Effects of cochlear implant surgical technique on post-operative electrode impedance

Abstract

Conclusions: The mCI surgical technique led to reduced impedance and minimized disturbance of the microenvironment inside the cochlea. Atraumatic surgical techniques and inflammation-reduction strategies may preserve the cochlear architecture and prevent fibrotic development. Objectives: To assess the advantages of a modified minimal access technique in cochlear implantation as well as to investigate the effects of intra-operative application of inflammation reduction strategies on the intra-cochlear impedance. Methods: One hundred patients received a 31.5 mm long Med-El standard electrode array fully inserted into the cochlea and did not have surgical complications post-operation. Patients were divided into two groups according to the surgical technique that was used for implantation: 50 were in the modified minimal access cochlear implant (mCI) surgery group and 50 were in the traditional CI surgery group. Intra-cochlear impedance values were measured at initial activation (4 weeks post-operatively). Electrode impedance values were compared between the surgery groups. Results: Electrode impedance values were significantly lower in the mCI group than in the CI surgery group at initial activation (5.01 kOhm vs 6.10 kOhm, respectively, F = 13.761, p = 0.000). The differences between the two groups were most prominent for the electrodes located at the basal region of the cochlea.