Identification of neonatal hearing impairment: infants with hearing loss

Neonatal hearing screening - does failure in TEOAE screening matter when the AABR test is passed?

PURPOSE

Newborns who fail the transient evoked otoacoustic emissions (TEOAE) but pass the automatic auditory brainstem response (AABR) in universal newborn hearing screening (UNHS), frequently have no further diagnostic test or follow-up. The present study aimed to investigate whether hearing loss might be missed by ignoring neonatal TEOAE failure in the presence of normal AABR.

METHODS

A retrospective analysis was conducted in newborns presenting between 2017 and 2021 to a tertiary referral centre due to failure in the initial UNHS. The main focus was on infants who failed TEOAE tests, but passed AABR screening. The clinical characteristics and audiometric outcomes were analysed and compared with those of other neonates.

RESULTS

Among 1,095 referred newborns, 253 (23%) failed TEOAE despite passing AABR screening. Of the 253 affected infants, 154 returned for follow-up. At 1-year follow-up, 46 (28%) achieved normal audiometric results. 32 (21%) infants had permanent hearing loss (HL) confirmed by diagnostic ABR, 58 (38%) infants had HL solely due to middle ear effusion (MEE), and for 18 (12%) infants HL was suspected without further differentiation. The majority of permanent HL was mild (78% mild vs. 13% moderate vs. 9% profound). The rate of spontaneous MEE clearance was rather low (29%) leading to early surgical intervention in 36 children. The profile of the risk factors for hearing impairment was similar to that of newborns with failure in both, TEOAE and AABR; however, there was a stronger association between the presence of risk factors and the incidence of HL (relative risk 1.55 vs. 1.06; odds ratio 3.61 vs. 1.80).

CONCLUSION

In newborns, the discordance between a "refer" in TEOAE and a "pass" in AABR screening is associated with a substantial prevalence of hearing impairment at follow-up, especially in the presence of risk factors.

Language Exposure for Preterm Infants is Reduced Relative to Fetuses

OBJECTIVE

To assess changes and deficits in language and auditory exposures consequent to preterm birth and neonatal intensive care unit stay compared with exposures in utero among typically developing fetuses.

STUDY DESIGN

We analyzed over 23 000 hours of auditory exposure data in a cohort study of 27 typically-developing fetuses and 24 preterm infants. Extrauterine exposures for fetuses were captured by having pregnant women wear 24-hour audio recording devices. For preterm infants, recording devices were placed in the infant's crib. Multilevel linear regressions were conducted to test for group differences and effects of infant sex, maternal education, and mother' occupation. A linear mixed-effects model was used to test for an effect of speaker gender.

RESULTS

Fetuses were exposed to an estimated 2.6 ± 1.8 hours/day of nearby, predominantly female language, nearly 5 times greater than 32 ± 12 minutes/day estimated for preterm infants (P < .001). Preterm infants had greater daily exposure to electronic sounds (5.1 ± 2.5 vs 1.3 ± 0.6 hours; P < .001) and noise (4.4 ± 2.1 vs 2.9 ± 2.8 hours; P < .05), with 4.7 ± 3.9 hours/day of silence. Language and extrauterine sound exposure for fetuses showed a marked day/night cyclical pattern, with low exposure during nighttime hours, but preterm infants' exposures showed significantly less change across the 24-hour cycle (P < .001). Maternal occupation requiring frequent communication predicted greater language exposure (P < .05).

CONCLUSIONS

Our findings provide the first comparison of preterm infant auditory exposures to typically-developing fetuses. Some preterm infants may incur deficits of over 150 hours of language exposure over the preterm period. Given known effects of prenatal/preterm language exposure on neurobehavioral outcomes, this magnitude of deficit is alarming.

Conductive hearing loss in newborns: Hearing profile, risk factors, and occasions of service

OBJECTIVE

Infants diagnosed with a conductive hearing loss (CHL) are at increased risk of developmental delays. Using a sample of infants diagnosed with CHL through UNHS, this study aimed to investigate the relationship between specific demographic or clinical characteristics and 1) occasions of service to reach a hearing diagnosis and 2) the profile of CHL.

METHODS

Retrospective analysis was conducted for all infants with CHL born between 01/01/2007 and 31/12/2018 who had received UNHS. Chi squared analysis was conducted on data from 1208 records.

RESULTS

Infants with ≥1 risk factor for hearing loss were more likely to attend more than three occasions of service. Infants who were bilateral refer/medical exclusion, Torres Strait Islander, had ≥1 risk factors for hearing loss or were born pre-term had greater proportions of bilateral CHL than unilateral CHL. Mild to moderate was the most frequent degree of CHL, although a unilateral or bilateral CHL did not have an association with the severity of CHL. Compared to other risk factors, infants with a syndrome had greater proportions of bilateral than unilateral CHL. Risk factors of craniofacial abnormality, prolonged ventilation, or syndrome had greater proportions of mild to moderate CHL than moderate or greater. On average, infants were diagnosed with a CHL at 37.29 weeks of age.

CONCLUSION

These findings highlight the relationship between clinical/demographic characteristics and occasions of service to diagnose CHL in children, including the CHL profile. An understanding of this relationship may help clinicians to better plan, assess and manage infants diagnosed with a CHL through UNHS.

"Association of High Risk Factors and Hearing Impairment in Infants-A Hospital Based Study"

The aim of the study was to find the association of various risk factors with permanent hearing impairment in infants. A case-control study was designed on 420 infants with permanent hearing impairment and normal hearing. The case control ratio was 1:1. Alternate sampling method was used for selecting the control group. Review of medical records and parent interview was done to collect the information of risk factors. Family history(adj. OR 7.5; 95% CI 3, 14; P = 0.000), Consanguinity (adj. OR: 4; 95% CI 2,4; P = 0.000), intra uterine infection (adj. OR 18, 95% CI: 2.3-126.5, P = 0.000), post natal infection (adj. OR 3, 95% CI: 1.3-5, P = 0.004), low Apgar score (adj.OR: 4.6, 95% CI: 1.3-15), craniofacial anomaly (OR-4.6, 95% CI: 1.4-9.5, P = 0.005) and low birth weight (adj. OR: 2.3, 95% CI: 1.2-3.8) were significantly associated with hearing impairment. Among the risk factors, intra uterine infection was having highest significant association with permanent hearing impairment. This is followed by family history, low Apgar score, craniofacial anomaly, consanguinity, post natal infection and low birth weight.

Status of Newborn Hearing Screening Program in the State of Tamil Nadu, India

Newborn hearing screening in India is gaining momentum and more programs are getting established every year. We need to know their performance levels, strengths and weaknesses to provide suggestions for building effective future programs. The study aimed to report the status of Newborn Hearing Screening (NHS) program in the state of Tamil Nadu, India. A questionnaire on "Newborn Hearing Screening Survey" was developed and sent to 80 sites with NHS facility all over Tamil Nadu, India. The information collected was subjected to descriptive statistical analyses. On a 95% return rate, private sector contribution towards NHS program are the highest and most of the private hospitals have outsourced the NHS program. In most of the sites, audiologists are incharge of the NHS program and carried out the NHS testing. The majority of sites (67.1%) follow selective screening such as high risk factors, doctor's referral and admission at NICU. The preferred testing was TEOAE in the screening program. NHS protocol was found to be variable at each site and for each patient. The time between second screening and diagnostic testing went up to 3-6 months. However, there is a lack of organized system for documenting the program outcome. The result of this study calls the need for wider implementation of UNHS and to introduce a centralised state or local reporting system for documenting and tracking the infants with hearing impairment.

Multiple congenital anomalies and adverse developmental outcomes are associated with neonatal intensive care admission and unilateral hearing loss

AIM

To determine congenital and developmental outcomes of children with Unilateral Hearing Loss (UHL) who were admitted to the Neonatal Intensive Care Unit (NICU).

METHOD

Retrospective, single-site study that followed 25 children with permanent congenital UHL and a NICU admission to a NICU of Nottingham University Hospital. Birth and two-year developmental follow-up data were collected. They were compared to matched control group who had a NICU admission but no hearing loss (matched on gestational age, weight and sex).

RESULTS

The median birthweights, gestational ages and number of days spent on the NICU for the UHL population were 2510 g, 36 weeks, and 12 days respectively. Most children (20/25; 80%) with UHL and a NICU admission were diagnosed with a congenital anomaly within the first two years of life. Only half (13/25) of these children were diagnosed with a congenital anomaly at discharge. Children with UHL and a NICU admission were more likely than the matched group (NICU admission only; p < .001) to have multiple congenital anomalies. We found a positive association between multiple congenital anomalies and developmental impairment for the NICU graduates with UHL (p = .019). This UHL-NICU group were also more likely than the matched NICU children to have developmental impairment (7/25 vs. 0/25; p = .01), speech and language therapy (13/25 vs. 1/25; p < .001), inner ear malformations (14/25 vs. 0/25, p < .001) or craniofacial anomalies (12/25 vs. 2/25; p = .004).

INTERPRETATION

Children with UHL and a NICU admission were at high risk of congenital anomalies and certain adverse developmental outcomes. Improved congenital anomaly screening is needed at birth for this population. Having multiple congenital anomalies suggests closer developmental monitoring is needed. This study contributes towards producing clinical screening and management guidelines to ensure consistent high-quality care for this unique population.

Cost-Effectiveness of Neonatal Hearing Screening Programs: A Micro-Simulation Modeling Analysis

Supplemental Digital Content is available in the text.

Early detection of neonatal hearing impairment moderates the negative effects on speech and language development. Universal neonatal hearing screening protocols vary in tests used, timing of testing and the number of stages of screening. This study estimated the cost-effectiveness of various protocols in the preparation of implementation of neonatal hearing screening in Albania.

Predicting hearing loss from 10 years of universal newborn hearing screening results and risk factors

OBJECTIVE

This study investigated whether demographic variables, risk factor presence or absence and universal newborn hearing screening (UNHS) results can be used to predict permanent childhood hearing loss (PCHL) in infants referred from screening.

DESIGN

Retrospective analysis of a UNHS database.

STUDY SAMPLE

Data were extracted from the state-wide UNHS database storing details of the 613,027 infants who were born in Queensland, Australia between 1 January 2007 and 31 December 2016 and participated in UNHS. This study included the 6735 children who were referred from the UNHS program for diagnostic audiology due to failing the screen in one or both ears or bypassing screening.

RESULTS

Factors with a significant positive association with PCHL that were incorporated into a logistic regression model were: female gender, non-indigenous status, family history of PCHL, craniofacial anomalies and syndromes associated with PCHL, and a bilateral refer result on screening.

CONCLUSIONS

Odds of PCHL vary among infants referred for diagnostic assessment from UNHS programs. When an infant refers on the newborn hearing screen, information about their gender, indigenous status, identified risk factors and specific screening outcome can be used to predict the likelihood of a congenital PCHL diagnosis.

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.

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.

Sensitivity and Specificity of Pure-Tone and Subjective Hearing Screenings Using Spanish-Language Questions

Purpose The purpose of this study is to determine the sensitivities and specificities of different audiometric hearing screening criteria and single-item and multi-item hearing disability questionnaires among a group of Spanish-speaking adults in a rural community. Method Participants were 131 predominantly older (77% 65+ years) Hispanic/Latinx adults (98%). A structured Spanish-language interview and pure-tone threshold test data were analyzed for each participant. The sensitivities and specificities of three single questions and the Hearing Handicap Index for the Elderly-Screening (HHIE-S; Ventry & Weinstein, 1983) in Spanish, as well as three audiometric screening criteria, were evaluated in relation to the pure-tone threshold test for detecting hearing loss. Results Sensitivity and specificity of audiometric screening criteria varied, but the highest sensitivity was found for the criterion of > 25 dB HL at 1-4 kHz in either ear. The single self-perception question, "¿Cree usted que tiene pérdida de audición? (Do you think you have a hearing loss?)," was shown to be the most sensitive self-report screening compared to other single-item questions and the HHIE-S. This single question was as sensitive as an audiometric screening to detect a moderate hearing loss (> 40 dB HL in either ear). Results from the Spanish HHIE-S indicated poor performance to detect hearing loss in this population, consistent with previous research. Conclusions Among older Spanish-speaking adults, self-reported hearing status had varying sensitivities depending on the question asked. However, of the tools evaluated, the self-perception question proved to be a more sensitive and specific tool than a multi-item screen. Objective audiometric testing (> 25 dB HL) resulted in the highest sensitivity to detect a mild hearing loss.

Auditory Neuropathy Spectrum Disorder due to Two Novel Compound Heterozygous OTOF Mutations in Two Chinese Families

Auditory neuropathy spectrum disorder (ANSD), also called auditory neuropathy (AN), is a unique type of prelingual hearing impairment. Up to 10% of deaf infants and children are affected by this disease. Mutation of the OTOF gene which encodes otoferlin is the common cause of congenital nonsyndromic ANSD. To date, over 110 mutations have been identified in the OTOF gene according to the Human Gene Mutation Database (HGMD). Here, next-generation sequencing (NGS) revealed that the compound heterozygous mutations c.4748G>A/c.2523+1G>T and c.5248G>C/c.5098G>C of the OTOF gene were present in two Chinese ANSD patients. Each patient had a known pathogenic mutation (c.4748G>A or c.5098G>C) and a novel mutation (c.2523+1G>T or c.5248G>C). Comparative amino acid sequence analysis across different species revealed that the residues at these novel mutation sites are evolutionarily highly conservative. This indicated that the novel mutations were possible causes of the disorder in the patients. Our findings extend the OTOF mutation spectrum and further confirm the role of the OTOF gene in ANSD.

Regional differences of Turkey in risk factors of newborn hearing loss

OBJECTIVE

The aim of this study was to discover Turkish regional differences in the risk factors of newborn hearing loss.

METHOD

A multi-centered retrospective design was used. A total of 443 children, registered to the national newborn hearing screening programme, with bilateral hearing loss, from five different regions of Turkey, were evaluated in terms of the types of hearing loss, the degree of hearing loss, the types of risk factors, parental consanguinity, age at diagnosis and age of auditory intervention, respectively.

RESULTS

There was no significant difference in the prevalence of hearing loss between regions (χ² = 3.210, P = 0.523). Symmetric Sensorineural Hearing Loss (SSHL) was the most common type of HL in all regions (91.8%). Profound HL was the most common degree of HL in all regions (46.2%). There were statistically significant differences between regions in terms of types of HL (χ² = 14.151, P = 0.000). As a total, 323 (72.9%) of subjects did not have any risk factors. There were statistically significant differences between regions in terms of the types of risk factors (pre, peri and post-natal) for SSNHL (χ² = 16.095, P = 0.000). For all regions, the age of diagnosis was convenient with the JCIH criteria. However the age of hearing aid application was prolonged in some regions. There were statistically significant differences between regions in terms of the age of diagnosis (χ² = 93.570, P = 0.000) and the age of auditory intervention (χ² = 47.323, P = 0.000). The confounding effects of gender, age of diagnosis, age of hearing aids applications, HL in the family, types of risk factors for HL on SSNHL were detected.

CONCLUSION

To reach the goal of a high quality newborn hearing screening, there is a need to develop an evidence-based standard for follow up guideline. In addition, risk factors should be re-evaluated according to regional differences and all regions should take their own precautions according to their evidence based data.

Congenital hearing loss

Congenital hearing loss (hearing loss that is present at birth) is one of the most prevalent chronic conditions in children. In the majority of developed countries, neonatal hearing screening programmes enable early detection; early intervention will prevent delays in speech and language development and has long-lasting beneficial effects on social and emotional development and quality of life. A diagnosis of hearing loss is usually followed by a search for an underlying aetiology. Congenital hearing loss might be attributed to environmental and prenatal factors, which prevail in low-income settings; congenital infections, particularly cytomegalovirus infection, are also a common risk factor for hearing loss. Genetic causes probably account for the majority of cases in developed countries; mutations can affect any component of the hearing pathway, in particular, inner ear homeostasis (endolymph production and maintenance) and mechano-electrical transduction (the conversion of a mechanical stimulus into electrochemical activity). Once the underlying cause of hearing loss is established, it might direct therapeutic decision making and guide prevention and (genetic) counselling. Management options include specific antimicrobial therapies, surgical treatment of craniofacial abnormalities and implantable or non-implantable hearing devices. An improved understanding of the pathophysiology and molecular mechanisms that underlie hearing loss and increased awareness of recent advances in genetic testing will promote the development of new treatment and screening strategies.

Project ASPIRE: Spoken Language Intervention Curriculum for Parents of Low-socioeconomic Status and Their Deaf and Hard-of-Hearing Children

OBJECTIVE

To investigate the impact of a spoken language intervention curriculum aiming to improve the language environments caregivers of low socioeconomic status (SES) provide for their D/HH children with CI & HA to support children's spoken language development.

STUDY DESIGN

Quasiexperimental.

SETTING

Tertiary.

PATIENTS

Thirty-two caregiver-child dyads of low-SES (as defined by caregiver education ≤ MA/MS and the income proxies = Medicaid or WIC/LINK) and children aged < 4.5 years, hearing loss of ≥ 30 dB, between 500 and 4000 Hz, using at least one amplification device with adequate amplification (hearing aid, cochlear implant, osseo-integrated device).

INTERVENTION

Behavioral. Caregiver-directed educational intervention curriculum designed to improve D/HH children's early language environments.

MAIN OUTCOME MEASURES

Changes in caregiver knowledge of child language development (questionnaire scores) and language behavior (word types, word tokens, utterances, mean length of utterance [MLU], LENA Adult Word Count (AWC), Conversational Turn Count (CTC)).

RESULTS

Significant increases in caregiver questionnaire scores as well as utterances, word types, word tokens, and MLU in the treatment but not the control group. No significant changes in LENA outcomes.

CONCLUSION

Results partially support the notion that caregiver-directed language enrichment interventions can change home language environments of D/HH children from low-SES backgrounds. Further longitudinal studies are necessary.

Etiology and associated GJB2 mutations in Mauritanian children with non-syndromic hearing loss

Origins of all hearing impairment forms may be divided into genetic mutations and acquired influence. Both carry damage to the inner ear structure resulting in a mild to profound dysfunction of the auditory system. The purpose of this study was to assess the different etiologies of deafness in two reference centers for hearing-impaired children in Nouakchott/Mauritania. Data on gender, age, consanguinity, etiology and family history of deafness were gathered by interviewing the custodians of 139 children with hearing loss. DNA of pupils with hereditary non-syndromic deafness was then screened for GJB2 mutations by sequencing methods. Postnatal hearing loss was found in 36 (25.8 %) out of the 139 children surveyed. The main etiologies of this group were infections caused by meningitis (12.9 %) and measles (2.8 %). Unknown and ototoxic origins accounted for, respectively, 5.7 and 3.5 %. In 103 (74.1 %) children, deafness was identified near after the time of birth and, therefore, presumed as congenital. 56.8 % of deaf children had consanguineous parents. Two GJB2 mutations, c.del35G with an allele frequency of 4.7 % and R32C (3.7 %) were detected. Infections such as meningitis and measles were the most prevalent causes of postnatal deafness. In cases of congenital hearing impairment, two GJB2 allele variants, i.e., del35G and R32C (3.7 %) were detected. Extended genetic testing is recommended for a more comprehensive determination of congenital causes.

Factors Affecting Early Services for Children Who Are Hard of Hearing

PURPOSE

To describe factors affecting early intervention (EI) for children who are hard of hearing, we analyzed (a) service setting(s) and the relationship of setting to families' frequency of participation, and (b) provider preparation, caseload composition, and experience in relation to comfort with skills that support spoken language for children who are deaf and hard of hearing (CDHH).

METHOD

Participants included 122 EI professionals who completed an online questionnaire annually and 131 parents who participated in annual telephone interviews.

RESULTS

Most families received EI in the home. Family participation in this setting was significantly higher than in services provided elsewhere. EI professionals were primarily teachers of CDHH or speech-language pathologists. Caseload composition was correlated moderately to strongly with most provider comfort levels. Level of preparation to support spoken language weakly to moderately correlated with provider comfort with 18 specific skills.

CONCLUSIONS

Results suggest family involvement is highest when EI is home-based, which supports the need for EI in the home whenever possible. Access to hands-on experience with this population, reflected in a high percentage of CDHH on providers' current caseloads, contributed to professional comfort. Specialized preparation made a modest contribution to comfort level.

Risk factors for hearing loss in infants under universal hearing screening program in Northern Thailand

OBJECTIVE

To define the risk factors for hearing loss in infants (aged 3 months) under universal hearing screening program.

MATERIALS AND METHODS

A total of 3,120 infants (aged 3 months) who underwent hearing screening using a universal hearing screening program using automated otoacoustic emission test between November 1, 2010 and May 31, 2012 in Uttaradit Hospital, Buddhachinaraj Hospital, and Sawanpracharuk Hospital (tertiary hospitals) located in Northern Thailand were included in this prospective cohort study.

RESULTS

Of the 3,120 infants, 135 (4.3%) were confirmed to have hearing loss with the conventional otoacoustic emission test. Five of these 135 infants (3.7%) with hearing loss showed test results consistent with auditory brainstem responses. From the univariable analysis, there were eleven potential risk factors associated with hearing deterioration. On multivariable analysis, the risk factors independently associated with hearing loss at 3 months were birth weight 1,500-2,500 g (risk ratio [RR] 1.6, 95% confidence interval [CI] 1.1-2.6), APGAR score <6 at 5 minutes (RR 2.2, 95% CI 1.1-4.4), craniofacial anomalies (RR 2.5, 95% CI 1.6-4.2), sepsis (RR 1.8, 95% CI 1.0-3.2), and ototoxic exposure (RR 4.1, 95% CI 1.9-8.6).

CONCLUSION

This study concluded that low birth weight, APGAR score <6 at 5 minutes, craniofacial anomalies, sepsis, and ototoxic exposure are the risk factors for bilateral hearing loss in infants (aged 3 months) and proper tests should be performed to identify these risk factors. As an outcome, under the present circumstances, it is suggested that infirmary/physicians/general practitioners/health action centers/polyclinics should carry out universal hearing screening in all infants before 36 weeks. The public health policy of Thailand regarding a universal hearing screening program is important for the prevention of disability and to enhance people's quality of life.

Gentamicin extended interval regimen and ototoxicity in neonates

OBJECTIVES

To assess the extended interval regimen gentamicin associated ototoxicity in neonatal intensive care unit using hearing tests.

METHODS

Two hundred and twenty neonates admitted to neonatal intensive care were assessed; 110 neonates who had received gentamicin and 110 neonates who had not received gentamicin served as control group. Gentamicin group were further subdivided according to the duration of treatment into 50 neonates who had received gentamicin for 5 days or less and 60 neonates who had received gentamicin for more than 5 days. TEOAEs were used for hearing screening. Auditory brain response was performed 3 months later for failed cases to confirm the hearing impairment.

RESULTS

Three neonates failed TEOAEs screening in each group but hearing impairment was confirmed in one neonate only (0.9%) in each group (gentamicin and control groups). Neonates who received gentamicin for more than 5 days showed comparable results as regard TEOAEs or ABR results with those who received gentamicin for 5 days or less, and control group.

CONCLUSIONS

Extended interval dosing of gentamicin therapy in neonates does not increase the incidence of hearing loss. This suggests that hearing loss in neonatal intensive care unit may be attributed to factors other than gentamicin treatment.

The validity of family history as a risk factor in pediatric hearing loss

OBJECTIVES

A family history of permanent childhood hearing loss is considered a risk factor for pediatric hearing loss, although its validity has been sparsely examined. This study aimed to: (1) investigate the prevalence and yield of this risk factor for congenital and postnatal hearing losses, (2) define the audiometric characteristics of hearing loss in children with positive family histories, and (3) assess the nature of the familial relationships.

METHOD

A retrospective cohort study including all children born in Queensland, Australia between September 2004 and December 2011 who had completed Healthy Hearing's newborn hearing screen (n=380,895).

RESULTS

(1) Prevalence of the risk factor was 1.09% (4138/380,895). Prevalence of the risk factor in congenital cases was 7.29% and in postnatal cases was 36.84%. A low yield was identified for both congenital and postnatal groups (1.43% and 1.7%, respectively). (2) The degree of loss in congenital cases was highly varied, whereas the predominant degree in postnatal cases was mild. The most frequent type of loss for congenital cases was sensorineural, whereas for postnatal cases it was conductive. (3) Maternal or sibling relationships were most commonly reported for congenital losses, and maternal or paternal relationships for postnatal losses.

CONCLUSIONS

Children with a family history of pediatric hearing loss should have their hearing screened at birth and be monitored throughout early childhood. However, more efficient surveillance methods should be considered in view of the high prevalence with low yield.

Aminoglycoside toxicity in neonates: something to worry about?

Toxicity has limited the use of aminoglycosides and adult studies report high rates of both ototoxicity and nephrotoxicity. Conversely paediatric studies have shown lower rates and extended interval dosing may have reduced toxicity further. We review the animal and human evidence for aminoglycoside toxicity in neonates including mechanisms, measurement and rates of toxicity; and differences between aminoglycosides and dosing regimens. We discuss genetic susceptibility and the impact of other synergistic effects.

Cognitive outcomes and familial stress after cochlear implantation in deaf children with and without developmental delays

OBJECTIVE

The benefits of cochlear implantation for children with developmental delays (DD) often are unclear. We compared cognition, adaptive behavior, familial stress, and communication in children with and without DD.

STUDY DESIGN

Retrospective review.

SETTING

Two tertiary care pediatric hospitals.

PATIENTS

Two hundred four children who underwent cochlear implantation assessed before and more than 1 year after implantation.

MAIN OUTCOME MEASURES

The Mullen Scales of Early Learning (MSEL), vineland adaptive behavior scales (VABS), Parental Stress Index, and Preschool Language Scale.

RESULTS

We developed a specific definition of DD for hearing-impaired children based upon diagnostic and statistical manual of mental disorders, fourth edition, criteria for mental retardation; 60 children met the criteria for DD, and 144 children did not. Before implantation, multiple linear regression demonstrated that children with DD had lower scores in every domain of the MSEL and VABS (p < 0.05), but no differences in any domains of the parental stress index and preschool language scale (p > 0.1) compared with children without DD. After implantation, children without DD demonstrated significant improvements in intelligence as measured by the MSEL and age-appropriate improvements in adaptive behavior as evaluated by the VABS, and their familial stress levels were not increased after cochlear implantation. In contrast, children with DD underwent implantation at a later age and demonstrated less comprehensive developmental improvements after cochlear implantation and higher stress levels. However, when the age differences were taken into account using multiple linear regression analyses, the differences between the 2 cohorts were reduced.

CONCLUSION

These data indicate that our definition of DD is a reliable method of stratifying deaf children. Although children with DD have a normal developmental rate of adaptive behavior after cochlear implantation, their developmental rate of intelligence is lower, and they have higher stress levels than children without DD. However, our data suggest that if children with DD could be implanted as early as children without DD, their intelligence and stress outcomes would be improved.

Mapping auditory nerve firing density using high-level compound action potentials and high-pass noise masking

Future implementation of regenerative treatments for sensorineural hearing loss may be hindered by the lack of diagnostic tools that specify the target(s) within the cochlea and auditory nerve for delivery of therapeutic agents. Recent research has indicated that the amplitude of high-level compound action potentials (CAPs) is a good predictor of overall auditory nerve survival, but does not pinpoint the location of neural damage. A location-specific estimate of nerve pathology may be possible by using a masking paradigm and high-level CAPs to map auditory nerve firing density throughout the cochlea. This initial study in gerbil utilized a high-pass masking paradigm to determine normative ranges for CAP-derived neural firing density functions using broadband chirp stimuli and low-frequency tonebursts, and to determine if cochlear outer hair cell (OHC) pathology alters the distribution of neural firing in the cochlea. Neural firing distributions for moderate-intensity (60 dB pSPL) chirps were affected by OHC pathology whereas those derived with high-level (90 dB pSPL) chirps were not. These results suggest that CAP-derived neural firing distributions for high-level chirps may provide an estimate of auditory nerve survival that is independent of OHC pathology.

Outcomes of very-low-birthweight infants at 3 years of age born in 2003-2004 in Japan

BACKGROUND

The aim of this study was to describe and compare neurodevelopmental outcomes with birthweight (BW) groups at 250-g intervals of very-low-birthweight (VLBW) infants at 3 years of age in a multicenter cohort in Japan.

METHODS

A total of 3104 VLBW infants born in 2003 and 2004 registered in a NICU-network database were followed in the study. Neurodevelopmental impairment (NDI) was defined as any of the following impairments: cerebral palsy, unilateral or bilateral blindness, severe hearing impairment, or developmental delay; a developmental quotient (DQ) <70 measured using the Kyoto Scale of Psychological Development test or judged by physicians in infants without the test.

RESULTS

A total of 257 infants died and follow-up data were obtained from 1826 infants. Of the 1826 infants, 155 (8.5%) had cerebral palsy, 25 (1.4%) had visual impairment, and 12 (0.7%) had hearing impairment. Of the 1197 infants in whom DQ was measured, 184 (15.4%) had DQ < 70. The proportion of NDI in the evaluated infants was 19.2% (n= 350), ranging from 11.9% (BW 1251-1500 g) to 42.0% (BW ≤ 500 g). Odds ratios (95%CI) of NDI or death against the group BW 1251-1500 g were 20.62 (13.29-31.97) in BW ≤ 500 g, 7.25 (5.45-9.64) in BW 501-750 g, 2.85 (2.12-3.82) in BW 751-1000 g and 1.18 (0.85-1.64) in BW 1001-1250 g.

CONCLUSION

The increasing proportion of NDI or death, an indicator of adverse outcome, was associated with decrement in the BW of the groups. Although we have to consider a bias due to loss of follow-up data, the incidence of NDI was similar to previous overseas cohort studies despite the higher survival proportion in our study.

Outcome of a universal newborn hearing-screening programme based on multiple transient-evoked otoacoustic emissions and clinical brainstem response audiometry

CONCLUSION

This universal newborn hearing-screening (UNHS) programme revealed high efficacy. The proportion of congenital sensorineural hearing loss was higher in left ears and in males than in right ears and females, which was in line with the systematic ear asymmetries and sex differences in transient-evoked otoacoustic emission (TEOAE) pass percentage.

OBJECTIVES

To study the long-term outcome of a UNHS programme based on multiple TEOAEs and clinical click-evoked auditory brainstem response (ABR).

METHOD

The study included all the newborns that were screened during a 6-year period (n = 31 092). TEOAE pass/fail was analysed in detail. In an assessment performed 10 years after the start of the 6-year UNHS, prevalence, degree and type of congenital hearing loss were studied.

RESULTS

The proportion of screened newborns was high, i.e. 98%. Multiple TEOAE recordings minimized the need for clinical ABR. Fifty-seven (0.18%) subjects showed bilateral hearing loss (exceeding ≈ 30 dB HL); median ABR threshold = 60 dB nHL (at 2.5 months of age). Bilateral and unilateral sensorineural hearing loss was found in 0.17% (n = 52; 56% males) and 0.06% (n = 18; 61% left ears, 56% males) of the screened newborns, respectively. Higher TEOAE pass percentages (p < 0.01) were demonstrated in right ears and in females than in left ears and males.

Making targeted screening for infant hearing loss an effective option in less developed countries

Developing countries account for a disproportionate burden of infant hearing loss globally but the prospects of the more ideal universal newborn hearing screening (UNHS) have been debated. The Joint Committee on Infant Hearing (JCIH) of USA has consistently proposed targeted newborn hearing screening (TNHS) for such countries. This study therefore set out to examine the appropriateness of JCIH risk factors as a basis for TNHS in Sub-Saharan Africa and Southeast Asia. From a review of relevant literature published in PubMed in the last 10 years, evidence on the effectiveness of TNHS based on JCIH or other risk factors is sparse or limited. Consistent with the prevailing epidemiological profile of these countries additional putative risk factors not listed or more prevalent than those listed by JCIH such as maternal hypertensive disorders in pregnancy, lack of skilled attendant at delivery, non-elective cesarean delivery and infant undernutrition have been demonstrated besides consanguinity. While TNHS has intuitive appeal in resource-poor settings, it is likely to be fraught with diverse operational constraints that could significantly curtail its effectiveness in these two regions. Well-conducted pilot UNHS studies to determine context-specific risk factors, screening efficiency and the potential trade-offs are warranted in each country prior to embarking on TNHS where UNHS is not immediately practicable.

Comparison of two hearing screening programs in the same population: oto-acoustic emissions (OAE) screening in newborns and behavioral screening when infants

OBJECTIVE

Hearing screening programs in infancy should identify hearing impairment as early as possible. The two common programs utilize either objective neonatal tests (oto-acoustic emissions (OAE) or automatic auditory brainstem responses (aABR)) or behavioral screening at 7-9 months of age. Most countries employ only one of these options. The uniqueness of this study is the comparison of both hearing screening programs on the same group of children.

METHODS

The study was conducted on 1545 children born between the years 1999 and 2003 who were followed up in public well baby clinics in the Jerusalem district. The children were tested with transient oto-acoustic emissions (TEOAE) before discharge from the neonatal ward, and later, at the age of 7-9 months, underwent a behavioral hearing screening test in a public well baby clinic. The results of both hearing screening programs were compared.

RESULTS

The compliance rates were 99.7% for the neonatal testing and 83% for the 7-9 months behavioral testing (p=0.0001). The failure rate was 4-6% in both screening programs; failure of OAE testing was unilateral in 65% of newborns; at 7-9 months bilateral failure was more common (56%). There was an 11.2% disagreement (kappa coefficient 0.03) between the outcomes of both tests. In another group of 49 known hearing-impaired children, 27 who had undergone newborn screening were diagnosed before the age of behavioral testing. Twelve children had failed either both tests or the only test they underwent. In nine cases, the children had passed one of the hearing screening tests and had failed the other, and one child had passed both tests.

CONCLUSIONS

Newborn hearing screening has the advantages of objectivity, early identification, and higher compliance. The major advantage of the later behavioral test is identification of later onset or progressive hearing impairment as well as auditory neuropathy spectrum disorder. Each screening test is testing different entities; hence they are complementary and not interchangeable or superfluous. We recommend a comprehensive two-step hearing screening plan (newborn and later behavioral) with close cooperation between the health care providers involved.

Repeated courses of antenatal corticosteroids: are there effects on the infant's auditory brainstem responses?

Our objective was to assess the effects of repeated antenatal corticosteroid treatments on the neonatal auditory brainstem response (ABR), a sensitive measure of neonatal brain maturity and auditory function. To achieve this, we performed and blindly evaluated neonatal ABRs on a subset of infants delivering within a multicenter randomized placebo-controlled clinical trial comparing single versus repeated courses of antenatal corticosteroid treatments for women at 23-31 weeks gestation who remained at increased risk for preterm birth. The women were randomly assigned to either the single or the repeated antenatal corticosteroid treatment group. Women in the repeated antenatal corticosteroid group received weekly antenatal corticosteroid treatments until 34 weeks gestation or until they reached a study-determined limited number of courses, whereas women in the single antenatal corticosteroid group received an initial course of corticosteroid followed by weekly placebo injections. We performed ABR testing on their infants prior to discharge. The latencies of waves I, III and V and the peak-to-trough amplitudes of waves I and V were compared between those in the single (n=27) and repeated antenatal corticosteroid treatment (n=24) groups. The majority of repeated antenatal corticosteroid infants (20 of 24) were exposed to ≥ 4 antenatal corticosteroid treatments. Even though gestational age was similar between our subset of single and repeated antenatal corticosteroid treatment groups, infant birth weight and length and head circumference were significantly smaller in the repeated antenatal corticosteroid group (p <0.05). Despite these differences in birth sizes, there were no significant group differences in the ABR wave latencies or amplitudes. We concluded that our repeated antenatal corticosteroid treatments, in comparison to a single treatment, did not significantly benefit or harm the neonatal ABR despite significant effects on birth size.

Test-retest reliability of the speech-evoked auditory brainstem response

OBJECTIVE

The speech-evoked auditory brainstem response (ABR) provides an objective measure of subcortical encoding of complex acoustic features. However, the intrasubject reliability of this response in both optimal and challenging listening conditions has not yet been systematically documented. This study aimed to evaluate test-retest reliability of the speech-evoked ABR in young adults.

METHODS

In each of two sessions, ABRs were obtained with: (1) a 170 ms /da/ syllable presented in quiet as well as 2-talker and 6-talker babble background noise conditions and (2) a 40 ms /da/ syllable presented in quiet. Test-retest reliability of the responses was analyzed in the frequency and time domains.

RESULTS

The speech-evoked ABR does not vary significantly across sessions within individuals on measures of temporal encoding (i.e., peak latencies, stimulus-to-response and response-to-response measures), frequency representation and response magnitude.

CONCLUSIONS

The subcortical auditory pathway produces a response to a complex sound that is stable and replicable from session to session.

SIGNIFICANCE

By demonstrating the high degree of replicability in optimal and challenging listening conditions, the applicability of the speech-evoked ABR may be increased to examining a range of auditory processing abilities in clinical and research settings.

Exploring the relationship between physiological measures of cochlear and brainstem function

OBJECTIVE

Otoacoustic emissions and the speech-evoked auditory brainstem response are objective indices of peripheral auditory physiology that are used clinically for assessing hearing function. While each measure has been extensively explored, their interdependence and the relationships between them remain relatively unexplored.

METHODS

Distortion product otoacoustic emissions (DPOAEs) and speech-evoked auditory brainstem responses (sABRs) were recorded from 28 normal-hearing adults. Through correlational analyses, DPOAE characteristics were compared to measures of sABR timing and frequency encoding. Data were organized into two DPOAE (Strength and Structure) and five brainstem (Onset, Spectrotemporal, Harmonics, Envelope Boundary, and Pitch) composite measures.

RESULTS

DPOAE Strength shows significant relationships with sABR Spectrotemporal and Harmonics measures. DPOAE Structure shows significant relationships with sABR Envelope Boundary. Neither DPOAE Strength nor Structure is related to sABR Pitch.

CONCLUSIONS

The results of the present study show that certain aspects of the speech-evoked auditory brainstem responses are related to, or covary with, cochlear function as measured by distortion product otoacoustic emissions.

SIGNIFICANCE

These results form a foundation for future work in clinical populations. Analyzing cochlear and brainstem function in parallel in different clinical populations will provide a more sensitive clinical battery for identifying the locus of different disorders (e.g., language based learning impairments, hearing impairment).

Hearing loss in children with very low birth weight: current review of epidemiology and pathophysiology

An association between birth weight <1500 g (very low birth weight (VLBW)) and hearing loss has been long recognised. As universal hearing screening programmes have become widely implemented and the survival rate of VLBW babies in modern intensive care units has increased, we have gained a substantially better understanding of the nature of this problem. However, many gaps in our knowledge base exist. This review describes recent data on hearing loss in the VLBW population and explains the current level of understanding about the physiological basis underlying the auditory deficits in these patients. Although VLBW alone may not have a severe impact on hearing, it is commonly associated with multiple other risk factors that can alter hearing in a synergistic fashion. Therefore, the risk of hearing loss is substantially higher than in the general newborn population. Also, it is important to perform a more comprehensive audiometric evaluation than standard otoacoustic emission screening for infants who are in the neonatal intensive care unit in order not to miss hearing loss due to retrocochlear pathology. Furthermore, children with VLBW are also at increased risk of experiencing progressive or delayed-onset hearing loss, and thus should continue to have serial hearing evaluations after discharge from the neonatal intensive care unit.

Outcomes in a population of healthy term and near-term infants with serum bilirubin levels of >or=325 micromol/L (>or=19 mg/dL) who were born in Nova Scotia, Canada, between 1994 and 2000

OBJECTIVE

The goal was to study the incidence of kernicterus, developmental delay, autism, cerebral palsy, and hearing loss in infants with peak total serum bilirubin levels of >or=325 micromol/L (>or=19 mg/dL), compared with infants with less-severe or no hyperbilirubinemia, in a population of healthy term and late preterm infants.

METHODS

Prospectively gathered, standardized, maternal and neonatal data for infants at >or=35 weeks of gestation who were born between January 1, 1994, and December 31, 2000, were extracted from the Nova Scotia Atlee Perinatal Database. Infants with Rh factor isoimmunization, significant congenital or chromosomal abnormalities, or severe peripartum asphyxia were excluded. Comparisons were made on the basis of peak total serum bilirubin levels. Diagnoses were obtained through data linkage with the Medical Services Insurance Database for office visits and the Canadian Institute for Health Information Database for hospital admissions. The registration file provided information allowing calculation of follow-up times, which were determined for each separate outcome. Follow-up periods ranged from 2 to 9 years, with the end point being the first time the diagnostic code was encountered in either database. Cox proportional-hazards regression analyses were used to examine the relationships between outcomes and total serum bilirubin levels.

RESULTS

Of 61238 infants included in the study cohort, 4010 (6.7%) did not have linkage data, which left 56019 infants for analysis. There were no cases of kernicterus and no significant differences in rates of cerebral palsy, deafness, developmental delay, or visual abnormalities between the groups. There were suggestions of associations with attention-deficit disorder in the severe hyperbilirubinemia group and with autism in the combined moderate and severe hyperbilirubinemia group.

CONCLUSIONS

There was no increase in adverse effects reported previously to be associated with bilirubin toxicity. Associations with developmental delay, attention-deficit disorder, and autism were observed.

Acoustic Immittance in children without otoacoustic emissions

Considering the hypothesis that middle ear changes can impair the recording of otoacoustic emissions, it is possible that absent otoacoustic emissions in infants could be associated with a light tympanometric change.

Aim

To study the association between transient otoacoustic emissions and changes in acoustic immittance measurements with 226Hz probe tone in neonates.

Methods

Cross-sectional contemporary cohort study. 20 infants with no transient otoacoustic emissions (study group) and 101 infants with transient otoacoustic emissions (control group), with ages ranged from birth to eight months, were assessed. Infants were submitted to: admittance tympanometry; contralateral acoustic reflex threshold with stimulus of 0.5, 1, 2, 4 kHz and broad band noise; transient and distortion product otoacoustic emissions. The auditory brain response was used to study the threshold in neonates without transient otoacoustic emissions.

Results

Significant statistical differences were observed between the groups (p < 0.005), characterized by reduction in tympanometric configuration and increase acoustic reflex thresholds in the study group. These data suggest the occurrence of middle ear mild impairment in infants without transient otoacoustic emissions associated with normal auditory brain response.

Conclusion

tympanometry associated with acoustic reflex adds accuracy to the diagnosis of middle ear abnormalities.

Post-natal hearing loss in universal neonatal hearing screening communities: current limitations and future directions

Universal hearing screening has dramatically improved outcomes for babies born with detectable hearing abnormalities; yet there are some infants who develop significant hearing problems after passing a neonatal screen. There is much conjecture as to the number and the characteristics of infants with post-natal hearing losses; yet evidence suggests that many children may be affected, and that a large proportion have no discoverable cause. Currently, screening programmes use lists of risk factors to enroll babies into surveillance programmes. This practice is problematic because audiological follow-ups are expensive and under-utilised, and parental disclosure is often inaccurate. The large databases from universal neonatal programmes could inform the development of effective, evidence-based practice and policy for the detection and intervention of children who develop post-natal hearing losses.

Causation of permanent unilateral and mild bilateral hearing loss in children

Children with permanent unilateral or mild bilateral hearing loss have been a focus of concern by audiologists, educators, and physicians for at least 2 decades. These children are known to be at risk for psychoeducational difficulties. However, despite this concern, little has been learned about the causative factors of these hearing losses and how those factors might be contributing to child development. This review of known causes of permanent unilateral and mild bilateral hearing loss in children is meant to draw attention to the importance of the search for etiologic factors. That is, the identification of the hearing loss should not signal the end of the diagnostic process but, rather, the beginning of a search for causation. With the combined efforts of audiologists, otolaryngologists, pediatricians, geneticists, and other medical professionals, we may enhance our understanding of the primary causes of unilateral and mild bilateral hearing loss and, perhaps, create links between causative factors and psychosocial and psychoeducational outcomes.

Bilateral cochlear implants should be the standard for children with bilateral sensorineural deafness

PURPOSE OF REVIEW

Bilateral cochlear implants are provided to children in an attempt to establish binaural processing and allow hearing with greater ease. Arguments against implantation, which prevailed for many years, are countered by some of the findings reported over the past 1-2 years.

RECENT FINDINGS

Behavioral and electrophysiological outcomes in children receiving cochlear implants suggest that two issues are most important when considering bilateral cochlear implants for any child: the duration of deafness prior to the first implantation affecting development of oral speech and language skills and the inter-stage interval (between implantation of the first and second ears) likely affecting development of binaural processing.

SUMMARY

Based on the data reported to date, both the interval between onset of deafness and cochlear implantation and the interval between implantation of the first and second ears should be narrow in children. We recommend that simultaneous bilateral implantation be provided when possible and, if not, the inter-stage interval should be limited. We further recommend continued exploration of outcomes in children with longer inter-stage intervals with a view to defining a point at which bilateral cochlear implantation provides so little benefit that it is not cost-effective.

Extremely low birth weight infants are at high risk for auditory neuropathy

Auditory neuropathy (AN) is a condition in which transmission of sound to the brain is abnormal. This is reflected as an electrophysiologic profile of normal otoacoustic emissions (OAE), with abnormal auditory brainstem evoked responses (ABR). Functionally speech perception is impaired and management strategies remain controversial. AN can be missed if high-risk newborns are screened for hearing loss with only OAE testing. The rate of sensorineural hearing loss (SNHL) in high-risk nursery infants is 10 times greater compared with normal term newborns. Therefore, we hypothesize that infants from the neonatal intensive care unit (NICU) are at significantly higher risk for AN than normal term infants.

OBJECTIVE

The objective of this study is to establish a prevalence rate and characterize risk factors for NICU graduates who demonstrate the AN electrophysiologic profile.

STUDY DESIGN

This retrospective study examined infants admitted to the NICU at Kapi'olani Medical Center for Women and Children in Honolulu, HI from 1999 through 2003. Infants were screened with automated ABR. Diagnostic testing and OAE were performed before discharge if the ABR was abnormal. Hospital courses of 24 AN, 71 SNHL and 95 gestational age (GA)-matched control infants with normal hearing were reviewed.

RESULT

With a SNHL prevalence of 16.7/1000, the rate for AN was 5.6/1000 NICU infants. Compared to infants with SNHL, infants with AN were significantly younger (GA 28.3+/-4.8 AN vs 32.9+/-5.2 weeks SNHL, P<0.0001) and smaller (BW 1318+/-894 AN vs 1968+/-1006 g SNHL). Nearly two-thirds of the AN infants were ELBW and had significantly longer hospital stays compared to SNHL infants of the same birth weight group. Exposure to furosemide, aminoglycosides, vancomycin or dexamethasone was associated with increased AN but not SNHL. Peak bilirubin level correlated with SNHL but not AN.

CONCLUSION

Low birth weight NICU infants are at significant risk for AN. ELBW infants are at significantly higher risk for both AN and SNHL. Infants admitted to the NICU should be routinely screened by automated ABR and if abnormal, further evaluation should be started before hospital discharge. Early identification of AN will result in better understanding of this disorder and lead to the development of appropriate intervention strategies.

OPA1, the disease gene for optic atrophy type Kjer, is expressed in the inner ear

Autosomal dominant optic atrophy (adOA) is the most common form of hereditary optic neuropathy. The majority of cases are associated with mutations in the OPA1 gene. A few cases of adOA are known to be associated with moderate progressive hearing loss. To gain insight into the pathogenesis of this hearing loss, we performed expression analyses of OPA1 in the rat auditory and vestibular organ. In cochlear tissue, several splice variants of OPA1 were detected, which are also expressed in retinal tissue. OPA1 mRNA and protein was found in the hair cells and ganglion cells of the cochlea and vestibular organ. In ganglion cells, OPA1 mRNA and protein was already detectable at birth, whereas in the organ of Corti OPA1 mRNA and protein was up-regulated after birth and reached mature-like expression level during the onset of hearing. Comparison of an antibody directed to the mitochondrial marker protein HSP60 with antibodies directed to different amino acid stretches of OPA1 revealed a sub-cellular distribution of OPA1 in areas of significant density of mitochondria. The data suggest that defects in OPA1 cause hearing disorders due to a progressing metabolic disturbance of hair and ganglion cells in the inner ear.

Triagem auditiva em hospital público de Belo Horizonte, Minas Gerais, Brasil: deficiência auditiva e seus fatores de risco em neonatos e lactentes

O objetivo do trabalho foi estimar a prevalência de deficiência auditiva em crianças de hospital público de Belo Horizonte, Minas Gerais, Brasil, e investigar sua associação com fatores de risco descritos na literatura. O estudo transversal, retrospectivo, analisou 798 neonatos e lactentes, avaliados no Programa de Triagem Auditiva Neonatal Universal entre junho de 2002 e dezembro de 2003. Foram pesquisados os fatores de risco estabelecidos pelo Joint Committee on Infant Hearing em 1994, e por Azevedo em 1996, além da prematuridade. A prevalência de deficiência auditiva foi de 1,8% (15 casos). Foi realizada análise multivariada por regressão logística para verificação da associação entre fatores de risco e perda auditiva, que revelou associação estatisticamente significativa (valor p < 0,05) entre perda auditiva e: suspeita de surdez por parte dos familiares, hiperbilirrubinemia (exsangüíneo transfusão), medicação ototóxica, peso ao nascer menor que 1.500g. Confirma-se prevalência significativa de déficit auditivo em neonatos e lactentes; portanto, deve ser dada atenção aos fatores de risco que aumentam as chances de ocorrência do problema. Verifica-se a importância de programas de saúde auditiva que contemplem prevenção, diagnóstico precoce e intervenção.

Universal hearing screening

OBJECTIVE

To determine the weighted incidence of hearing impairment in a standardized population of at risk and not at risk neonates seeking care at a tertiary level hospital in India.

METHODS

A prospective study of a nonrandomized cohort of 1769 neonates (1490: Not at risk; 279: At risk) from a total of 8192 neonates (6509: Not at risk; 1683: At risk) who sought care at St John's medical College hospital from 1st September 2002 to 31st March 2006 were screened for hearing impairment using transient evoked otoacoustic emissions. Weighting was performed using the expected value of 10 % at risk and 90 % not at risk infants in a typical tertiary care level center in India derived from the National Neonatology and Perinatology database 2002-2003. Z test and 95 % confidence interval was used to determine the external validity of the results. P less than 0.05 was considered as statistically significant. The power of the study is 90 %.

RESULTS

The incidence of hearing impairment in infants screened was 10 per 1769 infants screened (1490: Not at risk; 279: At risk) which is 5.65 per 1000 screened. 279 at risk infants were screened and 3 were detected to have hearing impairment which is an incidence of approximately 10.75 per 1000 screened. Of the 1490 not at risk infants screened 7 had hearing impairment that is 4.70 per 1000 screened. If this was extrapolated to a standardized population consisting of 10 % at risk and 90 % not at risk then the incidence would be 5.60 per 1000 screened with a 95 % confidence interval of 4.13-7.06. This narrow 95 % confidence interval with a p equal to 0.001 indicates that this value may be close to the caseload in a typical tertiary care center.

CONCLUSION

In this study the incidence of hearing impairment is 3 per 279 in at risk infants screened and 7 per 1490 in not at risk infants screened. The weighted incidence in a standardized population of neonates seeking care at tertiary level center in India is 5.60 per 1000 as per this study. This high incidence calls for all pediatricians to consider incorporating a basic hearing screen for all the neonates using cost effective and appropriate technology. Initial screening may be performed using behavioral observation techniques and confirmation by otoacoustic emissions.

Reliability of hearing screening in high-risk neonates: Comparative study of otoacoustic emission, automated and conventional auditory brainstem response

OBJECTIVE

To compare the diagnostic reliability of automated transient evoked otoacoustic emissions (a-TEOAE), automated auditory brainstem response (a-ABR) and conventional brainstem auditory evoked potential (BAEP/ABR) for identification of hearing loss in high-risk neonates.

METHODS

Two hundred and six neonatal intensive care unit (NICU) admitted neonates were tested pre-discharge. Follow-up included a-TEOAE in all children, repetition of a-ABR or BAEP if failed in NICU. Sensitivity and specificity were compared and correlated with auditory risk factors.

RESULTS

BAEP had the highest sensitivity (100%) and specificity (90.8%), a-ABR the lowest (88.9% and 70.6%). A statistically significant difference in risk factors for temporary hearing loss was observed between normal and false positive a-TEOAE and BAEP, but not a-ABR outcome. Differences in specificity between a-ABR and a-TEOAE explain the pattern of "absent a-ABR/present a-TEOAE" in 13.8% of ears.

CONCLUSIONS

The BAEP appears the more reliable test for hearing screening of high-risk neonates because of highest sensitivity and specificity and should be used to confirm the diagnosis of "auditory neuropathy" in high-risk neonates. The reliability of a-ABR devices in critically ill neonates needs further investigation.

SIGNIFICANCE

This is, to our knowledge, the first attempt to compare the diagnostic reliability of a-TEOAE, a-ABR and BAEP in high-risk neonates.

Differential expression of otoferlin in brain, vestibular system, immature and mature cochlea of the rat

Mutations of the human otoferlin gene lead to an autosomal recessive nonsyndromic form of prelingual, sensorineural deafness (deafness autosomal recessive 9, DFNB9). Several studies have demonstrated expression of otoferlin in the inner ear and brain, and suggested a role of otoferlin in Ca(2+)-triggered exocytosis. So far, otoferlin expression profiles were solely based on the detection of mRNA. Here, we analysed the expression of otoferlin protein and mRNA using immunohistochemistry, in situ hybridization and RT-PCR in neonatal and mature Wistar rat tissue. In agreement with previous studies, otoferlin expression was found in the brain and in inner and vestibular hair cells. Otoferlin mRNA and protein was, however, also detected in mature outer hair cells of low-frequency processing cochlear turns and in auditory nerve fibres. In outer, inner and vestibular hair cells, otoferlin was subcellularly localized at a considerable distance from the presumed active release sites. Double-staining with the synaptic ribbon marker, C-terminal binding protein 2 (CtBP2), or the presynaptic Ca(2+)-channel, Ca(v)1.3, both assumed to mark the sites of vesicle fusion and transmitter release, did not colocalize with otoferlin expression and thus do not necessarily support a selected role of otoferlin in Ca(2+)-triggered exocytosis. The widespread distribution of otoferlin in neurons, nerve fibres and hair cells, and its subcellular distribution extending beyond the regions of synaptic vesicle fusion, i.e. coenrichment with the cytosolic Golgi matrix protein 130 (GM130) in inner hair cells or the early endosomal autoantigen 1 (EEA1) in outer hair cells support instead the idea of a more ubiquitous role of otoferlin in early/recycling endosome trans-Golgi network dynamics.