Maturation Of Auditory Pathway Research Articles

Cortical auditory evoked potentials (P1 latency) in children with cochlear implants in relation to clinical language tests

Objective – To study the correlation between P1 latency and the results of clinical language tests (Reynell III and TROG-2), the latter were used as they are recommended for follow-up assessments of children with cochlear implants (Cis) by the Swedish National Quality Register for children with hearing impairment. Design – A clinical cohort study. Study sample – Cross-sectional and consecutive sampling of 49 children with CIs coming for clinical follow-up assessment from March 2017 – December 2019. Results – For all children tested, there was a significant negative correlation (Spearman’s rho= −0.403, p = 0.011) between hearing age and P1 latency. A significant correlation between P1 latency and the Reynell III result (Spearman’s rho = −0.810, p = 0.015) was found. In the TROG-2 group, there was no significant correlation between their P1 latency and their language test results (Spearman’s rho −0.239, p = 0.196). Conclusion – This method seems to be feasible and easily accepted. The study was conducted in a heterogeneous group of children that we meet daily in our clinic. The results indicated that P1 latency has a negative correlation with language development among our youngest patients fitted with CIs and might be a clinical tool to assess the maturation of central auditory pathways.

Auditory Pathway Maturation in Full-term Small for Gestational Age Children: A Systematic Review with Meta-analysis.

Introduction Factors of intrauterine growth restriction have been responsible for the births of full-term babies small for their gestational age (SGA). Scientific evidence points that this restriction can cause changes in the neural maturation process. Objectives To analyze the absolute latencies and interpeak intervals of brainstem auditory evoked potential waves in full-term and SGA children to investigate whether there are changes of neural maturation in this population. Data Synthesis The search for articles that reported the assessment of brainstem auditory evoked potential in SGA newborns compared with a control, appropriate for their gestational age, both born full-term, for the entire period available in the database research until October 31, 2021 was performed based on the MEDLINE/PubMed Central and on the Latin America and the Caribbean Health Sciences Literature and Virtual Health Library electronic databases. A total of 311 studies were found in the database research. Out of this total, 10 studies were included in the review, 5 of which were eligible for the meta-analysis, involving a total of 473 participants of both genders, with 193 participants belonging to the study group and 280 to the control group. Differences between the groups were only observed in the absolute latency of wave V (95% confidence interval [CI]: 0.02-0.15; p < 0.01). Conclusion The SGA condition is responsible for the appearance of brainstem neural conduction dysfunction measured by the brainstem auditory evoked potentials, probably by the maturation process of the auditory pathway of this population.

Exploring the impact hearing differences have on the development of speech perception during infancy

Early periods of perceptual skill development are driven by the dynamic interplay between language experiences and maturation of auditory sensory pathways. Among infants with normal hearing (INH), the first year of life is a seminal period for refining speech perception abilities shaped by exposure to language. Research suggests that refinement of speech discrimination abilities depends on an infant’s exposure to speech sounds, thus infants who are hard-of-hearing (IHH) are susceptible to atypical development during this period. Currently, the impact of inconsistent auditory cue access on development of speech perception is unknown among IHH. To investigate this, our lab has employed both electroencephalography (EEG) and a conditioned head turn (CHT) paradigm to examine auditory cue access and speech perception abilities, respectively, over the first year of life. We will provide a broad overview of our recent and continuing work among IHH and INH using EEG and CHT findings which suggest: (1) early EEG measures of cue access predict later behavioral speech perception abilities, (2) hearing age (duration of time between hearing aid fitting and testing) is related to speech perception abilities measured by CHT, and (3) a significant relationship between infant speech perception and both spoken expressive and receptive language abilities.

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 ofcompared 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.

The Effects of Clinical Factors and Neonatal Morbidities on Hearing Screening among Neonatal Admissions.

Hearing loss is an important disorder affecting newborns admitted to NICU. A national hearing screening program using otoacoustic emission testing is an essential tool to identify hearing loss early in neonates, enabling early intervention to avoid further challenges of pediatric deafness. On the other hand, a delay of the auditory pathway maturation in preterm babies compared to term newborns has already been suggested in the literature. Taking this information into account, in this paper, we aim to identify the best time to perform NICU infant hearing screening tests. We aim to study the clinical factors and neonatal morbidities that may affect neonatal hearing screening results using otoacoustic emission test in order to decrease the false-positive test results that increase parental anxiety and increase the need for subsequent investigations. This is a prospective cross-sectional study that included 204 infants who were admitted to a tertiary referral hospital NICU unit between September 2017 and May 2018. Both transients evoked otoacoustic emissions (TEOAE), and distortion product otoacoustic emission (DPOAE) screening tests were performed in order to screen hearing loss. Our study included 204 infants, 52.9 % of which were males and 47.1 % females. There were correlations between both hyperbilirubinemia and ventilation ≥ 5 days and the failure rate of the first OAE test results among NICU infants where the P-values were (p=0.0133) and (p=0.0456), respectively. Moreover, 165 babies (80.9 %) passed the first OAE with a mean birth weight of 2759 gram and mean maternal age of 30.6 years, while 39 babies (19.1 %) failed the test with a mean birth weight of 2436 gram and a mean maternal age of 32 years. There was no statistically significant relation between both maternal age and birth weight with failure of the first screening test. Our study suggests a higher failure rate of the first OAE in NICU infants who had hyperbilirubinemia or ventilation ≥ 5 days. Therefore, our recommendation is to postpone the first phase of hearing screening for those infants until the first scheduled vaccine appointment to achieve high compliance to attendance and decrease distress to the family that can be associated with false-negative results of the test.

Effect of Maternal Age and Anaemia on Auditory Brainstem Response of Preterm Infants in a Tertiary Care Hospital of Kolkata, West Bengal: A Cross-sectional Study

Introduction: Adolescent pregnancy and maternal anaemia have a detrimental effect on infant growth and development. They are associated with greater risk of premature births and Low Birth Weight (LBW). Wave Interpeak Latencies (IPLs) of infant Auditory Brainstem Response (ABR) indicate the degree of maturation of brainstem auditory pathways among preterm infants. Previous studies indicated that preterm infants show prolonged wave Interpeak Latencies (IPLs). Whether maternal parameters like age and haemoglobin level contributes to the changes in infant ABR is debated. Aim: To study the effect of maternal age and anaemic status on Brainstem Evoked Response Audiometry (BERA) changes among preterm infants. Materials and Methods: An observational, descriptive study of cross-sectional design was undertaken in the Neurophysiology laboratory of Department of Physiology, RG Kar Medical College and Hospital, Kolkata from December 2019 to December 2022. Total of 119 mother-preterm infant dyads were included. Click BERA was performed on the babies aged between 3 months to 1 year. Absolute and IPLs of wave I,III and V were obtained. Mothers were assigned anaemic status {Haempglobin (Hb) level&lt;9gm/dL} based on the information in their antenatal card. Student’s t test, Fisher’s exact test, one way ANOVA test were used for data analysis. A p-value less than 0.05 was considered significant. Results: Out of 76 adolescent mothers (age between 10 to &lt;18 years), 43 (56.6%) were anaemic. Out of 43 adult mothers (with age ≥18 years), 33 (76.7%) were anaemic. Mothers were divided into four groups, namely adolescent anaemic (n=43) and adolescent non anaemic (n=33), adult anaemic (n=33) and adult non anaemic (n=10). Distribution of data with respect to education years, social class and occupation among four mothers’ group was comparable [p-value&gt;0.05]. Preterm infants born to both anaemic adult [Hedges g=2.51] and anaemic adolescent mothers [Hedges g=1.06] showed dyssynchronous shortening of wave latencies compared to non anaemic counterparts (p-value&lt;0.05). Magnitude of difference with respect to infant ABR for non anaemic adolescent mothers vs non anaemic adult counterparts was large [Hedge s g=1.05] with p-value&lt;0.05. While maternal anaemia showed either shortening or prolongation of IPLs, adolescent maternal age was related with prolongation of the wave I-V. Effect size of maternal anaemia on infant ABR was more than for adolescent maternal age. Conclusion: Maternal anaemia may exaggerate abnormal maturation of the brain stem pathways in preterm infants irrespective of maternal age.

Bilateral EABR stimulating mode testing bilateral CI patients refecting binaural integration:a preliminary study

ObjectiveTo analyze binaural integration, we used a new stimulation mode of the electrically evoked auditory brainstem response (EABR), to reflect bilaterally implanted cochlear function. DesignEABR was tested using the following procedure: First, both ears were evaluated separately, with the contralateral speech processor closed (C), followed by another measurement with both processors open (O). Subsequently, the eV latencies and amplitudes were assessed. The Speech, Spatial, and Qualities of Hearing Scale (SSQ), Categories of auditory performance (CAP) and speech intelligibility rating (SIR) scores were used to assess binaural hearing ability subjectively. Study sampleFifteen subjects with bilateral CI from 1997 to 2018 were recruited, each diagnosed with severe to profound hearing loss. ResultsAll SSQ scores, except for one, were greater than six (the exception scored 1.3/0.8/1.0). All CAP/SIR scores except one were greater than 6/4 (the exception scored 0/1). All patients exhibited good quality EABR measurements. The open contralateral processor significantly reduced the eV latency while enhancing the eV amplitude compared to monaural stimulation. The objective EABR results were consistent with subjective speech perception and auditory ability assessed using the SSQ scale. ConclusionThe EABR accurately reflected auditory pathway maturation and development after CI; thus, reflecting accordance with subjective speech and hearing performances. Furthermore, bilateral CI facilitates binaural integration and auditory brainstem plasticity.

Effects of neurodevelopmental risk factors on brainstem maturation in premature infants.

Interpeak latencies (IPL), as measured by the auditory brainstem-evoked responses (ABR) test, represent the conduction time, and therefore the maturation of the brainstem auditory pathway. We aimed to study the effect of various risk factors for the neurodevelopmental delay on the conduction time in the auditory pathway among normal hearing premature infants, at term postmenstrual age (PMA). Retrospective analysis of 239 premature infants (gestational age 32.5 ± 2.1 weeks, birth weight 1827 ± 483 g). Interpeak latencies, demographic data, and risk factors were recorded. Sex, PMA at ABR test, being small for gestational age (SGA), intraventricular hemorrhage (IVH) or periventricular leukomalacia (PVL), and days of invasive ventilation were found to significantly affect the IPL's in the auditory pathway in a univariate analysis. Multivariable regression analysis revealed that male sex and less advanced PMA at the examination were independent factors associated with prolonged IPL's, while bronchopulmonary dysplasia, IVH or PVL and being SGA shortened the IPL's. Non-invasive mechanical ventilation, did not affect the caudal part of the auditory pathway, despite its high noise level. Among various risk factors for the neurodevelopmental delay, male sex was associated with delayed, while IVH or PVL, BPD and SGA could be associated with accelerated auditory brainstem maturation. Auditory brainstem-evoked response (ABR) test, among normal hearing infants, can serve as a clinical tool to assess brainstem auditory maturation. Different neurodevelopmental risk factors could have different effects on the maturity of the auditory pathway. Male sex is significantly associated with prolonged interpeak latencies (IPL) among preterm and term infants, while intraventricular hemorrhage or periventricular leukomalacia, bronchopulmonary dysplasia, and being small for gestation age may be associated with shortened IPL The corrected age at ABR testing is of significance, among preterm and term infants.

Monitoring of the auditory pathway maturation after early intervention during the first year of life in infants with sensorineural hearing loss

PurposeThe objective of this study was to investigate the auditory pathway maturation monitored by auditory brainstem responses (ABR) in infants with hearing loss during the first year of life. ABR were used to estimate hearing thresholds and the effect of early intervention strategies using hearing aids (HA).MethodsClick-evoked ABRs were measured in 102 infants aged from 0 to 12 months to determine their individual auditory threshold. Early therapy intervention was recommended before 12 months of age and analyzed. To evaluate the effect of hearing amplification on auditory maturation, different subgroups of infants with moderate hearing loss were analyzed and the auditory pathway maturation was determined based on IPL I–V shortening.ResultsOverall, 110 ears (54.0% of 204 ears) with mild to profound HL showed threshold changes of 10 dB up to 60 dB in the follow-up ABR testing. HA were prescribed at the age of 3.8 ± 3.9 months. Cochlear implantation (CI) was performed in cases of repeated profound HL at the age of 9.9 months ± 4.5 months. A significant shortening of IPL I–V in all subgroups of infants (with and without risk factors) who received HA was shown and assumed auditory pathway maturation.ConclusionAn early intervention using optimally fitted HA influenced auditory pathway maturation and may lead to improvements of hearing thresholds during the first year of life in infants. This study underscores the importance of not only providing HAs to infants, but also controlling for hearing threshold changes ensuring that HAs provide the optimal level of intervention or CI is indicated.

Neurodevelopmental Aspects and Cortical Auditory Maturation in Children with Cochlear Implants.

Background and objectives: The cochlear implant is not only meant to restore auditory function, but it also has a series of benefits on the psychomotor development and on the maturation of central auditory pathways. In this study, with the help of neuropsychological tests and cortical auditory potentials (CAEPs), we intend to identify a series of instruments that allow us to monitor children with a cochlear implant, and later on, to admit them into an individualized rehabilitation program. Materials and methods: This is a longitudinal study containing 17 subjects (6 boys and 11 girls) diagnosed with congenital sensorineural hearing loss. The average age for cochlear implantation in our cohort is 22 months old. Each child was tested before the cochlear implantation, tested again 3 months after the implant, and then 6 months after the implant. To test the general development, we used the Denver Developmental Screening Test (DDST II). CAEPs were recorded to assess the maturation of central auditory pathways. Results: The results showed there was progress in both general development and language development, with a significant statistical difference between the overall DQ (developmental quotient) and language DQ before the cochlear implantation and three and six months later, respectively. Similarly, CAEP measurements revealed a decrease of positive-going component (P1) latency after cochlear implantation. Conclusion: CAEPs and neuropsychological tests prove to be useful instruments for monitoring the progress in patients with cochlear implants during the rehabilitation process.

Auditory Brainstem Evoked Response Patterns in the Neonatal Intensive Care Unit.

Delayed maturation of auditory brainstem pathway in neonates admitted to the neonatal intensive care unit (NICU) may lead to misdiagnosis of children with normal peripheral hearing and inappropriate use of amplification devices. The aim of this study is to determine the pattern of auditory brain stem response in neonates admitted to the NICU for proper hearing assessment in this high-risk population. This prospective study was conducted on 1,469 infants who were admitted to the NICU, of which 1,423 had one or more risk factors for permanent congenital hearing loss and were screened with automated auditory brain stem response (AABR). A total of 60 infants were referred for diagnostic ABR analysis after failure on AABR screening. The control group comprised 60 well-baby nursery neonates with no risk factors for PCHL. Mean values of absolute latencies of waves III and V; interpeak latencies I-III, III-V, and I-V; amplitude of waves I, and V; and I/V amplitude ratio at 90 dBnHL measured for the right and left ears at 1 and 3 months of age show significant difference in NICU neonates compared with controls (p < 0.05). All the diagnostic ABR measurements significantly improved at the age of 3 months (p < 0.001) except wave I absolute latency of both groups (p > 0.05). Significant correlations were found between ABR readings at the age of 1 and 3 months and the gestational age of the NICU neonates (p < 0.05). Diagnostic ABR findings in NICU neonates suggested delayed maturation of the auditory brainstem pathway with a great impact of gestational age on this maturation. Auditory maturational changes were observed at 3 months of age of patient and control groups.

Cortical Auditory Evoked Potentials in 2-Year-Old Subjects.

Introduction Cortical auditory evoked potentials (CAEPs) can be used to evaluate both peripheral and cortical components of auditory function, and contribute to the assessment of functional sensitivity and auditory thresholds, especially in neonates and infants. Auditory evoked potentials reflect auditory maturity and precede the acquisition of more complex auditory and cognitive skills, and are therefore crucial for speech and language development. Objective The aim of the present study was to determine the presence, latency and amplitude of CAEP components in response to verbal stimuli in children aged 2 years old. Methods The sample consisted of 19 subjects, 10 of whom were male while 9 were female. All of the participants were 24 months old at the time of assessment. Results A total of 17 of the participants displayed all components of the CAEP. Additionally, no significant differences were observed between genders or ears in the present sample. The presence of all components of the CAEP in subjects aged 2 years old confirms the existence of a critical period for the maturation of auditory pathways in the first 2 years of life. Conclusion In the present study, in addition to the P1/N1 components, it was possible to observe the presence of the CAEP P2/N2 components in individuals aged 24 months, confirming the existence of a critical period for the maturation of the auditory pathways in the first 2 years of life.

Strengthening of the Efferent Olivocochlear System Leads to Synaptic Dysfunction and Tonotopy Disruption of a Central Auditory Nucleus.

The auditory system in many mammals is immature at birth but precisely organized in adults. Spontaneous activity in the inner ear plays a critical role in guiding this maturation process. This is shaped by an efferent pathway that descends from the brainstem and makes transient direct synaptic contacts with inner hair cells. In this work, we used an α9 cholinergic nicotinic receptor knock-in mouse model (of either sex) with enhanced medial efferent activity (Chrna9L9'T, L9'T) to further understand the role of the olivocochlear system in the correct establishment of auditory circuits. Wave III of auditory brainstem responses (which represents synchronized activity of synapses within the superior olivary complex) was smaller in L9'T mice, suggesting a central dysfunction. The mechanism underlying this functional alteration was analyzed in brain slices containing the medial nucleus of the trapezoid body (MNTB), where neurons are topographically organized along a mediolateral (ML) axis. The topographic organization of MNTB physiological properties observed in wildtype (WT) was abolished in L9'T mice. Additionally, electrophysiological recordings in slices indicated MNTB synaptic alterations. In vivo multielectrode recordings showed that the overall level of MNTB activity was reduced in the L9'T The present results indicate that the transient cochlear efferent innervation to inner hair cells during the critical period before the onset of hearing is involved in the refinement of topographic maps as well as in setting the properties of synaptic transmission at a central auditory nucleus.SIGNIFICANCE STATEMENT Cochlear inner hair cells of altricial mammals display spontaneous electrical activity before hearing onset. The pattern and firing rate of these cells are crucial for the correct maturation of the central auditory pathway. A descending efferent innervation from the CNS contacts the hair cells during this developmental window. The present work shows that genetic enhancement of efferent function disrupts the orderly topographic distribution of biophysical and synaptic properties in the auditory brainstem and causes severe synaptic dysfunction. This work adds to the notion that the transient efferent innervation to the cochlea is necessary for the correct establishment of the central auditory circuitry.

Newborn hearing screening at the Neonatal Intensive Care Unit and Auditory Brainstem Maturation in preterm infants

ObjectivesAim of this study is to report and discuss the results of 4 years of Newborn hearing screening (NHS) program at the Neonatal Intensive Care Unit (NICU), particularly evaluating the clinical ABR results. MethodsRetrospective study. NHS data from NICU newborns, admitted for ≥5 days, in the period from January 1st, 2013 and December 31st, 2016, were retrieved and analyzed. NHS results were classified as following: (i) “pass” when both ears for both the a-TEOAE (automated Transient-Evoked Otoacoustic Emissions) and the a-ABR (automated Auditory Brainstem Response) protocol resulted as “pass”; (ii) “fail” when one ear, at either one of the two performed tests resulted as “fail”; (iii) “missing” when the newborns were not tested with both protocols. All “fail” and “missing” newborns were retested (with both tests): in the case of a second “fail” result, a clinical ABR was performed within a period of 3 months. ResultsA total of 1191 newborns were screened. From those, 1044/1191 resulted as “pass”, 108/1191 as “fail”, and 39/1191 as “missing”. During the re-testing of these 147 newborns, 43 were assigned as “missing”, 63 were assigned as “pass” (showing bilaterally a wave V identifiable within 30 dB nHL) and 25 failed the retest and/or did not present an identifiable wave V within 30 dB nHL. Among the 147 retested infants, we identified a group of 16 subjects who resulted as NHS “refer” and who, during the audiological follow-up, showed either: (i) a unilateral or bilateral wave V identifiable over 30 dB nHL, at the first clinical ABR assessment; or (ii) a bilateral wave V identifiable within 30 dB nHL, in a following clinical ABR test during the first year of life. These 16 subjects were defined to have an ‘Auditory Brainstem Maturation’ issue. ConclusionsA possible “maturation” of the ABR response (and therefore of the auditory pathway) has been hypothesised in 16 out of 1191 infants (1.3%). A delay of the auditory pathway maturation in preterm babies compared to term newborns has already been suggested in the literature. A possible delay of the NHS retest could be considered, in selected cases, with significant savings in economic resources and parental anxiety.

Prenatal exposure to the herbicide 2,4-D is associated with deficits in auditory processing during infancy

IntroductionDespite widespread use, many herbicides and fungicides are not well studied for neurological effects. Fetal and infant brains are rapidly developing, yet the effects of early-life exposure to these classes of pesticides on visual and auditory function are unknown. Here we examined the effects of prenatal herbicide and fungicide exposure on infant grating visual acuity (VA) and auditory brainstem response (ABR). Methods9 herbicides and 13 fungicides were measured in umbilical cord blood plasma from a cohort of infants in Fuyang County, China (n = 232). Grating VA and ABR latencies for waves I, III, V were measured at 3 time points: 6 weeks, 9 months, and 18 months. Outcomes included VA score, ABR wave V latency and ABR central conduction time (CCT [wave V- wave I]). Pesticides were analyzed as 3-level ordinal (non-detect [ND]/medium/high), or dichotomous (ND/detect), depending on detection rates. Linear mixed models were used to evaluate relations between pesticides and VA and ABR outcomes. Results2,4-dichloroacetic acid (2,4-D), prometryn, simazine, and tetrahydrophthalamide (THPI, a metabolite of captan) were detected in 27%, 81%, 17%, and 16% of samples, respectively. Infants prenatally exposed to 2,4-D had slower auditory response times at 6 weeks. Infants with cord levels of 2,4-D > 1.17 ng/mL had wave V latencies that were 0.12 (95% CI: 0.03, 0.22) ms slower (p = 0.01) and overall CCTs that were 0.15 (95% CI:0.05, 0.25) ms slower (p = 0.003) than infants with non-detectable 2,4-D in their cord blood. No other statistically significant findings were observed for the other herbicides and fungicides or for the grating VA outcome. ConclusionsPrenatal exposure to the herbicide 2,4-D was associated with slower auditory signal transmission in early infancy. ABR latencies reflect auditory pathway maturation and longer latencies may indicate delayed auditory development.

Auditory maturation and psychological risk in the first year of life.

To assess the potential association between psychological risk and limited auditory pathway maturation. In this longitudinal cohort study, 54 infants (31 non-risk and 23 at-risk) were assessed from age 1 to 12 months. All had normal hearing and underwent assessment of auditory maturation through cortical auditory evoked potentials testing. Psychological risk was assessed with the Child Development Risk Indicators (CDRIs) and PREAUT signs. A variety of statistical methods were used for analysis of results. Analysis of P1 and N1 latencies showed that responses were similar in the both groups. Statistically significant differences between-groups were observed only for the variables N1 latency and amplitude at 1 month. Significant maturation occurred in both groups (p<0.05). There was moderate correlation between P1 latency and Phase II CDRIs, which demonstrates that children with longer latencies at age 12 months were more likely to exhibit absence of these indicators in Phase II and, therefore, were at greater psychological risk. The Phase II CDRIs also correlated moderately with P1 and N1 latencies at 6 months and N1 latencies at 1 month; again, children with longer latency were at increased risk. Less auditory pathway maturation correlated with presence of psychological risk. Problems in the mother-infant relationship during the first 6 months of life are detrimental not only to cognitive development, but also to hearing. A fragile relationship may reflect decreased auditory and linguistic stimulation.

Auditory brainstem response in very preterm, moderately preterm and late preterm infants

BackgroundAuditory brainstem response across preterm infants help in understanding difference if any in auditory maturation. Objective: To analyze and compare absolute and interpeak latencies of ABR in very preterm, moderate preterm and late preterm infants at term age. MethodABR traces were obtained from 148 ears of preterm infants (52 of very preterm, 44 of moderately preterm & 52 of late preterm) at term age. ABR was recorded with 11.1/s clicks at different intensity levels. ResultsAbsolute latencies of peak I, III, V and interpeak latencies of peak I-V, I-III and III-V were analyzed and compared between three preterm groups. One way ANOVA was used to compare ABR parameters between three groups of preterm infants and also to compare ABR parameters across various gestation ages. There were no overall differences in absolute latencies, interpeak latencies and amplitude of ABR between preterm groups and across various gestation ages (P>0.05). Pearson correlation was used to find the correlation between gestation age and ABR parameters. However, no correlation was found. ABRs were similar among preterm groups at term age which reflects that the brainstem maturation is similar among preterm groups. ConclusionGestational age at birth does not seem to influence absolute and interpeak latencies of ABR at term age. In preterm neonates, the findings lead to suggest that maturation of auditory pathway occurs in a similar manner in preterm infants regardless of gestational age at birth.We conclude that preterm birth alone as a risk factor does not appear to have any marked effect on the development of ABR at term age.

P1 cortical auditory evoked potential in children with unilateral or bilateral cochlear implants; implication for the timing of second cochlear implantation.

To examine maturation of the central auditory pathway, using P1 cortical auditory evoked potential (CAEP), in children who had received unilateral or bilateral cochlear implantation (CI). Prospective study. Tertiary referral hospital. Twenty children who had received CI due to congenital, or prelingual, deafness participated in the study. Participants had received the 1st implant at a mean age of 3.4 ± 0.7years; 16 had also received a 2nd CI for the contralateral ear, at a mean age of 11.1 ± 2.1years. P1 CAEP was recorded while using the 1st implant and, for those who received contralateral CI, within 2weeks of switching on the 2nd implant. Relations between P1 latency and duration with the 1st implant, and between age at 1st CI and P1 latency, were investigated. Relations between P1 latency with the 1st and 2nd implants, and between the interstage interval and difference between P1 latencies with the 1st and 2nd implants, were also examined. P1 CAEP with the 1st implant was present in 16 of the 20 children. Mean P1 latency was shorter in the early CI group compared with the late CI group, but this difference was not statistically significant (p = 0.154). There was a significant negative correlation between the duration with the 1st implant and P1 latency (r = - 0.783, p < 0.001). Among the 16 children with sequential bilateral CI, P1 CAEP with the 2nd implant was present in 10. There was a significant negative correlation between the duration with the 1st implant before receiving the 2nd implant and P1 latency with the 2nd implant (r = - 0.710, p = 0.021); there was also a significant positive correlation between P1 latency with the 1st and 2nd implants (r = 0.722, p = 0.018). There was not a significant correlation between interstage interval and the difference between the two P1 latencies (r = - 0.430, p = 0.248). Longer cochlear implant use is associated with shorter P1 latency. Unilateral hearing with the 1st implant may positively affect P1 latency with the 2nd CI ear. These findings imply that increased auditory experience may influence central auditory pathway maturation and that the degree of central auditory pathway maturation before the 2nd CI, rather than the timing when the surgery is received, may influence 2nd CI outcome in children with sequential bilateral cochlear implants.

S106. Normative data of auditory brainstem response in nepalese population

Introduction Auditory Brainstem Response (ABR) is the potential recorded from the ear and the scalp in response to a brief auditory stimulation. It is usually helpful in localizing the lesions in the brainstem. It is useful in diagnosing diseases like intrinsic brainstem tumor, multiple sclerosis, coma, brain death and strokes affecting the brainstem. It can also be used to assess the integrity of auditory pathway. Methods The study was conducted on 30 consenting healthy adult subjects. Auditory Brainstem Response (ABR) was recorded at 60 dB sound intensity. Mean and standard deviation were determined for waveforms I, II, III, IV, and V and interpeak intervals of waveforms I–III, III–V, and I–V. Student t-test was used for statistical analysis. Results In ABR, wave latencies and interpeak latencies were measured. Latencies of wave I [1.85 ± 0.23 ms], wave II [2.99 ± 0.27 ms], wave III [4.21 ± 0.41 ms], wave IV [5.38 ± 0.42 ms], wave V [6.48 ± 0.53 ms] and interpeak latencies I–III [2.35 ± 0.4 ms], III–V [2.28 ± 0.54 ms] and I–V [4.63 ± 0.54 ms]. Conclusion ABR parameters shows variation in values depending upon age, maturation of auditory pathway, environmental factors, laboratory setup. Hence it is concluded that each laboratory should have its own normative data which can be used as a baseline data for screening of patients with hearing loss.

Study of brainstem auditory evoked potentials in early diagnosis of congenital toxoplasmosis

IntroductionCongenital toxoplasmosis is an infectious disease with high prevalence in tropical countries. It is characterized by neurological, ophthalmological and auditory sequelae. ObjectiveThe aim of this study was to evaluate and describe the brainstem auditory evoked potential in infants aged 1–3 months diagnosed with congenital toxoplasmosis and to compare them with infants of the same age group without the infection. MethodsThis is an observational, analytical and cross-sectional study in which brainstem auditory evoked potential was investigated in infants with congenital toxoplasmosis. The following audiological exams were performed: transient-evoked otoacoustic emissions, clinical and automatic brainstem auditory evoked potential. Results100 children participated in the study, but the final sample consisted of 76 children. Of the 37 children with toxoplasmosis included in the study, 28 completed the neurological imaging evaluation, and of these, 3 (10.7%) showed an altered neurological examination. At the brainstem auditory evoked potential assessment, two children without toxoplasmosis and 10 children with congenital toxoplasmosis had results suggestive of alterations in the brainstem auditory pathway maturation. Conclusion10 (27%) children were identified with a possible unilateral alteration in the electrophysiological assessment. There was a 5-fold higher risk for a child between 1 and 3 months of age with toxoplasmosis to have an altered brainstem auditory evoked potential compared to a child of the same age range without the infection.