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Enhancing Electrode Location Assessment in Cochlear Implantation via Computed Tomography Image Fusion
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The Relationship Between Interaural Insertion-Depth Differences, Scalar Location, and Interaural Time-Difference
Miranda Cleary1, Joshua G W Bernstein2, Olga A Stakhovskaya1
1Department of Hearing and Speech Sciences, 1068University of Maryland, College Park, MD, USA.
Trends in Hearing
|November 15, 2022
Summary
Bilateral cochlear implant users
Area of Science:
- Auditory Neuroscience
- Binaural Hearing
- Cochlear Implant Technology
Background:
- Normal hearing relies on precise interaural time difference (ITD) processing.
- Bilateral cochlear implants (CIs) may have misaligned electrode arrays, potentially affecting binaural hearing.
- Understanding the impact of CI electrode placement mismatch on ITD sensitivity is crucial for improving binaural perception.
Purpose of the Study:
- To investigate the relationship between interaural electrode mismatch in bilateral CIs and ITD discrimination.
- To assess how angular insertion depth and scalar location influence binaural performance.
- To identify optimal electrode placement strategies for enhancing ITD sensitivity in CI users.
Main Methods:
- Examined ITD left-right discrimination thresholds in 23 postlingually deafened adult bilateral CI users.
- Used computed tomography (CT) scans to quantify interaural angular insertion depth and scalar location mismatch.
- Analyzed the association between electrode mismatch parameters and ITD discrimination performance.
Main Results:
- Median interaural insertion-depth mismatch was 18°, with generally good ITD discrimination thresholds.
- Listeners with more scala tympani electrode pairs showed better ITD thresholds.
- Wider ITD tuning curve bandwidths correlated with larger angular insertion-depth differences and monopolar stimulation.
Conclusions:
- Precise insertion depth matching is not essential for ITD discrimination thresholds, but scala tympani placement is beneficial.
- Atypical array placement can negatively impact ITD discrimination.
- Optimizing electrode placement, particularly in the scala tympani, can improve binaural hearing in bilateral CI users.
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