A New Lateral Wall Electrode: Evaluation of Surgical Handling, Radiographic Placement, and Histological Appraisal of Insertion Trauma

Objective: To describe histologic and radiographic findings associated with insertion of a new lateral wall electrode in human temporal bones, as well as quantify the ease of insertion as characterized by multiple cochlear implant surgeons. Setting: Multi-institutional cadaveric study. Methods: The Slim J electrode was inserted in cadaveric temporal bones via a standard mastoidectomy and facial recess approach. Insertion was performed by five cochlear implant surgeons with no previous experience with the Slim J electrode array. Electrode array insertion was performed via a round window, an extended round window, or a cochleostomy approach. Intracochlear trauma, and angular insertion depth was assessed histologically and radiologically, respectively, after placement of the Slim J electrode array. Results: Scala tympani insertion was accomplished in all 40 specimens. Thirty-eight specimens (95%) showed minimal trauma (Esrhaghi grade 0 or 1). One patient had rupture of basilar membrane (grade 2 trauma) at 380 degrees. One patient had grade 4 trauma with scalar translocation beginning at 210 degrees. The mean angular insertion depth was 416.4 degrees (range: 338.7-509.2 degrees, SD 44 degrees). Surgical handling was described as easy in 38 cases (95%). Conclusion: In a human cadaveric model the lateral wall Slim J electrode produced minimal intracochlear trauma that was positioned completely within the scala tympani in 97.5% of cases.