Relation between predischarge auditory brainstem responses and clinical factors in high-risk infants

UK and US risk factors for hearing loss in neonatal intensive care unit infants

IMPORTANCE

Early detection and intervention of hearing loss may mitigate negative effects on children's development. Children who were admitted to the neonatal intensive care unit (NICU) as babies are particularly susceptible to hearing loss and risk factors are vital for surveillance.

DESIGN, SETTING AND PARTICIPANTS

This single-centre retrospective cohort study included data from 142 inborn infants who had been admitted to the NICU in a tertiary regional referral centre. Data were recorded for 71 infants with confirmed permanent congenital hearing loss hearing loss. To determine impact of NICU admission independently of prematurity, babies were individually matched with 71 inborn infants on gestational age, birthweight, and sex.

MAIN OUTCOMES AND MEASURES

Neonatal indicators were recorded for all children with permanent congenital hearing loss. Presence of UK and US risk factors for hearing loss were collected on the neonatal population with hearing loss and for the matched controls.

RESULTS

A fifth (21%) of babies with hearing loss had one or more UK risk factors whereas most (86%) had at least one US risk factor. False positives would be evident if US factors were used whereas the matched controls had no UK risk factors. Ten babies who at birth had no UK or US risk factors did not have any significant neonatal indicators identified in their records, one was ventilated for one day and two had a genetic anomaly.

CONCLUSIONS AND RELEVANCE

Current risk factors for hearing loss we identified for follow-up in this high-risk group are highly specific for congenital hearing loss. UK risk factors were highly specific for hearing loss but not sensitive and conversely, US risk factors are sensitive but not specific so false positives would be recorded. A national study of neonatal indicators could provide the utility to test which combinations of risk factors provide high sensitivity without losing specificity.

Altered local cerebellar and brainstem development in preterm infants

BACKGROUND

Premature birth is associated with high prevalence of neurodevelopmental impairments in surviving infants. The putative role of cerebellar and brainstem dysfunction remains poorly understood, particularly in the absence of overt structural injury.

METHOD

We compared in-utero versus ex-utero global, regional and local cerebellar and brainstem development in healthy fetuses (n ​= ​38) and prematurely born infants without evidence of structural brain injury on conventional MRI studies (n ​= ​74) that were performed at two time points: the first corresponding to the third trimester, either in utero or ex utero in the early postnatal period following preterm birth (30-40 weeks of gestation; 38 control fetuses; 52 premature infants) and the second at term equivalent age (37-46 weeks; 38 control infants; 58 premature infants). We compared 1) volumetric growth of 7 regions in the cerebellum (left and right hemispheres, left and right dentate nuclei, and the anterior, neo, and posterior vermis); 2) volumetric growth of 3 brainstem regions (midbrain, pons, and medulla); and 3) shape development in the cerebellum and brainstem using spherical harmonic description between the two groups.

RESULTS

Both premature and control groups showed regional cerebellar differences in growth rates, with the left and right cerebellar hemispheres showing faster growth compared to the vermis. In the brainstem, the pons grew faster than the midbrain and medulla in both prematurely born infants and controls. Using shape analyses, premature infants had smaller left and right cerebellar hemispheres but larger regional vermis and paravermis compared to in-utero control fetuses. For the brainstem, premature infants showed impaired growth of the superior surface of the midbrain, anterior surface of the pons, and inferior aspects of the medulla compared to the control fetuses. At term-equivalent age, premature infants had smaller cerebellar hemispheres bilaterally, extending to the superior aspect of the left cerebellar hemisphere, and larger anterior vermis and posteroinferior cerebellar lobes than healthy newborns. For the brainstem, large differences between premature infants and healthy newborns were found in the anterior surface of the pons.

CONCLUSION

This study analyzed both volumetric growth and shape development of the cerebellum and brainstem in premature infants compared to healthy fetuses using longitudinal MRI measurements. The findings in the present study suggested that preterm birth may alter global, regional and local development of the cerebellum and brainstem even in the absence of structural brain injury evident on conventional MRI.

Prevalence and independent risk factors for hearing impairment among very low birth weight infants

BACKGROUND

Although we've made big strides in perinatal and neonatal care, auditory handicap remains a serious complication in those who were born very premature.

OBJECTIVES

The aim was to determine the prevalence and analyze possible risk factors of hearing impairment in very-low-birth-weight (VLBW) infants.

MATERIALS AND METHODS

This was a retrospective study by reviewing medical records of all VLBW infants (BW ≤ 1500 g) admitted to NICU of Chang Gung Children's Hospital over 2 years period from Jan. 2010 to 2011. Brainstem auditory evoked potentials (BAEP) hearing screening was performed at 3 months postnatal corrective age and repeated if failed the 1st time, then refer to ENT doctor if BAEP confirmed abnormal. All VLBW infants examined for hearing impairment were included and data were retrieved retrospectively and analyzed for neonatal risk factors using logistic regression.

RESULTS

Over the period, 309 VLBW infants were screened. Prevalence of uni- or bilateral hearing impairment was 3.9% (12/309; 95% CI 2.6-4.1). The mean corrective age on diagnosed of hearing impairment was 2.9 ± 1.1 (range 1-5) months. Mean gestational age was 27.9 weeks (SD 1.4) and mean birth weight was 1028 g (SD 180). By univariant analysis for hearing impairment, severe birth asphyxia, craniofacial anomalies, ventilator dependence, patent ductus arteriosus ligation, and use of postnatal ototoxins yielded good prediction of hearing impairment in this population. However, using multivariate analysis revealed that the only independent risk factors for hearing impairment were ototoxins (OR: 3.62; CI: 1.67-7.82), PDA ligation (OR: 4.96; CI: 2.34-10.52), craniofacial anomalies (OR: 3.42; CI: 1.70-6.88)and assisted prolonged use of oxygen at gestational age of >36 weeks (OR: 5.94; CI: 2.61-13.54).

CONCLUSION

The incidence of hearing impairment among VLBW infants was 3.9%. Prolonged supplemental oxygen use is a marker for predicting hearing impairment; this requires detailed analysis of the pathophysiologic features, to reduce the prevalence of hearing impairment.

Neonatal brainstem function and 4-month arousal-modulated attention are jointly associated with autism

The authors evaluated the contribution of initially abnormal neonatal auditory brainstem responses (ABRs) and 4-month arousal-modulated attention visual preference to later autism spectrum disorder (ASD) behaviors in neonatal intensive care unit (NICU) graduates. A longitudinal study design was used to compare NICU graduates with normal ABRs (n = 28) to those with initially abnormal ABRs (n = 46) that later resolved. At 4 months postterm age, visual preference (measured after feeding) for a random check pattern flashing at 1, 3, or 8 Hz and gestational age (GA) served as additional predictors. Outcome measures were PDD Behavior Inventory (PDDBI) scores at 3.4 years (standard deviation = 1.2), and developmental quotients (DQ) obtained around the same age with the Griffiths Mental Development Scales (GMDS). Preferences for higher rates of stimulation at 4 months were highly correlated with PDDBI scores (all P-values < 0.01) and the GMDS Hearing and Speech DQ, but only in those with initially abnormal ABRs. Effects were strongest for a PDDBI social competence measure most associated with a diagnosis of autism. For those with abnormal ABRs, increases in preference for higher rates of stimulation as infants were linked to nonlinear increases in severity of ASD at 3 years and to an ASD diagnosis. Abnormal ABRs were associated with later reports of repetitive and ritualistic behaviors irrespective of 4-month preference for stimulation. The joint occurrence of initially abnormal neonatal ABRs and preference for more stimulation at 4 months, both indices of early brainstem dysfunction, may be a marker for the development of autism in this cohort.

[Auditory processing evaluation in children born preterm]

PURPOSE

To verify the performance of children born preterm on auditory processing evaluation, and to correlate the data with behavioral hearing assessment carried out at 12 months of age, comparing the results to those of auditory processing evaluation of children born full-term.

METHODS

Participants were 30 children with ages between 4 and 7 years, who were divided into two groups: Group 1 (children born preterm), and Group 2 (children born full-term). The auditory processing results of Group 1 were correlated to data obtained from the behavioral auditory evaluation carried out at 12 months of age. The results were compared between groups.

RESULTS

Subjects in Group 1 presented at least one risk indicator for hearing loss at birth. In the behavioral auditory assessment carried out at 12 months of age, 38% of the children in Group 1 were at risk for central auditory processing deficits, and 93.75% presented auditory processing deficits on the evaluation. Significant differences were found between the groups for the temporal order test, the PSI test with ipsilateral competitive message, and the speech-in-noise test. The delay in sound localization ability was associated to temporal processing deficits.

CONCLUSION

Children born preterm have worse performance in auditory processing evaluation than children born full-term. Delay in sound localization at 12 months is associated to deficits on the physiological mechanism of temporal processing in the auditory processing evaluation carried out between 4 and 7 years.

Assessment of hearing organ activity in a group of neonates with central nervous system impairment

OBJECTIVE

Hypoxic-ischemic encephalopathy, primary subarachnoid hemorrhage in term newborns as well as periventricular leukomalacia and intraventricular hemorrhage in premature newborns are the major consequences of perinatal asphyxia. Intrauterine hypoxia and labor prolongation can also affect the hearing organ in newborns causing reversible or irreversible changes in the cochlea, brainstem or cortex. The aim of the study was to carry out the objective assessment of the cochlea and hearing pathway activity using CEOAEs and ABR; to find relationships between hearing status and parameters effecting on nervous system in neonates with central nervous system impairment occurring following perinatal asphyxia.

METHODS

To the investigation 36 newborns with hypoxic-ischemic encephalopathy, periventricular leukomalacia or intraventricular hemorrhage were included. The control group encompassed 32 health newborns matched as to the age. In all newborns otoscopic examination, CEOAEs after birth and CEOAEs with ABR 3 months later were performed. Perinatal anamnesis, general pediatric status, results of trans-fontanel ultrasonography and biochemical test results were taken into account in statistical analyses.

RESULTS

The mean amplitudes of CEOAEs in the first days of life were significantly reduced in investigation group comparing to control babies. 3months later the recorded responses significantly increased but did not reach values of control group. No differences were found between latencies of waves I and II. ABR latencies of waves III, IV, V and interpeak latencies I-III, III-V, I-V were delayed in investigation group when compared to control patients. Also morphology of ABR recordings in investigation group has slightly changed. Perinatal aspyxia leading to hypercapnia, low gestational age, prolonged artificial ventilation and meningitis were the main risk factors related to disturbances in ABR recordings.

CONCLUSIONS

The combined use of CEOAEs and ABR in neonates with central nervous system impairment involvement revealed the existence of abnormalities in cochlear micromechanics and retrocochlear auditory pathway. Etiology seems to be multifactoral.

Risk factors for elevation of ABR threshold in NICU-treated infants

OBJECTIVE

Several risk factors for hearing impairment among infants treated in the neonatal intensive care unit (NICU) have been reported, but there have been few studies that show the correlation strength between the risk factors in NICU-treated infants and hearing impairment in childhood. The aim of this study was to clarify the relationship between risk factors in NICU-treated infants and a deteriolation of auditory brainstem response (ABR) threshold in their childhood.

METHODS

One hundred one NICU-treated infants with ABR threshold of 50 dBnHL or more underwent 2nd ABR test at 20 months after delivery. Multiple regression analysis was performed with ABR threshold change as an objective variable and risk factors as explanatory variables.

RESULTS

Two ABR tests of the 101 infants resulted in that 7 showed an elevation of ABR threshold by 20 dB, 70 showed a drop of ABR threshold by 20 dB, and 24 showed no significant change. Multiple regression analysis revealed that the factors contributing to the elevation of ABR threshold were congenital diaphragmatic hernia, severe respiratory disease, and a high C-reactive protein (CRP) level.

CONCLUSIONS

In the infants treated in NICU, an incidence of ABR threshold of 50 dBnHL or more was 9.0%, and 6.9% of the infants with the ABR threshold abnormality showed a significant elevation of ABR threshold in their childhood. Factors significantly related to an elevation of ABR threshold were a history of congenital diaphragmatic hernia, severe respiratory disease, and elevation of CRP. In infants with such factors, periodical examination of hearing is required.

Risk indicators for hearing loss in infants treated in different neonatal intensive care units

AIM

To assess which infants' characteristics and specialized procedures are risk indicators for unilateral or bilateral hearing loss (HL) and to evaluate whether these risk indicators are associated with variation in prevalence of HL between Neonatal Intensive Care Units (NICUs).

METHODS

For 2002-2005, data from the NICU hearing screening database in the Netherlands were matched with the national neonatology database in which all NICU infants with their patient characteristics and specialized procedures are registered. Multivariate logistic regression analyses were performed to assess risk indicators for HL and to explain differences in prevalence rates between NICUs.

RESULTS

A total of 10 830 infants were available for analyses. The prevalence of HL was 1.8% and ranged from 0.7 to 3.7% between NICUs. Infants' characteristics that significantly increased the risk of HL were the presence of craniofacial anomalies, chomosomal/syndromal anomalies, central nervous system conditions, circulatory system conditions and intra-uterine infections. The specialized procedures involving > or =12 days of intensive care and high frequency oxygenation ventilation were independent risk indicators for HL. Approximately 20% of the variance can be explained by the studied risk indicators. Differences in prevalence rates between NICUs were slightly reduced after adjustment for these risk indicators. NICUs with the highest prevalence rates of HL were situated in the largest cities in the Netherlands with a mixed population because of immigration. Therefore, ethnicity may be a risk indicator.

CONCLUSIONS

Several independent risk indicators for HL were found, but they could not explain all differences in prevalence rates of HL between NICUs.

Prevalence and independent risk factors for hearing loss in NICU infants

AIM

To determine the prevalence and independent relationship between hearing loss and risk factors in a representative neonatal intensive care unit (NICU) population.

METHODS

Automated auditory brainstem response (AABR) hearing screening has been introduced since 1998 in the Dutch NICUs. After a second AABR failure, diagnostic ABR was used to establish diagnosis of hearing loss. Newborns who died before the age of 3 months were excluded. In the present study only the NICU infants who were born with a gestational age <30 weeks and/or a birth weight <1000 g between October 1, 1998 and January 1, 2002 were included. Risk factors included in the study were familial hearing loss, in utero infections, craniofacial anomalies, birth weight <1500 g, hyperbilirubinemia, ototoxic medications, cerebral complications, severe birth asphyxia, assisted ventilation > or =5 days and syndromes.

RESULTS

A nationwide cohort of 2186 newborns were included. Mean gestational age was 28.5 weeks (SD 1.6) and mean birth weight was 1039 g (SD 256). Prevalence of uni- or bilateral hearing loss was 3.2% (71/2186; 95% CI 2.6-4.1). Multivariate analysis revealed that the only independent risk factors for hearing loss were severe birth asphyxia (OR 1.7; 95% CI 1.0-2.7) and assisted ventilation > or =5 days (OR 3.6; 95% CI 2.1-6.0).

CONCLUSION

The prevalence of hearing loss in a representative NICU population was 3.2%. Independent risk factors for hearing loss were severe birth asphyxia and assisted ventilation > or =5 days.

Reliability of hearing screening in high-risk neonates: Comparative study of otoacoustic emission, automated and conventional auditory brainstem response

OBJECTIVE

To compare the diagnostic reliability of automated transient evoked otoacoustic emissions (a-TEOAE), automated auditory brainstem response (a-ABR) and conventional brainstem auditory evoked potential (BAEP/ABR) for identification of hearing loss in high-risk neonates.

METHODS

Two hundred and six neonatal intensive care unit (NICU) admitted neonates were tested pre-discharge. Follow-up included a-TEOAE in all children, repetition of a-ABR or BAEP if failed in NICU. Sensitivity and specificity were compared and correlated with auditory risk factors.

RESULTS

BAEP had the highest sensitivity (100%) and specificity (90.8%), a-ABR the lowest (88.9% and 70.6%). A statistically significant difference in risk factors for temporary hearing loss was observed between normal and false positive a-TEOAE and BAEP, but not a-ABR outcome. Differences in specificity between a-ABR and a-TEOAE explain the pattern of "absent a-ABR/present a-TEOAE" in 13.8% of ears.

CONCLUSIONS

The BAEP appears the more reliable test for hearing screening of high-risk neonates because of highest sensitivity and specificity and should be used to confirm the diagnosis of "auditory neuropathy" in high-risk neonates. The reliability of a-ABR devices in critically ill neonates needs further investigation.

SIGNIFICANCE

This is, to our knowledge, the first attempt to compare the diagnostic reliability of a-TEOAE, a-ABR and BAEP in high-risk neonates.