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Evaluating Intracochlear Trauma after Cochlear Implant Electrode Insertion through Middle Fossa Approach in Temporal
Juan Carlos Cisneros Lesser1,2, Rubens de Brito1, Graziela de Souza Queiroz Martins1
11 Otorhinolaryngology Department, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil.
Summary
Cochlear implant insertion via the middle fossa approach risks significant cochlear trauma, with 70% of temporal bones showing damage. This surgical technique, while allowing intracochlear placement, does not ensure correct electrode positioning or prevent microstructure injury.
Area of Science:
- Otolaryngology
- Neurosurgery
- Medical Imaging
- Histopathology
Background:
- The middle fossa approach is utilized for cochlear implant insertion.
- Evaluating potential cochlear trauma associated with this surgical technique is crucial for patient safety.
- Histologic and imaging studies are essential for detailed assessment of intracochlear structures.
Purpose of the Study:
- To histologically and via imaging evaluate cochlear trauma following cochlear implant insertion using a middle fossa approach.
- To compare trauma between straight and perimodiolar electrode insertion in a cadaveric model.
Main Methods:
- Prospective cadaveric study involving 20 fresh-frozen temporal bones.
- Cochlear implant insertion via a middle cranial fossa cochleostomy with straight or perimodiolar electrodes.
- Computed tomography (CT) for insertion analysis, followed by microgrinding and microscopic visualization for trauma assessment.
Main Results:
- All insertions were intracochlear, with varying directions and depths.
- A significant majority (70%) of samples exhibited important cochlear trauma (Eshraghi grades 3 and 4).
- No significant differences in trauma were observed between electrode types or insertion directions.
Conclusions:
- The middle fossa approach facilitates proper intracochlear insertion but carries a high risk of cochlear microstructure trauma.
- The technique does not guarantee correct scala tympani electrode positioning.
- Further refinement of surgical techniques is needed to minimize cochlear trauma during implantation.
