Lower initial electrode impedances in minimally invasive cochlear implantation

Abstract

Background: The round window approach and the cochleostomy approach are two widely practiced methods to insert cochlear implant electrode arrays. Yet, there is no consensus on which is more minimally invasive. Objective: To compare the initial electrode impedance (EI) values and the incidence of abnormal electrodes of the round window approach and the cochleostomy approach, and to evaluate the effects of surgical techniques on the intracochlear microenvironment. Material and methods: One hundred and seventy-one patients received a unilateral Nucleus cochlear implant. Eighty-two patients were implanted using the round window approach, and 89 patients were implanted using the cochleostomy approach. EI was measured immediately after closure of the incision. Results: The round window group had lower average initial EI values than the cochleostomy group. For the EI values at each position, statistically significant differences were found in the basal-middle region (Electrode 1–14), but not in the middle-apical region (Electrode 15–22) of the electrode arrays. A lower incidence of high-impedance electrodes was found in the round window group. Conclusions: The round window approach leads to lower initial EI and less disturbance to the intracochlear microenvironment.