Postoperative Intracochlear Electrocochleography in Pediatric Cochlear Implant Recipients: Association to Audiometric Thresholds and Auditory Performance

Abstract

Objectives: The aim of this study was to compare intracochlear-recorded cochlear microphonics (CM) responses to behavioral audiometry thresholds in young children, with congenital hearing loss, 2 to 5 years after cochlear implantation early in life. In addition, differences in speech and auditory outcomes were assessed among children with and without residual hearing. Design: The study was conducted at a tertiary, university-affiliated, pediatric medical center. CM responses by intracochlear electrocochleography technique were recorded from 102 implanted ears of 60 children and those responses correlated to behavioral audiometry thresholds at 0.125 to 2 kHz frequencies. All children had received Advanced Bionics cochlear implant with High Focus J1 or MidScala electrodes, along with extensive auditory rehabilitation before and after implantation, including the use of conventional hearing aids. Speech Spatial and Hearing Qualities, Category of Auditory Performance scale, and educational settings information were obtained for each participant. Those cochlear implantation (CI) outcomes were compared between children with or without residual CM responses. Results: Two distinctive CM responses patterns were found among the implanted children. Of all ears diagnosed with cochlear hearing loss (n = 88), only in 29 ears, clear CM responses were obtained. In all other ears, no CM responses were obtained at the maximum output levels. The CM responses were highly correlated with coefficients ranging from 0.7 to 0.83 for the audiometric behavioral thresholds at 0.125 to 2 kHz frequency range. Of all ears diagnosed with auditory neuropathy syndrome disorder (n = 14), eight ears had residual hearing and recordable CM postimplantation. The other six ears showed no recordable CM responses at maximum output levels for all tested frequencies. Those showed supposedly better CM responses than the behavioral audiometry threshold, however with poor correlations with tested frequency thresholds. Children with residual hearing showed significantly better auditory outcomes with CI, compared with those without residual hearing. Conclusions: In children with congenital cochlear hearing loss, the objective CM intracochlear responses can reliably predict the residual audiometric threshold. However, in children with auditory neuropathy syndrome disorder, the CM thresholds did not match the behavioral audiometric responses. Postoperatively, children with recordable CM responses, showing preserved residual hearing, demonstrated better CI outcomes.

Establishing Reproducibility and Correlation of Cochlear Microphonic Amplitude to Implant Electrode Position Using Intraoperative Electrocochleography and Postoperative Cone Beam Computed Tomography

“…Our findings with regard to audiometric correlation were slightly poorer than those reported in other studies ( Koka et al 2017 ; Attias et al 2020 ), but it is acknowledged that the stimulus level was not calibrated postoperatively for each patient in our study. Nonetheless, at 0.5 and 1 kHz, more than 80% of predicted thresholds were within 15 dB HL and more than 95% within 20 dB HL (Figs.…”

Intracochlear Electrocochleography and Speech Perception Scores in Cochlear Implant Recipients

“…Intracochlear ECochG-based measurements can estimate behavioral audiometric thresholds in CI recipients. 16,[19][20][21] While not significant, our data suggest a mild to moderate trend between preoperative behavioral thresholds and intraoperative ECochG threshold estimates. There are several possible explanations as to why we did not find a significant correlation.…”

“…First, the measurements in the present study are comparing thresholds taken at two separate time instances (preoperative versus intraoperative) as opposed to thresholds taken at the same time point. 16,[19][20][21] The status of the middle ear, mastoid, and inner ear are all very different in the intraoperative condition. Factors such as 1) blood and fluid in the middle ear, inner ear, and mastoid, 2) lack of a well-formed seal at the round window, and 3) a lack of skin covering the mastoid cavity create acoustic conditions different to those of the preoperative condition.…”

“…Only significant amplitudes of the target frequency and their harmonics were summed and then converted to dB relative to 1 uV (dB re: 1 uV) to generate an ECochG "total response" (TR). 5 The ECochG recording software used difference response as previously described 20,21 to yield ECochG estimated audiometric thresholds.…”

“…The majority of studies using intracochlear ECo-chG have focused on its utility as a surgical monitoring tool to prevent translocation of the electrode array 11,12 to preserve hearing, 10,[13][14][15][16][17] as an estimate of hearing thresholds, 16,[18][19][20][21] and as an adjunct for acoustic tuning. 22 A key unknown is whether intracochlear ECochG measurements made immediately after CI insertion explain more variance in speech perception scores compared to extracochlear ECochG.…”