Atraumaticity Study of 2 Cochlear Implant Electrode Arrays

Hypothesis Evaluate, based on morphologic and histologic parameters, the atraumaticity of 2 electrode arrays implanted in 10 human temporal bones. Background Atraumatic surgery and electrode arrays are current topics in otologic surgery. The preservation of cochlear anatomy and its functions is a priority and morphologic evaluation of the surgical trauma is essential to continue improving in this field. Methods Ten preserved human temporal bones (TB) without anatomic alterations were used in this study. They were divided into 2 groups of 5, and atraumatic surgery was performed to insert HiFocus 1J (group A) and HiFocus Helix (group B) electrode arrays. Anatomic comparisons were performed using computed tomography and histologic analysis. Results Group A: the mean length for the cochlear longitudinal axis was 10.30 mm, and the cochlear transversal axis was 7.2 mm. Scala tympani insertion was achieved in 4/5 TB studied, with a mean depth and angle of insertion of 19.2 mm and 325.5 degrees, respectively. Lateral location of the electrode array was achieved in all specimens. No significant correlation was observed between these dimensions and depth of insertion. Group B: the mean length for the cochlear longitudinal axis was 9.52 mm, and cochlear transversal axis was 6.38 mm. Scala tympani insertion was achieved in 4/5 TB studied, with a mean depth and angle of insertion of 17.5 mm and 352 degrees, respectively. Modiolar location of the electrode array was achieved in all specimens. A positive correlation was established between the linear and angular insertion depths (p = 0.044). Conclusion In summary, it is safe to state that neither electrode array shows significant insertion trauma.