Hyperbilirubinemia and language delay in premature infants

Risk factors for infant hearing loss: a meta-analysis

Hearing loss is a common disability in infants that significantly impacts their cognitive, language, and literacy development. This study aimed to systematically assess the risk factors for the early identification and intervention in infant hearing loss. Databases were searched for meta-analyses of observational studies until November 2023. The quality assessment was performed using the Cochrane risk of bias tool, and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to assess the certainty of the evidence. A meta-analysis identified 14 risk factors significantly associated with infant hearing loss. According to the GRADE approach, there were four factors with moderate-certainty evidence (low birth weight(LBW), congenital anomalies, craniofacial anomalies, intracranial hemorrhages), seven factors with low-certainty evidence (ototoxic medications, family history of hearing loss, mechanical ventilation > 5 days, intrauterine infection, admission to neonatal intensive care unit (NICU) > 5 days, mechanical ventilation and asphyxia) and six with extremely-low-certainty evidence (very low birth weight < 1500 g (VLBW), hyperbilirubinemia, sepsis or meningitis, male sex, premature birth, small for gestational age (SGA)). Nevertheless, no significant association was found between infant hearing loss and factors such as small for gestational age (SGA), male sex, and premature birth (P > 0.05).  Conclusion: The identification of these 14 interrelated risk factors can prove advantageous in clinical practice, as these findings could guide hearing screening and parental counseling. Furthermore, prospective research could be conducted to develop risk-based scoring systems based on these factors. What is Known: • Infant hearing loss is a worldwide issue. • Risk factors for this condition are debated. What is New: • This is the first meta-analysis to comprehensively evaluate perinatal and postnatal risk factors for hearing loss in infants. • Intracranial hemorrhage, mechanical ventilation, and low birth weight are associated with infant hearing loss. However, no evidence of an association was found between premature birth, being small for gestational age, or male sex and hearing loss.

An investigation of motor development and sensory processing skills in infants with a history of hyperbilirubinemia

BACKGROUND

Hyperbilirubinemia is a clinical picture frequently occurring in the neonatal period and may negatively affect the development of infants.

AIMS

To evaluate term infants with hyperbilirubinemia in terms of both motor development and sensory processing skills and to compare them with their healthy peers without hyperbilirubinemia.

STUDY DESIGN

A cross-sectional study.

SUBJECTS

Children born at term, aged 10-18 months, with and without a history of hyperbilirubinemia were included in the study.

OUTCOME MEASURES

After demographic information was recorded, motor development was evaluated with the Peabody Motor Development Scale-2 and sensory processing skills were evaluated with the Test of Sensory Function in Infant.

RESULTS

A total of 42 children (mean ± SD age of the children 13.07 ± 1.47 months, 22 with hyperbilirubinemia and 20 without hyperbilirubinemia) were included in the study. A statistically significant difference was found in the gross motor (p = 0.02), fine motor (p = 0.03), and total motor (p = 0.017) development scores of the Peabody Motor Development Scale-2 and in the adaptive motor functions (p = 0.004), visual tactile integration (p < 0.001), and total scores (p = 0.004) of The Test of Sensory Function in Infant in favor of the control group.

CONCLUSIONS

The motor and sensory processing skills of children born at term with hyperbilirubinemia may be negatively affected. Infants with hyperbilirubinemia should be evaluated from the early period not only in terms of motor but also sensory processing skills and should be supported with appropriate intervention programs.

Bilirubin-Induced Neurological Damage: Current and Emerging iPSC-Derived Brain Organoid Models

Bilirubin-induced neurological damage (BIND) has been a subject of studies for decades, yet the molecular mechanisms at the core of this damage remain largely unknown. Throughout the years, many in vivo chronic bilirubin encephalopathy models, such as the Gunn rat and transgenic mice, have further elucidated the molecular basis of bilirubin neurotoxicity as well as the correlations between high levels of unconjugated bilirubin (UCB) and brain damage. Regardless of being invaluable, these models cannot accurately recapitulate the human brain and liver system; therefore, establishing a physiologically recapitulating in vitro model has become a prerequisite to unveil the breadth of complexities that accompany the detrimental effects of UCB on the liver and developing human brain. Stem-cell-derived 3D brain organoid models offer a promising platform as they bear more resemblance to the human brain system compared to existing models. This review provides an explicit picture of the current state of the art, advancements, and challenges faced by the various models as well as the possibilities of using stem-cell-derived 3D organoids as an efficient tool to be included in research, drug screening, and therapeutic strategies for future clinical applications.

Hearing screening in neonates with hyperbilirubinemia

BACKGROUND

Hyperbilirubinemia is toxic to the auditory pathways and to the central nervous system, leaving sequelae such as hearing loss and encephalopathy. The damage to the auditory system occurs primarily within the brainstem and cranial nerve VIII, and manifests clinically as auditory neuropathy spectrum disorder.

AIM

to establish the relationship that exists between hyperbilirubinemia at birth as a risk factor of neonatal hearing loss in children born in ABOU-EL-REISH hospital.

MATERIALS AND METHODS

we carried out of 60 neonates categorized into two groups: Group (A n = 30), neonates with hyperbilirubinemia; Group (B n = 30), neonates without hyperbilirubinemia.

RESULTS

Ten neonates were boys and twenty were girls from group A and eleven boys and nigh-teen girls from group B.There was significant statistical difference between group A and group B regarding ABR (P-value = 0.001) and a statistical difference regarding OAE (P-value = 0.103 in the right ear and 0.028 in the left ear). Also, our study shows the area under the curve and the diagnostic accuracy of total serum bilirubin (TSB) level for detection of hearing screening results (ABR) at a cut-off point 21 mg/dl (P-value = 0.008 and 0.009 in the right and left ears respectively.) CONCLUSIONS: Our study showed a relevant association between bilirubin levels and abnormal hearing screening results and the importance of combined screening with OAE and ABR tests.

Long-term neurocognitive and educational outcomes of neonatal insults in Kilifi, Kenya

BACKGROUND

There is little data on the long-term neurocognitive and educational outcomes among school-aged survivors of neonatal jaundice (NNJ) and hypoxic-ischemic encephalopathy (HIE) in Africa. This study investigates the long-term neurocognitive and educational outcomes and the correlates of these outcomes in school-aged survivors of NNJ or HIE in Kilifi, Kenya.

METHODS

We conducted a cross-sectional study on neurocognitive and educational outcomes among school-aged survivors (6-12 years) of NNJ (n = 134) and HIE (n = 107) and compared them to a community comparison group (n = 134). We assessed nonverbal intelligence, planning, working memory, attention, syntax, pragmatics, word-finding, memory, perceptual-motor, mathematical, and reading abilities. We also collected information on medical history, caregivers' mental health, and family environment.

RESULTS

The survivors of NNJ had lower mean total scores in word-finding [F (1, 250) = 3.89, p = 0.050] and memory [F (1, 248) = 6.74, p = 0.010] than the comparison group. The survivors of HIE had lower mean scores in pragmatics [F (1, 230) = 6.61, p = 0.011] and higher scores higher scores in non-verbal reasoning [F (1, 225) =4.10, p = 0.044] than the comparison group. Stunted growth was associated with almost all the outcomes in HIE.

CONCLUSION

Survivors of NNJ and HIE present with impairment in the multiple domains, which need to be taken into consideration in the planning of educational and rehabilitative services.

Neonatal jaundice and developmental impairment among infants in Kilifi, Kenya

BACKGROUND

Neonatal jaundice (NNJ) is common in sub-Saharan Africa (SSA), and it is associated with sepsis. Despite the high incidence, little has been documented about developmental impairments associated with NNJ in SSA. In particular, it is not clear if sepsis is associated with greater impairment following NNJ.

METHODS

We followed up 169 participants aged 12 months (57 cases and 112 controls) within the Kilifi Health Demographic Surveillance System. The diagnosis of NNJ was based on clinical laboratory measurement of total serum bilirubin on admission, whereas the developmental outcomes were assessed using the Developmental Milestones Checklist and Kilifi Development Inventory.

RESULTS

There were significant differences between the cases and controls in all developmental domains. Cases scored lower in language functioning (mean [M] = 6.5, standard deviation [SD] = 4.3 vs. M = 8.9, SD = 4.6; p < .001); psychomotor functioning (Mdn = 23, interquartile range [IQR] = 17-34 vs. Mdn = 31.0, IQR = 22.0-44.0; Mann-Whitney U = 4,122, p = .002); and socio-emotional functioning ([Mdn = 30.0, IQR = 27.0-33.0 vs. Mdn = 34.0, IQR = 30.0-37.0], Mann-Whitney U = 4,289, p < .001). There was no evidence of association between sepsis and psychomotor (r_pb = -.2, p = .214), language (r_pb = -.1, p = .510), and socio-emotional functioning (r_pb = .0, p = .916). Significant and medium to large portions of the variance (34-64%) in the developmental outcomes among children who survived NNJ were associated with home birth, low maternal education, and feeding problems during the first days of life.

CONCLUSIONS

NNJ is associated with developmental impairments in the early childhood years; however, NNJ associated with sepsis does not lead to more severe impairment. Prenatal and postnatal care services are needed to reduce the negative impact of NNJ for children from low resourced settings.

Developmental influence of unconjugated hyperbilirubinemia and neurobehavioral disorders

Bilirubin-induced brain injury in the neonatal period has detrimental effects on neurodevelopment that persist into childhood and adulthood, contributing to childhood developmental disorders. Unconjugated bilirubin is a potent antioxidant that may be useful for protecting against oxidative injuries, but it becomes a potent neurotoxin once it crosses the blood brain barrier. Because bilirubin toxicity involves a myriad of pathological mechanisms, can damage most types of brain cells, and affects brain circuits or loops that influence cognition, learning, behavior, sensory, and language, the clinical effects of bilirubin-induced neurotoxicity are likely to be manifold. One possible effect that several experts have identified is bilirubin-induced neurological dysfunction (subtle kernicterus). However, the underlying biological mechanisms or pathways by which subtle kernicterus could lead to developmental disorders has not been elucidated previously. Our aim in this review is to describe a spectrum of developmental disorders that may reflect subtle kernicterus and outline plausible biological mechanisms for this possible association. We review existing evidence that support or refute the association between unconjugated hyperbilirubinemia and developmental disorders, and limitations associated with these studies.

Bilirubin Binding Capacity in the Preterm Neonate

Total serum/plasma bilirubin (TB), the biochemical measure currently used to evaluate and manage hyperbilirubinemia, is not a useful predictor of bilirubin-induced neurotoxicity in premature infants. Altered bilirubin-albumin binding in premature infants limits the usefulness of TB in premature infants. In this article, bilirubin-albumin binding, a modifying factor for bilirubin-induced neurotoxicity, in premature infants is reviewed.

Unbound Bilirubin and Auditory Neuropathy Spectrum Disorder in Late Preterm and Term Infants with Severe Jaundice

OBJECTIVE

This study evaluates whether unbound bilirubin is a better predictor of auditory neuropathy spectrum disorder (ANSD) than total serum bilirubin (TSB) or the bilirubin:albumin molar ratio (BAMR) in late preterm and term neonates with severe jaundice (TSB ≥20 mg/dL or TSB that met exchange transfusion criteria).

STUDY DESIGN

Infants ≥34 weeks' gestation with severe jaundice during the first 2 weeks of life were eligible for the prospective observational study. A comprehensive auditory evaluation was performed within 72 hours of peak TSB. ANSD was defined as absent or abnormal auditory brainstem evoked response waveform morphology at 80-decibel click intensity in the presence of normal outer hair cell function. TSB, serum albumin, and unbound bilirubin were measured using the colorimetric, bromocresol green, and modified peroxidase method, respectively.

RESULTS

Five of 44 infants developed ANSD. By logistic regression, peak unbound bilirubin but not peak TSB or peak BAMR was associated with ANSD (OR, 4.6; 95% CI, 1.6-13.5; P = .002). On comparing receiver operating characteristic curves, the area under the curve for unbound bilirubin (0.92) was significantly greater (P = .04) compared with the area under the curve for TSB (0.50) or BAMR (0.62).

CONCLUSIONS

Unbound bilirubin is a more sensitive and specific predictor of ANSD than TSB or BAMR in late preterm and term infants with severe jaundice.

Bilirubin-Induced Audiologic Injury in Preterm Infants

Although hyperbilirubinemia is extremely common among neonates and is usually mild and transient, it sometimes leads to bilirubin-induced neurologic damage (BIND). The auditory pathway is highly sensitive to the effects of elevated total serum/plasma bilirubin (TB) levels, with damage manifesting clinically as auditory neuropathy spectrum disorder. Compared to full-term neonates, preterm neonates are more susceptible to BIND and suffer adverse effects at lower TB levels with worse long-term outcomes. Furthermore, although standardized guidelines for management of hyperbilirubinemia exist for term and late preterm neonates, similar guidelines for neonates less than 35 weeks gestational age are limited.

Central auditory processing disorder profile in premature and term infants

OBJECTIVE

The aim of this study is to compare central auditory processing disorder (CAPD) profile between children born prematurely and at term.

METHODS

A retrospective study involving children 7 to 13 years of age who were referred for CAPD evaluation over the past 3 years. Parental reports and medical records were used to collect information. Children with a score ≥ two standard deviations below the mean for at least one ear on at least two different CAPD tests were considered to have CAPD.

RESULTS

A total of 82 children were evaluated for CAPD of which 22 met exclusion criteria, resulting in 60 children with CAPD (15 premature and 45 term). Premature children had higher prevalence of cesarean section delivery and neonatal jaundice compared with term children. Premature children had a higher total number of failed CAPD tests compared with the term children. Among CAPD tests, there was an increased frequency of abnormal Phonemic Synthesis test (PST) and decreased frequency of abnormal Staggered Spondaic Word test (SSW) among premature children compared with term children.

CONCLUSION

Premature children differ in CAPD profile compared with term children. Findings suggest possible etiological differences for CAPD such as jaundice or differential susceptibility of premature children for altered PST and SSW performance when compared with the term children.

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.

Impact of bilirubin-induced neurologic dysfunction on neurodevelopmental outcomes

Bilirubin-induced neurologic dysfunction (BIND) is the constellation of neurologic sequelae following milder degrees of neonatal hyperbilirubinemia than are associated with kernicterus. Clinically, BIND may manifest after the neonatal period as developmental delay, cognitive impairment, disordered executive function, and behavioral and psychiatric disorders. However, there is controversy regarding the relative contribution of neonatal hyperbilirubinemia versus other risk factors to the development of later neurodevelopmental disorders in children with BIND. In this review, we focus on the empiric data from the past 25 years regarding neurodevelopmental outcomes and BIND, including specific effects on developmental delay, cognition, speech and language development, executive function, and the neurobehavioral disorders, such as attention deficit/hyperactivity disorder and autism.

Cortical structural abnormalities in very preterm children at 7 years of age

We analyzed long-lasting alterations in brain morphometry associated with preterm birth using volumetric and surface-based analyses applied to children at age 7 years. Comparison of 24 children born very preterm (VPT) to 24 healthy term-born children revealed reductions in total cortical gray matter volume, white matter volume, cortical surface area and gyrification index. Regional cortical shape abnormalities in VPT children included the following: shallower anterior superior temporal sulci, smaller relative surface area in the inferior sensori-motor cortex and posterior superior temporal cortex, larger relative surface area and a cingulate sulcus that was shorter or more interrupted in medial frontoparietal cortex. These findings indicate a complex pattern of regional vulnerabilities in brain development that may contribute to the diverse and long-lasting neurobehavioral consequences that can occur after very premature birth.

A psychometric study of the Bayley Scales of Infant and Toddler Development - 3rd Edition for term and preterm Taiwanese infants

The Bayley Scales of Infant and Toddler Development - 3rd Edition (Bayley-III) was updated to enhance its usefulness for contemporary child developmental assessment. However, recent data in Western countries have implicated the overestimation of child development by the new instrument. This study aimed to investigate the psychometric features of the Bayley-III for term and preterm infants in Taiwan. Forty-seven term infants and 167 preterm infants were prospectively examined with the Bayley Scales of Infant Development - 2nd Edition (BSID-II) and the Bayley-III at 6, 12, 18, and 24 months of age (corrected for prematurity). The psychometric properties examined included reliability, construct validity, and known-group validity. The intra- and inter-rater reliabilities of the Bayley-III were good to excellent. The correlations between the BSID-II and Bayley-III raw scores were good to excellent for the cognitive and motor items and low to excellent for the language items. Term infants achieved higher composite scores than preterm infants on all of the Bayley-III scales (p<0.05). However, their rates of developmental delay were lower than the previously established prevalence estimates. The Bayley-III cut-off composite score was adjusted 10-20, 1-13, and 12-24 points higher than 70 for optimal prediction of cognitive, language, and motor delay, respectively, as defined by the BSID-II index score<70. The Bayley-III is a reliable instrument that extends its previous edition, especially in early language assessment. However, the upward adjustment of its cut-off score is recommended for the accurate identification of developmental delay in term and preterm Taiwanese infants.

Sensory integration, sensory processing, and sensory modulation disorders: putative functional neuroanatomic underpinnings

This paper examines conditions that have variously been called sensory integration disorder, sensory processing disorder, and sensory modulation disorder (SID/SPD/SMD). As these conditions lack readily and consistently agreed-upon operational definitions, there has been confusion as to how these disorders are conceptualized. Rather than addressing various diagnostic controversies, we will instead focus upon explaining the symptoms that are believed to characterize these disorders. First, to clarify the overall context within which to view symptoms, we summarize a paradigm of adaptation characterized by continuous sensorimotor interaction with the environment. Next, we review a dual-tiered, integrated model of brain function in order to establish neuroanatomic underpinnings with which to conceptualize the symptom presentations. Generally accepted functions of the neocortex, basal ganglia, and cerebellum are described to illustrate how interactions between these brain regions generate both adaptive and pathological symptoms and behaviors. We then examine the symptoms of SID/SPD/SMD within this interactive model and in relation to their impact upon the development of inhibitory control, working memory, academic skill development, and behavioral automation. We present likely etiologies for these symptoms, not only as they drive neurodevelopmental pathologies but also as they can be understood as variations in the development of neural networks.

Language development survey provides a useful screening tool for language delay in preterm infants

Developmental language disorder has been reported in 3% to 10% of term infants and 30% of preterm infants (<34 weeks gestation). Screening for language delay in preterm infants can be costly and time-consuming. The objective of this study was to assess the expressive language development of preterm infants using the Language Development Survey (LDS). A total of 178 preterm infants born at 23 to 34 weeks between 2006 and 2008 were enrolled. The LDS was completed by parents between 22 and 26 months at or shortly before 2-year neurodevelopmental assessment using the Bayley III Scale. A total of 26% of former preterm patients had language delay, using LDS. Significant correlations were observed between LDS results and Bayley III scores. Male gender and public health insurance were the most important risk factors for language delay in this cohort. Expressive language delay was present in 26% of preterm infants. LDS is a suitable and inexpensive screening tool for assessing language delay in preterm infants.

Is neonatal jaundice associated with Autism Spectrum Disorders: a systematic review

Using guidelines of the Meta-analysis of Observational Studies in Epidemiology Group, we systematically reviewed the literature on neonatal jaundice (unconjugated hyperbilirubinemia) and Autism Spectrum Disorder (ASD) in term and preterm infants. Thirteen studies were included in a meta-analysis. Most used retrospective matched case-control designs. There was significant heterogeneity (Q = 31, p = 0.002) and no evidence of publication bias (p = 0.12). Overall, jaundice, assessed by total serum bilirubin (TSB), was associated with ASD (OR, 1.43, 95% CI 1.22-1.67, random effect model). This association was not found in preterms (OR 0.7, 95% CI 0.38-1.02) but deserves further investigation since other measures of bilirubin such as unbound unconjugated bilirubin may be better predictors of neurotoxicity than TSB in preterms.

Adaptation, expertise, and giftedness: towards an understanding of cortical, subcortical, and cerebellar network contributions

Current cortico-centric models of cognition lack a cohesive neuroanatomic framework that sufficiently considers overlapping levels of function, from "pathological" through "normal" to "gifted" or exceptional ability. While most cognitive theories presume an evolutionary context, few actively consider the process of adaptation, including concepts of neurodevelopment. Further, the frequent co-occurrence of "gifted" and "pathological" function is difficult to explain from a cortico-centric point of view. This comprehensive review paper proposes a framework that includes the brain's vertical organization and considers "giftedness" from an evolutionary and neurodevelopmental vantage point. We begin by discussing the current cortico-centric model of cognition and its relationship to intelligence. We then review an integrated, dual-tiered model of cognition that better explains the process of adaptation by simultaneously allowing for both stimulus-based processing and higher-order cognitive control. We consider the role of the basal ganglia within this model, particularly in relation to reward circuitry and instrumental learning. We review the important role of white matter tracts in relation to speed of adaptation and development of behavioral mastery. We examine the cerebellum's critical role in behavioral refinement and in cognitive and behavioral automation, particularly in relation to expertise and giftedness. We conclude this integrated model of brain function by considering the savant syndrome, which we believe is best understood within the context of a dual-tiered model of cognition that allows for automaticity in adaptation as well as higher-order executive control.

Auditory neuropathy spectrum disorder in late preterm and term infants with severe jaundice

OBJECTIVE

To evaluate if severe jaundice is associated with acute auditory neuropathy spectrum disorder in otherwise healthy late preterm and term neonates.

METHODS

In a prospective observational study, all neonates who were admitted with severe jaundice at which exchange transfusion may be indicated as per American Academy of Pediatrics guidelines had comprehensive auditory evaluation performed before discharge to home. Neonates with infection, perinatal asphyxia, chromosomal disorders, cranio-facial malformations, or family history of childhood hearing loss were excluded. Comprehensive auditory evaluations (tympanometry, oto-acoustic emission tests, and auditory brainstem evoked responses) were performed by an audiologist unaware of the severity of jaundice. Total serum bilirubin and serum albumin were measured at the institutional chemistry laboratory using the Diazo and Bromocresol purple method, respectively.

RESULTS

A total of 13 neonates with total serum bilirubin concentration at which exchange transfusion is indicated as per American Academy of Pediatrics were admitted to the Neonatal Intensive Care Unit over 3 month period. Six out of 13 neonates (46%) had audiological findings of acute auditory neuropathy spectrum disorder. There was no significant difference in gestational age, birth weight, hemolysis, serum albumin concentration, peak total serum bilirubin concentrations, and peak bilirubin:albumin molar ratio between six neonates who developed acute auditory neuropathy and seven neonates who had normal audiological findings. Only two out of six infants with auditory neuropathy spectrum disorder had clinical signs and symptoms of acute bilirubin encephalopathy.

CONCLUSIONS

Our findings strongly suggest that auditory neuropathy spectrum disorder is a common manifestation of acute bilirubin-induced neurotoxicity in late preterm and term infants with severe jaundice. Our findings also suggest that comprehensive auditory evaluations should be routinely performed in neonates with severe jaundice irrespective of the presence of clinical findings of acute bilirubin encephalopathy.