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

Late Onset Hearing Loss in Very Low Birth Weight Infants

Objective

To determine the incidence of late onset hearing loss and associated risk factors in very low birth weight (VLBW) infants.

Study Design

Retrospective study (2003-2015) of post-discharge hearing outcomes and risk factors in the VLBW infant population, before and after the institution of a standardized follow-up program.

Results

Late onset hearing loss increased from 2.9 per 100 VLBW infants to 7.8 per 100 after instituting a monitoring protocol. The follow-up compliance rate nearly doubled. Both infants with late-onset sensorineural hearing loss and those with a conductive component were identified. The rate of conductive loss detection increased seven-fold.

Conclusion

The institution of a standardized hearing follow-up program significantly increased the detection of late onset hearing loss in VLBW infants. A significant proportion of those with late onset hearing loss had a conductive component. Without identification and treatment, even conductive losses may negatively impact speech and language development.

Choline supplementation mitigates effects of bilirubin in cerebellar granule neurons in vitro

BACKGROUND

Premature infants may suffer from high levels of bilirubin that could lead to neurotoxicity. Bilirubin has been shown to decrease L1-mediated ERK1/2 signaling, L1 phosphorylation, and L1 tyrosine 1176 dephosphorylation. Furthermore, bilirubin redistributes L1 into lipid rafts (LR) and decreases L1-mediated neurite outgrowth. We demonstrate that choline supplementation improves L1 function and signaling in the presence of bilirubin.

METHODS

Cerebellar granule neurons (CGN) were cultured with and without supplemental choline, and the effects on L1 signaling and function were measured in the presence of bilirubin. L1 activation of ERK1/2, L1 phosphorylation and dephosphorylation were measured. L1 distribution in LR was quantified and neurite outgrowth of CGN was determined.

RESULTS

Forty µM choline significantly reduced the effect of bilirubin on L1 activation of ERK1/2 by 220% (p = 0.04), and increased L1 triggered changes in tyrosine phosphorylation /dephosphorylation of L1 by 34% (p = 0.026) and 35% (p = 0.02) respectively. Choline ameliorated the redistribution of L1 in lipid rafts by 38% (p = 0.02) and increased L1-mediated mean neurite length by 11% (p = 0.04).

CONCLUSION

Choline pretreatment of CGN significantly reduced the disruption of L1 function by bilirubin. The supplementation of pregnant women and preterm infants with choline may increase infant resilience to the effects of bilirubin.

IMPACT

This article establishes choline as an intervention for the neurotoxic effects of bilirubin on lipid rafts. This article provides clear evidence toward establishing one intervention for bilirubin neurotoxicity, where little is understood. This article paves the way for future investigation into the mechanism of the ameliorative effect of choline on bilirubin neurotoxicity.

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.

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

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

Cumulative risk factors contributing to hearing loss in preterm infants

OBJECTIVE

To investigate individual and concomitant risk factors for hearing loss during neonatal care.

DESIGN

Case-control study.

SETTING

Community.

POPULATION

237 children born <32 weeks of gestation; 57 with hearing loss and 180 with normal hearing born between 2009 and 2013, matched for sex, gestation and year of birth.

MAIN OUTCOME MEASURES

Data were abstracted from clinical records for overall risk factors daily for the first 14 days and then weekly until discharge from neonatal care. All infants were screened for the presence of m.1555A>G mutation.

RESULTS

Children with hearing loss had lower birth weight for gestational age, more severe neonatal illness, with increased exposure to inotrope, steroid, gentamicin, vancomycin and furosemide, and more frequent physiological risk, elevated bilirubin and creatinine levels and acidosis, but no index child was found to have the m.1555A>G mutation, compared with one among controls. The duration of gentamicin, vancomycin or furosemide administration in the first 14 days was associated with impaired hearing (OR per dose: 1.25; 95% CI 1.14 to 1.38). Multivariate analyses revealed independent risks for hearing loss for each day when there was physiological risk (OR per day 1.15 (1.05 to 1.27)) and each day of medication exposure (OR 1.23 (1.1 to 1.37)).

CONCLUSION

Although the relative contribution of underlying illness and medication cannot be identified by this study, cumulative use of ototoxic medication and the presence of physiologic risk factors independently increased the likelihood of hearing loss, warranting close monitoring of coincident therapy throughout neonatal critical care.

Speech and Language outcomes in Auditory Neuropathy Spectrum Disorder (ANSD) children managed with amplification

OBJECTIVE

To evaluate speech and language outcomes in children with Auditory Neuropathy Spectrum Disorder (ANSD) without significant comorbidities who received hearing rehabilitation in the form of hearing aids and/or cochlear implantation.

METHODS

Retrospective chart review of pediatric ANSD patients at a large academic tertiary care institution from 2010 to 2019. Patients were included if they received a diagnosis of bilateral ANSD, had minimal to no comorbidities, and had speech and language testing (SLT) on at least two occasions.

RESULTS

51 patients were reviewed and 7 met inclusion criteria. Average age at ANSD diagnosis was 1 year and 11 months, and average age of hearing aid fitting was 3 years and 3 months. Hearing loss ranged from mild to profound, with four of the children wearing behind (BTE) hearing aids and three eventually receiving cochlear implants. Four of five patients who received hearing aids prior to their first speech and language evaluation demonstrated a delay at their initial evaluation, and all five patients continued to demonstrate a delay at their most recent evaluation, despite appropriate audiologic management and speech and language therapy. There were two patients who were unaided at the time of their initial and latest evaluations; one patient showed a delay at both timepoints, and one patient showed no speech delay at either timepoint.

CONCLUSIONS

Pediatric ANSD patients, who are otherwise typically developing and received hearing rehabilitation and speech and language therapy, continue to show a speech and language delay (SLD). This outcome underscores the importance of close monitoring of speech and language development, providing early amplification and/or cochlear implantation, and promoting additional education and psychosocial support.

Comparison of Otoacoustic Emission (OAE) and Brainstem Evoked Response Audiometry (BERA) in High Risk Infants and Children under 5 Years of Age for Hearing Assessment in Western India: A Modification in Screening Protocol

There are very few studies from India, which have compared Otoacoustic Emission (OAE) and Brainstem Evoked Response Audiometry (BERA) as a screening modality for detection of hearing loss in children. With the aim of establishing some guidelines regarding the protocols for hearing loss assessment and preventive measures, the present study has been undertaken to compare OAE with BERA done simultaneously, in the diagnosis of paediatric hearing loss, and also to study associated risk factors for hearing loss in children of Rural Central India. Prospective observational study was carried out on 100 children (200ears) in age group of 0-5 years. Selection was based on the inclusion and exclusion criteria. In all the 100 children detailed history was taken from the parents and were subjected to distortion product otoacoustic emissions (DPOAE). Irrespective of the pass or refer result children were subjected for BERA test. The interpretation of OAE and BERA test was as follows. Both the results of OAE refer and BERA fail were considered as confirmed HL, OAE pass and BERA fail were considered as children having Auditory Neuropathy (AN), OAE refer and BERA pass were considered as children at risk of permanent hearing loss (HL), OAE pass and BERA pass were considered as children with no evidence of HL. In the present study the male to female ratio was 1.32:1. Of the total 100 children 80% children showed presence of any one or more than one risk factors. In our study, eclampsia [7%] followed by multiparity [6%] and oligohydramnios [5%] were the most common risk factors in prenatal period. Maximum number of infants in AN profile were with Low Apgar score, children exposed to ototoxic medications, non-syndromic cardiac disorders in children [25.8% each]. Maximum number of infants in Confirmed HL profile were with congenital syndromes/ear anomalies [41.86%] followed by other risk factors. In our study, both OAE and BERA test were comparable and statistically significant with p value of 0.0001. OAE has a high specificity and positive predictive value of 93.33% and 97.22% respectively and it has a low sensitivity and negative predictive value of 67.74% and 45.65% respectively. In a developing country like India were universal screening protocols are not followed large number of children may be missed and may present late when it affects child's communication abilities. Hence, we need to modify our screening test and implement high risk screening even in the absence of any hearing or speech complaints.

Providing a Primary Care Medical Home for Children and Youth With Cerebral Palsy

Cerebral palsy (CP) is the most common motor disorder of childhood, with prevalence estimates ranging from 1.5 to 4 in 1000 live births. This clinical report seeks to provide primary care physicians with guidance to detect children with CP; collaborate with specialists in treating the patient; manage associated medical, developmental, and behavioral problems; and provide general medical care to their patients with CP.

Supra-Threshold Hearing Sensitivity Disorders and Mild Permanent Hearing Loss: Neglected Cause of Hidden Hearing Loss and Speech Defects

Supra-threshold disorders in the form of auditory neuropathy (AN)/auditory dys-synchrony (AD) or central auditory processing disorders (CAPD), a special type of retrocochlear hearing loss; and also children with mild permanent hearing loss (PHL), may be missed on current hearing protocols. Otoacoustic emissions (OAE) and Brain stem evoked response audiometry (BERA), are tests, when used in combination, can indirectly help diagnose the different types of hearing loss. To correlate the parental awareness and the pattern of hearing loss (HL) in children with/without auditory and/or speech problems, using both OAE and BERA as hearing tests for indirect identification of suprathreshold disorders and mild PHL. An Observational Prospective study carried out on 100 children in the age group of 0-5 years, for detection of type of HL by both OAE and BERA and correlating it with parental awareness of HL and speech defects. In 72.22% of children with speech problem only and without any complaints of HL, some form of HL (confirmed HL-OAE refer/BERA fail or auditory neuropathy/auditory dys-synchrony-OAE pass/BERA fail) was diagnosed, whereas 24.07% had no detectable HL on both OAE and BERA pass, and were considered as indirect evidence of CAPD. 3.7% with OAE refer and BERA pass were considered indicative of mild PHL. AN/AD/CAPD/Mild PHL are important cause of speech delay without parental awareness of HL. OAE and BERA together can be used as an indirect evidence of their presence.

Tracheobronchitis in children with tracheostomy tubes: Overview of a challenging problem

Tracheobronchitis is common in children with tracheostomy tubes. These children are predisposed to respiratory infections due to the bypassing of normal upper airway defense mechanisms by the tracheostomy, bacterial colonization of the tracheostomy tube itself, and underlying medical conditions. Diagnosis of bacterial tracheobronchitis is challenging due to the difficulty in differentiating between bacterial colonization and infection, as well as between viral and bacterial etiologies. Difficulty in diagnosis complicates management decisions, and there are currently no consensus guidelines to assist clinicians in the treatment of these patients. Frequent administration of systemic antibiotics causes adverse effects and leads to the emergence of resistant organisms. Topical administration of antibiotics via nebulization or direct instillation may lead to a significantly higher concentration of drug in the upper and lower airways without causing systemic side effects, although therapeutic trials in children with tracheostomy tubes are lacking. Several preventative measures such as regular airway clearance and the use of a speaking valve may mitigate the risk of developing respiratory infections.

[The issue of auditory neuropathy: from origins to the present]

The issue of auditory neuropathy spectrum disorders (ANSD) has been in a focus of specialists attention for a relatively short time, but during this time a huge amount of scientific and practical knowledge about this hearing disorder has been accumulated. ANSD is a specific auditory deficit caused by dysfunction of periphery part of the auditory system, which may affect the inner hair cells, the spiral ganglion neurons and the auditory nerve, as well as the area of synaptic contact between them, while the outer hair cells, as a rule, remain intact. 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, electrophysiological data may not correlate with hearing level, the discrepancy between pure tone audiometry and speech discrimination is observed. ANSD prevalence, epidemiology, contemporary views on its etiology, including detailed information on hereditary forms of the disorder and its risk factors are considered in the review. The data on the basic rungs of the ANSD pathogenesis, which underlie the development of various forms of the disorder and mainly determine the rehabilitation approach, are presented. The detailed clinical and audiological characteristics of ANSD are presented; contemporary approach to ANSD diagnosis and rehabilitation, including indications for surgical treatment, are considered.

[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.

Assessing Loss to Follow-up After Newborn Hearing Screening in the Neonatal Intensive Care Unit: Sociodemographic Factors That Affect Completion of Initial Audiological Evaluation

OBJECTIVES

Neonatal intensive care unit (NICU) patients are at high risk for congenital hearing loss. Previous studies have found sociodemographic factors associated with loss to follow-up for newborn hearing screening, but none have specifically studied the NICU population. Our objective is to determine if demographics and socioeconomic status is associated with loss to follow-up in a newborn population with extended NICU stay.

DESIGN

A retrospective cohort study was conducted on 443 NICU infants with extended NICU stay utilizing data extracted from infant and maternal medical records at an urban safety-net hospital.

RESULTS

Younger maternal age (adjusted odds ratio [OR] 0.95, confidence interval [CI] 0.91 to 0.99), higher gravidity (adjusted OR 1.39, CI 1.12 to 1.72), and former smoking status (adjusted OR 2.57, CI 1.07-6.18) were identified as independent predictors of loss to follow-up for NHS after conducting a multivariable logistic regression. Demographic and socioeconomic variables, such as sex, parity, birth weight, mode of birth, highest level of maternal education, maternal race/ethnicity, zip code metrics, and maternal language were not found to be associated with loss to follow-up.

CONCLUSIONS

Maternal age, gravidity, and smoking status are risk factors for loss to follow-up for NHS in newborns with extended NICU stay, a group at high risk for hearing loss. Our findings demonstrate that socioeconomic and demographic factors for loss to follow-up in the extended-stay NICU population are distinct from the well-baby population. Further investigation of these patients will allow prioritization of limited resources to subgroups within the extended-stay NICU population at risk for loss to follow-up for newborn hearing screening.

Diagnosis of Auditory Neuropathy Spectrum Disorder in the Neonatal Intensive Care Unit Population

OBJECTIVE

To determine the incidence of auditory neuropathy spectrum disorder (ANSD) and its risk factors among the neonatal intensive care unit (NICU) population from 2009 to 2018 in the Pediatric Health Information System database.

STUDY DESIGN

Retrospective national database review.

SETTING

Population-based study.

METHODS

The Pediatric Health Information System database was queried to identify patients ≤18 years old with NICU admission and ANSD diagnosis. Patient demographics, jaundice diagnosis, use of mechanical ventilation, extracorporeal membrane oxygenation, furosemide, and/or aminoglycosides were extracted. Multivariable linear regression was used to assess trends in incidence. Chi-square analysis was used to assess differences between patients with and without ANSD. Logistic regression was used to assess factors associated with ANSD.

RESULTS

From 2009 to 2018, there was an increase in (1) NICU admissions from 14,079 to 24,851 (P < .001), (2) total ANSD diagnoses from 92 to 1847 (P = .001), and (3) annual total number of patients with ANSD and NICU admission increased from 4 to 16 (P = .005). There was strong correlation between the increases in total number of NICU admissions and total ANSD diagnoses over time (R = 0.76). The average ANSD incidence was 0.052% with no statistically significant change over 10 years. When compared with all NICU admissions, children with ANSD had a higher association with use of furosemide (P < .001) and ventilator (P < .001).

CONCLUSION

Despite a statistically significant increase in NICU admissions and total ANSD diagnosis, the incidence of ANSD in the NICU population has not increased from 2009 to 2018. Furosemide and mechanical ventilator use were associated with increased likelihood of ANSD.

Bilirubin inhibits lipid raft dependent functions of L1 cell adhesion molecule in rat pup cerebellar granule neurons

BACKGROUND

The mechanism of bilirubin neurotoxicity is poorly understood. We hypothesize that bilirubin inhibits the function of lipid rafts (LR), microdomains of the plasma membrane critical for signal transduction. To test this hypothesis, we measured the effect of free bilirubin (Bf) between 7.6 and 122.5 nM on LR-dependent functions of L1 cell adhesion molecule (L1).

METHODS

Cerebellar granule neurons (CGN) were plated on poly-L-lysine overnight, and neurite length was determined after 1 h treatment with L1 alone or L1 and bilirubin. L1 activation of ERK1/2 was measured in CGN in the presence or absence of bilirubin. The effect of bilirubin on L1 distribution in LR was quantitated, and the localization of bilirubin to LR was determined.

RESULTS

The addition of bilirubin to CGN treated with L1 significantly decreased neurite length compared to L1 alone. L1 activation of ERK1/2 was inhibited by bilirubin. Bilirubin redistributed L1 into LR. Bilirubin was associated only with LR-containing fractions of a sucrose density gradient.

CONCLUSION

Bf significantly inhibits LR-dependent functions of L1 and are found only associated with LR, suggesting one mechanism by which bilirubin may exert neurotoxicity is through the dysfunction of protein-LR interactions.

IMPACT

This article establishes lipid rafts as a target for the neurotoxic effects of bilirubin. This article provides clear evidence toward establishing one mechanism of bilirubin neurotoxicity, where little is understood. This article paves the way for future investigation into lipid raft dependent functions, and its role in neurodevelopmental outcome.

Changes in auditory function in premature children: A prospective cohort study

OBJECTIVES

To analyze the age-specific pattern of auditory function in preterm children as a function of their gestational age at birth.

STUDY DESIGN

longitudinal cohort study.

METHODS

a prospective cohort study involved 271 preterm children aged from 6 months to 15 years old. Children were divided into two groups: 70 children with a gestational age at birth of 32-36 weeks (Group 1) and 201 children with a gestational age of 22-31 weeks (Group 2). Hearing was assessed by ABR, ASSR, OAE, behavioral audiometry, and pure tone audiometry. Additionally, for some children, CT, MRI, and GBJ2 evaluations were performed. Assessments of hearing impaired children were performed 3-4 times a year for children under 2 years of age; 2-3 times a year for children from 2 to 5 years of age; and 1-2 times a year for children over 5 years of age. Infants without any hearing problems were examined 2-3 times during their first year of life, followed by annual examinations as they aged.

RESULTS

The initial hearing examination identified SNHL and ANSD in 18 children (25.7%) and 64 children (31.8%) in Group 1 and Group 2, respectively. No significant difference in the occurrence of auditory impairment in the two groups was found at the initial assessment (p > 0.05). Further long-term follow-up revealed changes in hearing in 16 children: 15 from Group 2 and only one child from Group 1. Four different kinds of hearing changes were noted: hearing recovery to normal levels in children with ANSD; late onset hearing loss; the transformation of ANSD to SNHL, and vice versa. The age, factors, and possible mechanisms of such changes are discussed in the article.

CONCLUSION

The auditory function in prematurely born children tends to be unstable, especially at a very early age. In very preterm infants, it may either deteriorate or improve. Infants born before 31 weeks' gestation require long-term follow-up at least until they are 3-4 years of age. Caution is advised regarding very early cochlear implantation for children born before 32 weeks of gestation age.

Brainstem auditory pathway function at four months of corrected postnatal age in preterm infants born below 30 week gestation

OBJECTIVE

Functional status of the brainstem auditory pathway was examined at four months of corrected postnatal age in infants born below 30 week gestation to assess the effect of very or extremely preterm birth on postnatal development of the pathway.

METHODS

Thirty-four preterm infants born at 24-29 week gestation (GA24-29w) were studied at four months of corrected postnatal age. Normal controls were 38 postnatal age-matched term infants. Maximum length sequence brainstem auditory evoked response (MLS BAER) were recorded and analysed with 60 dB nHL clicks.

RESULTS

Compared with term control group, GA24-29w group manifested higher BAER threshold (p < 0.05), longer MLS BAER wave latencies at all click rates 91-910/s (p < 0.01-0.001), and lower wave amplitudes at most click rates (p < 0.05-0.01). No significant differences were found between the two groups in I-V interval at any click rates. I-III interval was shorter while III-V interval was longer in GA24-29w group than in term group at higher rates (all p < 0.05). III-V/I-III interval ratio in GA24-29w group was greater at 455 and 910/s clicks (p < 0.05 and 0.01). These interval variables showed similar changes when 4 GA24-29w infants with threshold elevation were excluded.

CONCLUSIONS

At four months of corrected postnatal age, infants born below 30 week gestation manifested elevated BAER threshold, increased wave latencies, and reduced amplitude. They also manifested a small decrease in I-III interval but a small increase in III-V interval at high rates. Very or extremely preterm birth exerts a mild or moderate effect on postnatal development of the brainstem auditory pathway.

Treatment for hypotension in the first 24 postnatal hours and the risk of hearing loss among extremely low birth weight infants

OBJECTIVE

To evaluate whether treated hypotension in the first 24 postnatal hours is associated with hearing loss in extremely low birth weight (ELBW) infants.

STUDY DESIGN

In a cohort of 735 ELBW infants, we identified 25 with sensorineural hearing loss (SNHL) at 12-24 months adjusted age. For each case, we selected three controls with normal hearing. Logistic regression models were used to adjust for confounding variables.

RESULTS

Sixty percent of cases and 25% of controls were treated for hypotension. After adjusting for confounding variables (gestational age, antenatal glucocorticoids, 5 min Apgar < 6, insertion of an umbilical catheter, treatment with high frequency ventilation, and major cranial ultrasound abnormality), treated hypotension was associated with an increased risk of SNHL (adjusted odds ratio: 3.6; 95% confidence interval: 1.3-9.7).

CONCLUSIONS

Treated hypotension in ELBW infants in the first 24 h of life is associated with an increased risk of SNHL.

Auditory Neuropathy Spectrum Disorders: From Diagnosis to Treatment: Literature Review and Case Reports

Auditory neuropathy spectrum disorder (ANSD) refers to a range of hearing impairments characterized by deteriorated speech perception, despite relatively preserved pure-tone detection thresholds. Affected individuals usually present with abnormal auditory brainstem responses (ABRs), but normal otoacoustic emissions (OAEs). These electrophysiological characteristics have led to the hypothesis that ANSD may be caused by various dysfunctions at the cochlear inner hair cell (IHC) and spiral ganglion neuron (SGN) levels, while the activity of outer hair cells (OHCs) is preserved, resulting in discrepancies between pure-tone and speech comprehension thresholds. The exact prevalence of ANSD remains unknown; clinical findings show a large variability among subjects with hearing impairment ranging from mild to profound hearing loss. A wide range of prenatal and postnatal etiologies have been proposed. The study of genetics and of the implicated sites of lesion correlated with clinical findings have also led to a better understanding of the molecular mechanisms underlying the various forms of ANSD, and may guide clinicians in better screening, assessment and treatment of ANSD patients. Besides OAEs and ABRs, audiological assessment includes stapedial reflex measurements, supraliminal psychoacoustic tests, electrocochleography (ECochG), auditory steady-state responses (ASSRs) and cortical auditory evoked potentials (CAEPs). Hearing aids are indicated in the treatment of ANSD with mild to moderate hearing loss, whereas cochlear implantation is the first choice of treatment in case of profound hearing loss, especially in case of IHC presynaptic disorders, or in case of poor auditory outcomes with conventional hearing aids.

A Gunn rat model of preterm hyperbilirubinemia

BACKGROUND

The impact of bilirubin in preterm infants is poorly understood. An animal model would assist in improving understanding. The Gunn rat lacks uridine diphosphate-glucuronylsyl transferase 1 and can be made acutely hyperbilirubinemic by injection of sulfodimethoxine (sulfa), a drug that displaces bilirubin from albumin and thus increases free bilirubin.

METHODS

On postnatal day (P) 5, Gunn rats either heterozygous (Nj) or homozygous (jj) for glucuronosyltransferase activity were injected with either saline or sulfa. Behavior and cerebellar weight were measured.

RESULTS

Pups did not show any signs of acute bilirubin encephalopathy. Pup weight dropped significantly on P8 only in the jj-sulfa group. Behavior was affected only in the jj-sulfa group. Cerebellar weight was significantly less in the jj-sulfa group.

CONCLUSION

The Gunn rat pup model may be a good model to study hyperbilirubinemia in preterm infants.

Evaluation of Gentamicin Exposure in the Neonatal Intensive Care Unit and Hearing Function at Discharge

OBJECTIVE

To characterize the association between gentamicin dosing, duration of treatment, and ototoxicity in hospitalized infants.

STUDY DESIGN

This retrospective cohort study conducted at 330 neonatal intensive care units (2002-2014) included inborn infants exposed to gentamicin with available hearing screen results, and excluded infants with incomplete dosing data and major congenital anomalies. Our primary outcome was the final hearing screen result performed during hospitalization: abnormal (failed or referred for further testing in one or both ears) or normal (bilateral passed). The 4 measures of gentamicin exposure were highest daily dose, average daily dose, cumulative dose, and cumulative duration of exposure. We fitted separate multivariable logistic regression models adjusted for demographics, comorbidities, and other clinical events.

RESULTS

A total of 84 808 infants met inclusion/exclusion criteria; median (25th, 75th percentile) gestational age and birth weight were 35 weeks (33, 38) and 2480 g (1890, 3184), respectively. Failed hearing screens occurred in 3238 (3.8%) infants; failed screens were more likely in infants of lower gestational age and birth weight, who had longer hospital lengths of stay, higher rates of morbidities, and were small for gestational age. Median highest daily dose, average daily dose, and cumulative dose were 4.0 mg/kg/day (3.0, 4.0), 3.8 mg/kg/day (3.0, 4.0), and 12.1 mg/kg (9.1, 20.5), respectively. Median cumulative duration of exposure was 3 days (3, 6). In adjusted analysis, gentamicin dose and duration of therapy were not associated with hearing screen failure.

CONCLUSIONS

Gentamicin dosing and duration of treatment were not associated with increased odds of failed hearing screen at the time of discharge from initial neonatal intensive care unit stay.

Association between furosemide in premature infants and sensorineural hearing loss and nephrocalcinosis: a systematic review

Furosemide is a potent loop diuretic commonly and variably used by neonatologists to improve oxygenation and lung compliance in premature infants. There are several safety concerns with use of furosemide in premature infants, specifically the risk of sensorineural hearing loss (SNHL), and nephrocalcinosis/nephrolithiasis (NC/NL). We conducted a systematic review of all trials and observational studies examining the association between these outcomes with exposure to furosemide in premature infants.

We searched MEDLINE, EMBASE, CINAHL, and clinicaltrials.gov. We included studies reporting either SNHL or NC/NL in premature infants (< 37 weeks completed gestational age) who received at least one dose of enteral or intravenous furosemide. Thirty-two studies met full inclusion criteria for the review, including 12 studies examining SNHL and 20 studies examining NC/NL. Only one randomized controlled trial was identified in this review. We found no evidence that furosemide exposure increases the risk of SNHL or NC/NL in premature infants, with varying quality of studies and found the strength of evidence for both outcomes to be low. The most common limitation in these studies was the lack of control for confounding factors.

The evidence for the risk of SNHL and NC/NL in premature infants exposed to furosemide is low. Further randomized controlled trials of furosemide in premature infants are urgently needed to adequately assess the risk of SNHL and NC/NL, provide evidence for improved FDA labeling, and promote safer prescribing practices.

An analysis of hearing screening test results in 2291 premature infants of Chinese population

OBJECTIVE

The aim of this study was to analyze the hearing screening program among preterm infants as well as to identify risk factors associated with failing primary newborn hearing screening.

METHODS

The retrospectively selected population included all preterm infants who had primary hearing screening in a neonatal ward from January 1st, 2013 to December 31st, 2015 at West China Second University Hospital, Sichuan University. The newborn hearing screening (NHS) procedure was performed in all preterm infants by automated auditory brainstem response (AABR). Infants who failed the primary hearing screening received a second screening at 42 days after birth. Infants who failed both tests were referred to a tertiary audiology center for diagnostic confirmation and management before 6 months of age. The final diagnosis for referred infants was obtained by telephone follow-up. The risk factors associated with failure to pass the primary hearing screen were evaluated and analyzed for preterm infants.

RESULTS

Among 2291 preterm infants recruited, 155 infants (6.8%) failed the primary hearing screening with an abnormal AABR. Of these 155 infants, 113 (72.9%) passed the secondary screening. At the end of the follow-up, 1 infant (0.04%) was diagnosed with hearing loss, 3 infants had delayed language development, and 40 infants were lost to follow up. Multivariate regression analysis revealed that gestational age ≤32 weeks (Odds ratio [OR] = 2.093, 95% confidence interval [CI] 1.370-3.196), super hyperbilirubinemia (≥25 mg/dl) (OR = 3.560, 95% CI 1.009-12.560), and respiratory failure (OR = 1.971, 95% CI 1.188-3.265) were associated with failure to pass newborn hearing screening.

CONCLUSION

The prevalence of failure to pass primary hearing screening among preterm infants was 6.8% in our study, and we found a relatively low prevalence of hearing loss (0.04%). Super hyperbilirubinemia, gestational age ≤32weeks, and respiratory failure were risk factors associated with failure of preterm infants to pass the primary hearing screening. Our results suggest that preterm infants with hyperbilirubinemia, gestational age ≤32 weeks, and respiratory failure should be closely followed.

Perinatal thiamine deficiency causes cochlear innervation abnormalities in mice

Neonatal thiamine deficiency can cause auditory neuropathy in humans. To probe the underlying cochlear pathology, mice were maintained on a thiamine-free or low-thiamine diet during fetal development or early postnatal life. At postnatal ages from 18 days to 22 wks, cochlear function was tested and cochlear histopathology analyzed by plastic sections and cochlear epithelial whole-mounts immunostained for neuronal and synaptic markers. Although none of the thiamine-deprivation protocols resulted in any loss of hair cells or any obvious abnormalities in the non-sensory structures of the cochlear duct, all the experimental groups showed significant anomalies in the afferent or efferent innervation. Afferent synaptic counts in the inner and outer hair cell areas were reduced, as was the efferent innervation density in both the outer and inner hair cell areas. As expected for primary neural degeneration, the thresholds for distortion product otoacoustic emissions were not affected, and as expected for subtotal hair cell de-afferentation, the suprathreshold amplitudes of auditory brainstem responses were more affected than the response thresholds. We conclude that the auditory neuropathy from thiamine deprivation could be produced by loss of inner hair cell synapses.

Decreasing vancomycin utilization in a neonatal intensive care unit

This study evaluated the efficacy of education versus audit and feedback in decreasing vancomycin utilization. Data were collected prospectively from October 1, 2012-April 30, 2014 over the following 3 periods: baseline, after education and introduction of a late-onset sepsis treatment guideline, and after prospective audit-feedback to physicians. Vancomycin utilization and administration duration >3 days significantly decreased with education and guideline use, but it was not affected by addition of audit and feedback.

Newborn hearing screening programme in Belgium: a consensus recommendation on risk factors

Background

Understanding the risk factors for hearing loss is essential for designing the Belgian newborn hearing screening programme. Accordingly, they needed to be updated in accordance with current scientific knowledge. This study aimed to update the recommendations for the clinical management and follow-up of newborns with neonatal risk factors of hearing loss for the newborn screening programme in Belgium.

Methods

A literature review was performed, and the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system assessment method was used to determine the level of evidence quality and strength of the recommendation for each risk factor. The state of scientific knowledge, levels of evidence quality, and graded recommendations were subsequently assessed using a three-round Delphi consensus process (two online questionnaires and one face-to-face meeting).

Results

Congenital infections (i.e., cytomegalovirus, toxoplasmosis, and syphilis), a family history of hearing loss, consanguinity in (grand)parents, malformation syndromes, and foetal alcohol syndrome presented a ‘high’ level of evidence quality as neonatal risk factors for hearing loss. Because of the sensitivity of auditory function to bilirubin toxicity, hyperbilirubinaemia was assessed at a ‘moderate’ level of evidence quality. In contrast, a very low birth weight, low Apgar score, and hospitalisation in the neonatal intensive care unit ranged from ‘very low’ to ‘low’ levels, and ototoxic drugs were evidenced as ‘very low’. Possible explanations for these ‘very low’ and ‘low’ levels include the improved management of these health conditions or treatments, and methodological weaknesses such as confounding effects, which make it difficult to conclude on individual risk factors. In the recommendation statements, the experts emphasised avoiding unidentified neonatal hearing loss and opted to include risk factors for hearing loss even in cases with weak evidence. The panel also highlighted the cumulative effect of risk factors for hearing loss.

Conclusions

We revised the recommendations for the clinical management and follow-up of newborns exhibiting neonatal risk factors for hearing loss on the basis of the aforementioned evidence-based approach and clinical experience from experts. The next step is the implementation of these findings in the Belgian screening programme.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-015-0479-4) contains supplementary material, which is available to authorized users.

Functional integrity of rostral regions of the immature brainstem is impaired in babies born extremely preterm

OBJECTIVE

Babies born extremely preterm are predisposed to brain damage. We test the hypothesis that functional integrity of the auditory brainstem, particularly the rostral regions, is impaired in extremely preterm babies.

METHODS

We recruited 68 babies who were born at 23-27 weeks of gestation. At term date, these babies were studied by recording and analysing maximum length sequence brainstem auditory evoked response (MLS BAER) with click rates 91-910/s. Detailed data analysis was performed in 65 babies from whom reliable MLS BAER measurements were obtained.

RESULTS

Compared with normal term controls, the extremely preterm babies showed a significant increase in wave V latency, and I-V interval at all rates 91-910/s (p<0.01-0.001). Of two small intervals, I-III interval showed no apparent abnormality, but III-V interval was significantly increased at all rates, which was supported by a significant increase in III-V/I-III interval ratio (all p<0.001). These abnormalities were more significant at higher than at lower rates. The slopes of wave V latency-, I-V interval- and particularly III-V interval-rate functions were all increased. The same was true for the slope of III-V/I-III interval ratio-rate function.

CONCLUSIONS

MLS BAER variables that mainly reflect central neural conduction in the extremely preterm babies were abnormally increased. The most important abnormality was a significant increase in III-V interval and its click rate-dependent change. The abnormalities tended to be more significant than those previously reported in late and very preterm babies.

SIGNIFICANCE

Babies born extremely preterm have a major impairment or maturational delay in functional integrity of the rostral regions of the immature brainstem, which is more significant than in less preterm babies.

Auditory Function in Immature Animals after Two Consecutive Courses of Ototoxic Antibiotics

In chronic experiments on immature rabbits receiving therapeutic courses of vancomycin, gentamicin, and consecutive administration of vancomicin and gentamicin by the scheme used in neonatology, hearing function was evaluated by the methods of auditory evoked potentials (auditory brainstem response, ABR) and distortion product otoacoustic emission (DPOAE). Comparison with the control group revealed ototoxic effects of all studied antibiotics that manifested in increased sound tolerance and more rapid shortening of latencies in 30-100 dB range. Higher thresholds were found only after gentamicin administration. Vancomycin administration significantly reduced the responses at 4 kHz. Subsequent gentamicin course did not potentiate this effect.

Audiologic impairment associated with bilirubin-induced neurologic damage

Hyperbilirubinemia occurs commonly in neonates and is usually mild and transient, with no long-lasting sequelae. However, bilirubin-induced neurologic damage may occur in some infants. The auditory pathway is the most sensitive part of the central nervous system to bilirubin-induced toxicity, and permanent sequelae may result from only moderately elevated total serum/plasma bilirubin levels. The damage to the auditory system occurs primarily within the brainstem and cranial nerve VIII, and manifests clinically as auditory neuropathy spectrum disorder.

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

INTRODUCTION

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

METHOD

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

RESULT

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

CONCLUSION

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

Effects of ventilation on hearing loss in preterm neonates: Nasal continuous positive pressure does not increase the risk of hearing loss in ventilated neonates

INTRODUCTION

There is increased risk of hearing loss in preterm neonates. This risk is further increased by environmental noise exposure especially from life support equipment such as ventilation. Nasal continuous positive airway pressure (NCPAP) used for respiratory support of preterm neonates is known to be associated with prolonged exposure to high levels of noise. However, there is paucity of information on the effect of NCPAP as compared to mechanical ventilation on hearing loss among preterm neonates.

METHODS

A retrospective chart review was performed on neonates with birth weight (BW) <1500g. Association of clinical factors including the use of NCPAP and mechanical ventilation with failure of hearing screen were studied. Those who failed hearing screen were followed for 2 years to observe long term effects of NCPAP on the hearing loss.

RESULTS

Of 344 neonates included in the study, 61 failed hearing screen. Gestational age (p=0.008), BW (p=0.03), ventilation (p=0.02), intrauterine growth retardation (p=0.02), necrotizing enterocolitis (NEC) (p=0.02), apnea (p<0.001), use of vancomycin (p=0.01) and furosemide (p=0.01) were associated with failure of hearing screen. On multivariate analysis, ventilation (OR 4.56, p=0.02), apnea (OR 2.2, p<0.001) and NEC (OR 2.4, p=0.02) were predictors of failed hearing screen. As compared to those not ventilated, the odds of failing hearing screen was 4.53 (p<0.01) and 4.59 (p<0.01) for those treated with NCPAP and mechanical ventilation respectively, with there being no difference between these two ventilatory modalities. Of the 61 neonates, 42 were followed for 2 years, of which 19 had confirmed hearing loss. Among these 19 neonates, there was no difference (p=0.12) between those who were treated with NCPAP or with mechanical ventilation.

CONCLUSION

There is no increase in the hearing loss in preterm neonates treated with NCPAP as compared to mechanical ventilation despite being exposed to higher environmental noise generated by the NCPAP.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Brainstem auditory response findings in term neonates in intensive care unit

OBJECTIVES

Whether term infants in neonatal intensive care unit (NICU) have brainstem auditory abnormalities remains to be determined. This study aimed to detect any abnormality in brainstem auditory function in term neonates who are admitted to NICU.

METHODS

From a NICU, we recruited 55 term neonates with various perinatal problems. They were studied during the first week after birth using brainstem auditory evoked response (BAER), and the results were compared with normal term controls.

RESULTS

Wave I and III latencies and I-III interpeak interval of the evoked response in the NICU term neonates were similar to those in the controls. Wave V latency and I-V and III-V interpeak intervals tended to be increased at 21/s clicks. The increase was more obvious at higher rates 51 and 91/s. Analysis of variance revealed that at 21/s clicks only III-V interval was significantly increased (p < 0.05). At 51 and 91/s clicks, wave V latency and III-V and I-V intervals were significantly increased (p < 0.05-0.01). The rates of the abnormalities were seen more at higher than at lower click rates. The amplitudes of waves I, III, and V in the NICU neonates were all slightly reduced, but none differed significantly from the controls.

CONCLUSIONS

There are some abnormalities in BAER in term neonates in NICU, suggesting functional abnormality in the auditory brainstem in NICU infants.

Hearing loss, auditory neuropathy, and neurological co-morbidity in children with birthweight <750 g

BACKGROUND AND AIMS

The current literature considers a birthweight <1,500 g as a risk factor for sensorineural hearing loss (SNHL, hearing threshold >25 decibels), auditory neuropathy (AN), and several neurological sequelae. The aim of the study was to determine the frequency and risk factors associated with SNHL, AN, and neurological morbidity in a group of children with birthweights of <750 g treated at a neonatal care unit and recruited into a long-term follow-up program.

METHODS

A case-control study was carried out. Inclusion criteria were birthweight <750 g and born between the years 2000 and 2010. We performed brainstem auditory-evoked potentials (BAEP), evoked otoacoustic emissions (EOAE) and free-field audiometry (FFA) in this population. Neonatal variables and procedures were compared between children with SNHL and children with normal bilateral hearing (NBH).

RESULTS

A total of 93 children with a mean age of 4 years were included in the follow-up. Six children (6.4%) had SNHL and 87 had NBH. We were unable to identify AN in the sample. Mean weight for this sample was 673 ± 68 g and gestational age 27.5 ± 2 weeks. Variables reflecting differences between groups included days under mechanical ventilation, furosemide treatment, and bronchopulmonary dysplasia. In the SNHL group, three patients had periventricular leukomalacia, two had hydrocephalus, and one patient had cerebral palsy.

CONCLUSIONS

Frequency of SNHL in children with birthweights <750 g was higher than in other premature infants and was related with mechanical ventilation, furosemide application, and bronchopulmonary dysplasia. Association with other neurological morbidities was frequent. Early diagnosis and intervention are required.

Auditory brain development in premature infants: the importance of early experience

Preterm infants in the neonatal intensive care unit (NICU) often close their eyes in response to bright lights, but they cannot close their ears in response to loud sounds. The sudden transition from the womb to the overly noisy world of the NICU increases the vulnerability of these high-risk newborns. There is a growing concern that the excess noise typically experienced by NICU infants disrupts their growth and development, putting them at risk for hearing, language, and cognitive disabilities. Preterm neonates are especially sensitive to noise because their auditory system is at a critical period of neurodevelopment, and they are no longer shielded by maternal tissue. This paper discusses the developmental milestones of the auditory system and suggests ways to enhance the quality control and type of sounds delivered to NICU infants. We argue that positive auditory experience is essential for early brain maturation and may be a contributing factor for healthy neurodevelopment. Further research is needed to optimize the hospital environment for preterm newborns and to increase their potential to develop into healthy children.

Incidence and pattern of hearing impairment in children with ≤ 800 g birthweight in British Columbia, Canada

AIM

This study aimed to evaluate changes over time in the characteristics of permanent hearing impairment (HI) in extremely low-birthweight (ELBW ≤800 g) children.

METHODS

Data from sequential visits up to 5 years of age assessing hearing and other neurodevelopmental outcomes were extracted from a cohort of ELBW subjects born between 1983 and 2006 at a single Canadian site. Trends in HI incidence, severity and association with other impairments were analysed in three 8-year epochs.

RESULTS

Fifty of 586 ELBW children had a HI. HI rates increased from 5% in epoch 1 to 7% in epoch 2-13% in epoch 3 (p = 0.01). Mild HI decreased from 78% in epoch 1 to 35% in epoch 3 (p = 0.03). Median age at diagnosis decreased from 13 to 8 months. Comorbidities were more common in HI children than non-HI children: cerebral palsy (40% vs 14%, p < 0.0001)), cognitive (38% vs 12%, p < 0.0001) and visual impairments (16% vs 6%, p = 0.009).

CONCLUSION

The incidence and severity of hearing impairment in a cohort of extremely low-birthweight children increased significantly from 5% to 13% (p = 0.01) over a 24-year period. Comorbidities were common. Potentially modifiable causes are explored.

Risk factors associated with hearing loss in infants: an analysis of 5282 referred neonates

OBJECTIVE

The aim of our study was to evaluate the frequency of risk factors and their influence on - the distribution and manifestation of - hearing loss in infants. The study was conducted at the Department of Laryngology in the Upper Silesian Center for Child Health in Katowice (Poland), as part of the Polish National Universal Neonatal Hearing Screening, conducted from 2003 to 2009.

MATERIALS AND METHODS

The selected population included every newborn that twice tested positive on the transient evoked otoacoustic emission (TEOAE) screening test, as well as all neonates with one or more risk factors as defined by the Joint Committee of Infant Hearing in 2000 (JCIH). The following procedures were used with each neonate: otolaryngological examination (with otoscopy), tympanometry, automated otoacoustic emission (AOAE), and auditory brainstem response (ABR). A total of 5282 infants were examined. Subjects were categorized into two groups: the first group consisted of 2986 (56.53%) neonates with risk factors of hearing loss, while the second group included 2296 (43.47%) neonates without any known risk factors, but who twice tested positive on the TEOAE screening.

RESULTS

Among all infants examined (5282), sensorineural hearing loss (SNHL) was identified in 240 cases (4.54%), and conductive hearing loss (CHL) in 40 cases (0.76%), while normal hearing (NH) appeared in 5002 cases (94.70%). In the first group, SNHL was identified in 128 neonates (4.29%), and CHL in 28 (0.94%), while NH appeared in 2830 (94.78%). The largest percentage of SNHL (15.52%) appeared in children with identified or suspected syndromes associated with hearing loss. The next highest frequency of SNHL was comprised of children subjected to mechanical ventilation for a period in excess of 5 days (11.45%). Only a small percentage (2.86%) of SNHL appeared to be due to the use of ototoxic medications, despite the fact that this factor is the most prevalent (33.13%) of all analyzed risk factors of hearing impairment. After ototoxic medications, the frequencies of risk factors are as follows: premature birth (16.21%); low birth weight (12.04%); intensive care in excess of 7 days (10.64%). Furthermore, as the number of coexisting risk factors increases, the probability of SNHL in infants is seen to also increase. For children with one to four coexisting risk factors, the probability of SNHL ranges from 3.15% to 5.56%; for five or more risk factors the probability nearly doubles.

CONCLUSION

Our results indicate that syndromes associated with hearing loss and mechanical ventilation for more than 5 days were statistically significant risk factors in the occurrence of hearing loss. The most common risk factors are ototoxic medications, premature birth, low birth weight, and intensive care in excess of 7 days. As the number of risk factors an infant is exposed to grows, the probability of hearing impairment increases. The large percentage of children with sensorineural hearing loss in the absence of any known risk factors demonstrates the necessity of hearing examinations in all neonates.

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.

Selective inner hair cell loss in prematurity: a temporal bone study of infants from a neonatal intensive care unit

Premature birth is a well-known risk factor for sensorineural hearing loss in general and auditory neuropathy in particular. However, relatively little is known about the underlying causes, in part because there are so few relevant histopathological studies. Here, we report on the analysis of hair cell loss patterns in 54 temporal bones from premature infants and a control group of 46 bones from full-term infants, all of whom spent time in the neonatal intensive care unit at the Hospital de Niños in San Jose, Costa Rica, between 1977 and 1993. The prevalence of significant hair cell loss was higher in the preterm group than the full-term group (41% vs. 28%, respectively). The most striking finding was the frequency of selective inner hair cell loss, an extremely rare histopathological pattern, in the preterm vs. the full-term babies (27% vs. 3%, respectively). The findings suggest that a common cause of non-genetic auditory neuropathy is selective loss of inner hair cells rather than primary damage to the cochlear nerve.

Universal neonatal audiological screening: experience of the University Hospital of Pisa

The early identification of pre-lingual deafness is necessary to minimize the consequences of hearing impairment on the future communication skills of a baby. According to the most recent international guidelines the deafness diagnosis must occur before the age of three months and the prosthetic-rehabilitative treatment with a traditional hearing aid should start within the first six months. When a Cochlear implant becomes necessary, the treatment should start between the age of 12 months and 18 months. The only way to diagnose the problem early is the implementation of universal neonatal audiological screening programs. Transient evoked otoacoustic emissions (TEOAE) is the most adequate test because it's accurate, economic and of simple execution. Automatic auditory brainstem response (AABR) is necessary to identify patients with auditory neuropathy but it is also important to reduce the number of false-positives.The 20-30% of infant hearing impairment is represented by progressive or late-onset hearing loss (HL) so it's also necessary to establish an audiological follow up program, especially in infants at risk.From November 2005 all neonates born in the University hospital of Pisa undergo newborn hearing screening. From 2008 the screening program follows the guidelines for the execution of the audiological screening in Tuscany which have been formulated by our group according to the 2007 JCIH Position Statement and adaptated to our regional reality by a multidisciplinary effort. From November 2005 to April 2009 8113 neonates born in the Neonatal Unit of Santa Chiara Hospital (Pisa) have undergone newborn hearing screening. 7621 neonates (93.9%) without risk factors executed only the TEOAE test. 492 (6.1%) neonates had audiological risk factors and thus underwent TEOAE and AABR. 84 patients (1,04%) failed both TEOAE and AABR tests. 78 of them underwent further investigations. 44 patients resulted false positives (the 0,54% of the screened newborns). 34 neonates (4,2 ‰) had a final diagnosis of hearing impairment. 8 patients (0.99 ‰) had unilateral hearing loss (HL). 26 patients (3,2 ‰) had bilateral hearing impairment.In our screening program the percentage of false-positives was quite low (0.54%) while the incidence of bilateral HL (3.2 ‰) is a little higher than that found in literature reports. In most of our patients premature birth or neonatal suffering represent the main cause of HL.

The medial olivocochlear system attenuates the developmental impact of early noise exposure

The early onset of peripheral deafness profoundly alters the functional maturation of the central auditory system. A prolonged exposure to an artificial acoustic environment has a similar disruptive influence. These observations establish the importance of normal patterns of sound-driven activity during the initial stages of auditory development. The present study was designed to address the role of cochlear gain control during these activity-dependent developmental processes. It was hypothesized that the regulation of auditory nerve activity by the medial olivocochlear system (MOCS) would preserve normal development when the immature auditory system was challenged by continuous background noise. To test this hypothesis, knock-out mice lacking MOCS feedback were reared in noisy or quiet environments and then evaluated with behavioral paradigms for auditory processing deficits. Relative to wild-type controls, noise-reared knock-out mice showed a decreased ability to process rapid acoustic events. Additional anatomical and physiological assessments linked these perceptual deficits to synaptic defects in the auditory brainstem that shared important features with human auditory neuropathy. Our findings offer a new perspective on the potentially damaging effects of environmental noise and how these risks are ameliorated by the protective role of MOCS feedback.

Risk factors for auditory neuropathy spectrum disorder in NICU infants compared to normal-hearing NICU controls

OBJECTIVES

To evaluate independent etiologic factors associated with auditory neuropathy spectrum disorder (ANSD) in infants who have been admitted to the neonatal intensive care unit (NICU) compared to normal-hearing controls.

STUDY DESIGN

Case-control study.

METHODS

We included all infants (n = 9) with the ANSD profile admitted to the NICU of Sophia Children's Hospital between 2004 and 2009. Each patient was matched with four normal-hearing controls of the same gender and postconceptional age. The following possible risk factors were studied: birth weight, dysmorphic features, APGAR scores (at 1, 5, and 10 minutes), respiratory distress (IRDS), cytomegalovirus (CMV) infection, sepsis, meningitis, cerebral bleeding, hyperbilirubinemia requiring phototherapy, peak total bilirubin level, furosemide, dexamethason, vancomycin, gentamycin, and tobramycin administration.

RESULTS

Nine infants met the ANSD criteria in one or both ears. IRDS (P = .02), meningitis (P = .04), and vancomycin administration (P = .009) were significantly increased in infants with ANSD compared to controls.

CONCLUSIONS

In high-risk NICU infants IRDS, meningitis and vancomycin administration are associated with auditory neuropathy spectrum disorder.

Risk factors for sensorineural hearing loss in NICU infants compared to normal hearing NICU controls

OBJECTIVES

To evaluate independent etiologic factors associated with sensorineural hearing loss in infants who have been admitted to the neonatal intensive care unit compared to normal hearing controls.

METHOD

Between 2004 and 2009, 3366 infants were admitted to the neonatal intensive care unit of Sophia Children's Hospital, of which 3316 were screened with AABR. A total of 103 infants were referred for auditory brainstem response analysis after failure on neonatal hearing screening. We included all infants diagnosed with sensorineural hearing loss. Each patient was matched with two normal hearing controls from the neonatal intensive care unit of the same gender and postconceptional age. The following risk factors were studied: birth weight, dysmorphic features, APGAR scores (at 1, 5 and 10 min), respiratory distress (IRDS), CMV infection, sepsis, meningitis, cerebral bleeding, cerebral infarction, hyperbilirubinemia requiring phototherapy, peak total bilirubin level, furosemide, dexamethason, vancomycin, gentamycin and tobramycin administration.

RESULTS

Fifty-eight infants were diagnosed with sensorineural hearing loss: 26 girls and 32 boys. The incidence of dysmorphic features (P=0.000), low APGAR score (1 min) (P=0.01), sepsis (P=0.003), meningitis (P=0.013), cerebral bleeding (P=0.016) and cerebral infarction (P=0.000) were significantly increased in infants with sensorineural hearing loss compared to normal hearing controls (n=116).

CONCLUSION

Dysmorphic features, low APGAR scores at 1 min, sepsis, meningitis, cerebral bleeding and cerebral infarction are associated with sensorineural hearing loss independent of neonatal intensive care unit admittance.