Stimulation parameters differ between current anti-modiolar and peri-modiolar electrode arrays implanted within the same child

2016 ◽  
Vol 130 (11) ◽  
pp. 1007-1021 ◽  
Author(s):  
M J Polonenko ◽  
S L Cushing ◽  
K A Gordon ◽  
B Allemang ◽  
S Jewell ◽  
...  
Keyword(s):  
Action Potential ◽  
Round Window ◽  
Compound Action Potential ◽  
Surgical Approaches ◽  
Electrode Arrays ◽  
Time Points ◽  
Stimulation Parameters ◽  
Evoked Compound Action Potential ◽  
Stapedial Reflex ◽  
Compound Action

AbstractObjective:To compare stimulation parameters of peri-modiolar and anti-modiolar electrode arrays using two surgical approaches.Methods:Impedance, stimulation thresholds, comfortably loud current levels, electrically evoked compound action potential thresholds and electrically evoked stapedial reflex thresholds were compared between 2 arrays implanted in the same child at 5 time points: surgery, activation/day 1, week 1, and months 1 and 3. The peri-modiolar array was implanted via cochleostomy in all children (n = 64), while the anti-modiolar array was inserted via a cochleostomy in 43 children and via the round window in 21 children.Results:The anti-modiolar array had significantly lower impedance, but required higher current levels to elicit thresholds, comfort, electrically evoked compound action potential thresholds and electrically evoked stapedial reflex thresholds than the peri-modiolar array across all time points, particularly in basal electrodes (p < 0.05). The prevalence of open electrodes was similar in anti-modiolar (n = 5) and peri-modiolar (n = 3) arrays.Conclusion:Significant but clinically acceptable differences in stimulation parameters between peri-modiolar and anti-modiolar arrays persisted four months after surgery in children using bilateral cochlear implants. The surgical approach used to insert the anti-modiolar array had no overall effect on outcomes.

scholarly journals Interpreting the Effect of Stimulus Parameters on the Electrically Evoked Compound Action Potential and on Neural Health Estimates

2020 ◽  
Author(s):  
Tim Brochier ◽  
Colette M. McKay ◽  
Robert P. Carlyon
Keyword(s):  
Theoretical Model ◽  
Action Potential ◽  
Compound Action Potential ◽  
Growth Function ◽  
Neural Population ◽  
Stimulation Parameters ◽  
Evoked Compound Action Potential ◽  
Neural Factors ◽  
Neural Survival ◽  
Compound Action

Abstract Variations in the condition of the neural population along the length of the cochlea can degrade the spectral and temporal representation of sounds conveyed by CIs, thereby limiting speech perception. One measurement that has been proposed as an estimate of neural survival (the number of remaining functional neurons) or neural health (the health of those remaining neurons) is the effect of stimulation parameters, such as the interphase gap (IPG), on the amplitude growth function (AGF) of the electrically evoked compound action potential (ECAP). The extent to which such measures reflect neural factors, rather than non-neural factors (e.g. electrode orientation, electrode-modiolus distance, and impedance), depends crucially upon how the AGF data are analysed. However, there is currently no consensus in the literature for the correct method to interpret changes in the ECAP AGF due to changes in stimulation parameters. We present a simple theoretical model for the effect of IPG on ECAP AGFs, along with a re-analysis of both animal and human data that measured the IPG effect. Both the theoretical model and the re-analysis of the animal data suggest that the IPG effect on ECAP AGF slope (IPG slope effect), measured using either a linear or logarithmic input-output scale, does not successfully control for the effects of non-neural factors. Both the model and the data suggest that the appropriate method to estimate neural health is by measuring the IPG offset effect, defined as the dB offset between the linear portions of ECAP AGFs for two stimuli differing only in IPG.

Contribution of auditory nerve fibers to compound action potential of the auditory nerve

2014 ◽  
Vol 112 (5) ◽  
pp. 1025-1039 ◽  
Author(s):  
Jérôme Bourien ◽  
Yong Tang ◽  
Charlène Batrel ◽  
Antoine Huet ◽  
Marc Lenoir ◽  
...  
Keyword(s):  
Action Potential ◽  
Auditory Nerve ◽  
Computational Simulation ◽  
Round Window ◽  
Hearing Threshold ◽  
Compound Action Potential ◽  
Nerve Fibers ◽  
Auditory Nerve Fibers ◽  
Round Window Niche ◽  
Compound Action

Sound-evoked compound action potential (CAP), which captures the synchronous activation of the auditory nerve fibers (ANFs), is commonly used to probe deafness in experimental and clinical settings. All ANFs are believed to contribute to CAP threshold and amplitude: low sound pressure levels activate the high-spontaneous rate (SR) fibers, and increasing levels gradually recruit medium- and then low-SR fibers. In this study, we quantitatively analyze the contribution of the ANFs to CAP 6 days after 30-min infusion of ouabain into the round window niche. Anatomic examination showed a progressive ablation of ANFs following increasing concentration of ouabain. CAP amplitude and threshold plotted against loss of ANFs revealed three ANF pools: 1) a highly ouabain-sensitive pool, which does not participate in either CAP threshold or amplitude, 2) a less sensitive pool, which only encoded CAP amplitude, and 3) a ouabain-resistant pool, required for CAP threshold and amplitude. Remarkably, distribution of the three pools was similar to the SR-based ANF distribution (low-, medium-, and high-SR fibers), suggesting that the low-SR fiber loss leaves the CAP unaffected. Single-unit recordings from the auditory nerve confirmed this hypothesis and further showed that it is due to the delayed and broad first spike latency distribution of low-SR fibers. In addition to unraveling the neural mechanisms that encode CAP, our computational simulation of an assembly of guinea pig ANFs generalizes and extends our experimental findings to different species of mammals. Altogether, our data demonstrate that substantial ANF loss can coexist with normal hearing threshold and even unchanged CAP amplitude.

scholarly journals Influence of Evoked Compound Action Potential on Speech Perception in Cochlear Implant Users

2007 ◽  
Vol 73 (4) ◽  
pp. 439-445 ◽  
Author(s):  
Mariana Cardoso Guedes ◽  
Raimar Weber ◽  
Maria Valéria S Goffi Gomez ◽  
Rubens Vuono de Brito Neto ◽  
Cristina Gomes O Peralta ◽  
...  
Keyword(s):  
Speech Perception ◽  
Action Potential ◽  
Cochlear Implant ◽  
Compound Action Potential ◽  
Evoked Compound Action Potential ◽  
Compound Action

Electrically evoked compound action potential using Nucleus RP8

2004 ◽  
Vol 1273 ◽  
pp. 80-83
Author(s):  
P.J. Abbas ◽  
C.P. Etler ◽  
C.J. Brown ◽  
T. Van Voorst ◽  
L. Zubrod ◽  
...  
Keyword(s):  
Action Potential ◽  
Compound Action Potential ◽  
Evoked Compound Action Potential ◽  
Compound Action
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