A Temporal Bone Study of Insertion Trauma and Intracochlear Position of Straight Type Electrode for Cochlear Implant

Background and Objectives：The goal of this study was to examine insertion depth, intracochlear position and insertion trau-ma with the stimulation electrode of the Nurobiosys cochlear implant. Subjects and Method：Four electrodes were implanted in fresh temporal bones of the human cadavers using realistic surgical procedures. Plain film X-ray images were taken from the electrode inserted in the specimens to estimate the insertion depth. After the electrode implantation, all human temporal bones were trimmed to extract the cochleae. The extracted cochleae from the temporal bone were immersed in acrylic resin to fix the position of electrode placed in the scala tympani. The resin treated cochleae were cut in radial section and polished. All cross-sections were imaged with a microscope to assess the trauma by the electrode implantation. Results：The mean insertion depth was about 300°with the cochlea angle. The insertion trauma was observed in one section of a temporal bone. The mean distance from electrode to modiolus was about 0.75 millimeter. Conclusion：The incidence, severity of trauma and insertion depth of the studied electrode showed similar results with that of other straight type electrode in literature. (Korean J Otorhinolaryngol-Head Neck Surg 2008;51:999-1003