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Human Histology after Structure Preservation Cochlear Implantation via Round Window Insertion
Alexander Geerardyn1,2,3, MengYu Zhu2, Tim Klabbers4,5
1Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, Massachusetts, U.S.A.
The Laryngoscope
|July 26, 2023
Summary
Round window cochlear implant (CI) insertion causes less intracochlear tissue formation than cochleostomy approaches. This suggests round window insertion may better preserve residual cochlear function after CI surgery.
Area of Science:
- Otolaryngology
- Neurosurgery
- Regenerative Medicine
Background:
- Current cochlear implant (CI) insertion techniques aim to preserve intracochlear structures and residual cochlear function.
- The optimal surgical approach to minimize insertion trauma remains debated.
Purpose of the Study:
- To histologically compare insertional trauma and intracochlear tissue formation in human cochleae following CI insertion via different techniques.
Main Methods:
- A temporal bone with full-length CI (576°) via round window (RW) insertion was compared to nine cases using cochleostomy (CO) or extended round window (ERW) approaches.
- Insertional trauma was assessed histologically, and intracochlear fibrosis and neo-ossification volumes were quantified using 3D reconstructions.
Main Results:
- The RW insertion showed minimal fibro-osseous tissue (10.8% total volume) compared to CO/ERW (mean 30.6%).
- In the basal 5mm of scala tympani, RW insertion resulted in 12.3% tissue formation versus 93.8% for CO/ERW approaches.
- Electrode translocation occurred in the RW case, while 2/9 CO/ERW cases had no insertional trauma.
Conclusions:
- Full-length CI insertion via the RW can be minimally traumatic, avoiding significant local fibro-osseous tissue formation.
- Drilling a cochleostomy and damaging the endosteum appears to incite a local tissue reaction, supporting the hypothesis.
