Aiding and occluding the contralateral ear in implanted children with auditory neuropathy spectrum disorder

Measurement of thresholds using Chirp-ABR in children with auditory neuropathy spectrum disorder and sensorineural hearing loss

AIM

This study explored the value of Chirp-auditory brainstem response (ABR) thresholds in assessing the hearing threshold of children diagnosed with auditory neuropathy spectrum disorder (ANSD).

METHODS

A total of 20 children with ANSD (40 ears, aged 1.5-7.0 years, median age 4.5 years) and 31 children with sensorineural hearing loss (SNHL) (52 ears, aged 0.9-8.0 years, median age 3.7 years) were included. Besides, 25 normal children (50 ears, aged 0.8-7.5 years, median age 4.6 years) were used as controls. Chirp-ABR and behavioral audiometry were performed simultaneously among three groups of children, allowing for a comparison of the thresholds obtained through both methods.

RESULTS

In ANSD children, the correlation (r-values) between the thresholds obtained from Chirp-ABR and behavioral audiometry at 500-4000 Hz were 0.84, 0.67, 0.59, and 0.60, respectively. The average threshold differences between two methods ranged from 9.7 to 13.3 dB at 500-4000 Hz. Notably, 20 % ears (8/40) exhibited considerable discrepancies (>30 dB) in thresholds at certain frequencies. For SNHL children, the r-values between two methods were 0.84, 0.89, 0.92, and 0.93, respectively. The average threshold differences between two methods were 5.7-8.2 dB at 500-4000 Hz. Similarly, in normal children, the average threshold differences between two methods ranged from 6.1 dB to 7.7 dB, the r-values were 0.81, 0.78, 0.80, and 0.80 at 500-4000 Hz, respectively.

CONCLUSION

Chirp-ABR threshold is not suitable to predict the behavioral audiometry threshold in ANSD children. When there is a significant discrepancy (>30 dB) between Chirp-ABR thresholds and behavioral audiometry thresholds in hearing loss, ANSD should be highly suspected.

Auditory neuropathy: from etiology to management

PURPOSE OF REVIEW

Auditory neuropathy is a disorder of auditory dysfunction characterized by the normal function of the outer hair cells and malfunction of the inner hair cells, synapses, postsynapses and/or auditory afferent nervous system. This review summarizes the process of discovery and naming of auditory neuropathy and describes the acquired, associated genetic disorders and management available.

RECENT FINDINGS

In the last 40 years, auditory neuropathy has undergone a process of discovery, naming and progressive elucidation of its complex pathological mechanisms. Recent studies have revealed numerous acquired and inherited causative factors associated with auditory neuropathy. Studies have analyzed the pathogenic mechanisms of various genes and the outcomes of cochlear implantation. New therapeutic approaches, such as stem cell therapy and gene therapy are the future trends in the treatment of auditory neuropathy.

SUMMARY

A comprehensive understanding of the pathogenic mechanisms is crucial in illustrating auditory neuropathy and assist in developing future management strategies.

Determination of language performance by discriminant function analysis in Mandarin-speaking preschoolers with auditory neuropathy spectrum disorder

OBJECTIVE

Characteristics of the audiological performance of children with auditory neuropathy spectrum disorder (ANSD) have been identified; however, studies regarding factors influencing their language development, especially those related to aural-oral rehabilitation, are relatively few. This study aimed to investigate classification functions among the factors regarding audiological, interventional (rehabilitation) and demographic variables that can help determine group membership in language performance for Mandarin-speaking preschoolers with ANSD.

METHODS

Children with ANSD aged 3-6 years (n = 27) enrolled in an auditory-verbal therapy were recruited. The combination of factors that could be used to predict memberships of children regarding whether they achieved age-appropriate language performance or were at risk of language delay were explored using discriminant function analysis.

RESULTS

Maternal education level, age at initial hearing aid fitting, and duration of rehabilitation were all significant factors in predicting the membership of children with ANSD and whether they could achieve an age-appropriate language level or were at risk for language delay. The correct rate for predicting the memberships ranged from 70.4% to 83.3%. Duration of rehabilitation accounted for the greatest effect on discriminant membership regarding achieving age-appropriate language performance and being at risk of language delay. Effect of maternal education level tended to centralize on language comprehension.

CONCLUSIONS

Differences were observed in the quantifiable effects of predictors in discriminant functions for language ability domains. Except for using suitable hearing devices, adequate duration of enrollment in aural and oral rehabilitation would also be important for children with ANSD to develop better language abilities.

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.

Spatial Release From Masking in 2-Year-Olds With Normal Hearing and With Bilateral Cochlear Implants

This study evaluated spatial release from masking (SRM) in 2- to 3-year-old children who are deaf and were implanted with bilateral cochlear implants (BiCIs), and in age-matched normal-hearing (NH) toddlers. Here, we examined whether early activation of bilateral hearing has the potential to promote SRM that is similar to age-matched NH children. Listeners were 13 NH toddlers and 13 toddlers with BiCIs, ages 27 to 36 months. Speech reception thresholds (SRTs) were measured for target speech in front (0°) and for competitors that were either Colocated in front (0°) or Separated toward the right (+90°). SRM was computed as the difference between SRTs in the front versus in the asymmetrical condition. Results show that SRTs were higher in the BiCI than NH group in all conditions. Both groups had higher SRTs in the Colocated and Separated conditions compared with Quiet, indicating masking. SRM was significant only in the NH group. In the BiCI group, the group effect of SRM was not significant, likely limited by the small sample size; however, all but two children had SRM values within the NH range. This work shows that to some extent, the ability to use spatial cues for source segregation develops by age 2 to 3 in NH children and is attainable in most of the children in the BiCI group. There is potential for the paradigm used here to be used in clinical settings to evaluate outcomes of bilateral hearing in very young children.

Auditory and speech performance in cochlear implanted ANSD children

BACKGROUND

Auditory neuropathy spectrum disorder (ANSD) is a distinct type of SNHL that is characterized by the presence of otoacoustic emissions and/or cochlear microphonics. Cochlear implantation was initially not recommended for ANSD children, later studies showed variable outcomes among those subjects.

OBJECTIVE

To assess the auditory and speech performance of cochlear implanted children with auditory neuropathy spectrum disorder (ANSD) and to compare these results to those obtained from cochlear implanted children with sensorineural hearing loss (SNHL) Material and methods: 18 cochlear implanted children with ANSD and 40 cochlear implanted children with SNHL were included in this study. Auditory and speech performance results were compared across both subject groups using the Category of Auditory Performance (CAP) and Speech Intelligibility Rate (SIR) tests, with measurements recorded one year post implantation.

RESULTS

Cochlear implanted children with ANSD showed clinically significant improvements that were comparable to those observed from cochlear implanted subjects without ANSD.

CONCLUSIONS

Children with ANSD benefit from early cochlear implantation and can reach similar auditory and speech performance results as that achieved by children without ANSD.

TMTC2 variant associated with sensorineural hearing loss and auditory neuropathy spectrum disorder in a family dyad

BACKGROUND

Sensorineural hearing loss (SNHL) is a common form of hearing loss that can be inherited or triggered by environmental insults; auditory neuropathy spectrum disorder (ANSD) is a SNHL subtype with unique diagnostic criteria. The genetic factors associated with these impairments are vast and diverse, but causal genetic factors are rarely characterized.

METHODS

A family dyad, both cochlear implant recipients, presented with a hearing history of bilateral, progressive SNHL, and ANSD. Whole-exome sequencing was performed to identify coding sequence variants shared by both family members, and screened against genes relevant to hearing loss and variants known to be associated with SNHL and ANSD.

RESULTS

Both family members are successful cochlear implant users, demonstrating effective auditory nerve stimulation with their devices. Genetic analyses revealed a mutation (rs35725509) in the TMTC2 gene, which has been reported previously as a likely genetic cause of SNHL in another family of Northern European descent.

CONCLUSION

This study represents the first confirmation of the rs35725509 variant in an independent family as a likely cause for the complex hearing loss phenotype (SNHL and ANSD) observed in this family dyad.

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.

Spatial release from masking in children with bilateral cochlear implants and with normal hearing: Effect of target-interferer similarity

In complex auditory environments, it is often difficult to separate a target talker from interfering speech. For normal hearing (NH) adult listeners, similarity between the target and interfering speech leads to increased difficulty in separating them; that is, informational masking occurs due to confusability of the target and interferers. This study investigated performance of children with bilateral cochlear implants (BiCIs) when target and interferers were either same-sex (male) talkers, or different-sex talkers (male target, female interferer). Comparisons between children with BiCIs and NH, when matched for age, were also conducted. Speech intelligibility was measured for target and interferers spatially co-located, or spatially separated with the interferers positioned symmetrically (+90° and -90°) or asymmetrically (both at +90°, right). Spatial release from masking (SRM) was computed as the difference between co-located and separated conditions. Within group BiCI comparisons revealed that in the co-located condition speech intelligibility was worse with the same-sex vs different-sex stimuli. There was also a trend for more SRM with the same-sex vs different-sex stimuli. When comparing BiCI to NH listeners, SRM was larger for the NH groups, suggesting that NH children are better able to make use of spatial cues to improve speech understanding in noise.

Cochlear implantation in unique pediatric populations

PURPOSE OF REVIEW

Over the last decade, the selection criteria for cochlear implantation have expanded to include children with special auditory, otologic, and medical problems. Included within this expanded group of candidates are those children with auditory neuropathy spectrum disorder, cochleovestibular malformations, cochlear nerve deficiency, associated syndromes, as well as multiple medical and developmental disorders. Definitive indications for cochlear implantation in these unique pediatric populations are in evolution. This review will provide an overview of managing and habilitating hearing loss within these populations with specific focus on cochlear implantation as a treatment option.

RECENT FINDINGS

Cochlear implants have been successfully implanted in children within unique populations with variable results. Evaluation for cochlear implant candidacy includes the core components of a full medical, audiologic, and speech and language evaluations. When considering candidacy in these children, additional aspects to consider include disorder-specific surgical considerations and child/caregiver counseling regarding reasonable postimplantation outcome expectations.

SUMMARY

Cochlear implants are accepted as the standard of care for improving hearing and speech development in children with severe-to-profound hearing loss. However, children with sensorineural hearing loss who meet established audiologic criteria for cochlear implantation may have unique audiologic, medical, and anatomic characteristics that necessitate special consideration regarding cochlear implantation candidacy and outcome. Individualized preoperative candidacy and counseling, surgical evaluation, and reasonable postoperative outcome expectations should be taken into account in the management of these children.

Cochlear Implantation versus Hearing Amplification in Patients with Auditory Neuropathy Spectrum Disorder

Objective

Patients with auditory neuropathy spectrum disorder (ANSD) exhibit altered neural synchrony in response to auditory stimuli. Cochlear implantation (CI) is thought to improve neural synchrony in response to auditory stimuli and improve speech perception relative to conventional hearing amplification (HA).

Study Design

Retrospective review.

Setting

Tertiary otologic practice.

Subjects and Methods

Subjects included patients with ANSD treated at Vanderbilt University from 1999 to 2011. Sixteen patients underwent CI, and 10 received binaural HAs. Pretreatment performance was assessed through speech reception thresholds and parent questionnaire (Infant-Toddler Meaningful Auditory Integration Scale [IT-MAIS]). Posttreatment outcomes were assessed using IT-MAIS and closed-/open-set speech perception scores.

Results

Two HA users underwent neuromaturation and were excluded from further analysis. For the remaining patients, median duration of device use was 48 months. All CI patients had a prior binaural HA trial with failure of auditory skills development. Median available pretreatment IT-MAIS score was 13 and 30 for CI and HA groups, respectively (rank sum test, P = .32). Posttreatment, 6 of 16 CI patients and 4 of 8 HA patients achieved open-set speech perception scores ≥60%. No differences between groups were found in posttreatment IT-MAIS scores (rank sum test, P = .11) or the percentage of patients achieving the above levels of open-set speech perception (Fisher exact test, P = .67).

Conclusions

A wide range of speech perception outcomes are observed in ANSD patients. In our ANSD population, patients who exhibited failure of auditory skills development with HAs were able to achieve comparable overall speech perception outcomes after CI relative to those who continued to make appropriate auditory progress with HAs alone.