Residual Hearing Outcomes After Cochlear Implant Surgery Using Ultra-flexible 28-mm Electrodes.

Objective: To evaluate the preservation of low frequency residual hearing after cochlear implant surgery using an electrode for atraumatic implantation and complete cochlear stimulation. Study

Design: Retrospective clinical record study. Setting: Tertiary referral center. Patients: Fifty-six patients with functional deafness who had undergone cochlear implant surgery and received a Flex electrode (MED-EL GmbH, Innsbruck, Austria) between 2011 and 2014. Intervention: Audiometric testing was performed before surgery and at the time of initial fitting. Main outcome measure: Change in low frequency residual hearing measured by pure tone audiometry.

Results: Preoperative hearing was relatively poor. After surgery low frequency residual hearing was partially preserved in most cases, however there was a significant hearing loss at all frequencies compared with the preoperative state. In only 23% of all cases complete hearing preservation was observed.

Conclusion: Despite the use of a flexible electrode, complete preservation of low frequency residual hearing can only be achieved in a minority of patients. The use of a full insertion electrode of 28 mm in patients with poor preoperative thresholds does not allow for usable additional hearing at present.