NRT test in auditory neuropathy patients with cochlear implants

Systematic Literature Review and Early Benefit of Cochlear Implantation in Two Pediatric Auditory Neuropathy Cases

Approximately 1 in 10 children with hearing loss is affected by auditory neuropathy spectrum disorder (ANSD). People who have ANSD usually have great difficulty understanding speech or communicating. However, it is possible for these patients to have audiograms that may indicate profound hearing loss up to normal hearing. This disorder is prognosed with positive, intact or present otoacoustic emissions (OAE) and/or cochlear microphonics (CM) as well as abnormal or absent auditory brainstem responses (ABR). Treatment methods include conventional hearing aids as well as cochlear implants. Cochlear implants (CI) usually promise better speech understanding for ANSD patients. We performed a systematic literature review aiming to show what improvements can effectively be achieved with cochlear implants in children with ANSD and compare this with our experience with two cases of ANSD implanted at our clinic. The retrospective review of two young CI patients diagnosed with ANSD during infancy demonstrated improvements over time in speech development communicated by their parents.

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.

Postoperative objective detecting techniques for cochlear implant children with inner ear malformation

OBJECTIVES

This study aims to investigate the changing characteristics and rules of electrically-evoked auditory brainstem response (EABR), electrically-evoked stapedius reflex threshold (ESRT) and neural response telemetry (NRT) after cochlear implant in children with inner ear malformation, and guide postoperative equipment debug.

METHODS

A total of 88 children with either normal cochlea (control group) or inner ear malformation (test group) received Australian 24 multi-channel cochlear implants. The EABR, ESRT and NRT thresholds at different time points within one year postoperatively and behavioral responses (T-level and C-level) after one year were detected. Furthermore, the changing characteristics and rules of these thresholds were analyzed.

RESULTS

The EABR, ESRT and NRT thresholds were all significantly higher at all time points in the test group than in the control group, but the general changing trends were similar. Particularly, these thresholds worsened at low frequencies and improved at high frequencies. Furthermore, EABR, ESRT and NRT thresholds gradually increased during the one year postoperative period. In addition, an extremely significant correlation was found between EABR and T-level and between ESRT and C-level, but a less significant correlation was found between NRT threshold and T-level in both groups.

CONCLUSIONS

The postoperative changes in characteristics and rules of EABR, ESRT and NRT thresholds among cochlear implant children with inner ear malformation were all the same as those with normal cochlea. Thus, these thresholds can be used to guide the postoperative equipment debug for cochlear implants into patients with inner ear malformation.