Neonatal auditory brainstem response failure of very low birth weight infants: 8-year outcome

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.

Auditory neural myelination is associated with early childhood language development in premature infants

BACKGROUND

Auditory neural myelination (ANM) as evaluated by auditory brainstem evoked response (ABR) during the neonatal period has been used as a surrogate outcome for long-term neurodevelopment. The validity of ANM as a surrogate outcome for long-term neurodevelopment has not been well studied.

AIM

Evaluate the association of ABR I-V interpeak latency (IPL), an index of ANM, at 35 week postmenstrual age (PMA) with language outcome at 3 years of age.

DESIGN

Prospective study.

SUBJECTS

24-33 week gestational age (GA) infants were eligible if they did not meet exclusion criteria: craniofacial malformation, chromosomal disorders, deafness, auditory dys-synchrony, TORCH infection, or non-English speaking parents. Infants with malignancy, head injury, encephalopathy, meningitis, blindness, or who died or relocated were also excluded.

OUTCOME MEASURES

ABRs were performed at 35 week PMA using 80 dB nHL and I-V IPL (ms) measured. Auditory Comprehension (AC) and Expressive Communication (EC) were evaluated by a speech-language pathologist at 3 years of age using Preschool Language Scale.

RESULTS

Eighty infants were studied. The mean GA and birth weight of infants were 29.2 weeks and 1336 g, respectively. There was association of worse ear I-V IPL and better ear I-V IPL with AC (Coefficient-5.4, 95% CI: -9.8 to -0.9 and Coefficient-5.5, 95% CI: -10 to-0.9, respectively) and EC (Coefficient-5.6, 95% CI: -9.5 to-1.8 and Coefficient-6.7, 95% CI: -10.6 to-2.7, respectively) after controlling for confounders.

CONCLUSION

The neonatal I-V IPL is a predictor of language development at 3 years of age in preterms.

Repeated courses of antenatal corticosteroids: are there effects on the infant's auditory brainstem responses?

Our objective was to assess the effects of repeated antenatal corticosteroid treatments on the neonatal auditory brainstem response (ABR), a sensitive measure of neonatal brain maturity and auditory function. To achieve this, we performed and blindly evaluated neonatal ABRs on a subset of infants delivering within a multicenter randomized placebo-controlled clinical trial comparing single versus repeated courses of antenatal corticosteroid treatments for women at 23-31 weeks gestation who remained at increased risk for preterm birth. The women were randomly assigned to either the single or the repeated antenatal corticosteroid treatment group. Women in the repeated antenatal corticosteroid group received weekly antenatal corticosteroid treatments until 34 weeks gestation or until they reached a study-determined limited number of courses, whereas women in the single antenatal corticosteroid group received an initial course of corticosteroid followed by weekly placebo injections. We performed ABR testing on their infants prior to discharge. The latencies of waves I, III and V and the peak-to-trough amplitudes of waves I and V were compared between those in the single (n=27) and repeated antenatal corticosteroid treatment (n=24) groups. The majority of repeated antenatal corticosteroid infants (20 of 24) were exposed to ≥ 4 antenatal corticosteroid treatments. Even though gestational age was similar between our subset of single and repeated antenatal corticosteroid treatment groups, infant birth weight and length and head circumference were significantly smaller in the repeated antenatal corticosteroid group (p <0.05). Despite these differences in birth sizes, there were no significant group differences in the ABR wave latencies or amplitudes. We concluded that our repeated antenatal corticosteroid treatments, in comparison to a single treatment, did not significantly benefit or harm the neonatal ABR despite significant effects on birth size.

Hyperbilirubinemia and language delay in premature infants

OBJECTIVE

Our goal was to evaluate whether language delay at 3 years in premature infants is associated with previous exposure to hyperbilirubinemia during the first 2 weeks after birth.

PATIENTS AND METHODS

We performed a retrospective case-control study of infants admitted to the NICU between January and October 2003. Inclusion criteria included a birth weight of < or =1500 g and follow-up to age 3 years. Exclusion criteria included genetic disorders and hearing loss or recurrent ear infections. Peak total serum bilirubin levels during the first 2 weeks and duration of hyperbilirubinemia (days with total serum bilirubin level at >8 mg/dL) were determined. Infants with language delay and who were receiving speech therapy by 3 years were identified through developmental clinic charts and a tracking program and compared with infants who had normal language development.

RESULTS

A total of 125 infants with birth weight of < or =1500 g were admitted to the NICU between January and October 2003. Fifteen infants died, and 110 were discharged from the hospital. A total of 102 (93%) of 110 infants had follow-up to the age of 3 years. Four infants were excluded (1 genetic disorder, 3 delayed hearing loss or recurrent ear infections). Twenty-four infants had a language delay and received speech therapy, whereas 74 infants had normal language development. There was no significant difference in peak total serum bilirubin level and duration of hyperbilirubinemia between the 2 groups. On logistic regression, only bronchopulmonary dysplasia was associated with language delay.

CONCLUSIONS

Hyperbilirubinemia, defined as peak total serum bilirubin level or duration of elevated bilirubin in days, is not associated with language delay in premature infants. However, this issue deserves investigation, because other measures of bilirubin, such as unbound bilirubin, may be associated with language delay.

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

BACKGROUND

Advances in perinatal medicine have increased the survival rate of infants admitted to neonatal intensive care units (NICU). Some of the infants will have health problems including hearing disorder and/or brainstem dysfunction, and may have associated communicative and cognitive difficulties and/or repeated apnea attacks that require therapy or care.

METHODS

In this study, the authors measured mean thresholds and mean I-V interpeak latencies in 56 high-risk infants and 30 controls who were about to be discharged from NICU. The authors retrospectively investigated whether predischarge auditory brainstem response (ABR) data, which seem to be related to a number of clinical factors affecting neonates, are useful for detecting hearing disorder and/or brainstem dysfunction, and we investigated six clinical factors.

RESULTS

The results showed that the positive risk factors for hearing impairment in infants who are about to be discharged from the NICU are: receiving mechanical ventilation (including for a period of <1 day) and the administration of five or more different antibiotics, especially in extremely low-birthweight (ELBW) infants. Another result showed that the high-risk mature infants had a significant high risk factor for brainstem dysfunction.

CONCLUSIONS

The findings of the study emphasize the importance of performing ABR examinations in high-risk infants, even in infants who are about to be discharged from an NICU. ABR examinations are especially important in ELBW infants or mature infants who have received mechanical ventilation or who have received five or more different antibiotics.

Brainstem auditory-evoked potentials of 8-year-old preterm children in relation to their psycholinguistic abilities and MRI findings

BACKGROUND

Brainstem auditory potential (BAEP) has been used to demonstrate brainstem damage and to provide prognosis for the outcome for newborn children. There are contradictory results of its power to predict problems in language development or problems at school. It is well known that preterm children experience an excess of these problems.

AIM

To study if BAEP findings of 8-year-old preterm children differ from those of the full-term born control children and whether there is correlation to their linguistic problems or to the findings in magnetic resonance imaging (MRI).

STUDY DESIGN

Population-based cohort study.

SUBJECTS

Forty-two preterm children aged 8 years born with birth weight <1750 g and their matched full-term control children with birth weight >2500 g, 24 of whom had BAEP recordings and MRI.

OUTCOME MEASURES

Differences in BAEPs between the preterm and the control children. Correlation of BAEPs with linguistic problems and with MRI findings.

RESULTS

No differences were found in the absolute latencies nor in the interpeak intervals and in the I/V amplitude ratio. Nor did the results differ even when cerebral palsy disabled preterm children, preterm children with mild neurodevelopmental dysfunction or healthy preterm children were compared to each other or to the control children. No correlation to the linguistic problems or to the findings of periventricular leukomalacia (PVL) in MRI or to the different measurements of the brainstem were found.

CONCLUSION

If hearing impairment does not exist, BAEP does not give further information on neurodevelopmental nor linguistic problems of the preterm children.

Prediction of outcome at school age in neonatal intensive care unit graduates using neonatal neurologic tools

Prediction of outcome for neonatal intensive care unit graduates is clinically useful to counsel families effectively and target those who may benefit from early interventions. Evoked potentials have proven prognostic value of neurologic outcomes in early childhood; however, their long-term predictive validity remains to be determined. The objective of this prospective study was to determine the long-term predictive value of three neonatal neurologic assessments: brainstem auditory evoked potentials, somatosensory evoked potentials, and the Einstein Neonatal Neurobehavioral Assessment Scale. Seventy-eight high-risk newborns and 28 healthy controls were recruited and were assessed in the newborn period using these tests. At 8 to 9 years of age, 42 subjects and 13 controls were re-evaluated for developmental progress using a range of psychologic, sensorimotor, and neurologic measures. Findings indicated that the somatosensory evoked potential was most accurate at predicting outcome at school age, with high specificity (83-100%) across all domains tested and good sensitivity (80-100%) for intellectual performance and sensorimotor abilities. The brainstem auditory evoked potential was limited by false-negatives, whereas the neonatal neurobehavioral assessment yielded many false-positives. This study provides new evidence that associations between neonatal somatosensory evoked potentials and developmental sequelae continue to be significant at school age.

Brainstem auditory evoked response in newborns and infants

Brainstem auditory evoked response studies were carried out on 105 neonates, with gestational ages ranging from 26 to 43 weeks. The mean chronologic and postconception ages of the subjects were 6.5 weeks and 40.6 weeks, respectively. Statistically significant relationships between brainstem auditory evoked response and gestational age, postconception age (gestational age plus chronologic age), and the 5-minute Apgar score, were demonstrated. Shortening of brainstem auditory evoked response as related to postconception age was demonstrated and this trend was statistically significant. However, of these factors a statistically significant shortening (maturation) of evoked response was demonstrated only in relation to postconception age.

Diagnostic and predictive value of auditory evoked responses in preterm infants: II. Auditory evoked responses

In this study, the diagnostic and predictive value of brainstem, middle latency, and cortical auditory evoked responses (BMC-AERs) obtained in the neonatal period in 81 preterm infants was assessed in relation to neurodevelopmental outcome. The preterm infants were neonatally classified according to risk category and gestational age. The BMC-AERs were analyzed with respect to detectability, latencies, and amplitudes as well as derived latency and amplitude measures. At 5 y of age the neurodevelopmental outcome was assessed from neurologic and neuropsychologic evaluations. The results showed that BMC-AER differences mainly correlated with risk category (low risk/high risk) and to some extent with degree of prematurity. In view of these findings the degree of prematurity and the effect of risk category have to be taken into account, when BMC-AERs are applied in the preterm period to predict neurodevelopmental outcome. In this study the BMC-AERs for infants with abnormal neurodevelopmental outcome were scarcely distinguishable from the BMC-AERs for infants with normal neurodevelopmental outcome. Thus far, this and previous reports have indicated that BMC-AERs in preterm infants are useful in maturational studies and with infants showing symptoms related to lesions or dysfunction of the peripheral and/or central auditory system. For predicting neurodevelopmental outcome in preterm infants, BMC-AERs are of limited clinical value.

Type of initial brainstem auditory evoked potentials (BAEP) impairment and risk factors in premature infants

Brainstem auditory evoked potentials (BAEPs) were recorded in 89 premature infants aged between 34 and 52 weeks. 47.2% had normal and 52.8% abnormal BAEPs in at least one ear. Seven risk factors were taken into account: birth weight lower than 1500 g, hypoxia, neurological damage, fetal pathology, associated malformation, the use of ototoxic drugs, and exchange transfusion. The type of BAEP impairment was defined as either endocochlear, transmission or retrocochlear damage. Percentage BAEP impairment was higher in case of hypoxia (63.3%) but remained similar whether the other risk factors were present or absent. Transmission impairment was more frequent in case of birth weight lower than 1500 g, hypoxia or ototoxic drug administration; Endocochlear damage occurred more frequently when ototoxic drugs had been used or exchange transfusion performed. When birth weight was lower than 1500 g, transmission damage was more frequent than when birth weight was higher than 1500 g. In contrast, endocochlear damage was more frequent when birth weight was higher than compared with lower than 1500 g. In male infants, BAEP impairment was more frequent and more often of retrocochlear type than in female infants. BAEP impairment was more frequently of endocochlear type in female compared to male infants. Among the 89 premature infants recorded, 11.2% has endocochlear damage corresponding to potentially handicapping hearing loss. These results are discussed with reference to the literature.

Recording of brainstem evoked potentials and their association with gentamicin in neonates

Brainstem auditory evoked potential (BAEP) recording was used to screen presymptomatically the hearing of 200 neonates treated with ampicillin (100 mg/kg daily) and gentamicin sulfate (5 mg/kg daily). The study included 130 male and 70 female neonates; post-conceptional age ranged from 34 to 57 weeks (mean 42.36 weeks). We divided neonates into 2 groups according to duration of antibiotic treatment; group 1 consisted of 179 patients who were treated with antibiotic agents for < or = 7 days. Although 15 (8.4%) in this group initially manifested abnormal BAEP recordings, only 8 of these brain-damaged neonates (4.5%) (6 with peripheral and 2 with central dysfunction) later manifested abnormal recordings. Group 2 consisted of 21 neonates who were treated for 10 to 30 days; BAEP recordings were abnormal in 7 patients (33.3%) (4 with peripheral and 3 with central dysfunction). We conclude that BAEP is indicated only for neonates treated with gentamicin sulfate for > 10 days. In this group, infants so treated usually have underlying disease or severe infection, including birth asphyxia, hypoxia, sepsis, and meningoencephalitis, all of which are clinically significant indicators of high risk for auditory pathway dysfunction.

Evoked potentials as predictors of outcome in neonatal intensive care unit survivors: review of the literature

Neonatal intensive care unit survivors are at substantial risk for a range of neurodevelopmental sequelae, and therefore a variety of clinical diagnostic techniques have been evaluated as predictors of outcome. We summarize the prognostic value of evoked potentials in newborns at risk. A review of the literature reveals that brainstem conduction abnormalities in auditory brainstem evoked potentials are associated with neuromotor impairment; however, there are many false negative studies. Visual evoked potentials are highly accurate in predicting neurologic deficits in early childhood in asphyxiated term neonates. Sensitivity and specificity are consistently high for somatosensory evoked potentials in term newborns; however, correlations with outcome in premature infants is controversial. Several studies have compared neonatal findings on neuroimaging studies and evoked potentials, and concordant results between these two tests are highly predictive. However, neurologic sequelae often can most accurately be predicted by visual or somatosensory evoked potentials. Evoked potentials may therefore be a useful adjunct to the clinical investigation and prognostication of outcome in the high risk newborn.

Multimodality evoked responses in the neurological assessment of the newborn

In recent years increased attention has been devoted to evoked potentials (EP) in newborns. This paper reviews the literature and data from our research group in an attempt to assess the diagnostic and prognostic value of evoked responses in the first weeks of life and their use in different age-specific clinical conditions. The results show that EP are a very sensitive measure of the integrity of the sensory pathways. They make it possible to follow normal physiological maturation and the abnormalities of development resulting from neurological lesions. Repeated measurements of visual evoked potentials and somatosensorial evoked potential are prognostically useful in term infants, but seem much more limited in preterm newborns in predicting neurodevelopmental outcome.

Risk for ABR abnormalities in the nursery

The records of 1087 full- and pre-term infants with normal hearing were reviewed for auditory brain-stem response (ABR) abnormalities. Subjects were classified according to various complications common to the newborn. A logistic regression analysis was performed in order to determine the risk of incurring ABR deviations associated with specific diagnoses in the nursery. Infants exposed to cocaine in utero and those with neurological signs or demonstrable brain anomalies were 4-5 times more likely to exhibit deviant ABRs. The synergistic effects of selected predictor variables further increased the risk for abnormal responses depending on gestational age and type of disorder. These results suggest subtle neurologic influences persisting at the time of discharge.