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Extracting the Cochlea from a Human Temporal Bone: A Cadaveric Protocol
Published on: August 18, 2023
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Morphologic Analysis of the Scala Tympani Using Synchrotron: Implications for Cochlear Implantation
Ashley Micuda1, Hao Li2, Helge Rask-Andersen2
1Department of Medical Biophysics, Western University, London, Ontario, Canada.
The Laryngoscope
|January 8, 2024
Summary
Synchrotron radiation phase-contrast imaging (SR-PCI) revealed significant variability in cochlear morphology. This imaging technique can precisely measure the scala tympani (ST) and assess cochlear implant (CI) electrode trajectories.
Area of Science:
- Otoacoustic emissions and audiology
- Biomedical imaging and engineering
- Neurosurgery and otolaryngology
Background:
- Cochlear implant (CI) electrode insertion is guided by anatomical knowledge, but individual cochlear morphology varies significantly.
- Accurate visualization and measurement of the cochlear scala tympani (ST) are crucial for optimizing CI placement and function.
- Current imaging techniques may lack the resolution to fully characterize the entire ST and electrode trajectories.
Purpose of the Study:
- To utilize synchrotron radiation phase-contrast imaging (SR-PCI) for comprehensive visualization and geometric measurement of the entire human cochlear ST.
- To assess the anatomical feasibility of cochlear implant electrode trajectories within the ST.
- To quantify cochlear morphology variability to inform surgical planning for CI patients.
Main Methods:
- SR-PCI was employed to acquire high-resolution images of 35 unimplanted and 3 implanted human cadaveric cochleae.
- Geometric measurements of the cochlear scalar diameter and area were systematically recorded at 5-degree increments.
- Analysis focused on characterizing the morphology of the entire ST from the round window to the apical tip.
Main Results:
- Cochlear cross-sectional diameter and area were found to decrease progressively from the base to the apex.
- Significant individual variability in cochlear morphology was observed across the studied specimens.
- The ST was shown to accommodate a 0.4 mm diameter electrode up to 720° even in the smallest cochleae, with all lateral wall array trajectories within the insertion zone.
Conclusions:
- This study pioneers the use of SR-PCI for complete ST morphology quantification and post-operative CI electrode trajectory assessment.
- High-resolution anatomical data derived from SR-PCI can guide the angular insertion depth for CI patients, accommodating individual anatomical differences.
- SR-PCI provides unprecedented detail for understanding cochlear anatomy and optimizing CI surgical outcomes.
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