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Intra-cochlear differences in the spread of excitation between biphasic and triphasic pulse stimulation in cochlear
David P Herrmann1, Randy K Kalkman2, Johan H M Frijns3
1Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University Hospital Würzburg, Josef-Schneider-Str. 11, Würzburg 97080, Germany.
Hearing Research
|April 5, 2023
Summary
Triphasic pulse stimulation in cochlear implants does not alter intracochlear spread of excitation differently than biphasic pulses. This suggests facial nerve benefits of triphasic stimulation occur at the nerve, not within the cochlea.
Area of Science:
- Biomedical Engineering
- Auditory Neuroscience
- Neurosurgery
Background:
- Facial nerve stimulation is a complication in cochlear implant (CI) use.
- Triphasic pulse stimulation is known to reduce facial nerve stimulation compared to biphasic pulses.
- The intracochlear mechanisms underlying this effect remain unclear.
Purpose of the Study:
- To investigate the intracochlear effects of triphasic versus biphasic pulse stimulation.
- To compare computational model predictions with experimental measurements of neural excitation spread.
- To explore the impact of neural degeneration on stimulation patterns.
Main Methods:
- Computational modeling of human cochleae simulating biphasic and triphasic stimulation.
- Experimental measurements of spread of excitation in 13 CI users with both pulse types.
- Simulations included effects of neural degeneration.
Main Results:
- Model predicted differences in excitation spread between pulse types at the cochlear apex.
- Experimental data showed no significant difference in excitation spread for either pulse type across electrode positions.
- Simulated neural degeneration amplified responses to biphasic but not triphasic stimulation.
Conclusions:
- The ameliorative effect of triphasic stimulation on facial nerve stimulation likely originates at the facial nerve itself, not from altered intracochlear excitation spread.
- Computational models and experimental data diverged regarding pulse shape effects on excitation spread.
- Understanding these differences is crucial for optimizing CI performance and patient comfort.
