Auditory neuropathy/auditory dys-synchrony detected by universal newborn hearing screening

Adjunct Methods for Alzheimer's Disease Detection: A Review of Auditory Evoked Potentials

The auditory afferent pathway as a clinical marker of Alzheimer's disease (AD) has sparked interest in investigating the relationship between age-related hearing loss (ARHL) and AD. Given the earlier onset of ARHL compared to cognitive impairment caused by AD, there is a growing emphasis on early diagnosis and intervention to postpone or prevent the progression from ARHL to AD. In this context, auditory evoked potentials (AEPs) have emerged as a widely used objective auditory electrophysiological technique for both the clinical diagnosis and animal experimentation in ARHL due to their non-invasive and repeatable nature. This review focuses on the application of AEPs in AD detection and the auditory nerve system corresponding to different latencies of AEPs. Our objective was to establish AEPs as a systematic and non-invasive adjunct method for enhancing the diagnostic accuracy of AD. The success of AEPs in the early detection and prediction of AD in research settings underscores the need for further clinical application and study.

Axonal polyneuropathy and ataxia in children: consider Perrault Syndrome, a case report

BACKGROUND

Perrault Syndrome (PRLTS) is a rare, autosomal recessive disorder that presents with bilateral sensorineural hearing loss in all patients and gonadal dysfunction in females. It has been linked to variants in CLPP, ERAL1, HARS2, HSD17B4, LARS2, and TWNK genes. All reported cases due to TWNK variants have included neurologic features, such as ataxia and axonal sensorimotor neuropathy.

CASE PRESENTATION

A 4.5-year-old female presented to neuromuscular clinic due to ataxia. Neurological examination revealed truncal ataxia and steppage gait, reduced deep tendon reflexes, and axonal sensorimotor polyneuropathy. Auditory brainstem response testing revealed an uncommon type of sensorineural hearing loss known as auditory neuropathy/auditory synaptopathy (AN/AS) affecting both ears. Magnetic Resonance Imaging (MRI) revealed subtle cauda equina enhancement. Nerve conduction studies led to a provisional diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP), and intravenous immune globulin (IVIG) was initiated. The patient was unresponsive to treatment, thus whole exome testing (WES) was conducted in tandem with IVIG weaning. WES revealed a compound heterozygous state with two variants in the TWNK gene and a diagnosis of Perrault Syndrome was made.

CONCLUSIONS

Perrault Syndrome should be considered in the differential for children who present with bilateral sensorineural hearing loss, axonal polyneuropathy, and ataxia. Further examination includes testing for ovarian dysgenesis and known PRLTS genetic variants.

Auditory Neuropathy/Auditory Synaptopathy

Patients with auditory neuropathy (AN)/auditory synaptopathy (AS) present unique evaluation and management challenges. Communication ability using auditory stimuli varies among patients, with particular difficulty understanding speech in noise. Auditory physiologic responses are key to accurate identification and monitoring of patients with AN/AS. Management approaches should consider individual variation and the possibility of change over time. Many patients with accurately characterized AN/AS demonstrate success with cochlear implants. Areas of discovery, including understanding of synaptic and neural mechanisms, genotype/phenotype relationships, and use of cochlear and cortical evoked potentials, will promote accurate clinical evaluation and management of infants, children, and adults with AN/AS.

Comprehensive evaluation of risk factors for neonatal hearing loss in a large Brazilian cohort

OBJECTIVES

To determine the incidence and risk factors of hearing loss (HL) in Brazilian neonates.

STUDY DESIGN

11,900 neonates were screened for hearing and congenital CMV (cCMV). Low and high-risk babies who did not pass their hearing screening and infants with cCMV were scheduled for a diagnostic audiologic evaluation.

RESULTS

The incidence of HL was 2 per 1000 live-born infants (95% CI: 1-3). HL was higher in high-risk neonates than in low risk babies (18.6 vs. 0.3/1000 live births, respectively). Among infants exposed to isolated risk factors, association of HL with craniofacial abnormalities/syndromes (RR = 24.47; 95% CI: 5.9-100.9) and cCMV (RR = 9.54; 95% CI: 3.3-27.7) were observed. HL was 20 to 100-fold more likely in neonates exposed to ototoxic drugs in combination with cCMV or craniofacial/congenital anomalies.

CONCLUSIONS

Strategies for the prevention of cCMV and exposure to ototoxic drugs may decrease the incidence of HL in this population.

Novel Mutation in AIFM1 Gene Associated with X-Linked Deafness in a Moroccan Family

INTRODUCTION

Auditory neuropathy is a hearing disorder where outer hair cell function within the cochlea is normal, but inner hair cell and/or the auditory nerve function is disrupted. It is a heterogeneous disorder, which can have either congenital or acquired causes.

METHODS

We found a disease-segregating mutation in the X-linked AIFM1 gene through whole-exome sequencing, encoding the apoptosis-inducing factor mitochondrion-associated 1.

RESULTS

The impact of the c.1045A>G; p.(Ser349Gly) mutation on the AIFM1 protein was predicted using different bioinformatics tools. The pedigree analysis in the examined family was consistent with X-linked dominant inheritance.

DISCUSSION/CONCLUSION

To our knowledge, this is the first study that identifies a mutation in the AIFM1 gene in Moroccan patients suffering from X-linked auditory neuropathy.

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.

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.

Study of cochlear microphonic potentials in auditory neuropathy

Introduction

Auditory Neuropathy/Dyssynchrony is a disorder characterized by the presence of Otoacoustic Emissions and Cochlear Microphonic Potentials, an absence or severe alteration of Brainstem Evoked Auditory Potential, auditory thresholds incompatible with speech thresholds and altered acoustic reflexes. The study of the Cochlear Microphonic Potential appears to be the most important tool for an accurate diagnosis of this pathology.

Objective

Determine the characteristics of the Cochlear Microphonic in Auditory Neuropathy/Dyssynchrony using an integrative review.

Methods

Bibliographic survey of Pubmed and Bireme platforms and MedLine, LILACS and SciELO data banks, with standardized searches up to July 2014, using keywords. Criteria were established for the selection and assessment of the scientific studies surveyed, considering the following aspects: author, year/place, degree of recommendation/level of scientific evidence, objective, sample, age range, mean age, tests, results and conclusion.

Results

Of the 1959 articles found, 1914 were excluded for the title, 20 for the abstract, 9 for the text of the article, 2 for being repeated and 14 were selected for the study.

Conclusion

The presence of the Cochlear Microphonic is a determining finding in the differential diagnosis of Auditory Neuropathy/Dyssynchrony. The protocol for the determination of Cochlear Microphonic must include the use of insert earphones, reverse polarity and blocking the stimulus tube to eliminate electrical artifact interference. The amplitude of the Cochlear Microphonic in Auditory Neuropathy/Dyssynchrony shows no significant difference from that of normal individuals. The duration of the Cochlear Microphonic is longer in individuals with Auditory Neuropathy/Dyssynchrony.

Evaluation of cochlear nerve diameter and cross-sectional area in ANSD patients by 3.0-Tesla MRI

CONCLUSIONS

The size of cochlear nerve (CN) is atrophic in adult auditory neuropathy spectrum disorder (ANSD) patients compared with non-ANSD sensorineural hearing loss (SNHL) patients and normal hearing subjects, and CN deficiency is one of the lesions for ANSD patients.

OBJECTIVES

To evaluate the dimensions of CN in adult ANSD patients on magnetic resonance imaging (MRI) and confirm the hypothesis that CN deficiency is one of the lesions for ANSD patients.

METHODS

Medical records and MRI of 24 adult ANSD patients reviewed retrospectively and 20 non-ANSD SNHL and 24 volunteers with normal hearing were recruited as control groups. The long diameter (LD), short diameter (SD), and cross-sectional area (CSA) of CN and facial nerve (FN) were measured.

RESULTS

Among the 24 ANSD patients, this study was able to reconstruct and measure the CN of 91.7% (22/24, total 43 ears) of patients and FN of 83.3% (20/24, total 38 ears) of patients. The mean values and standard deviations of LD, SD, and CSA of CN in ANSD patients were 0.65 ± 0.20 mm, 0.44 ± 0.15 mm, and 0.30 ± 0.19 mm(2), respectively. They were significantly smaller in ANSD patients than in control groups (p < 0.001).

Auditory neuropathy spectrum disorder (ANSD) in referrals from neonatal hearing screening at a well-baby clinic

Auditory neuropathy spectrum disorder (ANSD) is a particular kind of hearing disorder characterised by normal outer hair cell function and abnormal or absent auditory brain stem responses. Little data are available regarding the prevalence of this condition in healthy newborns. We performed a retrospective medical records review of 791 referrals from universal neonatal hearing screening (UNHS) at a well-baby clinic to investigate the prevalence of ANSD. Hearing screening was performed by automated auditory brain stem response (ABR) testing. A diagnosis of ANSD was established when ABR tracings were absent in the presence of otoacoustic emissions and/or a cochlear microphonic. Amongst 201 infants with confirmed congenital hearing loss, 13 infants were diagnosed with ANSD. The condition was unilateral in six and bilateral in seven infants. A risk factor for hearing loss could be identified in three infants. Abnormalities on magnetic resonance imaging were found in six infants; five of them had cochlear nerve deficiency.

CONCLUSION

The prevalence of ANSD was 6.5 % amongst well babies with confirmed congenital hearing loss identified through UNHS. The estimated incidence of ANSD in our population of newborns at the well-baby clinic was 0.09/1000 live births. Magnetic resonance revealed an underlying anatomical abnormality in about half of the patients.

WHAT IS KNOWN

• Auditory neuropathy dyssynchrony spectrum disorder (ANSD) is a particular form of hearing loss, mostly encountered in neonatal intensive care unit (NICU) graduates. • Little data are available on the prevalence and risk factors for ANSD in healthy newborns. What is new: • The estimated prevalence of ANSD in healthy newborns is 0.09/1000 live births. • In about half of the healthy newborns with ANSD, a structural abnormality was detected on magnetic resonance imaging of the posterior fossa/brain.

Auditory evoked potentials in a newborn Wistar rat model of hyperbilirubinemia

Introduction

Hyperbilirubinemia is a common health problem in newborns. Its effects can be different according to the level and duration of the hyperbilirubinemia. The toxic effect of bilirubin on the auditory system can be seen as a sensory neural hearing loss or auditory neuropathy spectrum disorder (ANSD).

Objective

The purpose of our study was to determine the effects of toxic bilirubin level on the auditory system by using Auditory Brainstem Response audiometry.

Methods

Rats are used as animal models due to their low cost and easy attainability. Auditory Brainstem Response was used for auditory assessment. In this study, three groups were established: experimental, control and placebo groups.

Results

In the experimental group, which consists of rats with hyperbilirubinemia, sensory neural hearing loss was found bilaterally in 4 rats (66.67%) and unilaterally in 2 rats (16.67%) and auditory neuropathy spectrum disorder was found unilaterally in 1 rat (8.33%). Auditory Brainstem Response thresholds were significantly elevated compared to control and placebo groups (p < 0.05).

Conclusion

Hyperbilirubinemia of newborn rats may result both in sensory neural hearing loss and auditory neuropathy spectrum disorder.

Factors Affecting the Variation of Maximum Speech Intelligibility in Patients With Sensorineural Hearing Loss Other Than Apparent Retrocochlear Lesions

OBJECTIVES

To examine the relationship between speech intelligibilities among the similar level of hearing loss and threshold elevation of the auditory brainstem response (ABR).

METHODS

The relationship between maximum speech intelligibilities among similar levels of hearing loss and relative threshold elevation of the click-evoked ABR (ABR threshold - pure tone average at 2,000 and 4,000 Hz) was retrospectively reviewed in patients with sensorineural hearing loss (SNHL) other than apparent retrocochlear lesions as auditory neuropathy, vestibular schwannoma and the other brain lesions.

RESULTS

Comparison of the speech intelligibilities in subjects with similar levels of hearing loss found that the variation in maximum speech intelligibility was significantly correlated with the threshold elevation of the ABR.

CONCLUSION

The present results appear to support the idea that variation in maximum speech intelligibility in patients with similar levels of SNHL may be related to the different degree of dysfunctions of the inner hair cells and/or cochlear nerves in addition to those of outer hair cells.

Auditory Neuropathy/Dys-Synchrony Disorder: Diagnosis and Management

Auditory neuropathy/dys-synchrony disorder affects neural responses, either directly or indirectly. Patients may demonstrate good ability to detect sound, but have significant difficulty listening in noise. Clinical auditory physiologic measures are used to characterize cochlear, eighth nerve, and brainstem function, and are needed to accurately identify this disorder. Cochlear implants provide benefit to many patients, and some patients derive benefit from amplification. This disorder can be identified and managed in infants, may have later onset, may be a part of a syndrome, and may include fluctuation in hearing ability.

Mutations in apoptosis-inducing factor cause X-linked recessive auditory neuropathy spectrum disorder

Background

Auditory neuropathy spectrum disorder (ANSD) is a form of hearing loss in which auditory signal transmission from the inner ear to the auditory nerve and brain stem is distorted, giving rise to speech perception difficulties beyond that expected for the observed degree of hearing loss. For many cases of ANSD, the underlying molecular pathology and the site of lesion remain unclear. The X-linked form of the condition, AUNX1, has been mapped to Xq23-q27.3, although the causative gene has yet to be identified.

Methods

We performed whole-exome sequencing on DNA samples from the AUNX1 family and another small phenotypically similar but unrelated ANSD family.

Results

We identified two missense mutations in AIFM1 in these families: c.1352G>A (p.R451Q) in the AUNX1 family and c.1030C>T (p.L344F) in the second ANSD family. Mutation screening in a large cohort of 3 additional unrelated families and 93 sporadic cases with ANSD identified 9 more missense mutations in AIFM1. Bioinformatics analysis and expression studies support this gene as being causative of ANSD.

Conclusions

Variants in AIFM1 gene are a common cause of familial and sporadic ANSD and provide insight into the expanded spectrum of AIFM1-associated diseases. The finding of cochlear nerve hypoplasia in some patients was AIFM1-related ANSD implies that MRI may be of value in localising the site of lesion and suggests that cochlea implantation in these patients may have limited success.

An auditory health program for neonates in ICU and/or intermediate care settings

Auditory screening and early identification and management of patients with hearing loss improve the development prospects of infants.

OBJECTIVE

To analyze the outcomes produced by an Auditory Health Program in neonates managed in an intensive care unit.

METHOD

This prospective cross-sectional study enrolled neonates referred to the neonatal care unit at hospital CAISM/Unicamp with stays lasting for 48 hours and more within a period of 13 months. Automated monitoring of brainstem auditory evoked potentials was used in the auditory screening of neonates at the time of discharge. Children with poor BAEPs were sent to undergo audiological, otorhinolaryngological, and genetic tests.

RESULTS

Auditory screening was performed for 84.7% of the live births; 39.7% were screened at 30 days or more of age. Diagnostic tests revealed that 63.8% of the children had normal hearing. Incidence of hearing loss was 4%; sensorineural hearing loss was observed in 1,4% of the subjects; 0.24% had auditory neuropathy spectrum disorder; and 2.2% had conductive hearing loss.

CONCLUSION

Neonatal auditory screening was not offered universally, and nor was it carried out, in many cases, within the child's first month of life. Screening must be performed before neonates are discharged and in more than one stage. A high incidence of hearing loss was observed.

Neonatal hearing screening in a rural/sub-urban community in Nigeria, sub-Saharan Africa-a preliminary report

INTRODUCTION

The implementation of Neonatal Hearing Screening (NHS) program is still at the preliminary stage particularly in developing countries despite the burden of permanent congenital and early-onset hearing impairment. There has been an earlier report of NHS in a city in Nigeria, however, this is a report of a preliminary NHS carried in a rural/sub-urban area in Nigeria.

METHOD

This prospective study, which took place between October 2009 and April 2010, involved all newborns delivered at the University College Hospital, Ibadan and the Bilal Missionary Maternity, Agodi, Ibadan, a small maternity service located in Agodi community serving predominantly low socioeconomic class people. All the neonates delivered during the study period were included in the screening. The screening was performed within 72 h of delivery using automated auditory brainstem response (AABR) and repeated after 6 weeks among those with referral result. Subsequently the neonates were referred to diagnostic audiology.

RESULT

Among the 453 newborns (231 males and 222 female), AABR screening showed referral, in 43.7% of neonates. At first screening, 224 (49.4%) were referred while 229 (50.6%) passed, however, during the post-natal period 40/229 (17.5%) reported for second screening, out of these 26 showed pass to the screening. This gave a total pass of 255/453 (56.3%). The presence of maternal pre-ecclampsia (P = 0.05) was found to be a significant morbidity factor associated with referral in the screening, while parental socioepidemiological variables; and the neonates' birthweight, gestational age and APGAR score were not.

CONCLUSION

The proportion of referral on hearing screening encountered was far higher than previously reported, however, continuation of infant screening in future should be comprehensive with viral and genetic analysis in order to address the issue of aetiologic diagnosis; in addition, the implementation should factor the high drop out from the first stage screening in order to substantiate the findings in our region.

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.

Childhood hearing loss and risk profile in a South African population

OBJECTIVE

To describe the nature of hearing loss and associated risk profile in a South African population of infants and children diagnosed at a pediatric referral clinic.

METHODS

A retrospective review of patient files for a pediatric auditory evoked potential clinic in Pretoria was conducted (January 2007-December 2011). Collected data included demographical information, risk factors from case history questionnaire, diagnosis (type and degree of hearing loss), documented age of caregiver suspicion and age of first diagnosis.

RESULTS

Hearing loss was present in 73% (73/100) of cases evaluated. Permanent hearing losses (SNHL, ANSD and mixed) constituted 76% of losses. Unilateral hearing losses constituted 8% of SNHL and 20% of conductive hearing loss. ANSD was diagnosed in 21.4% and SNHL in 78.6% of permanent non-conductive hearing loss cases. The most prevalent SNHL risk was family history of hearing loss and for ANSD it was admittance to the NICU for more than 5 days. The majority of the sample was diagnosed with a permanent bilateral SNHL and ANSD after 36 months of age (47%) despite 40% already suspected of having a hearing loss before 12 months of age.

CONCLUSIONS

A high prevalence of ANSD was found with preventable risk factors often indicated. Age of diagnosis was significantly delayed, evidencing the lack of early hearing detection services in South Africa. The majority of children were diagnosed at ages precluding optimal benefits from early detection and subsequent intervention.

Auditory neuropathy in a low-risk population: a review of the literature

OBJECTIVE

Collect all available published evidence on the prevalence of auditory neuropathy in the well baby population and calculate the contribution of this to the false negative rate of oto-acoustic emission based newborn hearing screening programs.

METHOD

PubMed and EMBASE were searched for relevant articles published between 1996 and 2010. Medical Subject Headings terms included 'Auditory disease', 'Prevalence' and 'Child' and their relevant synonyms. Included were original studies, which focused on well babies and reported the prevalence of auditory neuropathy.

RESULTS

Of 519 citations 4 articles met the inclusion criteria. The population based prevalence of auditory neuropathy in children in population hearing screening was found to vary between 0.006% (SD 0.006) and 0.03% (SD 0.02). The false negative rate, caused by missed children with auditory neuropathy, is between 4 and 17%.

CONCLUSION

The available information on the prevalence of auditory neuropathy in the well baby population is poor. However, if oto-acoustic emission screening is used in the first stage of a neonatal hearing screening program, children with auditory neuropathy are missed. The cost-effectiveness of population-based screening using auditory brainstem response should be studied.

Prevalence and risk factors for auditory neuropathy spectrum disorder in a screened newborn population at risk for hearing loss

OBJECTIVE

To determine the prevalence of Auditory Neuropathy Spectrum Disorder (ANSD) among infants with sensorineural hearing loss (SNHL) and discuss the risk factors.

METHODS

The study group was comprised of children diagnosed with ANSD. Criteria for inclusion in the study group were as follows: permanent sensorineural hearing loss (SNHL); normal transient evoked or distortion product OAEs; absent or elevated middle-ear muscle reflexes (MEMR); severely abnormal or absent ABR waveform. All newborns were screened via a two-stage protocol, involving OAEs and ABR for the repeatedly referred cases and all neonates with one or more risk factors.

RESULTS

From 2002 to 2011, 9419 infants whose hearing ability was uncertain or who had risk factors for hearing loss were investigated. From this population, 352 were diagnosed with SNHL. Of these 352 children, 18 (5.1%) were diagnosed with ANSD. In the ANSD group, prematurity and low birth weight (<1500 g) were observed in 5 cases; ototoxical medication in 8 cases; mechanical ventilation in excess of 5 days in 5 cases. Hyperbilirubinemia was observed in 7 cases, but severe hyperbilirubinemia requiring an exchange transfusion was not observed; 4 patients had no risk factors, 6 patients had only one risk factor, and the 8 remaining had two or more risk factors.

CONCLUSION

Auditory Neuropathy Spectrum Disorder is not an extremely rare hearing disorder. Screening for hearing loss via OAEs, MEMR and ABR examinations concurrently are essential for the accurate diagnosis of ANSD.

Unilateral auditory neuropathy spectrum disorder

CONCLUSIONS

The majority of the patients with unilateral auditory neuropathy spectrum disorder (UANSD) were pediatric and mostly showed a great degree of hearing loss when diagnosed. Abnormal auditory brainstem response (ABR) and preserved otoacoustic emissions (OAEs) and/or cochlear microphonics (CM) were important features to differentiate it from common sensorineural deafness and central nerve hearing loss.

OBJECTIVE

To identify the clinical characteristics of patients with UANSD.

METHODS

This was a retrospective study involving 14 patients diagnosed as having UANSD between 2004 and 2010 in the Chinese PLA Hospital.

RESULTS

In all, 50% of the cases were males (1:1 sex ratio) and the average age of onset was 4.1 years. Of the 14 affected ears with UANSD in these cases, 6 were left-sided, while 8 were right-sided. Of the 14 contralateral ears, 4 presented with sensorineural hearing loss, while the other 10 showed normal hearing. The degree of hearing loss in the 14 affected ears varied, including moderate in 1, moderately severe in 4, severe in 5, and profound in 4. ABRs were absent in the 14 affected ears, while the OAEs, and/or CM were present.

Neuropatia auditiva: alerta aos pediatras

OBJETIVO: Alertar os pediatras sobre a neuropatia auditiva, doença descrita recentemente e ainda desconhecida por muitos médicos. Descrever seus fatores de risco, características clínicas e diagnósticas, com a finalidade de possibilitar uma intervenção terapêutica precoce e eficaz. FONTES DE DADOS: Realizada pesquisa nas bases de dados PubMed, Lilacs e SciELO utilizando os descritores "neuropatia auditiva" e "auditory neuropathy", entre os anos de 1996 e 2010. SÍNTESE DOS DADOS: A neuropatia auditiva, também conhecida como dessincronia auditiva, descrita em 1996, caracteriza-se clinicamente pela dificuldade na compreensão das palavras, mesmo em casos de perdas auditivas leves ou moderadas. Foi relacionada a diversas neuropatias generalizadas e fatores de risco neonatais, como internação em terapia intensiva, hiperbilirrubinemia, sepse e hipóxia. Após suspeita clínica, o diagnóstico é confirmado pela presença das emissões otoacústicas associada a um potencial evocado auditivo de tronco encefálico ausente ou alterado. Sua terapêutica permanece controversa, tendo como opções a protetização auditiva, o acompanhamento fonoterápico para habilitação ou reabilitação da linguagem e, em casos de insucesso, há relatos de resultados satisfatórios com o implante coclear. CONCLUSÕES: Enfatiza-se a importância do reconhecimento pelo pediatra da neuropatia auditiva, entidade ainda pouco citada na literatura latino-americana da especialidade.

Triagem auditiva neonatal com emissões otoacusticas e reflexo cocleo-palpebral: estudo da sensibilidade e especificidade

OBJETIVO: analisar a especificidade e sensibilidade da TAN com emissões otoacústicas evocadas por estimulo transiente (EOAT) associadas à pesquisa do reflexo cócleo-palpebral (RCP), comparando-os aos resultados do Potencial Evocado Auditivo de Tronco Encefalico (PEATE). MÉTODO: a casuística do presente estudo foi composta por 369 RN de risco para deficiência auditiva que foram submetidos à triagem com a captação das emissões otoacústicas evocadas por estímulo transiente e pesquisa do reflexo cócleo- palpebral. Os resultados foram comparados aos resultados do Potencial Evocado Auditivo de Tronco Encefalico (PEATE). RESULTADOS: a incidência do tipo da perda auditiva na população geral foi de 4RN (1,1%) com perda coclear, 22 (5,9%) com perda condutiva, 2 (0,5%) com espectro da neuropatia auditiva (ENA), 14 (3,8%) com alteração central e 15 (4,1%) com atraso de maturação da via auditiva. A TAN mostrou 100% de sensibilidade e 94,6% de especificidade na detecção de alterações cocleares e espectro da neuropatia auditiva; 77,3% de sensibilidade e 94,6% de especificidade na detecção de alterações condutivas e 42,9% de sensibilidade e 94,6% de especificidade na detecção de alterações centrais. Todos os achados evidenciaram diferenças estatisticamente significantes em relação aos neonatos auditivamente normais. CONCLUSÃO: este protocolo de TAN mostrou-se eficaz na detecção de RN com alterações de cocleares e espectro da neuropatia auditiva com sensibilidade e especificidade elevadas.

PEATE automático em recém nascidos de risco: estudo da sensibilidade e especificidade

OBJETIVO: verificar a sensibilidade e especificidade do teste de potencial evocado auditivo de tronco encefálico em equipamento automático (PEATEa), comparando-o ao teste de potencial evocado auditivo de tronco encefálico em equipamento diagnóstico (PEATE) em um programa de triagem auditiva neonatal em neonatos de risco. MÉTODO: foram avaliados 186 neonatos, 83 nascidos a termo e 103 pré-termo, sendo 88 do sexo masculino e 98 feminino. A triagem constou de emissões otoacústicas evocadas por estímulos transientes (EOAT), PEATEa e ao PEATE na mesma semana. RESULTADOS: dos 186 neonatos avaliados, 156 (83,9%) apresentaram audição normal. A perda condutiva foi encontrada em 9 neonatos (4,8%),sendo 7 bilaterais e 2 unilaterais. A perda auditiva coclear foi observada em 5 neonatos (2,7%) sendo um unilateral. Alteração central foi obtida em 11 neonatos (5,9%) e um neonato foi diagnosticado como espectro da neuropatia auditiva -ENA(0,5%).Em 4 casos houve atraso maturacional na avaliação inicial com normalização das respostas no mês seguinte Comparando-se os resultados do PEATEa com o PEATE, observou-se alta sensibilidade ( superior a 99%) para identificação de perda coclear,condutiva, central, atraso maturacional e ENA .A especificidade do PEATEa foi de 100% para ENA, mediana para perda coclear (75% na OD e 60% na OE), e para alterações centrais (54,5%OD e 63,6% OE). Para identificação de perdas condutivas (inferior a 43%). CONCLUSÃO: o PEATEa foi eficaz na identificação das neuropatias auditivas com elevada especificidade e sensibilidade. Contudo, falsos negativos foram observados para perdas cocleares, condutivas, para alterações centrais e atraso maturacional.

Early detection of hearing impairment in newborns and infants

BACKGROUND

1-2 out of 1000 newborns have markedly impaired hearing.

METHODS

Review of the pertinent literature, which was retrieved with a selective search of the following databases: NHS EED (Economic Evaluation Database), HTA (Health Technology Assessment), DARE (Database of Abstracts of Reviews on Effectiveness), Clinical Trials, CDSR (Cochrane Database of Systematic Reviews), and PubMed.

RESULTS

The current scientific evidence favors universal neonatal hearing screening (UNHS) for the early detection of hearing impairment. UNHS is best performed in two stages: first measurement of otoacoustic emissions and then automated assessment of the brainstem auditory evoked response. To be effective, UNHS programs must have a high coverage rate, high sensitivity and specificity, and proper tracking with a low rate of loss to follow-up. Children with positive screening tests for hearing impairment should undergo confirmatory testing as soon as possible and then receive the appropriate treatment. Early intervention is particularly critical for speech acquisition.

CONCLUSION

The early detection and treatment of hearing impairment in newborns and infants has a beneficial effect on language acquisition.

The genetic basis of auditory neuropathy spectrum disorder (ANSD)

OBJECTIVE

Auditory neuropathy is a hearing disorder where outer hair cell function within the cochlea is normal, but inner hair cell and/or the auditory nerve function is disrupted. It is a heterogeneous disorder which can have either congenital or acquired causes. Furthermore, the aetiology of auditory neuropathy is vast, which may include prematurity, hyperbilirubinaemia, anoxia, hypoxia, congenital brain anomalies, ototoxic drug exposure, and genetic factors. It is estimated that approximately 40% of cases have an underlying genetic basis, which can be inherited in both syndromic and non syndromic conditions. This review paper provides an overview of the genetic conditions associated with auditory neuropathy spectrum disorders (ANSDs) and highlights some of the defective genes that have been found to be linked to the pathological auditory changes.

METHOD

Literature search was conducted using a number of resources including textbooks, professional journals and the relevant websites.

RESULTS

The largest proportion of auditory neuropathy spectrum disorders (ANSDs) is due to genetic factors which can be syndromic, non-syndromic or mitochondrial related. The inheritance pattern can include all the four main types of inheritances such as autosomal dominant, autosomal recessive, X-linked and mitochondrial.

CONCLUSION

This paper has provided an overview of mutation with some of the genes and/or loci discovered to be the cause for auditory neuropathy spectrum disorders (ANSDs). It has been noted that different gene mutations may trigger different pathological changes in patients with this disorder. These discoveries have provided us with vital information as to the sites of pathology in auditory neuropathy spectrum disorders (ANSDs), and the results highlight the heterogeneity of the disorder.

Universal newborn hearing screening in 2010

PURPOSE OF REVIEW

The objectives of this review are to provide the reader with a current and concise review of the data and trends in universal newborn hearing screening. Within a relatively short period of time, the concept of screening all infants for hearing loss at the time of birth has evolved from a nascent process to a truly universal system in most developed countries. As a result, the focus and challenges of universal newborn hearing screening have shifted to topics of developing even more efficient and cost-effective approaches, and potentially melding physiologic hearing screenings with ancillary screening techniques.

RECENT FINDINGS

Enhancement of the universal newborn hearing screening process is likely to be accomplished by implementation of novel tools such as wideband reflectance technologies and intelligent incorporation of screening for common genetic and viral causes of congenital hearing loss.

SUMMARY

With such a rapidly evolving process, it will be critical for clinicians to understand the benefits and limitations of various newborn hearing screening methodologies in order to determine the most appropriate management of children referred from their universal newborn hearing screening. This will entail a working knowledge of emerging audiologic tools as well as infectious and genetic causes of pediatric hearing loss.

Early detection of hearing loss

The universal newborn hearing screening (UNHS) is currently spreading in Germany, as well, even though there can be no talk of a comprehensive establishment. The introduction of UNHS in several federal states such as Hamburg, Hessen, and Schleswig-Holstein can be ascribed to the personal commitment of individual pediatric audiologists. Apart from the procurement of the screening equipment and the training of the staff responsible for the examination of the newborns, the tracking, i.e. the follow-up on children with conspicuous test results, is of utmost importance. This involves significant administration effort and work and is subject to data protection laws that can differ substantially between the various federal states. Among audiologists, there is consensus that within the first three months of a child's life, a hearing loss must be diagnosed and that between the age of 3 and 6 months, the supply of a hearing aid must have been initiated. For this purpose, screening steps 1 (usually a TEOAE measurement) and 2 (AABR testing) need to be conducted in the maternity hospital. The follow-up of step 1 then comprises the repetition of the TEOAE- and AABR measurement for conspicuous children by a specialized physician. The follow-up of step 2 comprises the confirmatory diagnostics in a pediatric audiological center. This always implies BERA diagnostics during spontaneous sleep or under sedation. The subsequent early supply of a hearing aid should generally be conducted by a (pediatric) acoustician specialized on children.

Evaluation of hearing loss after failed neonatal hearing screening

OBJECTIVE

We evaluated the causes of hearing loss found after failed universal newborn hearing screening and compared the results with the previously used behavioral observation test (Ewing/CAPAS).

STUDY DESIGN

Hearing loss in neonates, born between September 1999 and October 2007 and referred to our center after failed screening, was determined by audiologic testing and physical examination.

RESULTS

In 340 included neonates the results of hearing tests were as follows: normal hearing 21.2%, conductive hearing loss 20.3%, and sensorineural hearing loss (SNHL) 57.9%. Children referred from the neonatal intensive care unit were more at risk of SNHL (71%) than those from the well-baby clinics (54%). Hearing aids were provided at a median age of 8 months. The positive predictive value of SNHL screening was 54% for a child from a well-baby clinic and 71% for a child from the neonatal intensive care unit.

CONCLUSION

The use of universal newborn hearing screening results in a lower proportion of infants positive because of otitis media with effusion than the previously used Ewing/CAPAS test (20% vs 59-81%). Second, screening leads to identification of hearing loss and intervention at a younger age (8 months vs 15-18 months). Third, the positive predictive value for SNHL has improved (54% vs 2%).

Evaluation of inner hair cell and nerve fiber loss as sufficient pathologies underlying auditory neuropathy

Auditory neuropathy is a hearing disorder characterized by normal function of outer hair cells, evidenced by intact cochlear microphonic (CM) potentials and otoacoustic emissions (OAEs), with absent or severely dys-synchronized auditory brainstem responses (ABRs). To determine if selective lesions of inner hair cells (IHCs) and auditory nerve fibers (ANFs) can account for these primary clinical features of auditory neuropathy, we measured physiological responses from chinchillas with large lesions of ANFs (about 85%) and IHCs (45% loss in the apical half of the cochlea; 73% in the basal half). Distortion product OAEs and CM potentials were significantly enhanced, whereas summating potentials and compound action potentials (CAPs) were significantly reduced. CAP threshold was elevated by 7.5dB, but response synchrony was well preserved down to threshold levels of stimulation. Similarly, ABR threshold was elevated by 5.6dB, but all waves were present and well synchronized down to threshold levels in all animals. Thus, large lesions of IHCs and ANFs reduced response amplitudes but did not abolish or severely dys-synchronize CAPs or ABRs. Pathologies other than or in addition to ANF and IHC loss are likely to account for the evoked potential dys-synchrony that is a clinical hallmark of auditory neuropathy in humans.

Etiology of unilateral neural hearing loss in children

OBJECTIVE

Unilateral sensorineural hearing loss (SNHL) can be caused by a variety of lesions of the inner ear and central nervous system. An inner hair cell or neural site of pathology must be suspected when otoacoustic emissions (OAEs) are present, and inconsistent with audiologic data. We reviewed unilateral neural hearing loss (UNHL) in children, to better understand its etiology, clinical and audiologic features.

DESIGN

Retrospective series.

SETTING

Tertiary pediatric center.

METHODS

From a database of 480 children with unilateral SNHL, 148 had OAE data. Patients with a neural pattern (present OAEs in the affected ear) were reviewed.

OUTCOME MEASURES

Clinical course, audiologic data, imaging findings.

RESULTS

Of 148 patients with OAE data, 11 (7.4%) had the unilateral neural phenotype. Most had stable, severe-to-profound loss in the affected ear. MRI determined an etiology in all 10 patients who received it. Absent cochlear nerves were remarkably common, being found in eight patients (73%). Tumors, previously unsuspected, were identified in the other two patients who received MRI.

CONCLUSIONS

Cochlear nerve aplasia appears by far the most common cause of UNHL in children. As in adults, mass lesions must also be considered in children with unilateral SNHL with a neural pattern. As both lesions elude diagnosis on CT, MRI is the better modality for evaluating this condition.

The frequency of auditory neuropathy detected by universal newborn hearing screening program

OBJECTIVE

Auditory neuropathy/auditory dyssynchrony (AN/AD) has become a well-accepted clinical entity. The combined use of oto-acoustic emissions (OAEs) and auditory brainstem response (ABR) testing in the universal newborn hearing screening (UNHS) has led to the easy recognition of this disorder. Although, we are now able to diagnose AN/AD reliably, little is known about its epidemiology, etiology, and especially the frequency of its occurrence. The primary goal of this study was to determine the frequency of AN/AD in the Western Anatolian region of Turkey. The secondary goal was to compare the detection rate of AN/AD before and after the implementation of the UNHS in the audiology department of Dokuz Eylul University Hospital.

METHOD

Between 2005 and 2007, among the 23,786 newborns who were screened by automated click evoked oto-acoustic emissions (a-CEOAE) and automated auditory brainstem responses (a-ABRs), 2236 were referred to our department. All necessary audiological tests were performed for all the referred newborns. Among them, babies with deficient or abnormal ABR in combination with normal OAEs were considered as having AN/AD. These babies were evaluated with additional diagnostic audiological tests. Furthermore, comparison of the incidence of children diagnosed with AN/AD before and after the implementation of UNHS in our audiology department was also performed.

RESULTS

Among the referred newborns, 65 had abnormal or deficient ABR test results. Ten of these 65 newborn babies (mean diagnostic age: 5.7 months) with hearing impairment showed electrophysiological test results that were consistent with AN/AD. The frequency of AN/AD in these 65 children with hearing loss was 15.38%. Moreover, the frequency of AN/AD within UNHS was found to be 0.044%. Seven of the 10 babies with AN/AD had hyperbilirubinemia as a risk factor, which is a high rate to be emphasized. On the other hand, the retrospective investigation of children diagnosed with AN/AD in the same audiology department between 1999 and 2005 (i.e. before the implementation of UNHS) revealed only 7 children, with an average diagnostic age of 34 months.

CONCLUSION

After implementing the UNHS, the incidence of AN/AD in the audiology department increased from 1.16 to 4.13. Furthermore, the age of diagnosis of AN/AD decreased from 34 months to 5.7 months. This study shows that AN/AD, when screened, is a comparatively common disorder in the population of hearing-impaired infants. While newborn hearing screening provides early detection of babies with hearing loss, it also helps to differentiate AN/AD cases when the screening is performed with both a-ABR and automated oto-acoustic emission (a-OAE) tests. Thus, the routine combined use of a-ABR and a-OAE tests in UNHS programs, especially for the high-risk infants, can provide better detection of newborns with AN/AD. Furthermore, hyperbilirubinemia is merely an association and maybe etiologically linked.

Auditory neuropathy: endocochlear lesion or temporal processing impairment? Implications for diagnosis and management

BACKGROUND/OBJECTIVE

Auditory neuropathy/dys-synchrony, characterized by absent auditory brainstem responses, normal otoacoustic emissions or cochlear microphonics, and word discrimination disproportional to the pure-tone audiogram, may be accompanied by perceptual consequences that could jeopardize language acquisition in affected children. However, the related evidence is constantly changing leading to a serious debate. The aim of the present paper is to review the current knowledge on auditory neuropathy/dys-synchrony, and to present the therapeutic strategies that can be employed in its management, taking into account the potentially underlying pathophysiology.

MATERIALS/METHODS

Literature review from Medline and database sources. Related books were also included.

STUDY SELECTION

Controlled clinical trials, prospective and retrospective cohort studies, nested-based case-control and analytical family studies, laboratory and electrophysiological studies, animal models, case-reports, joint statements and review articles.

DATA SYNTHESIS

Auditory neuropathy/dys-synchrony, in contrast to what is widely believed, is a very frequent disease, responsible for approximately 8% of newly diagnosed cases of hearing loss in children per year. Hyperbilirubinemia and hypoxia represent major risk factors, whereas generalized neuropathic disorders, or a genetic substrate involving the otoferlin gene, are responsible for the phenotype of auditory neuropathy/dys-synchrony in certain cases. Auditory nerve myelinopathy and/or desynchrony of neural discharges are the most probable underlying pathophysiologic mechanisms. Genetic testing may be helpful in cases of non-syndromic prelingual children. Auditory neuropathy/dys-synchrony management aims at restoring the compromised processing of auditory information, either through conventional amplification and/or alternative forms of communication, or by cochlear implantation (combined with intensive speech and language therapy).

CONCLUSION

Auditory neuropathy/dys-synchrony is more frequent than considered in the past, especially amongst hearing-impaired children. Accurate diagnosis, based on subjective and objective hearing assessment techniques (including the various electrophysiological assessment measures), and timely treatment of the affected children is of paramount importance, with hearing aids, intensive speech and language therapy (and sign language when indicated) providing the mainstay of habilitation, and cochlear implantation representing a valid therapeutic alternative.

Impact of early hearing screening and treatment on language development and education level: evaluation of 6 years of universal newborn hearing screening (ALGO) in Flanders, Belgium

OBJECTIVES

Early intervention in hearing-impaired children may improve language outcomes and subsequent school and occupational performance. The objective of this study was to retrospectively analyze over 6 years the educational outcome and language development of a first cohort of children, detected by the Flemish universal newborn hearing screening (UNHS) program based on automated auditory brainstem response (AABR), with the oldest children being in primary school.

METHODS

We studied 229 hearing-impaired children from 1998 till 2003. The following variables were considered: the age during the school year 2005-2006, the degree of hearing loss, additional impairments including presence of intellectual disability, school placement and early intervention.

RESULTS

Analysis showed that 85.4% of the children with moderate, severe or profound hearing loss and no additional disability, older than 5.5 years, reach mainstream education. Further detailed description was provided for the outcomes of children with uni- and bilateral cochlear implants. Overall results stress that 46% of all children with a cochlear implant obtain mainstream education. Of all cochlear implant (CI) children above 5.5 years, without additional handicaps, 78.9% of children attend primary mainstream school. Data on language development show that up to 45% of the children with unilateral cochlear implant and no additional disabilities had normal to slight delay on language development. These data are fulfilling the goals stated by the JCIH and the American Academy of Pediatrics (AAP) in 2000. The role and impact of additional handicaps is discussed. The importance of early hearing loss identification and hearing therapy for appropriate language development is highlighted. Finally our preliminary results on children with bilateral cochlear implants without additional handicaps present an improved language development in comparison to unilateral CI-children.

CONCLUSION

A vast majority of the children detected by the UNHS program, with moderate, severe or profound hearing loss and no additional disability, older than 5.5 years, reach mainstream education. Additional disabilities have a major influence.

Extratympanic electrocochleography in the diagnosis of auditory neuropathy/auditory dyssynchrony

The brainstem auditory evoked potential (BAEP) is being extensively used as a method for the evaluation of cochlear function in individuals with diagnosis of auditory neuropathy/auditory dyssynchrony (AN/AD). In the absence of otoacoustic emissions, many cases of AN/AD have been diagnosed by the presence of CM identified in the BAEP.

Aim

to demonstrate the clinical applicability of extratympanic electrocochleography (ET-Ecochg) in the differential diagnosis of AN/AD compared to the BAEP.

Method

a 4-year-old child with a diagnosis of AN/AD seen at the Audiological Research Center was submitted to ET-Ecochg with a 2000 Hz tone burst in rarefaction and condensation polarities.

Results

the ET-Ecochg exam was illustrated. Using an appropriate protocol, it was possible to demonstrate CM and to confirm it in the Ecochg, with a recording quality superior to that obtained in the BAEP.

Conclusion

ET-Ecochg permitted a more detailed analysis of CM compared to the BAEP, thus showing clinical applicability for the investigation of cochlear function in AN/AD.

Universal neonatal hearing screening: the Siena (Italy) experience on 19,700 newborns

BACKGROUND

Hearing loss (HL) is likely to be the most common congenital abnormality in humans, with a reported prevalence of 1 to 3 per 1000 live births. Early detection and intervention is critical to prevent the adverse consequences of a delayed diagnosis on speech, language and cognitive development. As 33-50% of all congenital HLs cannot be detected in a selective hearing risk, use of universal neonatal hearing screening (UNHS) programs is expanding.

AIMS

We tested the value of a UNHS protocol, based on a two-stage strategy of Transient Evoked Otoacoustic Emissions (TEOAEs) in all infants, followed by diagnostic auditory brainstem response (ABR) testing in those infants who did not meet TEOAE pass criteria and those infants at high risk for hearing loss.

METHODS

TEOAES (292 DP Echoport OAE Analyzer) served as the initial screen, followed by diagnostic ABR (Amplaid MK12) in newborns that did not meet pass criteria for TEOAEs. Additionally, all infants at high audiologic risk according to the Joint Committee on Infant Hearing received a diagnostic ABR evaluation. Of 21,125 total live births, 19,700 were tested (April 1, 1998-July 31, 2006). Accuracy of the UNHS strategy in predicting congenital HL was evaluated by calculating sensitivity, specificity, positive predictive value and negative predictive value.

RESULTS

Prevalence for all HLs in the neonatal period was 1.78/1000 l.b. (35/19,700), with bilateral HL in 1.42/1000 l.b. (28/19,700) [low risk rate: 0.43/1000 l.b. (8/18,356); high risk infants rate: 14.88/1000 l.b. (20/1344)]. All the HL infants were diagnosed <3 and received intervention <6 months age. ROC curves results showed 100% sensitivity (95% C.I.: 89.0-100) and 99.3% specificity (95% C.I.: 99.2-99.4) of the two-stage strategy in detecting congenital HLs [area under the ROC curve: 0.997 (95% C.I.: 0.995-0.997)].

CONCLUSIONS

(1) The epidemiology of congenital HLs widely justifies UNHS; (2) a two-stage TEOAE and diagnostic ABR screening for congenital HL is feasible, minimally invasive and accurate in the early detection of congenital HL; and (3) a congenital HL screening strategy based exclusively on the use of TEOAEs should always consider the possibility of false negative cases.