Detection Rates of Cortical Auditory Evoked Potentials at Different Sensation Levels in Infants with Sensory/Neural Hearing Loss and Auditory Neuropathy Spectrum Disorder.

With the introduction of newborn hearing screening, infants are being diagnosed with hearing loss during the first few months of life. For infants with a sensory/neural hearing loss (SNHL), the audiogram can be estimated objectively using auditory brainstem response (ABR) testing and hearing aids prescribed accordingly. However, for infants with auditory neuropathy spectrum disorder (ANSD) due to the abnormal/absent ABR waveforms, alternative measures of auditory function are needed to assess the need for amplification and evaluate whether aided benefit has been achieved. Cortical auditory evoked potentials (CAEPs) are used to assess aided benefit in infants with hearing loss; however, there is insufficient information regarding the relationship between stimulus audibility and CAEP detection rates. It is also not clear whether CAEP detection rates differ between infants with SNHL and infants with ANSD. This study involved retrospective collection of CAEP, hearing threshold, and hearing aid gain data to investigate the relationship between stimulus audibility and CAEP detection rates. The results demonstrate that increases in stimulus audibility result in an increase in detection rate. For the same range of sensation levels, there was no difference in the detection rates between infants with SNHL and ANSD.

Auditory neuropathy in Brown-Vialetto-Van Laere syndrome due to riboflavin transporter RFVT2 deficiency.

AIM: Mutations in the genes encoding the riboflavin transporters RFVT2 and RFVT3 have been identified in Brown-Vialetto-Van Laere syndrome, a neurodegenerative disorder characterized by hearing loss and pontobulbar palsy. Treatment with riboflavin has been shown to benefit individuals with the phenotype of RFVT2 deficiency. Understanding the characteristics of hearing loss in riboflavin transporter deficiency would enable early diagnosis and therapy. METHOD: We performed hearing assessments in seven children (from four families) with RFVT2 deficiency and reviewed results from previous assessments. Assessments were repeated after 12 months and 24 months of riboflavin therapy and after cochlear implantation in one individual. RESULTS: Hearing loss in these individuals was due to auditory neuropathy spectrum disorder (ANSD). Hearing loss was identified between 3 years and 8 years of age and progressed rapidly. Hearing aids were not beneficial. Riboflavin therapy resulted in improvement of hearing thresholds during the first year of treatment in those with recent-onset hearing loss. Cochlear implantation resulted in a significant improvement in speech perception in one individual. INTERPRETATION: Riboflavin transporter deficiency should be considered in all children presenting with an auditory neuropathy. Speech perception in children with ANSD due to RFVT2 deficiency may be significantly improved by cochlear implantation.

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.

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.

Evaluation of NRT and behavioral measures for MAPping elderly cochlear implant users.

We investigated the acceptability of electrophysiologically derived MAPs and the effect of these MAPs on speech perception in elderly adults using Nucleus 24 cochlear implants. Eight implant recipients aged 75 years or older trialed an electrophysiologically derived MAP and a behavioral MAP. The electrophysiologically derived MAP was based on the threshold and maximum comfort level for electrode 10 and evoked compound action potential thresholds measured on six electrodes using neural response telemetry (NRT). Word perception at 55 dB SPL and sentence perception in noise at 70 dB SPL were assessed after six weeks take-home experience and again after an additional two weeks of experience. During the final two weeks of take-home experience participants indicated their preferred MAP for different listening situations. The NRT derived MAP estimated behavioral T levels well, but underestimated behavioral C levels for apical electrodes in some subjects. Speech perception with NRT derived MAPs was comparable to speech perception with behaviorally measured MAPs. MAPs estimated from NRT data provided good speech perception outcomes for elderly implant recipients and were well tolerated.

Cochlear implantations in children with Waardenburg syndrome: an electrophysiological and psychophysical review.

Waardenburg syndrome presents with dystopia canthorum, pigmentary abnormalities of hair, iris and skin (often a white forelock and heterochromia iridis) and sensorineural deafness. The authors review the electrophysiological and psychophysical findings of implanted children with Waardenburg syndrome at the Sydney Cochlear Implant Centre. Twenty children with Waardenburg syndrome received cochlear implants between 1985 and 2001. Electrical auditory brainstem response (EABR) was performed in all of these patients intra-operatively as part of the routine investigations. Only 13 of these patients were assessed one year or more post-operatively by means of the Melbourne Categories (0-7). Four patients (20%) were found to have abnormal EABR recordings. The mode of Melbourne Categories in this group (n = 3) was 1 at one year post-operation. The other 16 patients were found to have normal EABR and the mode of Melbourne Categories in this group (n = 10) was 7. A poor outcome after cochlear implantation was associated with abnormal EABR recordings (a 'true' auditory neuropathy) and was found in a significant proportion of patients with Waardenburg syndrome.