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

COVID-19 during pregnancy and its impact on the developing auditory system

BACKGROUND

This study compared distortion product otoacoustic emissions (DPOAEs) and click-evoked auditory brainstem responses (ABRs) recorded from infants whose mother had Covid-19 during pregnancy (Covid-19 group) to infants whose mother did not have Covid-19 (Control group) during pregnancy.

METHODS

This study retrospectively examined records of infants in the Covid-19 group (n = 15) and control group (n = 46) who had distortion product otoacoustic emissions (DPOAEs) and click-evoked auditory brainstem responses (ABRs) recorded as part of their clinical assessment. DPOAE amplitudes, absolute latencies (I, III, and V), and I-V interpeak intervals were examined.

RESULTS

DPOAE amplitudes were similar between the Covid-19 group and the control group. The absolute latency of wave I was similar between groups. But absolute latencies III and V and I-V interpeak intervals of the Covid-19 group were significantly prolonged compared to the control group.

CONCLUSION

Covid-19 infection and its complications during pregnancy may not affect the cochlear function but may affect the functioning of the auditory brainstem.

Distortion product otoacoustic emissions in very preterm infants: A longitudinal study

BACKGROUND

Very preterm infants are at a greater risk of developing neurodevelopmental impairments such as neuro-motor delays, vision and hearing deficits (Roze and Breart, 2004; Saigal and Doyle, 2008) [1,2]. The hearing difficulties in preterm infants vary depending on the co-morbid conditions. However, prematurity itself is considered as a risk factor that influence the functioning of auditory system.

AIM

The current study aims to compare the DPOAEs in very preterm infants and term infants at 1 month, 3 months and 6 months of age (corrected age in preterm infants).

METHOD

DPOAEs were recorded in 72 very preterm infants and 30 term infants at 1 month, 3 months and 6 months of age. All these infants had obtained 'pass' results in newborn hearing screening using ABR. DPOAE f2 test frequency was measured at six frequencies (1500 Hz, 2000 Hz, 3000 Hz, 4500 Hz, 6000 Hz and 8000 Hz) with primary tone stimulus intensity L1 equal to 65 dBSPL and L2 equal to 55 dBSPL with primary tone f2/f1 frequency ratio of 1.2. Otoscopic examination and tympanometry was performed prior to DPOAE testing, to ascertain normal middle ear status.

RESULTS

DPOAE amplitude did not change significantly between two groups from 1 month till 6 months of age (p > 0.05). DPOAE amplitude and noise floor in very preterm infants were not different from term infants and DPOAE amplitude did not vary significantly across f2 frequencies at various time periods.

CONCLUSION

The current study findings provided evidence that prematurity did not constitute as a factor to influence the results of DPOAE in very preterm infants who passed newborn hearing screening test. Any significant reduction in DPOAE amplitude or absence of DPOAE in very preterm infants has to be considered and monitored effectively, as it may not reflect a developmental process of cochlear function; instead it could indicate the presence of inner ear or middle ear pathology.

Maturation of auditory brainstem response in early term infants at 6 weeks and 9 months

BACKGROUND

Emerging evidence indicates that infants who were born between 37 and 38 weeks of gestation are at higher risk of adverse long-term neurodevelopmental outcomes. Yet little is known about the auditory neural maturation during the first year of their life.

AIM

To compare the development of auditory brainstem response in early term (ET, 37-38 weeks gestational age, GA) and full term (FT, 39-41 weeks GA) infants.

METHODS

126 infants received ABR testing at 6 weeks. 107 of them returned for the second assessment at 9 months, among which, 93 completed the ABR recordings. Comparison of the ABR variables were made depending on gestational age.

RESULTS

Analysis of covariance (ANCOVA) was used to identify the differences in ABR outcomes between two groups. After controlling for confounders, latencies for wave III, V and I-III, III-V and I-V intervals were prolonged in ET group compared with FT group at 6 weeks (all p<0.03). ABR parameters of both groups developed as the infants got older. At 9 months, ET infants remain showing the longer wave V latency and I-V interval (all p < 0.02) than FT infants.

CONCLUSION

During early postnatal life, ET has a different pattern of functional auditory brainstem development comparing with FT infants. The prolonged auditory conduction time suggests less mature of the central auditory system in ET infants before 9 months.

Auditory brainstem maturation in normal-hearing infants born preterm: a meta-analysis

AIM

Children born preterm often have neurodevelopmental problems later in life. Abnormal maturation of the auditory brainstem in the presence of normal hearing might be a marker for these problems. We conducted a meta-analysis of auditory brainstem response (ABR) latencies at term age to describe differences in auditory brainstem maturation between normal-hearing preterm and term-born infants.

METHOD

Computerized databases were searched for studies published between 1995 and 2014 that reported ABR measurements at term age in infants born preterm in a case-control design. Five peaks reflect the conduction of a neural signal along the brainstem auditory pathway. We collected I to V interpeak latency data, and III to V interpeak latency data, which refers to the more central part of the pathway.

RESULTS

Preterm-born infants' III to V interval is significantly longer compared to infants born at term (0.081ms, effect-size=0.974), which also reflects on the I to V interval. Moreover, significantly increased ABR interpeak latencies of infants born preterm are related to lower gestational age and the need for neonatal intensive care treatment.

INTERPRETATION

The delayed conduction time towards and into the auditory brainstem at term age suggests atypical maturation of the brainstem in normal-hearing infants born preterm. Both the duration of gestation and the consequences of the preterm birth (intensive care needed) negatively affect maturation of the auditory brainstem, which may influence later development.

Auditory brainstem responses as a clinical evaluation tool in children after perinatal encephalopathy

Auditory brainstem responses (ABR) reveals the neurophysiological status of the neural axis. In this study we compared the ABR of healthy children, under 1-year-old, with children who suffered from perinatal encephalopathy (PE).

OBJECTIVE

The purpose of this study was to characterize the ABR differences between children with PE and healthy children in order to identify groups with specific neurophysiological profiles, associated with their neurological condition.

METHODS

Thirty-six children with perinatal encephalopathy (PE) and 36 healthy children, ages 1-12 months, were studied. The variables considered were: latencies of waves I, II, N1, III, V, and N2; interpeak latency interval (IPL) of waves I-III, III-V, and I-V; as well as amplitudes of waves I, III, and V. The results were analyzed using ANOVA, as well as Ji(2), and Ward's cluster analysis.

RESULTS

The absolute latencies of the ABR showed an inverse correlation with the children's age. Latencies of waves I, II, N1, V, and N2, IPL III-V, and amplitude of waves III and V show significant differences (p<0.05) between healthy and PE children. Children with PE showed greater absolute latencies and larger wave amplitudes than the control group. Ward's cluster analysis, used to define the groups with similar functional characteristics, revealed three groups: fast, intermediate, and slow-responders, depending on their wave latencies and IPL wave amplitudes. These groups were gender- (p<0.03), age- (p<0.0001), and neurological damage- (p<0.01) related.

CONCLUSIONS

Our data clearly show that the ABR obtained from PE children differ from ABR obtained from healthy children. PE infants showed larger wave latencies, intervals amplitudes than the control group. Three functional profiles resulted from the groups established using the Ward's method, and these indicate their neurological functional condition.

Clinical use of AEVP- and AERP-measures in childhood speech disorders

It has long been recognized that from the first months of life auditory perception plays a crucial role in speech and language development. Only in recent years, however, is the precise mechanism of auditory development and its interaction with the acquisition of speech and language beginning to be systematically revealed. This paper presents the results of a series of studies exploring the relevance of electrophysiological measurements for the objective diagnosis of children with language and speech disorders. In the first, retrospective, study, an inventory was made of clinical neurological, neuropsychological, logopedic and neurophysiological findings obtained from 43 children referred to the Paediatric Neurology Centre for the diagnosis of their speech and language deficits. Neurophysiological abnormalities were found in 95% of these children, among these deviant auditory evoked potentials (AEVPs). The second study demonstrated developmental trends in the waveform of the cortical AEVPs up to age 6 years; the implications for longitudinal studies are discussed. Preliminary results from the third study show emerging differences in auditory event-related potentials (AERPs) for young children who are at risk for developmental dyslexia based on their family history. These findings underscore the clinical usefulness of neurophysiological measures for the diagnosis of speech-language disorders. Clinical protocols are further developed and tested.

Development of MEG sleep patterns and magnetic auditory evoked responses during early infancy

OBJECTIVE

To follow the development of MEG sleep patterns and auditory evoked responses (AERs) during the first six months of life.

METHODS

The subjects were 18 neonates, born at conceptional age (CA) 36-42 weeks, following uncomplicated pregnancies. During each session, several 10-min MEG recordings were acquired in the presence of auditory stimulation. The recordings were classified into three distinct MEG patterns-low amplitude irregular; high-amplitude slow; and mixed-based largely on MEG amplitude and frequency. Averaged AERs were computed for the entire recording and for each MEG pattern within the recording. The results were based on analysis of 61 recording sessions of the 10 subjects who yielded three or more sessions of usable data.

RESULTS

Developmental changes in the MEG sleep patterns were most pronounced at the earliest ages. By CA 48 weeks the patterns had progressed to a more mature form, characterized by the prevalence of delta wave sleep, absence of discontinuity, and development of spindling and higher amplitude delta rhythms. In contrast to the MEG patterns, the AERs did not change markedly during the first 8 weeks (CA 40-48 weeks) and showed a simple morphology, consisting of a prominent deflection at 250 ms (P250m) and a more diffuse one at around 750 ms (N750m). During the period CA 48-54 weeks, however, a relatively abrupt transition occurred to a more complex morphology, characterized by a double peak with peak latencies 150ms (P150m) and 350 ms (P350m). Beyond this period the AERs continued to evolve, showing biphasic complexes and the emergence of late components arising from outside the auditory cortex.

CONCLUSIONS

Over the age range of this study the MEG sleep patterns and AER developed in succession, rather than concurrently; i.e. development of the sleep patterns was most rapid during the first 8 weeks (CA 40-48 weeks) while major development of the AERs commenced after this time.

SIGNIFICANCE

This finding suggests that the brain must achieve a certain level of overall maturity, reflected in the character of the MEG sleep patterns at CA 48 weeks, before the cortex enters a phase of significant functional development, reflected in the more rapid evolution of the AER after CA 48 weeks. The results of this study affirm the efficacy of MEG for spatiotemporal characterization of neonatal brain activity.

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.

Brain-stem auditory evoked potentials in children with perinatal encephalopathies

OBJECTIVE

We sought to describe if neurological damage, in terms of brain lesions, syndrome and syndrome severity led to abnormalities in the brain-stem auditory evoked potentials (BAEPs) in order to provide a profile of children that could be used as an indicator of subsequent neurological sequelae. We analyzed the BAEPs from a group of children having prior evidence of neurological damage and determined the presence of neurological sequelae when the subjects were 3 years old.

METHODS

Brain-stem auditory evoked potentials (BAEPs) were carried out in a group of 154 children with perinatal neurological damage. The children were classified with neurofunctional (clinical and EEG alterations) or organic and neurofunctional brain disease (clinical, EEG and image alteration) and were all followed from the first month of life and serially for 3 years. We used principal component analysis (PCA), clustered analysis and linear correlation to determine association between BAEPs, risk factors and future sequelae.

RESULTS

Latencies of BAEPs decreased significantly with age, and the time of conduction was modified by the presence of neurological damage. All statistical analyses suggested positive and significant associations between risk factors (trophism and condition at birth), and the latencies of waves I, III and V as well as with IPL III-V (interpeak latency) and I-V. PCA showed that IPL I-III was also positively associated with condition at birth, severity of the neurological syndrome and encephalopathy. In addition, we found that the presence and type of sequela reflected changes in the latencies of the waves, as well as IPLs, primarily those of IPL I-III.

CONCLUSIONS

Our results suggest that statistical methods are often needed to analyze neurological damage. The relation between BAEPs, risk factors and neurological sequelae allowed us to obtain a profile of children, which can be then used as an aid in the prognosis of children having a risk of developing neurological sequelae.

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: I. Patient characteristics and long-term neurodevelopmental outcome

The diagnostic and predictive value of brainstem, middle latency, and cortical auditory evoked responses, obtained in the neonatal period, in 81 preterm infants was assessed in relation to neurodevelopmental outcome. Eighteen healthy term infants served as a control group. In this report the patient characteristics and neurodevelopmental outcome are presented. The preterm infants were neonatally classified according to risk category and gestational age. At 5 y of age the neurodevelopmental outcome was assessed based on neurologic and neuropsychologic evaluations. The neuropsychologic test results showed the highest IQ scores in term infants, intermediate IQ scores in low risk preterm infants, and lowest IQ scores in high risk preterm infants. The intermediate IQ scores in the low risk preterm group were due to significantly lower test scores in a small subgroup of low risk preterm infants. In a post hoc analysis 12 low risk preterm infants with an unfavorable outcome could be identified. The neuropsychologic test results of the remaining low risk infants showed no clear differences compared with the term infants. The results suggest that the unfavorable outcome of the low risk preterm group as a whole is due to moderate to severe impairment of the few, rather than slight impairment of the majority.