Recovery of Abnormal ABR in Neonates and Infants at Risk of Hearing Loss

Sensorineural hearing impairment among preterm children: a Norwegian population-based study

OBJECTIVE

To investigate the risk for sensorineural hearing impairment (SNHI) in preterm infants, and to what extent the risk is attributed to perinatal morbidities and therapies.

DESIGN

Population-based cohort study using data from several nationwide registries.

SETTING

Norwegian birth cohort 1999-2014, with data on SNHI until 2019.

PARTICIPANTS

60 023 live-born preterm infants, divided in moderate-late preterm (MLP) infants (32-36 weeks), very preterm (VP) infants (28-31 weeks) and extremely preterm (EP) infants (22-27 weeks), and a reference group with all 869 797 term-born infants from the study period.

MAIN OUTCOME MEASURES

SNHI defined by selected ICD-10 codes, recorded during minimum 5-year observation period after birth.

RESULTS

The overall SNHI prevalence in the preterm cohort was 1.4% compared with 0.7% in the reference group. The adjusted risk ratios (95% CIs) for SNHI were 1.7 (1.5-1.8) in MLP infants, 3.3 (2.8-3.9) in VP infants and 7.6 (6.3-9.1) in EP infants. Among EP infants, decreasing gestational age was associated with a steep increase in the risk ratio of SNHI reaching 14.8 (7.7-28.7) if born at 22-23 weeks gestation. Among the VP and MLP infants, mechanical ventilation and antibiotic therapy had strongest association with increased risk of SNHI, but infants not receiving these therapies remained at increased risk. Among EP infants intracranial haemorrhage increased the already high risk for SNHI. We found no signs of delayed or late-onset SNHI in preterm infants.

CONCLUSION

Preterm birth is an independent risk factor for SNHI. Invasive therapies and comorbidities increase the risk, predominantly in infants born after 28 weeks gestation.

Outcomes and Management of Infants Who Refer Newborn Hearing Screening

OBJECTIVES

With the implementation of Universal Newborn Hearing Screening, early diagnosis and referral has been expedited. Many patients who refer screening pass subsequent testing with otoacoustic emissions (OAE) or auditory brainstem response (ABR). The objective of our study was to identify the incidence and etiology of hearing loss in infants who refer initial testing in an urban, tertiary care pediatric otolaryngology practice.

METHODS

We performed a chart review of infants who were evaluated after referring newborn hearing screening from 2017 to 2021. Data collected included birth history, hospital screening results, subsequent audiology and otolaryngology visit findings, final hearing diagnoses, interventions, and outcomes.

RESULTS

Of the 450 patients, 83.8% (n = 377) had normal hearing bilaterally after repeat testing (OAE and/or ABR). Thirty five patients were diagnosed with otitis media with effusion (OME) (7.8%) and 17 patients (3.8%) were diagnosed with sensorineural hearing loss. Twenty seven patients (6.0%) were diagnosed with obstructing cerumen/vernix, many times in addition to another diagnosis. Of the 17 patients with sensorineural hearing loss, 2 had genetic syndromes and 2 had congenital cytomegalovirus. Sensorineural hearing loss was significantly associated with the presence of a deafness syndrome (P = .004) and in-utero infections (P = .04). About 11 (2.4%) underwent myringotomy with tube placement, 5 (1.1%) were fitted with hearing aids, 2 (0.4%) were referred for hearing aids, 4 (0.9%) had both myringotomy with tube placement and hearing aids, 1 child had a soft band/Bone Anchored Hearing Aid (BAHA) (0.2%), and 1 child (0.2%) had a cochlear implant.

CONCLUSION

Our incidence of sensorineural hearing loss was 3.8% (95% CI 2.0, 5.5), compared to rates of 0.44 to 68% in the published literature. Most patients had normal hearing, usually identified after only 1 repeat test. OME requiring myringotomy tube insertion was the most common pathology requiring intervention. Close observation for resolution and intervention, if warranted, is critical to prevent sequelae.

Comparing Auditory Brain Stem Responses and Transient Otoacoustic Emissions in Premature Infants with Auditory Developmental Delay: Evidence of Temporary Auditory Neuropathy

Objectives

Premature birth causes some permanent or temporary abnormalities in the hearing system of the newborn. Inadequate development of the central auditory nervous system and balance, as well as the delay in the formation of the nerve myelin, can be the cause of many hearing disorders, including permanent or temporary auditory neuropathy spectrum disorder (ANSD). The present study aims to identify and understand developmental delay disorder in the hearing system of infants and investigate the possibility of temporary auditory neuropathy in infants.

Materials & Methods

In this comparative analytical study, twenty premature infants were randomly selected for hearing tests using auditory brainstem response and transient otoacoustic emissions at the time of discharge and three months after the first evaluation. The different components of these tests were analyzed and compared before and after developing the auditory system.

Results

The OAEs test showed a signal-to-noise ratio above six dB with appropriate amplitudes in all infants. The grand average waveform of the ABR showed a significant difference between the amplitudes of waves III and V before and after maturation in both ears (p<0.05). In addition, the absolute latency of waves, specifically III and V, showed a significant difference between the two assessment times (0.05).

Conclusions

The present study confirmed the occurrence of temporary ANSD or delayed maturation in premature infants following the lack of complete growth and myelination of auditory nerve fibers. There is a need to determine the hearing status of premature infants by frequent examinations and prevent any unnecessary prescription of amplifications.

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

OBJECTIVES

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

DESIGN

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

RESULTS

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

CONCLUSIONS

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

Hearing outcomes in preterm infants with confirmed hearing loss

OBJECTIVES

Premature infants are at high risk for hearing loss (HL). The aim of the present study is to assess the frequency of preterm infants affected by HL who experience hearing improvement over months and evaluate possible factors associated with hearing changes.

METHODS

This retrospective study was conducted in a third-level referral audiologic center. Preterm infants with a confirmed diagnosis of sensorineural HL within the first 3 months of life were reassessed at 18 months corrected age using the click-evoked auditory brainstem response between January 1, 2012, and June 30, 2020. The frequency of hearing improvement and associations between possible risk factors and hearing changes were evaluated.

RESULTS

A total of 138 preterm infants (71 male and 67 female; mean gestational age: 30⁺² weeks) were assessed. The percentages of hearing improvement and hearing threshold normalization were 58.7% (81/138) and 35.5% (49/138), respectively. We observed a higher frequency of hearing improvement among preterm infants who had received exclusive breastfeeding or mixed feeding compared with those who had received exclusive infant formula (80% versus 29.3%, P < 0.001).

CONCLUSION

This study confirms the importance of performing a long audiological follow-up and postponing the indication for cochlear implantation in children with a history of preterm birth. Because of the expression of mesenchymal stem cells and high total antioxidant capacity, breast milk might play a protective role in the auditory system of preterm infants. These findings could have important implications for clinical practice, positively impacting the long-term hearing outcomes of preterm infants.

[Auditory neuropathy and prematurity: modern view of the issue (literature review)]

Auditory neuropathy spectrum disorder (ANSD) is a specific auditory disorder caused by dysfunction of periphery part of the auditory system, in which the function of the outer hair cells is preserved, but the afferent input at the cochlear level suffers due to the pathology of the inner hair cells, neurons of the spiral ganglion and/or the auditory nerve, as well as synaptic contact between them. As a result, a specific condition is formed, in which a patient's otoacoustic emissions and/or cochlear microphonics are present, auditory brainstem responses are abnormal or absent, the discrepancy between the hearing level and the electrophysiological data, poor speech perception which may not correlate with the hearing thresholds. ANSD is a multifactorial disease. One of the main risk factors is perinatal pathology and, in particular, prematurity. The possible factors associated with prematurity that provoke the onset of the disease, features of the pathogenesis, clinical and audiological peculiarities of ANSD in premature infants, contemporary approaches to the habilitation of such patients are discussed in the article. The necessity of an individual, patient-oriented approach to the treatment of premature infants with ANSD is substantiated; such an approach should be based both on the genesis of the disorder, taking into account possible points of lesion in the auditory system, and the developmental peculiarities of a premature baby considering the presence of concomitant diseases associated with prematurity. In the article attention is focused on the main directions of habilitation work with such children, including a multidisciplinary approach, regular careful monitoring of the auditory, speech and language skills, intensive psychological and speech therapist support, the choice of an adequate way of intervention and its improvement as necessary.

Prevalence, risk factors, and audiological characteristics of auditory neuropathy

OBJECTIVE

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

DESIGN

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

STUDY SAMPLE

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

RESULTS

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

CONCLUSION

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

Neuronal development in the cochlea of a nonhuman primate model, the common marmoset

Precise cochlear neuronal development is vital to hearing ability. Understanding the developmental process of the spiral ganglion is useful for studying hearing loss aimed at aging or regenerative therapy. Although interspecies differences have been reported between rodents and humans, to date, most of our knowledge about the development of cochlear neuronal development has been obtained from rodent models because of the difficulty in using human fetal samples in this field. In this study, we investigated cochlear neuronal development in a small New World monkey species, the common marmoset (Callithrix jacchus). We examined more than 25 genes involved in the neuronal development of the cochlea and described the critical developmental steps of these neurons. We also revealed similarities and differences between previously reported rodent models and this primate animal model. Our results clarified that this animal model of cochlear neuronal development is more similar to humans than rodents and is suitable as an alternative for the analysis of human cochlear development. The time course established in this report will be a useful tool for studying primate‐specific neuronal biology of the inner ear, which could eventually lead to new treatment strategies for human hearing loss.

Auditory Brainstem Evoked Response Patterns in the Neonatal Intensive Care Unit

OBJECTIVE

Delayed maturation of auditory brainstem pathway in neonates admitted to the neonatal intensive care unit (NICU) may lead to misdiagnosis of children with normal peripheral hearing and inappropriate use of amplification devices. The aim of this study is to determine the pattern of auditory brain stem response in neonates admitted to the NICU for proper hearing assessment in this high-risk population.

STUDY DESIGN

This prospective study was conducted on 1,469 infants who were admitted to the NICU, of which 1,423 had one or more risk factors for permanent congenital hearing loss and were screened with automated auditory brain stem response (AABR). A total of 60 infants were referred for diagnostic ABR analysis after failure on AABR screening. The control group comprised 60 well-baby nursery neonates with no risk factors for PCHL.

RESULTS

Mean values of absolute latencies of waves III and V; interpeak latencies I-III, III-V, and I-V; amplitude of waves I, and V; and I/V amplitude ratio at 90 dBnHL measured for the right and left ears at 1 and 3 months of age show significant difference in NICU neonates compared with controls (p < 0.05). All the diagnostic ABR measurements significantly improved at the age of 3 months (p < 0.001) except wave I absolute latency of both groups (p > 0.05). Significant correlations were found between ABR readings at the age of 1 and 3 months and the gestational age of the NICU neonates (p < 0.05).

CONCLUSION

Diagnostic ABR findings in NICU neonates suggested delayed maturation of the auditory brainstem pathway with a great impact of gestational age on this maturation. Auditory maturational changes were observed at 3 months of age of patient and control groups.

Auditory brainstem response in preterm infants with bilirubin encephalopathy

AIM

To clarify auditory brainstem response (ABR) in preterm infants with bilirubin encephalopathy and the relationships between ABR and clinical variables.

METHOD

We retrospectively reviewed the ABR waveforms of 56 preterm infants with BE and graded them as "no response", "abnormal interwave separation", or "normal". Patient backgrounds, the peak total bilirubin level, the bilirubin/albumin ratio, verbal communication ability, and newborn hearing screening test results from an automated ABR evaluation had been collected during an earlier nationwide survey.

RESULTS

The frequency of abnormal ABR findings decreased with age. Verbal communication tended to be poorer in patients with more severe ABR abnormalities. ABR findings improved in 7 of 29 infants with available serial ABR data. Both gestational age and the peak total bilirubin level were relatively lower in patients with than in those without improved ABR findings. Newborn hearing screening using automated ABR evaluation yielded data consistent with manual ABR findings in 16 of 20 patients who underwent both examinations.

CONCLUSIONS

ABR abnormalities in preterm infants with bilirubin encephalopathy may improve over time, especially in those with a lower gestational age and peak total bilirubin level. Newborn hearing screening using automated ABR may fail to detect abnormalities in some infants.

Three Cases of Recovery from Sensorineural Hearing Loss in the First Year of Life: Implications for Monitoring and Management

BACKGROUND

 Three infants with different risk factors, behavioral and physiologic audiometric histories, and diagnoses were fit with amplification between 3 and 8 months of age. Two of the three met criteria for cochlear implantation.

PURPOSE

 This article aims to heighten awareness of the rare possibility of recovery from sensorineural hearing loss in infants with varying histories and emphasize the importance of a full diagnostic test battery in all infants diagnosed with sensorineural hearing loss every 3 months until objective and subjective thresholds are stable to ensure appropriate intervention.

RESEARCH DESIGN

 Case reports.

RESULTS

 All three infants demonstrated improvement or full recovery of hearing and cochlear function by approximately 12 months old. Their change in hearing was discovered due to frequent follow-up and/or caregiver report. One of these infants was tentatively scheduled to have cochlear implant surgery 2 months later.

CONCLUSION

 Appropriate early intervention for infants with hearing loss is critical to ensure maximum accessibility to speech and language cues. The Federal Drug Administration approves cochlear implantation in infants as young as 12 months. When providing audiometric management of infants with sensorineural hearing loss, it is imperative to conduct a full diagnostic test battery every 3 months (including tympanometric, acoustic reflex, and otoacoustic emission measurement) until objective and subjective thresholds are stable. There was no apparent pattern of factors to predict that the infants highlighted in these cases would recover. Discussion among pediatric audiologists and otologists and comparison of data from clinics across the U.S. is needed to identify predictive patterns and determine appropriate, consistent monitoring of infants with sensorineural hearing loss.

Isolated auditory neuropathy at birth in congenital cytomegalovirus infection

Background

Congenital cytomegalovirus (cCMV) infection is the most frequent non-genetic cause of sensorineural hearing-loss (SNHL) (i.e., hearing loss due to a cochlear and/or auditory nerve damage). It is widely accepted that SNHL at birth, when associated to cCMV symptomatic infection involving the central nervous system, benefits from antiviral therapy started in the neonatal period. Conversely, there is no consensus for antiviral treatment in congenitally infected infants diagnosed with isolated SNHL (i.e., SNHL in an otherwise asymptomatic infant) at birth.

Our aim was to assess the frequency and the auditory outcome of isolated SNHL at birth due to auditory neuropathy (AN) (i.e., SNHL in a patient with normal cochlear function and auditory nerve dysfunction) in infants with cCMV infection.

Methods

We retrospectively reviewed the clinical history of 60 infants, born at term, with cCMV asymptomatic infection, without additional risk factors for SNHL, and exhibiting bilateral “pass” otoacustic emissions (OAE). None of them underwent antiviral therapy.

Hearing thresholds were assessed by means of Auditory Brainstem Responses (ABR). AN affected children were followed up until possible normalization of the hearing thresholds or definitive diagnosis of AN. Each infant diagnosed with monolateral or bilateral AN was classified according to the worst ear threshold.

Results

In our population, the first ABR was performed at a mean age of 5.00 ± 2.79 (SD) months and AN was diagnosed in 16/60 (26.67%) infants; in 4 infants the AN was defined as mild (4/4 monolateral), moderate in 11 (5/11 bilateral), and severe in 1 (bilateral). The mean age at first ABR was 3.69 ± 2.80 (SD) months in the 16 babies with AN and 5.48 ± 2.66 (SD) months in the 44 infants with normal hearing (p = 0.007). All AN cases spontaneously recovered a normal auditory threshold over time. The mean length of the audiological follow-up was 32.44 ± 17.58 (SD) months (range 5–60 months).

Conclusion

A delayed maturation of the auditory pathways should be considered when a mild/moderate isolated AN at birth is detected in cCMV infected infants. Prospective studies conducted on larger populations, and with a longer audiological follow-up, are needed to confirm our findings.

Prevalence of permanent childhood hearing loss detected at the universal newborn hearing screen: Systematic review and meta-analysis

CONTEXT

Permanent childhood hearing loss (PCHL) can affect speech, language, and wider outcomes. Adverse effects are mitigated through universal newborn hearing screening (UNHS) and early intervention.

OBJECTIVE

We undertook a systematic review and meta-analysis to estimate prevalence of UNHS-detected PCHL (bilateral loss ≥26 dB HL) and its variation by admission to neonatal intensive care unit (NICU). A secondary objective was to report UNHS programme performance (PROSPERO: CRD42016051267).

DATA SOURCES

Multiple electronic databases were interrogated in January 2017, with further reports identified from article citations and unpublished literature (November 2017).

STUDY SELECTION

UNHS reports from very highly-developed (VHD) countries with relevant prevalence and performance data; no language or date restrictions.

DATA EXTRACTION

Three reviewers independently extracted data and assessed quality.

RESULTS

We identified 41 eligible reports from 32 study populations (1799863 screened infants) in 6195 non-duplicate references. Pooled UNHS-detected PCHL prevalence was 1.1 per 1000 screened children (95% confidence interval [CI]: 0.9, 1.3; I2 = 89.2%). This was 6.9 times (95% CI: 3.8, 12.5) higher among those admitted to NICU. Smaller studies were significantly associated with higher prevalences (Egger's test: p = 0.02). Sensitivity and specificity ranged from 89-100% and 92-100% respectively, positive predictive values from 2-84%, with all negative predictive values 100%.

LIMITATIONS

Results are generalisable to VHD countries only. Estimates and inferences were limited by available data.

CONCLUSIONS

In VHD countries, 1 per 1000 screened newborns require referral to clinical services for PCHL. Prevalence is higher in those admitted to NICU. Improved reporting would support further examination of screen performance and child demographics.