Evolution of electrode array diameter for hearing preservation in cochlear implantation

Conclusion: Residual hearing could be preserved with various arrays ranging from 16 to 18 mm in insertion length and 0.25 to 0.5 mm tip diameter. Whether array insertion is performed through a cochleostomy or a round window, tip diameter is an essential criterion for the array design to improve hearing preservation results. Objectives: The goal of this study was to report the outcome of patients implanted with electric acoustic cochlear implants with various surgical techniques and array designs. Methods: Thirty-two implanted ears (30 patients) were included in this retrospective study. Three array models were inserted: Contour Advance implant (n = 16), Nucleus Hybrid-L (n = 12), and Med-El Flex EAS (n = 4). Postoperative pure tone audiometry was performed at 3 and 12 months after implantation. Results: Three months postoperatively, hearing preservation within 30 dB was achieved in 50%, 50%, and 84% cases of patients implanted with a Contour Advance, Flex-EAS, and Hybrid-L, respectively. Two patients (Hybrid-L group) had a delayed sudden hearing loss (> 30 dB) 3 months postoperatively and three patients (Contour Advance group) had total hearing loss at 1 year. Best results were achieved using arrays with small tip diameters. Cochleostomy or round window insertion did not affect hearing preservation results.