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Updated: May 19, 2026
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Cochlear Implant Surgery and Electrically-evoked Auditory Brainstem Response Recordings in C57BL/6 Mice
Published on: January 9, 2019
Simulation of apically grounded cochlear implant stimuli using neural stimulation models.
Jared A Rybarczyk1, Erin L Bratu2, Robert F Labadie3
1Vanderbilt University, Nashville, USA. jared.a.rybarczyk@vanderbilt.edu.
Summary
Placing an apical ground contact in cochlear implants (CI) can improve stimulation of apical auditory nerve fibers (ANFs). This method enhances low-frequency hearing without needing longer electrode arrays, potentially improving overall hearing quality.
Area of Science:
- Auditory neuroscience
- Biomedical engineering
- Medical imaging analysis
Background:
- Cochlear implant (CI) electrode arrays often fail to stimulate apical auditory nerve fibers (ANFs) due to limited array length.
- Directing current apically using an isolated ground contact in the helicotrema is a potential strategy to enhance apical ANF stimulation.
Purpose of the Study:
- To investigate the impact of apical ground placement on apical ANF stimulation using computational models.
- To compare the effectiveness of an apical ground versus a traditional extracochlear ground in stimulating ANFs.
Main Methods:
- Finite difference method (FDM) simulations were employed to generate cochlear voltage maps based on patient-specific CT scans.
- Computational ANF models were driven by voltage maps from both extracochlear and helicotrema ground configurations.
- Activation thresholds for 75 modeled ANF bundles were calculated and compared between the two grounding methods.
Main Results:
- A reduction in stimulation thresholds for apical ANFs was observed with an apical ground compared to an extracochlear ground across all three patients.
- Conversely, an increase in stimulation thresholds for basal ANFs was noted when utilizing an apical ground.
Conclusions:
- Apical ground contacts offer a method to increase the activation of under-stimulated low-frequency ANFs.
- This approach may improve low-frequency sound perception and enhance hearing quality in cochlear implant users without requiring longer electrode arrays.
