Cortical maturation and behavioral outcomes in children with auditory neuropathy spectrum disorder

Predictors of cochlear implant outcomes in pediatric auditory neuropathy: A matched case-control study

OBJECTIVES

Current evidence supports the benefits of cochlear implants (CIs) in children with hearing loss, including those with auditory neuropathy spectrum disorder (ANSD). However, there is limited evidence regarding factors that hold predictive value for intervention outcomes.

DESIGN

This retrospective case-control study consisted of 66 children with CIs, including 22 with ANSD and 44 with sensorineural hearing loss (SNHL) matched on sex, age, age at CI activation, and the length of follow-up with CIs (1:2 ratio). The case and control groups were compared in the results of five open-set speech perception tests, and a Forward Linear Regression Model was used to identify factors that can predict the post-CI outcomes.

RESULTS

There was no significant difference in average scores between the two groups across five outcome measures, ranging from 88.40% to 95.65%. The correlation matrix revealed that younger ages at hearing aid fitting and CI activation positively influenced improvements in speech perception test scores. Furthermore, among the variables incorporated in the regression model, the duration of follow-up with CIs, age at CI activation, and the utilization of two CIs demonstrated prognostic significance for improved post-CI speech perception outcomes.

CONCLUSIONS

Children with ANSD can achieve similar open-set speech perception outcomes as children with SNHL. A longer CI follow-up, a lower age at CI activation, and the use of two CIs are predictive for optimal CI outcome.

Exploring the relationship between auditory late latency response and language age in children using cochlear implant

AIM & OBJECTIVES

The study aimed to compare P1 latency and P1-N1 amplitude with receptive and expressive language ages in children using cochlear implant (CI) in one ear and a hearing aid (HA) in non-implanted ear.

METHODS

The study included 30 children, consisting of 18 males and 12 females, aged between 48 and 96 months. The age at which the children received CI ranged from 42 to 69 months. A within-subject research design was utilized and participants were selected through purposive sampling. Auditory late latency responses (ALLR) were assessed using the Intelligent hearing system to measure P1 latency and P1-N1 amplitude. The assessment checklist for speech-language skills (ACSLS) was employed to evaluate receptive and expressive language age. Both assessments were conducted after cochlear implantation.

RESULTS

A total of 30 children participated in the study, with a mean implant age of 20.03 months (SD: 8.14 months). The mean P1 latency and P1-N1 amplitude was 129.50 ms (SD: 15.05 ms) and 6.93 μV (SD: 2.24 μV) respectively. Correlation analysis revealed no significant association between ALLR measures and receptive or expressive language ages. However, there was significant negative correlation between the P1 latency and implant age (Spearman's rho = -0.371, p = 0.043).

CONCLUSIONS

The study suggests that P1 latency which is an indicative of auditory maturation, may not be a reliable marker for predicting language outcomes. It can be concluded that language development is likely to be influenced by other factors beyond auditory maturation alone.

Cochlear implantation in children with auditory neuropathy spectrum disorder: an updated systematic review

BACKGROUND

The goal of managing auditory neuropathy spectrum disorder (ANSD) is to restore the children's ability to discriminate auditory information. Children who are not making sufficient progress in speech comprehension, and speech and language development after receiving adequate auditory re/habilitation and/or acoustic amplification may be candidates for cochlear implantation (CI). Despite the growing number of published literature on CI outcomes in children with ANSD, the current evidence is primarily based on case reports or retrospective chart reviews some of which had a limited number of children. In addition, the outcomes of CI seem to vary between children with ANSD. Thus, compelling evidence is lacking. This updated systematic review evaluated the speech perception, language, and speech intelligibility outcomes of children with ANSD post-CI.

METHODS

An online bibliographic search was conducted in PubMed, Scopus, Web of Science, and CENTRAL databases. We included both interventional and observational studies that assessed the outcomes of the CI in  children with ANSD.

RESULTS

Thirty-three studies were included in this systematic review. Several tests were used to assess speech perception following CI in children with ANSD. The findings of this study revealed that  children with ANSD had mean Categories of Auditory Performance scores ranging from 4.3 to 7 post-operatively, this result was better than the pre-operative scores which ranged between 0.4 to 2.5. Likewise, the Infant-Toddler Meaningful Auditory Integration Scale, Phonetically Balanced Kindergarten, and multisyllabic lexical neighborhood test showed clinically relevant improvement after CI. The same findings were reported for language and speech intelligibility scores. One study investigated the quality of life/children satisfaction after CI and showed overall good satisfaction with the outcomes.

CONCLUSIONS

The present systematic review suggests that CI is a feasible and effective hearing  rehabilitation modality for children with ANSD.

REGISTRATION AND PROTOCOL

PROSPERO ID: CRD42021279140.

Cortical Auditory Evoked Potential Testing in Children With Auditory Neuropathy Spectrum Disorder

PURPOSE

In the present report, we reviewed the role of cortical auditory evoked potentials (CAEPs) as an objective measure during the evaluation and management process in children with auditory neuropathy spectrum disorder (ANSD).

METHOD

We reviewed the results of CAEP recordings in 66 patients with ANSD aged between 2 months and 12 years and assessed the relationship between their characteristics (prevalence, morphology, latencies, and amplitudes) and various clinical features, including the mode of medical management.

RESULTS

Overall, the CAEPs were present in 85.2% of the ears tested. Factors such as prematurity, medical complexity, neuronal issues, or presence of syndromes did not have an effect on the presence or absence of CAEPs. CAEP latencies were significantly shorter in ears with cochlear nerve deficiency than in ears with a normal caliber nerve. Three different patterns of CAEP responses were observed in patients with bilateral ANSD and present cochlear nerves: (a) responses with normal morphology and presence of both P1-P2complex and N2 components, (b) responses with abnormal morphology and presence of the N2 component but undefined P1-P2complex peak, and (c) entirely absent responses. None of the patients with normal, mild, or moderate degree of hearing loss had a complete absence of CAEP responses. No significant differences were uncovered when comparing the latencies across unaided and aided children and children who later received cochlear implants.

CONCLUSIONS

The CAEP protocol used in our ANSD program did inform about the presence or absence of central auditory stimulation. Absent responses typically fit into an overall picture of complete auditory deprivation and all of these children were ultimately offered cochlear implants after failing to develop oral language. Present responses, on the other hand, were acknowledged as a sign of some degree of auditory stimulation but always interpreted with caution given that prognostic implications remain unclear.

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.

Predicting Hearing aid Benefit Using Speech-Evoked Envelope Following Responses in Children With Hearing Loss

Electroencephalography could serve as an objective tool to evaluate hearing aid benefit in infants who are developmentally unable to participate in hearing tests. We investigated whether speech-evoked envelope following responses (EFRs), a type of electroencephalography-based measure, could predict improved audibility with the use of a hearing aid in children with mild-to-severe permanent, mainly sensorineural, hearing loss. In 18 children, EFRs were elicited by six male-spoken band-limited phonemic stimuli--the first formants of /u/ and /i/, the second and higher formants of /u/ and /i/, and the fricatives /s/ and /∫/--presented together as /su∫i/. EFRs were recorded between the vertex and nape, when /su∫i/ was presented at 55, 65, and 75 dB SPL using insert earphones in unaided conditions and individually fit hearing aids in aided conditions. EFR amplitude and detectability improved with the use of a hearing aid, and the degree of improvement in EFR amplitude was dependent on the extent of change in behavioral thresholds between unaided and aided conditions. EFR detectability was primarily influenced by audibility; higher sensation level stimuli had an increased probability of detection. Overall EFR sensitivity in predicting audibility was significantly higher in aided (82.1%) than unaided conditions (66.5%) and did not vary as a function of stimulus or frequency. EFR specificity in ascertaining inaudibility was 90.8%. Aided improvement in EFR detectability was a significant predictor of hearing aid-facilitated change in speech discrimination accuracy. Results suggest that speech-evoked EFRs could be a useful objective tool in predicting hearing aid benefit in children with hearing loss.

Within- and across-frequency temporal processing and speech perception in cochlear implant users

OBJECTIVE

Cochlear implant (CI) recipient's speech perception performance is highly variable and is influenced by temporal processing abilities. Temporal processing is commonly assessed using a behavioral task that requires the participant to detect a silent gap with the pre- and post-gap stimuli of the same frequency (within-frequency gap detection) or of different frequencies (across-frequency gap detection). The purpose of the study was to evaluate behavioral and electrophysiological measures of within- and across-frequency temporal processing and their correlations with speech perception performance in CI users.

DESIGN

Participants included 11 post-lingually deafened adult CI users (n = 15 ears; Mean Age = 50.2 yrs) and 11 age- and gender-matched normal hearing (NH) individuals (n = 15 ears; Mean Age = 49.0 yrs). Speech perception was assessed with Consonant-Nucleus-Consonant Word Recognition (CNC), Arizona Biomedical Sentence Recognition (AzBio), and Bamford-Kowal-Bench Speech-in-Noise Test (BKB-SIN) tests. Within- and across-frequency behavioral gap detection thresholds (referred to as the GDTwithin and GDTacross) were measured using an adaptive, two-alternative, forced-choice procedure. Cortical auditory evoked potentials (CAEPs) were elicited using within- and across-frequency gap stimuli under four gap duration conditions (no gap, GDT, sub-threshold GDT, and supra-threshold GDT). Correlations among speech perception, GDTs, and CAEPs were examined.

RESULTS

CI users had poorer speech perception scores compared to NH listeners (p < 0.05), but the GDTs were not different between groups (p > 0.05). Compared to NH peers, CI users showed increased N1 latency in the CAEPs evoked by the across-frequency gap stimuli (p < 0.05). No group difference was observed for the CAEPs evoked by the within-frequency gap (p > 0.05). Three CI ears showing the longest GDTwithin also showed the poorest performance in speech in noise. The within-frequency CAEP increased in amplitude with the increase of gap duration; while the across-frequency CAEP displayed a similar amplitude for all gap durations. There was a significant correlation between speech scores and within-frequency CAEP measures for the supra-threshold GDT condition, with CI users with poorer speech performance having a smaller N1-P2 amplitude and longer N1 latency. No correlations were found among GDTacross, speech perception, and across-frequency CAEP measures.

CONCLUSIONS

Within- and across-frequency gap detection may involve different neural mechanisms. The within-frequency gap detection task can help identify CI users with poor speech performance for rehabilitation. The within-frequency CAEP is a better predictor for speech perception performance than the across-frequency CAEP.

Acoustic Change Complex and Visually Reinforced Infant Speech Discrimination Measures of Vowel Contrast Detection

OBJECTIVES

To measure the effect of stimulus rate and vowel change direction on the acoustic change complex (ACC) latencies and amplitudes and compare ACC metrics to behavioral measures of vowel contrast detection for infants tested under the age of 1 year. We tested the hypothesis that the direction of spectral energy shift from a vowel change would result in differences in the ACC, owing to the sensitivity of cortical neurons to the direction of frequency change. We evaluated the effect of the stimulus rate (1/s versus 2/s) on the infants' ACC. We evaluated the ACC amplitude ratio's sensitivity (proportion of ACCs present for each change trial) and compared it to perceptual responses obtained using a visually reinforced infant speech discrimination paradigm (VRISD). This report provides normative data from infants for the ACC toward the ultimate goal of developing a clinically useful index of neural capacity for vowel discrimination.

DESIGN

Twenty-nine infants, nine females, 4.0 to 11.8 months of age, participated. All participants were born at full term and passed their newborn hearing screens. None had risk factors for hearing or neurologic impairment. Cortical auditory evoked potentials were obtained in response to synthesized vowel tokens /a/, /i/, /o/, and /u/ presented at a rate of 1- or 2/s in an oddball stimulus paradigm with a 25% probability of the deviant stimulus. All combinations of vowel tokens were tested at the two rates. The ACC was obtained in response to the deviant stimulus. The infants were also tested for vowel contrast detection using a VRISD paradigm with the same combinations of vowel tokens used for the ACC. The mean age at the time of the ACC test was 5.4 months, while the mean age at the behavioral test was 6.8 months.

RESULTS

Variations in ACC amplitude and latency occurred as a function of the initial vowel token and the contrast token. However, the hypothesis that the direction of vowel (spectral) change would result in significantly larger change responses for high-to-low spectral changes was not supported. The contrasts with /a/ as the leading vowel of the contrast pair resulted in the largest ACC amplitudes than other conditions. Significant differences in the ACC presence and amplitude were observed as a function of rate, with 2/s resulting in ACCs with the largest amplitude ratios. Latency effects of vowel contrast and rate were present, but not systematic. The ACC amplitude ratio's sensitivity for detecting a vowel contrast was greater for the 2/s rate than the 1/s rate. For an amplitude ratio criterion of ≥1.5, the sensitivity was 93% for ACC component P2-N2 at 2/s, whereas at 1/s sensitivity was 70%. VRISD tests of vowel-contrast detection had a 71% hit and a 21% false-positive rate. Many infants who could not reach performance criteria for VRISD had ACC amplitude ratios of ≥2.0.

CONCLUSIONS

The ACC for vowel contrasts presented at a rate of 2/s is a robust index of vowel-contrast detection when obtained in typically developing infants under the age of 1 year. The ACC is present in over 90% of infants tested at this rate when an amplitude ratio criterion of ≥1.5 is used to define a response. The amplitude ratio appears to be a sensitive metric for the difference between a control and contrast condition. The ACC can be obtained in infants who do not yet exhibit valid behavioral responses for vowel change contrasts and may be useful for estimating neural capacity for discriminating these sounds.

[The issue of auditory neuropathy: from origins to the present]

The issue of auditory neuropathy spectrum disorders (ANSD) has been in a focus of specialists attention for a relatively short time, but during this time a huge amount of scientific and practical knowledge about this hearing disorder has been accumulated. ANSD is a specific auditory deficit caused by dysfunction of periphery part of the auditory system, which may affect the inner hair cells, the spiral ganglion neurons and the auditory nerve, as well as the area of synaptic contact between them, while the outer hair cells, as a rule, remain intact. As a result, a specific condition is formed, in which a patient's otoacoustic emissions and/or cochlear microphonics are present, auditory brainstem responses are abnormal or absent, electrophysiological data may not correlate with hearing level, the discrepancy between pure tone audiometry and speech discrimination is observed. ANSD prevalence, epidemiology, contemporary views on its etiology, including detailed information on hereditary forms of the disorder and its risk factors are considered in the review. The data on the basic rungs of the ANSD pathogenesis, which underlie the development of various forms of the disorder and mainly determine the rehabilitation approach, are presented. The detailed clinical and audiological characteristics of ANSD are presented; contemporary approach to ANSD diagnosis and rehabilitation, including indications for surgical treatment, are considered.

[Auditory neuropathy and prematurity: modern view of the issue (literature review)]

Auditory neuropathy spectrum disorder (ANSD) is a specific auditory disorder caused by dysfunction of periphery part of the auditory system, in which the function of the outer hair cells is preserved, but the afferent input at the cochlear level suffers due to the pathology of the inner hair cells, neurons of the spiral ganglion and/or the auditory nerve, as well as synaptic contact between them. As a result, a specific condition is formed, in which a patient's otoacoustic emissions and/or cochlear microphonics are present, auditory brainstem responses are abnormal or absent, the discrepancy between the hearing level and the electrophysiological data, poor speech perception which may not correlate with the hearing thresholds. ANSD is a multifactorial disease. One of the main risk factors is perinatal pathology and, in particular, prematurity. The possible factors associated with prematurity that provoke the onset of the disease, features of the pathogenesis, clinical and audiological peculiarities of ANSD in premature infants, contemporary approaches to the habilitation of such patients are discussed in the article. The necessity of an individual, patient-oriented approach to the treatment of premature infants with ANSD is substantiated; such an approach should be based both on the genesis of the disorder, taking into account possible points of lesion in the auditory system, and the developmental peculiarities of a premature baby considering the presence of concomitant diseases associated with prematurity. In the article attention is focused on the main directions of habilitation work with such children, including a multidisciplinary approach, regular careful monitoring of the auditory, speech and language skills, intensive psychological and speech therapist support, the choice of an adequate way of intervention and its improvement as necessary.

Cortical Auditory Plasticity Following Cochlear Implantation in Children With Auditory Neuropathy Spectrum Disorder: A Prospective Study

OBJECTIVES

The cortical auditory evoked potential (CAEP) can provide an insight into the maturation of the central auditory nervous system by recording the auditory cortex responses to speech stimuli. This study aimed to explore the central auditory system development in children with auditory neuropathy spectrum disorder (ANSD) using cochlear implants (CIs) and to find the correlation of CAEP biomarkers with speech perception.

METHODS

This study was performed on 23 children with prelingual deafness, diagnosed with ANSD, as well as 23 children with prelingual deafness, without ANSD as the control group. All children underwent unilateral CI before the age of 3 years. Children with ANSD were classified into two groups, based on their CAEP results prior to implantation: children with a clear CAEP response (ANSD-I) and children without an identifiable CAEP (ANSD-II). The P1 component of CAEPs and speech intelligibility rating (SIR) were recorded before the initial device activation (baseline) and at 6, 12, and 24 months postimplantation.

RESULTS

The P1 CAEP responses were present in all children in the control group, while they were recorded in only 52% of ANSD children before the CI surgery. The longitudinal analysis revealed a significant reduction in the P1 latency and a significant improvement in the P1 amplitude across different time points in all study groups. However, the P1 latency and P1 amplitude were significantly shorter and larger in the control group than the ANSD group, respectively. Also, children in the ANSD-I group exhibited a slightly shorter P1 latency, a larger P1 amplitude, and a higher SIR score than the ANSD-II group after 2 years of follow-up. The P1 CAEP latency was significantly correlated with the SIR score.

CONCLUSION

The CAEP can be used as an objective indicator of auditory cortical maturation and a predictor of speech perception performance in implanted children with ANSD.

Central auditory maturation and behavioral outcomes after cochlear implantation in prelingual auditory neuropathy spectrum disorder related to OTOF variants (DFNB9): Lessons from pilot study

The cortical auditory evoked potential (CAEP)-based P1 component acts as a biomarker for cochlear implantation (CI) outcomes in children with auditory neuropathy spectrum disorder (ANSD). To date, early intervention primarily before the age of two years and six months of CI usage is necessary and sufficient to achieve age-appropriate cortical maturation and good prognosis. However, varying degrees of neural dyssynchrony, resulting from the etiological heterogeneity of ANSD, may preclude uniform application of this hypothesis to ensure auditory cortical maturation. Thus, a focused evaluation of those carrying OTOF variants, which may be the salient molecular etiology of prelingual ANSD, would circumvent the issue of heterogeneity. Here, we sought to provide a much better understanding of the brain perspectives (i.e., P1 maturation) in OTOF-associated ANSD subjects and set the stage for an optimal strategy to enhance language development. We conducted a preliminary study comprising 10 subjects diagnosed with OTOF-related ANSD who underwent CI by a single surgeon and subsequently underwent measurements of the P1 component. We observed that DFNB9 subjects who received CI after 2 years of age exhibited “absent” or “anomalous” P1 components that correspond to delayed language development. However, timely implantation, as early as 12 months of age per se, might be insufficient to achieve age-appropriate cortical maturation of DFNB9 in cases with six to seven months of device use. This suggests the importance of sustained rehabilitation in DFNB9 than in other etiologies. Indeed, an additional follow-up study showed that a reduction in P1 latency was linked to an improvement in auditory performance. Collectively, our results suggest that central auditory maturation and successful outcome of CI in DFNB9 may have more demanding requirements, that is, earlier implantation and more sustained rehabilitation. We believe that the current study opens a new path toward genome-based neuroimaging in the field of hearing research.

Central Auditory Nervous System Stimulation through the Cochlear Implant Use and Its Behavioral Impacts: A Longitudinal Study of Case Series

The purpose of this study was to investigate, over a period of five years, the cortical maturation of the central auditory pathways and its impacts on the auditory and oral language development of children with effective use and without effective use of a Cochlear Implant (CI). A case series study was conducted with seven children who were CI users and seven children with normal hearing, with age- and gender-matched to CI users. The assessment was performed by long-latency auditory evoked potentials and auditory and oral language behavioral protocols. The results pronounced P1 latency decrease in all CI users in the first nine months. Over five years, five children with effective CI use presented decrease or stabilization of P1 latency and a gradual development of auditory and oral language skills, although, for most of the children, the electrophysiological and behavior results remained poor than their hearing peers' results. Two children who stopped the effective use of CI after the first year of activation had worsened auditory and oral language behavioral skills and presented increased P1 latency. A negative correlation was observed between behavioral measures and the P1 latency, the P1 component being considered an important clinical resource capable of measuring the cortical maturation and the behavioral evolution.

Cortical Neurophysiologic Correlates of Auditory Threshold in Adults and Children With Normal Hearing and Auditory Neuropathy Spectrum Disorder

Purpose Auditory threshold estimation using the auditory brainstem response or auditory steady state response is limited in some populations (e.g., individuals with auditory neuropathy spectrum disorder [ANSD] or those who have difficulty remaining still during testing and cannot tolerate general anesthetic). However, cortical auditory evoked potentials (CAEPs) can be recorded in many such patients and have been employed in threshold approximation. Thus, we studied CAEP estimates of auditory thresholds in participants with normal hearing, sensorineural hearing loss, and ANSD. Method We recorded CAEPs at varying intensity levels to speech (i.e., /ba/) and tones (i.e., 1 kHz) to estimate auditory thresholds in normal-hearing adults (n = 10) and children (n = 10) and case studies of children with sensorineural hearing loss and ANSD. Results Results showed a pattern of CAEP amplitude decrease and latency increase as stimulus intensities declined until waveform components disappeared near auditory threshold levels. Overall, CAEP thresholds were within 10 dB HL of behavioral thresholds for both stimuli. Conclusions The above findings suggest that CAEPs may be clinically useful in estimating auditory threshold in populations for whom such a method does not currently exist. Physiologic threshold estimation in difficult-to-test clinical populations could lead to earlier intervention and improved outcomes.

Auditory Neuropathy Spectrum Disorders: From Diagnosis to Treatment: Literature Review and Case Reports

Auditory neuropathy spectrum disorder (ANSD) refers to a range of hearing impairments characterized by deteriorated speech perception, despite relatively preserved pure-tone detection thresholds. Affected individuals usually present with abnormal auditory brainstem responses (ABRs), but normal otoacoustic emissions (OAEs). These electrophysiological characteristics have led to the hypothesis that ANSD may be caused by various dysfunctions at the cochlear inner hair cell (IHC) and spiral ganglion neuron (SGN) levels, while the activity of outer hair cells (OHCs) is preserved, resulting in discrepancies between pure-tone and speech comprehension thresholds. The exact prevalence of ANSD remains unknown; clinical findings show a large variability among subjects with hearing impairment ranging from mild to profound hearing loss. A wide range of prenatal and postnatal etiologies have been proposed. The study of genetics and of the implicated sites of lesion correlated with clinical findings have also led to a better understanding of the molecular mechanisms underlying the various forms of ANSD, and may guide clinicians in better screening, assessment and treatment of ANSD patients. Besides OAEs and ABRs, audiological assessment includes stapedial reflex measurements, supraliminal psychoacoustic tests, electrocochleography (ECochG), auditory steady-state responses (ASSRs) and cortical auditory evoked potentials (CAEPs). Hearing aids are indicated in the treatment of ANSD with mild to moderate hearing loss, whereas cochlear implantation is the first choice of treatment in case of profound hearing loss, especially in case of IHC presynaptic disorders, or in case of poor auditory outcomes with conventional hearing aids.

Evidence of Vowel Discrimination Provided by the Acoustic Change Complex

OBJECTIVES

The objectives of this study were to measure the effects of level and vowel contrast on the latencies and amplitudes of acoustic change complex (ACC) in the mature auditory system. This was done to establish how the ACC in healthy young adults is affected by these stimulus parameters that could then be used to inform translation of the ACC into a clinical measure for the pediatric population. Another aim was to demonstrate that a normalized amplitude metric, calculated by dividing the ACC amplitude in the vowel contrast condition by the ACC amplitude obtained in a control condition (no vowel change) would demonstrate good sensitivity with respect to perceptual measures of vowel-contrast detection. The premises underlying this research were that: (1) ACC latencies and amplitudes would vary with level, in keeping with principles of an increase in neural synchrony and activity that takes place as a function of increasing stimulus level; (2) ACC latencies and amplitudes would vary with vowel contrast, because cortical auditory evoked potentials are known to be sensitive to the spectro-temporal characteristics of speech.

DESIGN

Nineteen adults, 14 of them female, with a mean age of 24.2 years (range 20 to 38 years) participated in this study. All had normal-hearing thresholds. Cortical auditory evoked potentials were obtained from all participants in response to synthesized vowel tokens (/a/, /i/, /o/, /u/), presented in a quasi-steady state fashion at a rate of 2/sec in an oddball stimulus paradigm, with a 25% probability of the deviant stimulus. The ACC was obtained in response to the deviant stimulus. All combinations of vowel tokens were tested at 2 stimulus levels: 40 and 70 dBA. In addition, listeners were tested for their ability to detect the vowel contrasts using behavioral methods.

RESULTS

ACC amplitude varied systematically with level, and test condition (control versus contrast) and vowel token, but ACC latency did not. ACC amplitudes were significantly larger when tested at 70 dBA compared with 40 dBA and for contrast trials compared with control trials at both levels. Amplitude ratios (normalized amplitudes) were largest for contrast pairs in which /a/ was the standard token. The amplitude ratio metric at the individual level demonstrated up to 97% sensitivity with respect to perceptual measures of discrimination.

CONCLUSIONS

The present study establishes the effects of stimulus level and vowel type on the latency and amplitude of the ACC in the young adult auditory system and supports the amplitude ratio as a sensitive metric for cortical acoustic salience of vowel spectral features. Next steps are to evaluate these methods in infants and children with hearing loss with the long-term goal of its translation into a clinical method for estimating speech feature discrimination.

Cortical auditory evoked potential in assessment of neonates: a study about minimum level of responses in term and preterm newborns

INTRODUCTION

The study of the threshold level of cortical auditory response in adults has been investigated in previous studies. Due to maturational issues, little is known about these responses in neonates. Technological advances with automatic analysis devices now allow investigation in specific populations. Thus, new studies are needed to establish the feasibility of using this auditory potential to identify the lowest levels of responses in children.

OBJECTIVE

Verify and compare latency and amplitude in 80dBnNA and the minimum level of cortical auditory response in term and preterm neonates.

METHODS

A cross-sectional, comparative study involving 59 neonates, 35 full-term births and 24 preterm births, with positive results in the Neonatal Hearing Screening. The Hearlab system was used to investigate the P1i auditory potential with tone burst stimulus at frequencies of 500, 1000, 2000 and 4000Hz. The minimum response level search ranged from 80 to 0dBNA and was detected automatically. The results were compared between groups, evaluating the latency and amplitude in 80dBNA and the minimum level of cortical auditory response.

RESULTS

The mean values obtained for the minimum level of cortical auditory response in term group were 26±8.81; 26.14±6.97; 29±7.65 and 29.43±7.04dBNA and for preterm neonates of 31.96±10.41; 34.13±11.34; 33.64±11.03 and 37.73±11.92dBNA, for the frequencies of 500, 1000, 2000 and 4000Hz, respectively. There was a difference between groups for the latency of P1i at 4000Hz and the minimum response levels at 500, 1000 and 4000Hz, with higher values for preterm infants.

CONCLUSION

It was possible to obtain latency and amplitude values at 80dBnNA and the minimum level of cortical response in term and preterm newborns, with different results between groups, with higher values in those born preterm.

Auditory synaptopathy, auditory neuropathy, and cochlear implantation

Cochlear implantation has become the standard-of-care for adults and children with severe to profound hearing loss. There is growing evidence that qualitative as well as quantitative deficits in the auditory nerve may affect cochlear implant (CI) outcomes. Auditory neuropathy spectrum disorder (ANSD) is characterized by dysfunctional transmission of sound from the cochlea to the brain due to defective synaptic function or neural conduction. In this review, we examine the precise mechanisms of genetic lesions causing ANSD and the effect of these lesions on CI outcomes. Reviewed data show that individuals with lesions that primarily affect the cochlear sensory system and the synapse, which are bypassed by the CI, have optimal CI outcomes. Individuals with lesions that affect the auditory nerve show poor performance with CIs, likely because neural transmission of the electrical signal from the CI is affected. We put forth a nuanced molecular classification of ANSD that has implications for preoperative counseling for patients with this disorder prior to cochlear implantation. We propose that description of ANSD patients should be based on the molecular site of lesion typically derived from genetic evaluation (synaptopathy vs. neuropathy) as this has implications for expected CI outcomes. Improvements in our understanding of genetic site of lesions and their effects on CI function should lead to better CI outcomes, not just for individuals with auditory neuropathy, but all individuals with hearing loss.

Auditory Neuropathy: Bridging the Gap Between Hearing Aids and Cochlear Implants

Auditory neuropathy spectrum disorder (ANSD) is a complex and heterogeneous disorder associated with altered neural synchrony with respect to auditory stimuli. Patients have characteristic auditory findings including normal otoacoustic emissions in the setting of abnormal auditory brainstem response. Patients with ANSD have a high incidence of comorbid developmental delay that may impact speech outcomes. Treatment options for ANSD include hearing amplification and cochlear implantation. The article highlights issues and controversies with the diagnosis and treatment of this complex disorder.

Cortical Auditory Evoked Potentials in Children with Auditory Neuropathy/Dys-Synchrony

Auditory neuropathy/spectrum disorder (ANSD), also referred to as auditory neuropathy/dys-synchrony (AN/AD) is a recently described form of hearing impairment. Many studies have shown that changing the pattern of afferent input to the cortex significantly affects cortical organization and there is little studies about cortical neuromaturation and plasticity in children with ANSD. Study of P1 component of cortical auditory evoked potentials (CAEPs) in children with ANSD. This survey was descriptive cross-sectional. During that 97 hearing impairment children were under hearing screening tests. Of these, 14 selected subjects (ear = 28) diagnosed with ANSD (an average age of 8.5 years) and evaluated by P1 component of CAEPs. Based on latency results of p1 wave, the ears of the subjects fell into two seperate groups: Control (normal: n = 10) and case {total: n = 18 (delayed: n = 12) + (absent: n = 6)}. The averages of mean latency of P1 components of the case group in the right and the left ears compared to the control group had significant differences (p < 0.05). Abnormal latency of p1 component in ANSD children shows the possibility of different scales of disturbances in cortical auditory maturation and grow.

Neural Correlates of Sensory Abnormalities Across Developmental Disabilities

Abnormalities in sensory processing are a common feature of many developmental disabilities (DDs). Sensory dysfunction can contribute to deficits in brain maturation, as well as many vital functions. Unfortunately, while some patients with DD benefit from the currently available treatments for sensory dysfunction, many do not. Deficiencies in clinical practice surrounding sensory dysfunction may be related to lack of understanding of the neural mechanisms that underlie sensory abnormalities. Evidence of overlap in sensory symptoms between diagnoses suggests that there may be common neural mechanisms that mediate many aspects of sensory dysfunction. Thus, the current manuscript aims to review the extant literature regarding the neural correlates of sensory dysfunction across DD in order to identify patterns of abnormality that span diagnostic categories. Such anomalies in brain structure, function, and connectivity may eventually serve as targets for treatment.

Efeito do estado atencional na detecção automática das respostas auditivas corticais em neonatos

RESUMO Objetivo O objetivo desse estudo foi comparar a latência e amplitude do potencial evocado auditivo cortical P1i entre neonatos em estado de alerta e durante o sono leve. Métodos Vinte e cinco neonatos com emissões otoacústicas evocadas transientes presentes foram testados, por meio do potencial evocado auditivo cortical (PEAC), sendo dez em estado de alerta e 15 durante o sono leve. Para pesquisa dos potenciais corticais, utilizou-se o equipamento Hearlab System, de um canal, no módulo Cortical Tone Evaluation (CTE). O potencial P1i foi pesquisado de forma monoaural, na intensidade de 80 dBnNA, para as frequências de 500, 1000, 2000 e 4000Hz. A detecção do P1i foi feita de maneira automática pelo equipamento. A marcação da latência e amplitude foi realizada por três juízes. Resultados Não houve diferença estatisticamente significativa entre os dois grupos de neonatos para os valores de amplitude e latência, nas quatro frequências testadas. Conclusão Não houve influência do estado comportamental dos neonatos na avaliação do potencial cortical P1i.

The Effects of Stimulus Rate on ABR Morphology and its Relationship to P1 CAEP Responses and Auditory Speech Perception Outcomes in Children with Auditory Neuropathy Spectrum Disorder: Evidence from Case Reports

OBJECTIVE

Auditory Neuropathy Spectrum Disorder (ANSD) affects approximately 5-15% of children with sensorineural hearing loss. ANSD is characterized by the presence of otoacoustic emissions (OAE) and an absent or abnormal auditory brainstem response (ABR). The purpose of this study was to investigate the prognostic value of slow-rate ABR in predicting the auditory cortical development and auditory speech perception outcomes in case studies of children with ANSD.

DESIGN

ABR waveform characteristics were collected at slow stimulation rates (5.1 clicks/second) and a fast stimulation rates (>11-31.1 clicks/second, rates typically used in a clinical setting) in 3 case reports of children with ANSD. P1 CAEP responses and measures of auditory speech perception using the Infant Toddler Meaningful Auditory Integration Scale (IT-MAIS) were also collected in these children. Retrospective analysis was performed to evaluate the prognostic value of slow- versus fast-rate ABR in predicting P1 CAEP responses and auditory speech perception outcomes in these children.

STUDY SAMPLE

Participants included case reports of 3 pediatric participants with a clinical diagnosis of ANSD.

RESULTS

Slow-rate ABR did not elicit significant improvements in waveform morphology compared to fast-rate ABR. P1 CAEP results were present in 2 out of 3 cases and were consistent with auditory speech perception outcomes.

CONCLUSIONS

Even when ABR stimulation rates were slowed, ABR responses in these children with ANSD did not display any characteristic or replicable pattern, and ABR responses were not predictive of cortical auditory maturation or behavioral performance. In contrast, P1 CAEP responses provided valuable information regarding the maturational status of the auditory cortex and P1 CAEP responses were consistent with behavioral measures of auditory speech perception. Overall, results highlight the high prognostic value of P1 CAEP testing when used in conjunction with behavioral measures of auditory speech perception in children with ANSD.

Cortical maturation in children with cochlear implants: Correlation between electrophysiological and behavioral measurement

Central auditory pathway maturation in children depends on auditory sensory stimulation. The objective of the present study was to monitor the cortical maturation of children with cochlear implants using electrophysiological and auditory skills measurements. The study was longitudinal and consisted of 30 subjects, 15 (8 girls and 7 boys) of whom had a cochlear implant, with a mean age at activation time of 36.4 months (minimum, 17 months; maximum, 66 months), and 15 of whom were normal-hearing children who were matched based on gender and chronological age. The auditory and speech skills of the children with cochlear implants were evaluated using GASP, IT-MAIS and MUSS measures. Both groups underwent electrophysiological evaluation using long-latency auditory evoked potentials. Each child was evaluated at three and nine months after cochlear implant activation, with the same time interval adopted for the hearing children. The results showed improvements in auditory and speech skills as measured by IT-MAIS and MUSS. Similarly, the long-latency auditory evoked potential evaluation revealed a decrease in P1 component latency; however, the latency remained significantly longer than that of the hearing children, even after nine months of cochlear implant use. It was observed that a shorter P1 latency corresponded to more evident development of auditory skills. Regarding auditory behavior, it was observed that children who could master the auditory skill of discrimination showed better results in other evaluations, both behavioral and electrophysiological, than those who had mastered only the speech-detection skill. Therefore, cochlear implant auditory stimulation facilitated auditory pathway maturation, which decreased the latency of the P1 component and advanced the development of auditory and speech skills. The analysis of the long-latency auditory evoked potentials revealed that the P1 component was an important biomarker of auditory development during the rehabilitation process.

Selective Neuronal Activation by Cochlear Implant Stimulation in Auditory Cortex of Awake Primate

Despite the success of cochlear implants (CIs) in human populations, most users perform poorly in noisy environments and music and tonal language perception. How CI devices engage the brain at the single neuron level has remained largely unknown, in particular in the primate brain. By comparing neuronal responses with acoustic and CI stimulation in marmoset monkeys unilaterally implanted with a CI electrode array, we discovered that CI stimulation was surprisingly ineffective at activating many neurons in auditory cortex, particularly in the hemisphere ipsilateral to the CI. Further analyses revealed that the CI-nonresponsive neurons were narrowly tuned to frequency and sound level when probed with acoustic stimuli; such neurons likely play a role in perceptual behaviors requiring fine frequency and level discrimination, tasks that CI users find especially challenging. These findings suggest potential deficits in central auditory processing of CI stimulation and provide important insights into factors responsible for poor CI user performance in a wide range of perceptual tasks.

SIGNIFICANCE STATEMENT

The cochlear implant (CI) is the most successful neural prosthetic device to date and has restored hearing in hundreds of thousands of deaf individuals worldwide. However, despite its huge successes, CI users still face many perceptual limitations, and the brain mechanisms involved in hearing through CI devices remain poorly understood. By directly comparing single-neuron responses to acoustic and CI stimulation in auditory cortex of awake marmoset monkeys, we discovered that neurons unresponsive to CI stimulation were sharply tuned to frequency and sound level. Our results point out a major deficit in central auditory processing of CI stimulation and provide important insights into mechanisms underlying the poor CI user performance in a wide range of perceptual tasks.

Cortical Auditory Evoked Potentials Reveal Changes in Audibility with Nonlinear Frequency Compression in Hearing Aids for Children: Clinical Implications

Hearing loss in children is detected soon after birth via newborn hearing screening. Procedures for early hearing assessment and hearing aid fitting are well established, but methods for evaluating the effectiveness of amplification for young children are limited. One promising approach to validating hearing aid fittings is to measure cortical auditory evoked potentials (CAEPs). This article provides first a brief overview of reports on the use of CAEPs for evaluation of hearing aids. Second, a study that measured CAEPs to evaluate nonlinear frequency compression (NLFC) in hearing aids for 27 children (between 6.1 and 16.8 years old) who have mild to severe hearing loss is reported. There was no significant difference in aided sensation level or the detection of CAEPs for /g/ between NLFC on and off conditions. The activation of NLFC was associated with a significant increase in aided sensation levels for /t/ and /s/. It also was associated with an increase in detection of CAEPs for /t/ and /s/. The findings support the use of CAEPs for checking audibility provided by hearing aids. Based on the current data, a clinical protocol for using CAEPs to validate audibility with amplification is presented.

Current trends in outcome studies for children with hearing loss and the need to establish a comprehensive framework of measuring outcomes in children with hearing loss in China

Since the 1970s, outcome studies for children with hearing loss expanded from focusing on assessing auditory awareness and speech perception skills to evaluating language and speech development. Since the early 2000s, the multi-center large scale research systematically studied outcomes in the areas of auditory awareness, speech-perception, language development, speech development, educational achievements, cognitive development, and psychosocial development. These studies advocated the establishment of baseline and regular follow-up evaluations with a comprehensive framework centered on language development. Recent research interests also include understanding the vast differences in outcomes for children with hearing loss, understanding the relationships between neurocognitive development and language acquisition in children with hearing loss, and using outcome studies to guide evidence-based clinical practice. After the establishment of standardized Mandarin language assessments, outcomes research in Mainland China has the potential to expand beyond auditory awareness and speech perception studies.

Auditory evoked potentials in a newborn Wistar rat model of hyperbilirubinemia

Introduction

Hyperbilirubinemia is a common health problem in newborns. Its effects can be different according to the level and duration of the hyperbilirubinemia. The toxic effect of bilirubin on the auditory system can be seen as a sensory neural hearing loss or auditory neuropathy spectrum disorder (ANSD).

Objective

The purpose of our study was to determine the effects of toxic bilirubin level on the auditory system by using Auditory Brainstem Response audiometry.

Methods

Rats are used as animal models due to their low cost and easy attainability. Auditory Brainstem Response was used for auditory assessment. In this study, three groups were established: experimental, control and placebo groups.

Results

In the experimental group, which consists of rats with hyperbilirubinemia, sensory neural hearing loss was found bilaterally in 4 rats (66.67%) and unilaterally in 2 rats (16.67%) and auditory neuropathy spectrum disorder was found unilaterally in 1 rat (8.33%). Auditory Brainstem Response thresholds were significantly elevated compared to control and placebo groups (p < 0.05).

Conclusion

Hyperbilirubinemia of newborn rats may result both in sensory neural hearing loss and auditory neuropathy spectrum disorder.

Evaluating long-latency auditory evoked potentials in the diagnosis of cortical hearing loss in children

In centrally related hearing loss, there is no apparent damage in the auditory system, but the patient is unable to hear sounds. In patients with cortical hearing loss (and in the absence of communication deficit, either total or partial, as in agnosia or aphasia), some attention-related or language-based disorders may lead to a wrong diagnosis of hearing impairment. The authors present two patients (8 and 11 years old) with no anatomical damage to the ear, the absence of neurological damage or trauma, but immature cortical auditory evoked potentials. Both patients presented a clinical history of multiple diagnoses over several years. Because the most visible symptom was moderate hearing loss, the patients were recurrently referred to audiological testing, with no improvement. This report describes the use of long-latency evoked potentials to determine cases of cortical hearing loss, where hearing impairment is a consequence of underdevelopment at the central nervous system.

Acoustically evoked auditory change complex in children with auditory neuropathy spectrum disorder: a potential objective tool for identifying cochlear implant candidates

OBJECTIVES

The overall aim of the study was to evaluate the feasibility of using electrophysiological measures of the auditory change complex (ACC) to identify candidates for cochlear implantation in children with auditory neuropathy spectrum disorder (ANSD). To achieve this overall aim, this study (1) assessed the feasibility of measuring the ACC evoked by temporal gaps in a group of children with ANSD across a wide age range and (2) investigated the association between gap detection thresholds (GDTs) measured by the ACC recordings and open-set speech-perception performance in these subjects.

DESIGN

Nineteen children with bilateral ANSD ranging in age between 1.9 and 14.9 years (mean: 7.8 years) participated in this study. Electrophysiological recordings of the auditory event-related potential (ERP), including the onset ERP response and the ACC, were completed in all subjects and open-set speech perception was evaluated for a subgroup of 16 subjects. For the ERP recordings, the stimulus was a Gaussian noise presented through ER-3A insert earphones to the test ear. Two stimulation conditions were used. In the "control condition," the stimulus was an 800-msec Gaussian noise. In the "gapped condition," the stimuli were two noise segments, each being 400 msec in duration, separated by one of five gaps (i.e., 5, 10, 20, 50, or 100 msec). The interstimulation interval was 1200 msec. The aided open-set speech perception ability was assessed using the Phonetically Balanced Kindergarten (PBK) word lists presented at 60 dB SPL using recorded testing material in a sound booth. For speech perception tests, subjects wore their hearing aids at the settings recommended by their clinical audiologists. For a subgroup of five subjects, psychophysical GDTs for the Gaussian noise were also assessed using a three-interval, three-alternative forced-choice procedure.

RESULTS

Responses evoked by the onset of the Gaussian noise (i.e., onset responses) were recorded in all stimulation conditions from all subjects tested in this study. The presence/absence, peak latency and amplitude, and response width of the onset response did not correlate with aided PBK word scores. The objective GDTs measured with the ACC recordings from 17 subjects ranged from 10 to 100 msec. The ACC was not recorded from two subjects for any gap durations tested in this study. There was a robust negative correlation between objective GDTs and aided PBK word scores. In general, subjects with prolonged objective GDTs showed low-aided PBK word scores. GDTs measured using electrophysiological recordings of the ACC correlated well with those measured using psychophysical procedures in four of five subjects who were evaluated using both procedures.

CONCLUSIONS

The clinical application of the onset response in predicting open-set speech-perception ability is relatively limited in children with ANSD. The ACC recordings can be used to objectively evaluate temporal resolution abilities in children with ANSD having no severe comorbidities, and who are older than 1.9 years. The ACC can potentially be used as an objective tool to identify poor performers among children with ANSD using properly fit amplification, and who are thus, cochlear implant candidates.

Speech processing in children with cochlear implant

Cochlear implants (CIs) can be used effectively in the profoundly impaired children individuals.

OBJECTIVES

This work was designed to assess speech processing at brainstem and cortical level in children fitted with CIs to investigate the possible influence of brainstem processing of speech on the cortical processing in those children.

METHOD

Twenty children fitted with CIs underwent aided sound-field audiologic evaluation, speech evoked cortical auditory evoked potentials (S-CAEPs) and according to the results, children were classified into two groups: group I with good cortical response and group II with poor cortical response. This was followed by speech evoked ABR (S-ABR) recoding.

RESULTS

P1 component of CAEPs was recorded in all children while other component showed variable results. S-ABR was recorded in all children even those with poor S-CAEPs response who showed delayed D, E, F and O latencies. However, S-ABR amplitudes did not show any significant difference between both groups.

CONCLUSIONS

Children fitted with CI showed immediate cortical activation following device programming and this activity depends on the age of implantation as well as the child's age. S-ABR provides a new clinical tool that showed an important role of brainstem in complex sound processing that contribute to cortical processing.

Cortical development and neuroplasticity in Auditory Neuropathy Spectrum Disorder

Cortical development is dependent to a large extent on stimulus-driven input. Auditory Neuropathy Spectrum Disorder (ANSD) is a recently described form of hearing impairment where neural dys-synchrony is the predominant characteristic. Children with ANSD provide a unique platform to examine the effects of asynchronous and degraded afferent stimulation on cortical auditory neuroplasticity and behavioral processing of sound. In this review, we describe patterns of auditory cortical maturation in children with ANSD. The disruption of cortical maturation that leads to these various patterns includes high levels of intra-individual cortical variability and deficits in cortical phase synchronization of oscillatory neural responses. These neurodevelopmental changes, which are constrained by sensitive periods for central auditory maturation, are correlated with behavioral outcomes for children with ANSD. Overall, we hypothesize that patterns of cortical development in children with ANSD appear to be markers of the severity of the underlying neural dys-synchrony, providing prognostic indicators of success of clinical intervention with amplification and/or electrical stimulation. This article is part of a Special Issue entitled <Auditory Synaptology>.

Parents' perspectives on the dilemmas with intervention for infants with auditory neuropathy spectrum disorder: A qualitative study

OBJECTIVE

This paper explores parental experiences of choices surrounding auditory management and language and communication development for infants and children with auditory neuropathy spectrum disorder (ANSD) in the light of the heterogeneity of condition, a poor evidence base for best outcomes in relation to management options, and the scarcity of data rooted in parent and family experience.

DESIGN

Qualitative narrative study.

STUDY SAMPLE

Twenty-five parents of 21 children (aged four months to six years) identified with ANSD through the newborn hearing screening programme.

RESULTS

Families identify barriers to early management due to conflicting expert opinions and ANSD-specific challenges with diagnosis and prognosis in infants, and share their accounts on their own evaluations of intervention benefit in their children.

CONCLUSIONS

The results are of relevance to the clinicians and other professionals involved in early intervention, management, and support of infants with ANSD.

The audiological journey and early outcomes of twelve infants with auditory neuropathy spectrum disorder from birth to two years of age

OBJECTIVE

To describe the audiological journey of a group of infants with auditory neuropathy spectrum disorder (ANSD) following the fitting of hearing aids, and to investigate the potential benefits of including cortical auditory-evoked potentials (CAEPs) and a measure of functional auditory behaviour during early audiological management.

DESIGN

Results from chart revision of estimated hearing threshold, early behavioural testing, parental observation, and functional auditory behaviour assessments were described, and compared to visual reinforcement audiometry (VRA) thresholds obtained at a mean corrected age of 10 months (SD 3). The relationship with CAEPs and functional performance was examined.

STUDY SAMPLE

The study included 12 infants diagnosed with ANSD and fitted with amplification.

RESULTS

The estimated 4FA at a mean corrected age of four months (SD5) was within ± 10 dB of VRA results in 75% of infants when unaided and aided behavioural observation audiometry (BOA), together with unaided and aided parental observations was combined. Infants with a greater proportion of CAEPs present had higher PEACH scores.

CONCLUSIONS

Delaying amplification until VRA results were available would have led to a significant period of auditory deprivation for infants in this study group. None of the assessments could accurately determine hearing thresholds when used in isolation, however when used in combination clinicians were able to obtain sufficient information to fit hearing aids early, and identify infants requiring closer monitoring.

P300 in individuals with sensorineural hearing loss

Introduction

Behavioral and electrophysiological auditory evaluations contribute to the understanding of the auditory system and of the process of intervention.

Objective

To study P300 in subjects with severe or profound sensorineural hearing loss.

Methods

This was a descriptive cross-sectional prospective study. It included 29 individuals of both genders with severe or profound sensorineural hearing loss without other type of disorders, aged 11 to 42 years; all were assessed by behavioral audiological evaluation and auditory evoked potentials.

Results

A recording of the P3 wave was obtained in 17 individuals, with a mean latency of 326.97 ms and mean amplitude of 3.76 V. There were significant differences in latency in relation to age and in amplitude according to degree of hearing loss. There was a statistically significant association of the P300 results with the degrees of hearing loss (p = 0.04), with the predominant auditory communication channels (p < 0.0001), and with time of hearing loss.

Conclusions

P300 can be recorded in individuals with severe and profound congenital sensorineural hearing loss; it may contribute to the understanding of cortical development and is a good predictor of the early intervention outcome.

Objective measures of electrode discrimination with electrically evoked auditory change complex and speech-perception abilities in children with auditory neuropathy spectrum disorder

OBJECTIVES

This study aimed to (1) determine the sensitivity of the electrically evoked auditory change complex (eACC) to changes in stimulating electrode position; and (2) investigate the association between results of eACC measures and behavioral electrode discrimination and their association with speech-perception performance in pediatric cochlear implant (CI) users who have auditory neuropathy spectrum disorder (ANSD).

DESIGN

Fifteen children with ANSD ranging in age between 5.4 and 18.6 years participated in this study. All subjects used Cochlear Nucleus devices. For each subject, open-set speech-perception ability was assessed using the Phonetically Balanced Kindergarten word lists presented at 60 dB SPL, using monitored live voice in a sound booth. Behavioral and objective measures of electrode discrimination were assessed in a nonclinical test environment. The stimuli used to elicit these measures were 800 msec biphasic pulse trains delivered by a direct interface to the CI. Data were collected from two basic stimulation conditions. In the standard condition, the entire pulse train was delivered to a mid-array electrode (electrode 11 or 12) at the maximum comfortable level (C level). In the change condition, the stimulus was split into two 400 msec pulse train segments presented sequentially on two different electrodes. The stimulation level of the second 400 msec pulse train was loudness balanced to the C level of the mid-array electrode used in the standard condition. The separation between the pair of stimulating electrodes was systematically varied. For behavioral electrode-discrimination measures, each subject was required to determine whether he or she heard one or two sounds for stimuli presented in different stimulation conditions. For the eACC measures, two replicates of 100 artifact-free sweeps were recorded for each stimulation condition.

RESULTS

The eACC in response to changes in stimulating electrode position was recorded from all subjects with ANSD using direct electrical stimulation. Electrode-discrimination thresholds determined with the eACC and behavioral measures were consistent. Children with ANSD using CIs who showed poorer speech performance also required larger separations between the stimulating electrode pair to reliably elicit the eACC than subjects with better speech-perception performance. There was a robust correlation between electrode-discrimination capacities and speech-perception performances in subjects tested in this study. The effect of electrode separation on eACC amplitudes was not monotonic.

CONCLUSIONS

These results demonstrate the feasibility of using eACC to evaluate electrode-discrimination capacities in children with ANSD. These results suggest that the eACC elicited by changes in stimulating electrode position holds great promise as an objective tool for evaluating spectral-pattern detection in such subjects, which may be predictive of their potential speech-perception performance.

Infant cortical electrophysiology and perception of vowel contrasts

Cortical auditory evoked potentials (CAEPs) were obtained for vowel tokens presented in an oddball stimulus paradigm. Perceptual measures of vowel discrimination were obtained using a visually-reinforced head-turn paradigm. The hypothesis was that CAEP latencies and amplitudes would differ as a function of vowel type and be correlated with perceptual performance. Twenty normally hearing infants aged 4-12 months were evaluated. CAEP component amplitudes and latencies were measured in response to the standard, frequent token /a/ and for infrequent, deviant tokens /i/, /o/ and /u/, presented at rates of 1 and 2 tokens/s. The perceptual task required infants to make a behavioral response for trials that contained two different vowel tokens, and ignore those in which the tokens were the same. CAEP amplitudes were larger in response to the deviant tokens, when compared to the control condition in which /a/ served as both standard and deviant. This was also seen in waveforms derived by subtracting the response to standard /a/ from the responses to deviant tokens. CAEP component latencies in derived responses at 2/s also demonstrated some sensitivity to vowel contrast type. The average hit rate for the perceptual task was 68.5%, with a 25.7% false alarm rate. There were modest correlations of CAEP amplitudes and latencies with perceptual performance. The CAEP amplitude differences for vowel contrasts could be used as an indicator of the underlying neural capacity to encode spectro-temporal differences in vowel sounds. This technique holds promise for translation to clinical methods for evaluating speech perception.

Monitoring the Hearing Handicap and the Recognition Threshold of Sentences of a Patient with Unilateral Auditory Neuropathy Spectrum Disorder with Use of a Hearing Aid

Introduction Treatment for auditory neuropathy spectrum disorder (ANSD) is not yet well established, including the use of hearing aids (HAs). Not all patients diagnosed with ASND have access to HAs, and in some cases HAs are even contraindicated.

Objective To monitor the hearing handicap and the recognition threshold of sentences in silence and in noise in a patient with ASND using an HA.

Resumed Report A 47-year-old woman reported moderate sensorineural hearing loss in the right ear and high-frequency loss of 4 kHz in the left ear, with bilateral otoacoustic emissions. Auditory brainstem response suggested changes in the functioning of the auditory pathway (up to the inferior colliculus) on the right. An HA was indicated on the right. The patient was tested within a 3-month period before the HA fitting with respect to recognition threshold of sentences in quiet and in noise and for handicap determination. After HA use, she showed a 2.1-dB improvement in the recognition threshold of sentences in silence, a 6.0-dB improvement for recognition threshold of sentences in noise, and a rapid improvement of the signal-to-noise ratio from +3.66 to −2.4 dB when compared with the same tests before the fitting of the HA.

Conclusion There was a reduction of the auditory handicap, although speech perception continued to be severely limited. There was a significant improvement of the recognition threshold of sentences in silence and in noise and of the signal-to-noise ratio after 3 months of HA use.

Does parental experience of the diagnosis and intervention process differ for children with auditory neuropathy?

OBJECTIVES

This study compared parental experience of the audiological diagnosis and intervention process in children with auditory neuropathy spectrum disorder and sensory neural hearing loss.

METHODS

A matched group survey was used with parents of children with auditory neuropathy spectrum disorder (ANSD) matched with a control group of parents and children with sensorineural hearing loss (SNHL). The two groups were matched in terms of the child's gender, age, amplifications used, social background and utilisation of private or public health care sectors. An interview questionnaire, consisting of 45 questions in six categories (1. biographic information, 2. experiences of audiological diagnosis, 3. hearing aid benefit, 4. parental experience of the rehabilitation decision making process, 5. parental needs for emotional support and 6. parental needs for information) using a 5-point Likert scale for categories 2-7, was administered by the same audiologist.

RESULTS

Children with ANSD experienced a significantly longer waiting period from diagnosis to hearing aid fitting (p=0.025) and/or cochlear implantation (p=0.036). Parents of children with ANSD reported significantly different experiences of the diagnostic process (p=0.001) with poorer understanding of the diagnosis and reporting insufficient time allowed for asking questions. During the rehabilitation decision-making process 47% of parents with ANSD children (vs. 0% of parents with SNHL children) reported receiving conflicting information. Parents of children with ANSD were also less likely to recommend hearing aids to other parents. Information needs were similar between groups.

CONCLUSIONS

Parents of children with ANSD have different experiences and greater uncertainty during the diagnostic and rehabilitation process. Providing regular consultation and structured timelines through the diagnostic process and decision-making process may facilitate this process with less uncertainty.

Developmental and cross-modal plasticity in deafness: evidence from the P1 and N1 event related potentials in cochlear implanted children

Cortical development is dependent on extrinsic stimulation. As such, sensory deprivation, as in congenital deafness, can dramatically alter functional connectivity and growth in the auditory system. Cochlear implants ameliorate deprivation-induced delays in maturation by directly stimulating the central nervous system, and thereby restoring auditory input. The scenario in which hearing is lost due to deafness and then reestablished via a cochlear implant provides a window into the development of the central auditory system. Converging evidence from electrophysiologic and brain imaging studies of deaf animals and children fitted with cochlear implants has allowed us to elucidate the details of the time course for auditory cortical maturation under conditions of deprivation. Here, we review how the P1 cortical auditory evoked potential (CAEP) provides useful insight into sensitive period cut-offs for development of the primary auditory cortex in deaf children fitted with cochlear implants. Additionally, we present new data on similar sensitive period dynamics in higher-order auditory cortices, as measured by the N1 CAEP in cochlear implant recipients. Furthermore, cortical re-organization, secondary to sensory deprivation, may take the form of compensatory cross-modal plasticity. We provide new case-study evidence that cross-modal re-organization, in which intact sensory modalities (i.e., vision and somatosensation) recruit cortical regions associated with deficient sensory modalities (i.e., auditory) in cochlear implanted children may influence their behavioral outcomes with the implant. Improvements in our understanding of developmental neuroplasticity in the auditory system should lead to harnessing central auditory plasticity for superior clinical technique.

Language Outcomes Using Hearing Aids in Children with Auditory Dys-Synchrony

There is a considerable debate on the use of hearing aid in children with auditory dys-synchrony (AD). To current date there are no similar Studies which show the effect of acoustic amplification on outcomes on speech and language development in children with AD are found in the literature. Thus, in the present study three children diagnosed to have AD were recruited and subjected to hearing aid trial and fitting based on the late latency response thresholds. Ranging from 7 months to 41 months of intervention period, each child's language age was reassessed and compared with that of their pre-therapy language age. The comparison showed a good improvement in receptive age, though the children had moderate to severe degree of hearing loss. But their expressive age was significantly delayed irrespective of their age of identification and duration of intervention. Thus the delay in expression with a good amount of improvement in reception can be a characteristic of an AD child with amplification.

Impact of the presence of auditory neuropathy spectrum disorder (ANSD) on outcomes of children at three years of age

OBJECTIVE

To determine the influence of the presence of auditory neuropathy spectrum disorder (ANSD) on speech, language, and psycho-social development of children at three years of age.

DESIGN

A population-based, longitudinal study was performed on outcomes of children with hearing impairment (LOCHI) in Australia. The demographic characteristics of the children were described, and their developmental outcomes were evaluated at three years of age. Performance of children with ANSD was compared with that of children without ANSD in the LOCHI study.

STUDY SAMPLE

There were 47 children with ANSD in the study sample.

RESULTS

Sixty-four percent of children with ANSD have hearing sensitivity loss ranging from mild to severe degree, and the remaining have profound hearing loss. At three years, 27 children used hearing aids, 19 used cochlear implants, and one child did not use any hearing device. Thirty percent of children have disabilities in addition to hearing loss. On average, there were no significant differences in performance level between children with and without ANSD. Also, the variability of scores was not significantly different between the two groups.

CONCLUSIONS

There was no significant difference in performance levels or variability between children with and without ANSD, both for children who use hearing aids, and children who use cochlear implants.

Inter-trial coherence as a marker of cortical phase synchrony in children with sensorineural hearing loss and auditory neuropathy spectrum disorder fitted with hearing aids and cochlear implants

OBJECTIVE

Although brainstem dys-synchrony is a hallmark of children with auditory neuropathy spectrum disorder (ANSD), little is known about how the lack of neural synchrony manifests at more central levels. We used time-frequency single-trial EEG analyses (i.e., inter-trial coherence; ITC), to examine cortical phase synchrony in children with normal hearing (NH), sensorineural hearing loss (SNHL) and ANSD.

METHODS

Single trial time-frequency analyses were performed on cortical auditory evoked responses from 41 NH children, 91 children with ANSD and 50 children with SNHL. The latter two groups included children who received intervention via hearing aids and cochlear implants. ITC measures were compared between groups as a function of hearing loss, intervention type, and cortical maturational status.

RESULTS

In children with SNHL, ITC decreased as severity of hearing loss increased. Children with ANSD revealed lower levels of ITC relative to children with NH or SNHL, regardless of intervention. Children with ANSD who received cochlear implants showed significant improvements in ITC with increasing experience with their implants.

CONCLUSIONS

Cortical phase coherence is significantly reduced as a result of both severe-to-profound SNHL and ANSD.

SIGNIFICANCE

ITC provides a window into the brain oscillations underlying the averaged cortical auditory evoked response. Our results provide a first description of deficits in cortical phase synchrony in children with SNHL and ANSD.

Gap detection measured with electrically evoked auditory event-related potentials and speech-perception abilities in children with auditory neuropathy spectrum disorder

OBJECTIVES

This study aimed (1) to investigate the feasibility of recording the electrically evoked auditory event-related potential (eERP), including the onset P1-N1-P2 complex and the electrically evoked auditory change complex (EACC) in response to temporal gaps, in children with auditory neuropathy spectrum disorder (ANSD); and (2) to evaluate the relationship between these measures and speech-perception abilities in these subjects.

DESIGN

Fifteen ANSD children who are Cochlear Nucleus device users participated in this study. For each subject, the speech-processor microphone was bypassed and the eERPs were elicited by direct stimulation of one mid-array electrode (electrode 12). The stimulus was a train of biphasic current pulses 800 msec in duration. Two basic stimulation conditions were used to elicit the eERP. In the no-gap condition, the entire pulse train was delivered uninterrupted to electrode 12, and the onset P1-N1-P2 complex was measured relative to the stimulus onset. In the gapped condition, the stimulus consisted of two pulse train bursts, each being 400 msec in duration, presented sequentially on the same electrode and separated by one of five gaps (i.e., 5, 10, 20, 50, and 100 msec). Open-set speech-perception ability of these subjects with ANSD was assessed using the phonetically balanced kindergarten (PBK) word lists presented at 60 dB SPL, using monitored live voice in a sound booth.

RESULTS

The eERPs were recorded from all subjects with ANSD who participated in this study. There were no significant differences in test-retest reliability, root mean square amplitude or P1 latency for the onset P1-N1-P2 complex between subjects with good (>70% correct on PBK words) and poorer speech-perception performance. In general, the EACC showed less mature morphological characteristics than the onset P1-N1-P2 response recorded from the same subject. There was a robust correlation between the PBK word scores and the EACC thresholds for gap detection. Subjects with poorer speech-perception performance showed larger EACC thresholds in this study.

CONCLUSIONS

These results demonstrate the feasibility of recording eERPs from implanted children with ANSD, using direct electrical stimulation. Temporal-processing deficits, as demonstrated by large EACC thresholds for gap detection, might account in part for the poor speech-perception performances observed in a subgroup of implanted subjects with ANSD. This finding suggests that the EACC elicited by changes in temporal continuity (i.e., gap) holds promise as a predictor of speech-perception ability among implanted children with ANSD.

Abnormal pre-attentive arousal in young children with autism spectrum disorder contributes to their atypical auditory behavior: an ERP study

Auditory sensory modulation difficulties and problems with automatic re-orienting to sound are well documented in autism spectrum disorders (ASD). Abnormal preattentive arousal processes may contribute to these deficits. In this study, we investigated components of the cortical auditory evoked potential (CAEP) reflecting preattentive arousal in children with ASD and typically developing (TD) children aged 3-8 years. Pairs of clicks (‘S1’ and ‘S2’) separated by a 1 sec S1-S2 interstimulus interval (ISI) and much longer (8-10 sec) S1-S1 ISIs were presented monaurally to either the left or right ear. In TD children, the P50, P100 and N1c CAEP components were strongly influenced by temporal novelty of clicks and were much greater in response to the S1 than the S2 click. Irrespective of the stimulation side, the ‘tangential’ P100 component was rightward lateralized in TD children, whereas the ‘radial’ N1c component had higher amplitude contralaterally to the stimulated ear. Compared to the TD children, children with ASD demonstrated 1) reduced amplitude of the P100 component under the condition of temporal novelty (S1) and 2) an attenuated P100 repetition suppression effect. The abnormalities were lateralized and depended on the presentation side. They were evident in the case of the left but not the right ear stimulation. The P100 abnormalities in ASD correlated with the degree of developmental delay and with the severity of auditory sensory modulation difficulties observed in early life. The results suggest that some rightward-lateralized brain networks that are crucially important for arousal and attention re-orienting are compromised in children with ASD and that this deficit contributes to sensory modulation difficulties and possibly even other behavioral deficits in ASD.

CENTRAL AUDTIORY DEVELOPMENT IN CHILDREN WITH HEARING LOSS: CLINICAL RELEVANCE OF THE P1 CAEP BIOMARKER IN HEARING-IMPAIRED CHILDREN WITH MULTIPLE DISABILITIES

OBJECTIVE

First, we review the development and plasticity of the central auditory pathways in infants and children with hearing loss who are fitted with cochlear implants (CIs). Second, we describe case studies demonstrating the clinical utility of the P1 central auditory evoked potential (CAEP) for evaluating cortical auditory maturation in the rapidly increasing number of cochlear-implanted children who have multiple disabilities.

STUDY DESIGN

Children who receive CIs provide a platform to examine the trajectories of deprivation-induced and experience-dependent plasticity in the central auditory system. We review the evidence for, and time limits of sensitive periods for cortical auditory maturation framing an optimal period for cochlear implantation. Finally, we evaluate the use of the P1 biomarker as an objective assessment tool in the special case of children with multiple disabilities.

RESULTS

The P1 response was useful in assessing central auditory maturation in patients with CHARGE association, ANSD, and Pallister-Killian Syndrome concomitant with hearing loss.

CONCLUSION

The presence of co-existing disabilities in addition to hearing loss poses unique challenges regarding both pre-intervention evaluation and post-intervention rehabilitation for children with multiple disabilities. When combined with a standard audiological test battery, the P1 CAEP biomarker has a useful role in objectively evaluating the maturation of central auditory pathways to determine the effectiveness of various intervention strategies in hearing-impaired children with multiple disabilities.

Central auditory maturation and behavioral outcome in children with auditory neuropathy spectrum disorder who use cochlear implants

OBJECTIVE

We examined cortical auditory development and behavioral outcomes in children with ANSD fitted with cochlear implants (CI).

DESIGN

Cortical maturation, measured by P1 cortical auditory evoked potential (CAEP) latency, was regressed against scores on the infant toddler meaningful auditory integration scale (IT-MAIS). Implantation age was also considered in relation to CAEP findings.

STUDY SAMPLE

Cross-sectional and longitudinal samples of 24 and 11 children, respectively, with ANSD fitted with CIs.

RESULTS

P1 CAEP responses were present in all children after implantation, though previous findings suggest that only 50-75% of ANSD children with hearing aids show CAEP responses. P1 CAEP latency was significantly correlated with participants' IT-MAIS scores. Furthermore, more children implanted before age two years showed normal P1 latencies, while those implanted later mainly showed delayed latencies. Longitudinal analysis revealed that most children showed normal or improved cortical maturation after implantation.

CONCLUSION

Cochlear implantation resulted in measureable cortical auditory development for all children with ANSD. Children fitted with CIs under age two years were more likely to show age-appropriate CAEP responses within six months after implantation, suggesting a possible sensitive period for cortical auditory development in ANSD. That CAEP responses were correlated with behavioral outcome highlights their clinical decision-making utility.