic mutations play a large and direct role in both congenital and late-onset cases of SNHL (e.g., age-dependent hearing loss, ADHL). Although hearing aids can help moderate to severe hearing loss the only effective treatment for deaf patients is the cochlear implant (CI). Gene- and cell-based therapies potentially may preserve or restore hearing with more natural sound perception, since their theoretical frequency resolution power is much higher than that of cochlear implants. These biologically-based interventions also carry the potential to re-establish hearing without the need for implanting any prosthetic device; the convenience and lower financial burden afforded by such biologically-based interventions could potentially benefit far more SNHL patients. Recently major progress has been achieved in preclinical studies of cochlear gene therapy. This review critically evaluates recent advances in the preclinical trials of gene therapies for SNHL and the major remaining challenges for the development and eventual clinical translation of this novel therapy. The cochlea bears many similarities to the eye for translational studies of gene therapies. Experience gained in ocular gene therapy trials, many of which have advanced to clinical phase III, may provide valuable guidance in improving the chance of success for cochlear gene therapy in human trials. A discussion on potential implications of translational knowledge gleaned from large numbers of advanced clinical trials of ocular gene therapy is therefore included.

Cortical processing of speech in individuals with auditory neuropathy spectrum disorder

OBJECTIVE

Auditory neuropathy spectrum disorder (ANSD) is a condition where cochlear amplification function (involving outer hair cells) is normal but neural conduction in the auditory pathway is disordered. This study was done to investigate the cortical representation of speech in individuals with ANSD and to compare it with the individuals with normal hearing.

DESIGN

Forty-five participants including 21 individuals with ANSD and 24 individuals with normal hearing were considered for the study. Individuals with ANSD had hearing thresholds ranging from normal hearing to moderate hearing loss. Auditory cortical evoked potentials-through odd ball paradigm-were recorded using 64 electrodes placed on the scalp for /ba/-/da/ stimulus. Onset cortical responses were also recorded in repetitive paradigm using /da/ stimuli. Sensitivity and reaction time required to identify the oddball stimuli were also obtained.

RESULT

Behavioural results indicated that individuals in ANSD group had significantly lower sensitivity and longer reaction times compared to individuals with normal hearing sensitivity. Reliable P300 could be elicited in both the groups. However, a significant difference in scalp topographies was observed between the two groups in both repetitive and oddball paradigms. Source localization using local auto regressive analyses revealed that activations were more diffuses in individuals with ANSD when compared to individuals with normal hearing sensitivity.

CONCLUSION

Results indicated that the brain networks and regions activated in individuals with ANSD during detection and discrimination of speech sounds are different from normal hearing individuals. In general, normal hearing individuals showed more focused activations while in individuals with ANSD activations were diffused.

International consensus (ICON) on audiological assessment of hearing loss in children

The prevalence of hearing loss in newborns and infants is estimated between 1 to 3.47 cases per 1000 live births. Early diagnosis and rehabilitation of congenital hearing loss are mandatory in order to achieve a satisfactory linguistic and cognitive development. Without appropriate opportunities to learn language, these children will fall behind their normal hearing peers in communication, cognition, reading and socio-emotional development. After promising results, neonatal screening for hearing loss and audiological evaluation are becoming more extensively carried out. In planning universal neonatal hearing screening programs, transient evoked otoacoustic emissions and auditory brainstem responses are the gold standard for the screening and diagnosis program. However, there is no consensus regarding the use of audiometry and other electrophysiological tests (such as auditory steady-state responses) in current practices. Several screening and audiological assessment procedures have been described and advocated all around the world. But, a systematic scheme of performing diagnosis in the pediatric audiology population is lacking. A consensus conference was held at the International Federation of Oto-rhino-laryngological Societies Congress, in June 2017, to discuss the different current practices and to identify the best neonatal hearing screening and audiological assessment management. This article is intended to provide professionals with recommendations about the "best practice" based on consensus opinion of the session's speakers, and a review of the literature on the efficacy of various assessment options for children with hearing loss.

Is tinnitus a major concern in individuals with auditory neuropathy spectrum disorder? - Questionnaire based study

Objective

Our study attempted to determine if tinnitus is a major concern in individuals with auditory neuropathy spectrum disorder (ANSD). The study also attempted to determine if pure tone average (PTA), speech identification scores (SIS), or reported duration of hearing loss could predict the tinnitus severity and functional handicap in adults with ANSD.

Methods

Tinnitus functional index (TFI) and tinnitus severity index (TSI) were administered on all the 40 participants diagnosed with ANSD.

Results

The mean TFI score was 44.3, which suggested moderate degree of tinnitus related functional impairment. The mean TSI score was found to be 33.3, which suggested moderate degree of severity in individuals with ANSD. The study also showed that tinnitus causes functional impairment that leading to sleep disturbances, emotional problems, and affecting the quality of life. There was no significant correlation (P > 0.05) between PTA, SIS, reported onset of hearing loss and scores of TFI or TSI.

Conclusion

Tinnitus in individuals with ANSD should also be given priority during assessment and provide appropriate tinnitus management.

AUNA2: A Novel Type of Non-Syndromic Slowly Progressive Auditory Synaptopathy/Auditory Neuropathy with Autosomal-Dominant Inheritance

BACKGROUND

Auditory synaptopathy/neuropathy (AS/AN) is a heterogeneous disorder, which may be caused by environmental factors like postnatal hyperbilirubinemia or by genetic factors. The genetic forms are subdivided into syndromic and non-syndromic types, and show different inheritance patterns with a strong preponderance of autosomal-recessive forms. To date, only a single locus for non-syndromic autosomal-dominant AS/AN (AUNA1) has been reported in a single family, in which a non-coding DIAPH3 mutation was subsequently described as causative.

MATERIALS AND METHODS

Here, we report detailed clinical data on a large German AS/AN family with slowly progressive postlingual hearing loss. Affected family members developed their first symptoms in their second decade. Moderate hearing loss in the fourth decade then progressed to profound hearing impairment in older family members. Comprehensive audiological and neurological tests were performed in the affected family members. Genetic testing comprised linkage analyses with polymorphic markers and a genome-wide linkage analysis using the Affymetrix GeneChip® Human Mapping 250K.

RESULTS AND CONCLUSION

We identified a large family with autosomal-dominant AS/AN. By means of linkage analyses, the AUNA1 locus was excluded, and putatively linked regions on chromosomal bands 12q24 and 13q34 were identified as likely carrying the second locus for autosomal-dominant AS/AN (AUNA2). AUNA2 is associated with a slowly progressive postlingual hearing loss without any evidence for additional symptoms in other organ systems.

Modiolar ossification in paediatric patients with auditory neuropathy

Objective:

To describe our finding of increased ossification of the modiolus in paediatric patients with auditory neuropathy who met criteria for cochlear implantation.

Methods:

A retrospective case series with a comparison group at a tertiary referral centre is described. Seven paediatric patients with auditory neuropathy who met criteria for and underwent cochlear implantation were identified. Fifteen paediatric implantees with bilateral profound sensorineural hearing loss were included as the comparison group. All patients underwent pre-operative computed tomography. Attenuation at the modiolus was measured in all subjects by a neuroradiologist blinded to clinical information.

Results:

Attenuation values in the modiolus in the auditory neuropathy patients (mean ± standard deviation = 796.2 ± 53.0 HU) was statistically significantly higher than in the comparison sensorineural hearing loss patients (267.1 ± 45.6 HU; p < 0.05, t-test).

Conclusion:

Patients with auditory neuropathy who meet criteria for cochlear implantation demonstrate significantly higher modiolar attenuation on computed tomography imaging, consistent with increased ossification at the modiolus.

Prevalence of vestibular symptoms in individuals with auditory neuropathy spectrum disorder - A retrospective study

The objective of the study was to retrospectively determine the prevalence of vestibular symptoms in individuals with auditory neuropathy spectrum disorder (ANSD). It was also attempted to determine the prevalence of vestibular symptoms and factors (gender and age of reported hearing loss) that could affect the prevalence in individuals with ANSD. The vestibular symptoms reported in the case history were analyzed in individuals diagnosed with ANSD. The symptoms reported by a total of 316 individuals (185 females and 131 males) with ANSD were analyzed. The result of the study showed that one in five individuals with ANSD reported at least one of the vestibular symptom. The vestibular symptoms were in more females and in individuals with earlier onset of hearing loss. The result of the study supports that there is a vestibular damage in individuals with ANSD. However, it is essential to carry out prospective studies validating these vestibular symptoms with objective vestibular tests before generalizing the results.

Audiological Profile of Adult Persons with Auditory Neuropathy Spectrum Disorders

BACKGROUND AND OBJECTIVES

The auditory profile of a large number of persons with late onset auditory neuropathy spectrum disorder (ANSD) is recently described in the Indian context. The purpose of study was 1) to profile data on routine audiological parameters, cortical evoked potentials, and temporal processing, 2) to analyze the benefit from hearing aids for persons with ANSD, and 3) to understand the association between benefit from hearing aids and auditory profile.

SUBJECTS AND METHODS

Thirty-eight adults with late onset ANSD and a matched group of 40 normally hearing adults participated in the study. Basic audiological tests, recording of cortical evoked potentials, and temporal processing tests were carried out on both groups of participant while only persons with ANSD were fitted with hearing aid.

RESULTS

Subjects in the two groups were significantly different on all the audiological parameters. ANSD group seemed to benefit from hearing aids variably. The mean amplitude of N2 was significantly different between normally-hearing participants and patients with ANSD.

CONCLUSIONS

Residual temporal processing, particularly amplitude modulation detection seems to be associated with benefit from hearing aids in patients with ANSD.

Language and hearing outcomes of preterm infants

Multiple factors including degree of prematurity, neonatal morbidities, illness severity, hearing status, gender, language environment in the neonatal intensive care unit and in the home, maternal education level, social and environmental status of the family, and access to early intervention all contribute to the language outcomes of extremely preterm infants with and without hearing loss. Early screening, early diagnosis, and early intervention services by 6 months of age are necessary to optimize the language outcomes of preterm infants with permanent hearing loss. There is increasing evidence of the potential for improved language skills with increasing age of extreme preterm infants and infants with hearing loss.

Auditory neuropathy in Brown-Vialetto-Van Laere syndrome due to riboflavin transporter RFVT2 deficiency

AIM

Mutations in the genes encoding the riboflavin transporters RFVT2 and RFVT3 have been identified in Brown-Vialetto-Van Laere syndrome, a neurodegenerative disorder characterized by hearing loss and pontobulbar palsy. Treatment with riboflavin has been shown to benefit individuals with the phenotype of RFVT2 deficiency. Understanding the characteristics of hearing loss in riboflavin transporter deficiency would enable early diagnosis and therapy.

METHOD

We performed hearing assessments in seven children (from four families) with RFVT2 deficiency and reviewed results from previous assessments. Assessments were repeated after 12 months and 24 months of riboflavin therapy and after cochlear implantation in one individual.

RESULTS

Hearing loss in these individuals was due to auditory neuropathy spectrum disorder (ANSD). Hearing loss was identified between 3 years and 8 years of age and progressed rapidly. Hearing aids were not beneficial. Riboflavin therapy resulted in improvement of hearing thresholds during the first year of treatment in those with recent-onset hearing loss. Cochlear implantation resulted in a significant improvement in speech perception in one individual.

INTERPRETATION

Riboflavin transporter deficiency should be considered in all children presenting with an auditory neuropathy. Speech perception in children with ANSD due to RFVT2 deficiency may be significantly improved by cochlear implantation.

Molecular study of patients with auditory neuropathy

Auditory neuropathy is a type of hearing loss that constitutes a change in the conduct of the auditory stimulus by the involvement of inner hair cells or auditory nerve synapses. It is characterized by the absence or alteration of waves in the examination of brainstem auditory evoked potentials, with otoacoustic and/or cochlear microphonic issues. At present, four loci associated with non‑syndromic auditory neuropathy have been mapped: Autosomal recessive deafness‑9 [DFNB9; the otoferlin (OTOF) gene] and autosomal recessive deafness‑59 [DFNB59; the pejvakin (PJVK) gene], associated with autosomal recessive inheritance; the autosomal dominant auditory neuropathy gene [AUNA1; the diaphanous‑3 (DIAPH3) gene]; and AUNX1, linked to chromosome X. Furthermore, mutations of connexin 26 [the gap junction β2 (GJB2) gene] have also been associated with the disease. OTOF gene mutations exert a significant role in auditory neuropathy. In excess of 80 pathogenic mutations have been identified in individuals with non‑syndromic deafness in populations of different origins, with an emphasis on the p.Q829X mutation, which was found in ~3% of cases of deafness in the Spanish population. The identification of genetic alterations responsible for auditory neuropathy is one of the challenges contributing to understand the molecular bases of the different phenotypes of hearing loss. Thus, the present study aimed to investigate molecular changes in the OTOF gene in patients with auditory neuropathy, and to develop a DNA chip for the molecular diagnosis of auditory neuropathy using mass spectrometry for genotyping. Genetic alterations were investigated in 47 patients with hearing loss and clinical diagnosis of auditory neuropathy, and the c.35delG mutation in the GJB2 gene was identified in three homozygous patients, and the heterozygous parents of one of these cases. Additionally, OTOF gene mutations were tracked by complete sequencing of 48 exons, although these results are still preliminary. Studying the genetic basis of auditory neuropathy is of utmost importance for obtaining a differential diagnosis, developing more specific treatments and more accurate genetic counseling.

High frequency of OTOF mutations in Chinese infants with congenital auditory neuropathy spectrum disorder

Auditory neuropathy spectrum disorder (ANSD) is one of the most common diseases leading to hearing and speech communication barriers in infants and young children. The OTOF gene is the first gene identified for autosomal recessive non-syndromic ANSD, and patients with OTOF mutations have shown marked improvement of auditory functions from the cochlear implantation, but the true involvement of OTOF mutations in Chinese ANSD patients is still unknown which precludes the effective management of this disease. Here, we investigated the contribution of OTOF mutations to congenital ANSD patients in China. In all, 37 infants and young Children with ANSD were screened for all the exons of OTOF gene, of them 34 patients had no neonatal risk factors who were considered as congenital ANSD. The clinical manifestation and audiometric features were also investigated and compared in patients with and without OTOF mutations. In all, 14 of these subjects were shown to carry two or three mutant alleles of OTOF with the high frequency of 41.2% in congenital ANSD patients. In total, 15 novel pathogenic mutations and 10 reported mutations were identified. Our results confirmed that mutations in OTOF gene were a major cause of congenital ANSD in China. Identification of OTOF mutations can facilitate diagnosis, clinical intervention and counseling for congenital ANSD.