Dataset Information

The Effect of Interphase Gap on Neural Response of the Electrically Stimulated Cochlear Nerve in Children With Cochlear Nerve Deficiency and Children With Normal-Sized Cochlear Nerves.

ABSTRACT: OBJECTIVES:This study aimed to compare the effects of increasing the interphase gap (IPG) on the neural response of the electrically stimulated cochlear nerve (CN) between children with CN deficiency (CND) and children with normal-sized CNs. DESIGN:Study participants included 30 children with CND and 30 children with normal-sized CNs. All subjects were implanted with a Cochlear Nucleus device with the internal electrode array 24RE[CA] in the test ear. The stimulus was a charge-balanced, cathodic leading, biphasic pulse with a pulse-phase duration of 50 ?sec. For each subject, the electrically evoked compound action potential (eCAP) input/output (I/O) function was measured for 6 IPGs (i.e., 7, 14, 21, 28, 35, and 42 ?sec) at 3 electrode locations across the electrode array. For each subject and each testing electrode, the highest stimulation used to measure the eCAP I/O function was the maximum comfortable level measured with an IPG of 42 ?sec. Dependent variables (DVs) were the maximum eCAP amplitude, the eCAP threshold, and the slope of the eCAP I/O function estimated using both linear and sigmoidal regression functions. For each DV, the size of the IPG effect was defined as the proportional change relative to the result measured for the 7 ?sec IPG at the basal electrode location. Generalized linear mixed effect models with subject group, electrode location, and IPG duration as the fixed effects and subject as the random effect were used to compare these DVs and the size of the IPG effect on these DVs. RESULTS:Children with CND showed smaller maximum eCAP amplitudes, higher eCAP thresholds, and smaller slopes of eCAP I/O function estimated using either linear or sigmoidal regression function than children with normal-sized CNs. Increasing the IPG duration resulted in larger maximum eCAP amplitudes, lower eCAP thresholds and larger slopes of eCAP I/O function estimated using sigmoidal regression function at all three electrode locations in both study groups. Compared with children with normal-sized CNs, children with CND showed larger IPG effects on both the maximum eCAP amplitude and the slope of the eCAP I/O function estimated using either linear or sigmoidal regression function, and a smaller IPG effect on the eCAP threshold than those measured in children with normal-sized CNs. CONCLUSIONS:Increasing the IPG increases responsiveness of the electrically stimulated CN in both children with CND and children with normal-sized CNs. The maximum eCAP amplitude and the slope of the eCAP I/O function measured in human listeners with poorer CN survival are more sensitive to changes in the IPG. In contrast, the eCAP threshold in listeners with poorer CN survival is less sensitive to increases in the IPG. Further studies are warranted to identify the best parameters of eCAP results for predicting CN survival before this eCAP testing paradigm can be used as a clinical tool for evaluating neural health for individual cochlear implant patients.

SUBMITTER: He S

PROVIDER: S-EPMC7211427 | biostudies-literature | 2020 Jul/Aug

REPOSITORIES: biostudies-literature

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The Effect of Interphase Gap on Neural Response of the Electrically Stimulated Cochlear Nerve in Children With Cochlear Nerve Deficiency and Children With Normal-Sized Cochlear Nerves.

He Shuman S Xu Lei L Skidmore Jeffrey J Chao Xiuhua X Jeng Fuh-Cherng FC Wang Ruijie R Luo Jianfen J Wang Haibo H

Ear and hearing 20200701 4

<h4>Objectives</h4>This study aimed to compare the effects of increasing the interphase gap (IPG) on the neural response of the electrically stimulated cochlear nerve (CN) between children with CN deficiency (CND) and children with normal-sized CNs.<h4>Design</h4>Study participants included 30 children with CND and 30 children with normal-sized CNs. All subjects were implanted with a Cochlear Nucleus device with the internal electrode array 24RE[CA] in the test ear. The stimulus was a charge-bal ...[more]

PMID: 31688319

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Project description:OBJECTIVES:This study aimed to (1) investigate the responsiveness of the cochlear nerve (CN) to a single biphasic-electrical pulse in implanted children with cochlear nerve deficiency (CND) and (2) compare their results with those measured in implanted children with normal-size CNs. DESIGN:Participants included 23 children with CND (CND1 to CND23) and 18 children with normal-size CNs (S1 to S18). All subjects except for CND1 used Cochlear Nucleus cochlear implants with contour electrode arrays in their test ears. CND1 was implanted with a Cochlear Nucleus Freedom cochlear implant with a straight electrode array in the test ear. For each subject, the CN input/output (I/O) function and the refractory recovery function were measured using electrophysiological measures of the electrically evoked compound action potential (eCAP) at multiple electrode sites across the electrode array. Dependent variables included eCAP threshold, the maximum eCAP amplitude, slope of the I/O function, and time-constants of the refractory recovery function. Slopes of I/O functions were estimated using statistical modeling with a sigmoidal function. Recovery time-constants, including measures of the absolute refractory period and the relative refractory period, were estimated using statistical modeling with an exponential decay function. Generalized linear mixed-effect models were used to evaluate the effects of electrode site on the dependent variables measured in children with CND and to compare results of these dependent variables between subject groups. RESULTS:The eCAP was recorded at all test electrodes in children with normal-size CNs. In contrast, the eCAP could not be recorded at any electrode site in 4 children with CND. For all other children with CND, the percentage of electrodes with measurable eCAPs decreased as the stimulating site moved in a basal-to-apical direction. For children with CND, the stimulating site had a significant effect on the slope of the I/O functions and the relative refractory period but showed no significant effect on eCAP threshold and the maximum eCAP amplitude. Children with CND had significantly higher eCAP thresholds, smaller maximum eCAP amplitudes, flatter slopes of I/O functions, and longer absolute refractory periods than children with normal-size CNs. There was no significant difference in the relative refractory period measured in these two subject groups. CONCLUSIONS:In children with CND, the functional status of the CN varied along the length of the cochlea. Compared with children with normal-size CNs, children with CND showed reduced CN responsiveness to electrical stimuli. The prolonged CN absolute refractory period in children with CND might account for, at least partially, the observed benefit of using relatively slow pulse rate in these patients.

Project description:ObjectivesIn this study, we aimed to (1) review the long-term outcomes of cochlear implantation in children with cochlear nerve aplasia and (2) compare the development of their auditory and speech abilities to children with normal-sized cochlear nerves.DesignThis is a retrospective case-control study. Patients who underwent unilateral cochlear implant (CI) surgery in a tertiary referral center from September 2012 to December 2018 were reviewed. The study group included 55 children with cochlear nerve aplasia diagnosed using preoperative images. The control group included 35 children with normal-sized cochlear nerves. The control group did not differ from the study group in terms of age at implantation, pre-implantation auditory and speech abilities, or the electrode array type. Cochlear implantation outcomes were assessed using a test battery, including the Categories of Auditory Performance (CAP) score, the Speech Intelligibility Rating (SIR) score, behavioral audiometry, and closed- or open-set speech recognition tests. The development of auditory and speech abilities was compared between the two groups using Generalized Linear Mixed-effect Models.ResultsThe mean duration of CI usage was 4.5 years (SD = 1.5, range = 2.0 to 9.5) in the study group. The CAP scores, SIR scores, and aided hearing thresholds improved significantly post-implantation in the study group, but were significantly poorer than those in the control group. Generalized Linear Mixed-effect Models showed that the development of CAP and SIR scores was significantly slower in the study group than in the control group. Overall, 27 (49%) children with cochlear nerve aplasia had some degree of open-set speech perception skills, but the monosyllabic and bisyllabic word recognition rates were significantly lower than those in the control group.ConclusionFor children with cochlear nerve aplasia, auditory perception and speech intelligibility continued to improve in the long-term follow-up, but this progress was significantly slower than in children with normal-sized cochlear nerves. Most children with cochlear nerve aplasia could obtain the ability of common phrase perception and understanding simple spoken language with consistent CI usage and auditory rehabilitation.

Dataset Information

The Effect of Interphase Gap on Neural Response of the Electrically Stimulated Cochlear Nerve in Children With Cochlear Nerve Deficiency and Children With Normal-Sized Cochlear Nerves.

Publications

The Effect of Interphase Gap on Neural Response of the Electrically Stimulated Cochlear Nerve in Children With Cochlear Nerve Deficiency and Children With Normal-Sized Cochlear Nerves.

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