First Experience With a New Thin Lateral Wall Electrode in Human Temporal Bones.

Introduction: A modern cochlear implant electrode array design must combine: improved surgical ease of use, structure preservation, particularly important for pediatric application, stable position within the cochlea over time, and a meaningful balance between hearing preservation against addressing sufficient cochlear tissue to support electrical-only hearing. The aim of this study was to investigate a new lateral wall electrode array design from Advanced Bionics on human temporal bones (TBs). Methods: Ten fresh-frozen TBs were implanted with the SlimJ electrode array via the round window. The electrode array is 23mm long, with a cross-section varying from 0.25 x 0.55mm at the most apical contact to 0.6 x 0.8mm at the proximal marker contact. To assess location of the electrode array, the TBs were postoperatively scanned using cone beam computed tomography, and histology was performed to assess intracochlear trauma (Grades 0-4). Results: All electrode arrays were considered easy to insert. The average insertion depth was 432 degrees measured from the round window with a range from 411 to 450 degrees azimuth. Nine out of 10 electrode arrays were inserted fully (<0.5mm out of the cochlea), one electrode array was left 1.5mm out of the cochlea. No translocations were observed in all 10 cochleae, slight touching of the basilar membrane at the distal portion of the array was observed in 50% of the cases. Conclusion: The results from the new thin lateral wall electrode array from Advanced Bionics provided consistent scala tympani locations. No translocations were observed and almost all electrode arrays were fully inserted. These results are promising and the new electrode array will be further studied in clinical practice investigating hearing preservation capabilities and speech performance.