Intracochlear Pressure Changes due to 2 Electrode Types: An Artificial Model Experiment.

Objective To preserve residual hearing in cochlear implant surgery, the electrode design has been refined, and an atraumatic insertion has become one aspect of cochlear implant research. Previous studies have described the effect of insertion speed and opening of the round window membrane on intracochlear pressure changes. The aim of our current study was to observe intracochlear pressure changes due to different cochlear implant electrodes in an artificial cochlear model with stable surrounding factors. Study Design Prospective controlled study. Setting Tertiary referral center. Subjects and Methods The experiments were performed in an artificial cochlear model with a pressure sensor in the apical area. With straight and perimodiolar electrode arrays, 5 insertions with the same insertion speed and 5 insertions over the same time were performed. Results With the perimodiolar high-volume electrode, significantly greater intracochlear fluid pressure changes were observed than with the straight electrode. Compared with the straight electrode, the perimodiolar electrode induces significantly higher pressure peaks (1.12 ± 0.15 vs 0.86 ± 0.05 mm Hg, P = .006) and significantly higher amplitudes (0.38 ± 0.07 vs 0.09 ± 0.07 mm Hg, P < .001). Conclusion The reliable preservation of residual hearing is an important multifactorial challenge in modern cochlear implant surgery. Insertion speed, handling, and electrode design are known to influence the preservation of residual hearing. In our artificial model experiments, we could prove objectively that the volume of the electrodes has a significant influence on the intracochlear pressure changes during cochlear implantation.