Neonatal brainstem auditory function associates with early receptive language development in preterm children

Prenatal current-use pesticide exposure and children's neurodevelopment at one year of age in the Infants' Environmental Health (ISA) birth cohort, Costa Rica

BACKGROUND

Pesticide exposure may affect young children's neurodevelopment, but only few cohort studies have addressed possible effects of non-organophosphate pesticides.

OBJECTIVE

We evaluated associations between prenatal current-use pesticide exposure and neurodevelopmental outcomes among 1-year-old children from the Infants' Environmental Health (ISA) birth cohort.

METHODS

To determine prenatal pesticide exposure, we measured biomarkers of pyrimethanil, chlorpyrifos, synthetic pyrethroids, and 2,4-D in urine samples among 355 women, 1-3 times during pregnancy. One-year post-partum, we evaluated children's neurodevelopment with the Bayley Scales of Infant and Toddler Development 3rd edition (BSID-III). We assessed associations between exposures and neurodevelopmental outcomes (composite and z-scores) using single-chemical linear regression models adjusted for possible confounders (maternal education, parity, sex, gestational age at birth, child age, HOME-score, location of assessment, biomarkers of mancozeb), and studied effect-modification by sex. We evaluated non-linear associations of multiple pesticide exposures with Bayesian kernel machine regression (BKMR).

RESULTS

We found higher prenatal urinary 2,4-D concentrations were associated with lower language (βper ten-fold increase = -2.0, 95 % confidence interval (CI) = -3.5, -0.5) and motor (βper ten-fold increase = -2.2, 95 %CI = -4.2, -0.1) composite scores among all children. Also, higher chlorpyrifos exposure [measured as urinary 3,5,6-trichloro-2-pyridinol (TCPy)] was associated with lower cognitive composite scores (βper ten-fold increase = -1.9, 95 %CI = -4.7, 0.8), and lower motor composite scores among boys (βper ten-fold increase = -3.8, 95 % CI = -7.7, 0.1) but not girls (βper ten-fold increase = 2.3, 95 %CI = -1.6, 6.3, pINT = 0.11). Finally, higher pyrimethanil was associated with lower language abilities among girls, but not boys. Pyrethroid metabolite concentrations did not explain variability in BSID-III composite scores. Associations were similar for BSID-III z-scores, and we found no evidence for non-linear associations or mixture effects.

DISCUSSION

Prenatal exposure to common-use pesticides may affect children's neurodevelopment at 1-year of age, some effects may be sex-specific.

Impact of Prematurity on Auditory Processing in Children

Prematurity is one of the most crucial risk factors negatively affecting the maturation of the auditory system. Children born preterm demonstrate high rates of hearing impairments. Auditory processing difficulties in preterm children might be a result of disturbances in the central auditory system development and/or sensory deprivation due to peripheral hearing loss. To investigate auditory processing in preterm children, we utilized a set of psychoacoustic tests to assess temporal processing and speech intelligibility. A total of 241 children aged 6-11 years old (136 born preterm and 105 healthy full-term children forming the control group) were assessed. The preterm children were divided into three groups based on their peripheral hearing status: 74 normal hearing (NH group); 30 children with bilateral permanent sensorineural hearing loss (SNHL group) and 32 children with bilateral auditory neuropathy spectrum disorder (ANSD group). The results showed significantly worse performance in all tests in premature children compared with full-term children. NH and SNHL groups showed significant age-related improvement in speech recognition thresholds in noise that might signify a "bottom-up" auditory processing maturation effect. Overall, all premature children had signs of auditory processing disorders of varying degrees. Analyzing and understanding the auditory processing specificity in preterm children can positively contribute to the more effective implementation of rehabilitation programs.

Various aspects of hearing loss in newborns: A narrative review

Hearing loss is considered the most common birth defect. The estimated prevalence of moderate and severe hearing loss in a normal newborn is 0.1%-0.3%, while the prevalence is 2%-4% in newborns admitted to the newborn intensive care unit. Neonatal hearing loss can be congenital (syndromic or non-syndromic) or acquired such as ototoxicity. In addition, the types of hearing loss can be conductive, sensorineural, or mixed. Hearing is vital for the acquisition of language and learning. Therefore, early detection and prompt treatment are of utmost importance in preventing the unwanted sequel of hearing loss. The hearing screening program is mandatory in many nations, especially for high-risk newborns. An automated auditory brainstem response test is used as a screening tool in newborns admitted to the newborn intensive care unit. Moreover, genetic testing and screening for cytomegalovirus in newborns are essential in identifying the cause of hearing loss, particularly, mild and delayed onset types of hearing loss. We aimed to update the knowledge on the various aspects of hearing loss in newborns with regard to the epidemiology, risk factors, causes, screening program, investigations, and different modalities of treatment.

A Comparison of the Clinical Presentation of Preterm Birth and Autism Spectrum Disorder: Commonalities and Distinctions in Children Under 3

Premature infants and infants later diagnosed with autism spectrum disorder (ASD) share many commonalities in clinical presentations. However, prematurity and ASD also have differences in clinical presentation. These overlapping phenotypes can lead to misdiagnoses of ASD or missing a diagnosis of ASD in preterm infants. We document these commonalities and differences in various developmental domains with the hope of aiding in the accurate early detection of ASD and timely intervention implementation in children born premature. Given the degree of similarities in presentation, evidence-based interventions designed specifically for preterm toddlers or toddlers with ASD may ultimately aid both populations.

Brainstem auditory pathway maturation in term neonates with congenital cytomegalovirus infection: a cohort study

Congenital cytomegalovirus infection (cCMVi) is a leading cause of sensorineural hearing loss (SNHL) and developmental delay. Brainstem auditory evoked potentials (BAEPs) recording allows assessment of central auditory pathway maturation in neonates. We aimed to characterize the effect of cCMVi on the maturation of the brainstem auditory pathway in term neonates. We retrospectively reviewed medical records of neonates born with cCMVi in 2010-2018 and characterized their auditory pathway maturation using brainstem auditory-evoked potentials (BAEPs). We compared inter-peak latency differences (IPLDs) of the main BAEP components (I-V, I-III, and III-V) in terms of cCMVi patients and healthy controls and described their changes in cCMVi patients throughout the first year of life. Of 101 cCMVi patients, 57 (56.4%) were considered symptomatic, 6 (5.9%) were small for gestational age, 6 (5.9%) had microcephaly, 4 (4%) had thrombocytopenia, 5 (6.6%) had hepatitis, 2 (2.1%) had retinitis, 47 (49.5%) had typical abnormalities on head ultrasound, 9 (8.9%) developed SNHL, and 34 (59.6%) received antiviral therapy. No significant difference was found between IPLDs of full-term cCMVi patients compared to controls throughout the entire auditory pathway (I-III, III-V, and I-V IPLDs), for both ears (p > 0.05). On serial BAEP examinations, cCMVi patients presented decreased IPLDs throughout the first year of life (p < 0.05 of compared 1st, 2nd, and 3rd BAEPs in both ears).   Conclusions: Intrauterine cytomegalovirus infection does not affect the auditory brainstem maturation process in term neonates. Our findings support previous studies noting the normal neurodevelopmental outcome of asymptomatic cCMVi patients, suggesting antiviral treatment is not warranted in these cases. What is Known: • cCMVi is a leading cause of developmental delay and hearing loss. Treatment is recommended for patients with symptomatic diseases who are at significant risk of long-term sequelae. • It is unknown whether cCMVi affects the central nervous system maturation process. What is New: • We performed a neurophysiological evaluation of brainstem conduction by recording the BAEPs. We found that cCMVi has no significant impact on central conduction times along the auditory pathways in the brainstem at birth nor changes the neuronal maturation process during the first year of life. • Our findings suggest that cCMVi does not universally affect central nervous system maturation, supporting a highly selective approach when considering the benefits of antiviral therapy.

Long-term predictivity of early neurological assessment and developmental trajectories in low-risk preterm infants

Prematurity represents 10.6% of all births, and although preterm infants usually show adequate neurodevelopmental outcomes, some may develop significant and long-lasting neurological sequelae. Many studies have analyzed predictive factors for developing severe neurodevelopmental impairments (cerebral palsy, other motor and socio-relational disorders such as autism). In this study, 148 preterm infants were enrolled to investigate the neurodevelopmental trajectories in a population of low-risk premature infants using standardized assessment methods. Significant correlations were found between the general movements, the Hammersmith Infant Neurological Examination, and the Griffiths Mental and Development Scales. Moreover, this study showed their validity and predictivity for adverse neurodevelopmental outcomes even in low-risk infants.

Cortical auditory evoked potentials in 1-month-old infants predict language outcomes at 12 months

The neurophysiological assessment of infants in their first developmental year can provide important information about the functional changes of the brain and supports the study of behavioral and developmental characteristics. Infants' cortical auditory evoked potentials (CAEPs) reflect cortical maturation and appear to predict subsequent language abilities. This study aimed to identify CAEP components to two auditory stimulus intensities in 1-month-old infants and to understand how these are associated with social interactive and self-regulatory behaviors. In addition, it examined whether CAEPs predicted developmental outcomes when infants were assessed at 12 months of age. At 1 month, P2 and N2 components were present for both auditory stimulus intensities, with an increased P2 amplitude being observed for the higher-intensity stimuli. We also observed that an increased P2 amplitude in the lower intensity predicted receptive and expressive language competencies at 12 months. These results are consistent with previous findings indicating an association between auditory processing and developmental outcomes in infants. This study suggests that specific auditory neurophysiological markers are associated with developmental outcomes in the first developmental year.

Continuous positive airway pressure treatment may negatively affect auditory maturation in preterm infants

AIM

Nasal continuous positive airway pressure (CPAP) devices generate loud noise, which might harm auditory function and maturation. The function of auditory pathways can be examined by using brainstem auditory evoked potential (BAEP) and brainstem audiometry (BA) recordings. Our objective was to study whether CPAP treatment during the neonatal period is associated with abnormalities in BAEP and BA recordings.

METHODS

Included in this retrospective study were preterm infants (birth weight ≤1500 g and/or gestational age ≤32 weeks) born between 2002 and 2006 with a comprehensive clinical background and follow-up data, including the duration of CPAP treatment (n = 162). BAEP and BA were recorded near the mean corrected age of one month. The following variables from BAEP and BA examinations were analysed: latencies of BAEP components I, III, V, interpeak intervals (IPI) I-V, I-III, III-V (ms), amplitude I and V (µV), amplitude ratio I/V and BA thresholds.

RESULTS

In the adjusted analysis, a longer CPAP treatment leads to longer latencies of BAEP component III (p = 0.01) and V (p = 0.02) in the right ear.

CONCLUSION

CPAP treatment may impair the auditory maturation and processing mediated via the dominant right ear. The hearing and neurodevelopment of the children who are treated with CPAP should be followed.

Relationships between click auditory brainstem response and speech frequency following response with development in infants born preterm

The speech evoked frequency following response (sFFR) is used to study relationships between neural processing and functional aspects of speech and language that are not captured by click or toneburst evoked auditory brainstem responses (ABR). The sFFR is delayed, deviant, or weak in school age children having a variety of disorders, including autism, dyslexia, reading and language disorders, in relation to their typically developing peers. Much less is known about the developmental characteristics of sFFR, especially in preterm infants, who are at risk of having language delays. In term neonates, phase locking and spectral representation of the fundamental frequency is developed in the early days of life. Spectral representation of higher harmonics and latencies associated with transient portions of the stimulus are still developing in term infants through at least 10 months of age. The goal of this research was to determine whether sFFR could be measured in preterm infants and to characterize its developmental trajectory in the time and frequency domain. Click ABR and sFFR were measured in 28 preterm infants at ages 33 to 64 weeks gestational age. The sFFR could be measured in the majority of infants at 33 weeks gestational age, and the detectability of all sFFR waves was 100% by 64 weeks gestational age. The latency of all waves associated with the transient portion of the response (waves V, A, and O), and most waves (waves D and E) associated with the quasi-steady state decreased with increasing age. The interpeak wave A-O latency did not change with age, indicating that these waves share a neural generator, or the neural generators are developing at the same rate. The spectral amplitude of F₀ and the lower frequencies of the first formant increased with age, but that for higher frequencies of the first formant and higher harmonics did not. The results suggest that the sFFR can be reliably recorded in preterm infants, including those cared for in the neonatal intensive care unit. These findings support that in preterm infants, F₀ amplitude continues to develop within the first 6 months of life and develops before efficient representation of higher frequency harmonics. Further research is needed to determine if the sFFR in preterm infants is predictive of long-term language or learning disorders.

Impact of Prematurity on the Tissue Properties of the Neonatal Brain Stem: A Quantitative MR Approach

BACKGROUND AND PURPOSE

Preterm birth interferes with regular brain development. The aim of this study was to investigate the impact of prematurity on the physical tissue properties of the neonatal brain stem using a quantitative MR imaging approach.

MATERIALS AND METHODS

A total of 55 neonates (extremely preterm [n = 30]: <28 + 0 weeks gestational age; preterm [n = 10]: 28 + 0-36 + 6 weeks gestational age; term [n = 15]: ≥37 + 0 weeks gestational age) were included in this retrospective study. In most cases, imaging was performed at approximately term-equivalent age using a standard MR protocol. MR data postprocessing software SyMRI was used to perform multidynamic multiecho sequence (acquisition time: 5 minutes, 24 seconds)-based MR postprocessing to determine T1 relaxation time, T2 relaxation time, and proton density. Mixed-model ANCOVA (covariate: gestational age at MR imaging) and the post hoc Bonferroni test were used to compare the groups.

RESULTS

There were significant differences between premature and term infants for T1 relaxation time (midbrain: P < .001; pons: P < .001; basis pontis: P = .005; tegmentum pontis: P < .001; medulla oblongata: P < .001), T2 relaxation time (midbrain: P < .001; tegmentum pontis: P < .001), and proton density (tegmentum pontis: P = .004). The post hoc Bonferroni test revealed that T1 relaxation time/T2 relaxation time in the midbrain differed significantly between extremely preterm and preterm (T1 relaxation time: P < .001/T2 relaxation time: P = .02), extremely preterm and term (T1 relaxation time/T2 relaxation time: P < .001), and preterm and term infants (T1 relaxation time: P < .001/T2 relaxation time: P = .006).

CONCLUSIONS

Quantitative MR parameters allow preterm and term neonates to be differentiated. T1 and T2 relaxation time metrics of the midbrain allow differentiation between the different stages of prematurity. SyMRI allows for a quantitative assessment of incomplete brain maturation by providing tissue-specific properties while not exceeding a clinically acceptable imaging time.

Neonatal brainstem auditory function associates with early receptive language development in preterm children

AIM

To study whether auditory function measured with brainstem auditory evoked potential and brainstem audiometry recordings in the neonatal period associates with language development 1 year later in preterm infants.

METHODS

This retrospective study included 155 preterm infants (birthweight ≤1500 g and/or birth ≤32 gestational weeks) born between 2007 and 2012 at the Turku University Hospital. Auditory function was recorded in neonatal period. Information of language development was gathered at the mean corrected age of 1 year by using the Finnish version of the MacArthur Communicative Development Inventory.

RESULTS

Slower auditory processing (longer interpeak interval, IPI I-V) in the right ear in the neonatal brainstem auditory evoked potential recording associated with smaller receptive lexicon size at 1 year (P = .043). Infants with longer IPI I-V were more likely to have a deviant (≤17 words) receptive lexicon size (P = .033). The absence of a contralateral response with right ear stimulation increased the risk for deviant lexicon size (P = .049).

CONCLUSION

The results suggest that impaired auditory function in the neonatal period in preterm infants may lead to a poorer receptive language outcome 1 year later. Auditory pathway function assessment provides information for the identification of preterm children at risk for weak language development.