Hyperbilirubinemia and Follow-up Auditory Brainstem Responses in Preterm Infants

Review of Precision Medicine and Diagnosis of Neonatal Illness

Background/Objectives: Precision medicine is a state-of-the-art medicine tactic that tailors information about people's genes, environment, and lifestyle to aid the prevention, diagnosis, and treatment of various diseases to provide an overview of the currently available knowledge and applicability of precision medicine in the diagnosis of different cases admitted to the NICU, such as encephalopathies, respiratory distress syndrome of prematurity, hemodynamic instability, acute kidney injury, sepsis, and hyperbilirubinemia. Methods: The authors searched databases, such as PubMed and PubMed Central, for the terms neonatal "precision medicine", "personalized medicine", "genomics", and "metabolomics", all related to precision medicine in the diagnosis of neonatal illness. The related studies were collected. Results: The review highlights the diagnostic approach that serves to implement precision medicine in the NICU and provide precision diagnosis, monitoring, and treatment. Conclusions: In this review, we projected several diagnostic approaches that provide precision identification of health problems among sick neonates with complex illnesses in the NICU; some are noninvasive and available in ordinary healthcare settings, while others are invasive or not feasible or still in ongoing research as machine learning algorithms. Future studies are needed for the wide implementation of artificial intelligence tools in the diagnosis of neonatal illnesses.

How should hyperbilirubinemia be considered in the definition of the hearing screening protocol for neonates at risk?

PURPOSE

To analyze hyperbilirubinemia as an indicator for the definition of risk protocol in newborn hearing screening (NHS) and in auditory monitoring in full-term and preterm neonates.

METHODS

This is an observational, cross-sectional and retrospective study. A total of 554 children born in a public maternity hospital were included and divided into two groups: (G1) with 373 full-terms neonates; (G2) with 181 preterm neonates. Data were collected from the participant's medical records to obtain information regarding the result of the NHS, performed by recording the automated auditory brainstem response (AABR), birth conditions, clinical characteristics, interventions performed, and results of the first test of total bilirubin (TB) and indirect bilirubin (IB) as well as the peak of TB and IB. A descriptive statistical analysis of the results was performed, and the level of significance adopted was 5%.

RESULTS

On the NHS test, quotes of retest referral rates were smaller in G1 when compared to G2. There was no significant difference between the groups regarding type of delivery, gender, presence of Rh and ABO incompatibility, G6PD enzyme deficiency, and performance of phototherapy. TB and IB levels at the first exam and at peak time did not differ between neonates with "pass" and "fail" results on the NHS test in both groups.

CONCLUSION

Bilirubin levels in the neonatal period below the recommended values for indication of exchange transfusion are not directly related to the "fail" result on the NHS tests in term and preterm neonates.

Hyperbilirubinemia Requiring Exchange Transfusion as a Risk Factor for Later-Onset Hearing Loss

Background

Previous position statements by the Joint Committee on Infant Hearing (JCIH) have recommended the presence of hyperbilirubinemia requiring exchange transfusion as a risk factor for childhood hearing loss. This article examines the strength of the evidence to support this recommendation.

Methods

A PubMed® query using the keywords hyperbilirubinemia and hearing loss identified 77 original papers. All abstracts were reviewed for consideration of full article review and 44 articles were reviewed for consideration of inclusion and grading, with 21 articles graded using structured evidence-grading forms. Nineteen articles were included to provide supporting rationale for recommendations. Evidence grading was completed by recommendation.

Results

A moderate level of evidence supports hyperbilirubinemia requiring exchange transfusion as a risk factor for elevated hearing thresholds among infants and young children. It is recommended to employ Automated Auditory Brainstem Response screening in this population of infants. These recommendations are based on the findings across multiple graded studies where the net benefit is moderate or substantial. Intervals for on-going monitoring of hearing previously recommended by JCIH are supported by expert consensus.

Conclusion

If an infant with hyperbilirubinemia requiring exchange transfusion passes the newborn hearing screening, close monitoring of hearing, speech, and language milestones are important and should lead to improved outcomes for the child.

Hearing Loss and Disorders: The Repercussions of Climate Change

PURPOSE

Climate change is considered to be the greatest threat to human health in the 21st century, and its effects are accelerating. Extensive research has clearly demonstrated its increasing impact across the continuum of health conditions. Despite this, there has been limited attention to the ramifications of climate change on hearing loss and hearing disorders. This lack of consideration is somewhat surprising as the environment itself and its changing nature have a substantial effect on hearing.

METHOD

Tackling climate change could be the greatest global health opportunity of the 21st century. To address this issue, this tutorial provides a general introduction to climate change and its three major elements (pollution, infectious diseases, and extreme weather events) and their effects on health. The substantial consequences of climate change for the incidence, development, and exacerbation of hearing loss and disorders are clearly described and detailed.

CONCLUSIONS

The challenge of responding to this very real and escalating threat to hearing requires a combination of prevention, advocacy, and education. These three roles place audiologists in the perfect position to take action on the far-reaching effects of climate change on hearing loss and disorders. To respond to this challenge and to fulfill these roles, several strategies, ranging from the individual level to the global level, are delineated for audiologists to incorporate into their practice.

Risk Factors for Sensorineural Hearing Loss and Auditory Maturation in Children Admitted to Neonatal Intensive Care Units: Who Recovered?

Background: Newborns admitted to neonatal intensive care units (NICUs) are at higher risk of developing sensorineural hearing loss (SNHL), which may improve over time. The aim of this study was to describe the prevalence of the main risk factors for SNHL in a NICU cohort, focusing on children who underwent auditory maturation. Methods: An observational study of 378 children admitted to NICUs, who were followed for at least 18 months, with periodic audiologic assessments. Results: Out of 378 patients, 338 had normal hearing and 40 were hearing-impaired; we found a higher percentage of extremely preterm (EPT) and extremely low-birthweight (ELBW) infants in SNHL children (p < 0.05). Seventeen infants presented auditory improvement, with a mean maturation time of 6.17 months. A significant difference emerged between patients with stable SNHL and those who improved only in the case of hyperbilirubinemia (p = 0.005). The initial hearing threshold was a predictor of auditory improvement and moderately correlated to the time of auditory maturation (p = 0.02). Conclusions: Our study supports the trend toward recognizing worse prognoses and slower maturation processes among NICU children who suffer from severe to profound SNHL. Caution must be taken when deciding on earlier cochlear implantation.

[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.

[Association between the inter-aural latency difference of brainstem auditory evoked potential wave V and neonatal hyperbilirubinemia]

OBJECTIVE

To study brainstem auditory evoked potential (BAEP) in neonates with hyperbilirubinemia using short auditory stimuli (60 dBnHL), and to investigate the differences in the inter-aural latency difference (ILD) of wave V between neonates with different total serum bilirubin (TSB) levels.

METHODS

A prospective study was conducted in neonates with hyperbilirubinemia who were admitted to the Department of Neonatology, Yuhuan People's Hospital of Zhejiang Province, from May 2019 to October 2020. The neonates were divided into a severe group (n=50) and a mild group (n=50) according to their TSB levels. The mild group was divided into two subgroups: 7-10 days (n=20) and 11-14 days (n=20) according to their age. ILD was compared between the neonates with different TSB levels, and its diagnostic value was analyzed.

RESULTS

Compared with the mild group, the severe group had significantly higher proportions of neonates with abnormal hearing threshold and abnormal ILD (P < 0.05) and a significantly larger ILD of wave V (P < 0.05). The latency of wave V (left ear) in the 7-10 days subgroup was significantly longer than that in the 11-14 days subgroup (P < 0.05), but there was no significant difference in the ILD of wave V between the two groups (P > 0.05). The receiver operating characteristic (ROC) analysis showed that ILD had predictive value for hearing impairment caused by neonatal hyperbilirubinemia (P < 0.05), with an area under the ROC curve of 0.727 as well as a sensitivity of 52.4% and a specificity of 90.9% at the optimal cut-off value of 0.365 ms.

CONCLUSIONS

Serum bilirubin in neonates affects the ILD of BAEP wave V, especially in those with severe hyperbilirubinemia. ILD at the optimal cut-off value of ≥0.4 ms shows potential value in the diagnosis of hearing impairment caused by neonatal hyperbilirubinemia.

Neonatal Jaundice in Preterm Infants with Bilirubin Encephalopathy

INTRODUCTION

The aim of this study is to clarify bilirubin parameters and its treatment in preterm infants with bilirubin encephalopathy (pBE).

METHODS

We asked the responders to an earlier nationwide Japanese survey on pBE to provide additional information. pBE was diagnosed based on the criteria used in the nationwide survey. We collected data on serum total bilirubin (TB), direct bilirubin (DB), albumin, and unbound bilirubin (UB) levels during the first 8 weeks of life, and on phototherapy and exchange transfusion treatments.

RESULTS

We obtained clinical data from 75 patients with pBE from 58 hospitals (response rate of 59%), who were born between 2002 and 2016. The average peak TB level was 12.6 mg/dL (215 μmol/L), and the average age at peak attainment was 19.7 days after birth. Albumin level was <2.5 g/dL in 44 patients, and the peak DB level was ≥2 mg/dL (34.2 μmol/L) in 20 patients. The average peak bilirubin/albumin (B/A) (mg/g) ratio was 3.8 (molar ratio of 0.475), and the average age at peak attainment was 18.6 days. The average peak UB level was 0.67 μg/dL (11.5 nmol/L). The median duration of phototherapy was 6 days, and the median day of the last session was 12. The peak TB level occurred after the last day of phototherapy in 30 of the 61 patients available for comparison.

CONCLUSIONS

Most patients with pBE lacked marked elevations in serum TB levels and the B/A ratio, the peaks of which were sometimes delayed to >4 weeks after birth.

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.

Early Hyperbilirubinemia in Neonates with Down Syndrome

OBJECTIVE

To compare total serum bilirubin (TSB) levels, phototherapy usage, and hospital readmission for jaundice among neonates with Down syndrome vs controls.

STUDY DESIGN

A retrospective cohort study using 15 years of multihospital data. We created control reference intervals (5th, median, and 95th percentiles) for initial TSB values hourly during the first days after birth, and determined the proportion of neonates with Down syndrome whose TSB exceeded the 95th percentile control interval. We determined the proportion with an initial TSB exceeding the upper control reference interval, the highest TSB recorded, the percentage of neonates receiving phototherapy, and the rate of hospital readmission for jaundice treatment.

RESULTS

We compared 357 neonates with Down syndrome with 377 368 controls. Compared with controls, those with Down syndrome had 4.7 times the risk (95% CI, 3.9-5.7; P < .0001) of an initial TSB exceeding the 95th percentile control interval (23.5% vs 5.0%), 8.9 times (95% CI, 8.1-9.8; P < .0001) the phototherapy usage (62.2% vs 7.0%), and 3.6 times (95% CI, 1.6-8.2; P = .0075) the readmission rate for jaundice (17.4 vs 4.8 per 1000 live births).

CONCLUSIONS

Neonates with Down syndrome have a substantial risk of early hyperbilirubinemia. The American Academy of Pediatrics currently advises obtaining an early screening complete blood count from neonates with Down syndrome. We submit that assessing their TSB is also advisable.

Bilirubin Induced Encephalopathy

Hyperbilirubinemia is one of the most common neonatal disorders. Delayed diagnosis and treatment of the pathologic and progressive indirect hyperbilirubinemia lead to neurological deficits, defined as bilirubin induced encephalopathy (BIE) (2). The incidence of this disorder in underdeveloped countries is much more than developed areas. All neonates with the risk factors for increased the blood level of indirect bilirubin are at risk for BIE, especially preterm neonates which are prone to low bilirubin kernicterus . BIE can be transient and acute (with early, intermediate and advanced phases)or be permanent, chronic and lifelong ( with tetrad of symptoms including visual (upward gaze palsy), auditory (sensory neural hearing loss), dental dysplasia abnormalities, and extrapyramidal disturbances (choreoathetosis cerebral palsy).Beside the abnormal neurologic manifestations of the jaundiced neonates ,brain MRI is the best imaging modality for the confirmation of the diagnosis. Although early treatment of extreme hyperbilirubinemia by phototherapy and exchange transfusion can prevent the BIE, unfortunately the chronic bilirubin encephalopathy does not have definitive treatment.