Cochlear implant surgery with slim modiolar electrodes

Abstract

The Slim Modiolar electrode (CI532/632), a pre-curved electrode for cochlear implants released by Cochlear^®, can effectively stimulate the nerves in its proximity and reduce the risk of cochlear injury and the likelihood of electrode translocation from the scala tympani to scala vestibuli in comparison with the Slim Straight electrode (CI522/622). In this study, 31 ears underwent implantation of the CI532/632 electrode. The neural response telemetry (NRT) thresholds and impedances for CI532/632 electrodes around the cochlear cupula were lower than those for CI522. No difference was observed in the operative time and the short-term postoperative hearing and clinical performance of the two electrodes. Due to the complexity of the sheath and electrode configuration, insertion of the electrode can be challenging, and tip folding can occur. A broad extension of posterior tympanotomy is required while inserting the CI532/632 electrode. The round-window niche overhang (the ridge of bone around the round window fossa) has to be drilled out following exposure of the round window fossa. If electrode insertion via the round window is difficult, an extended round-window approach should be employed inserted. The NRT threshold and impedance of the Slim Modiolar electrodes were better in the short term. However, Slim Modiolar electrodes showed no significant difference from Slim Straight electrodes in terms of cochlear implant performance after six months. Thus, Slim Modiolar electrodes are options for cases with a normal cochlear study, and long-term evaluations of cochlear implant performance with these electrodes are essential.