Hearing Preservation Outcomes With a Mid-Scala Electrode in Cochlear Implantation.

Abstract

To evaluate hearing preservation (HP) outcomes in adult cochlear implant recipients with a mid-scala electrode. Tertiary academic center. Adult patients implanted with a mid-scala electrode between May 2013 and July 2015. Cochlear implantation. Age, sex, surgical approach, residual hearing changes post cochlear implantation, HP rates using different published classifications, and speech perception scores. Fifty ears for 47 patients (mean age, 58.2 yr; range, 23-86) were implanted with the electrode. Recognizing that not all patients were true HP candidates and/or underwent generally accepted HP surgical techniques, 39 ears had preoperative low-frequency hearing (audiometric threshold ≤ 85dB HL at 250Hz), 24 preserved acoustic hearing postoperatively (75.0%). Patients who had preserved acoustic hearing were implanted via round window (N = 18), extended round window (N = 4), or via cochleostomy (N = 2) approaches. Mean threshold elevation for low-frequency pure-tone average (125, 250, and 500 Hz) was 20.2 dB after surgery. 43.8% of patients had aidable low-frequency hearing at activation, 30.0% at 6-months postoperatively, and 30.8% 1-year postopera tively. Using a formula outlined by Skarzynski and colleagues, at 6-months postoperatively, 15.0% of patients had complete HP, whereas 40.0% had partial HP. At 1-year, these percentages decreased to 0% and 38.5%, respectively. Age, type of approach, and perioperative steroid use were not correlated with HP outcomes at activation and 6-months postoperatively (p > 0.05). The mid-scala electrode evaluated allows preservation of low-frequency hearing in patients undergoing cochlear implantation at rates and degrees of preservation close to other reports in the cochlear implant literature.