gms | German Medical Science

Introduction: In recent years it has been possible to preserve hearing after cochlear implantation in patients with significant amounts of low-frequency residual hearing. Due to the dimensions and characteristics of the cochlear implants, MEDL-EL Flex 20 mm^®, MEDL-EL Flex 24 mm^® and MEDL-EL Flex 28 mm^®, Nucleus Hybrid-L24 and Nucleus CI422, they can be used to preserve residual hearing. Aim of this analysis was to determine the degree of hearing preservation and its relation to electrode length after cochlear implantation using theses electrodes.

Material and methods: Over all 340 adult patients were included in this retrospective analysis. All patients reached preoperative air conduction thresholds better or equal than 80 dB between 125–1500 Hz and they underwent Cochlear implantation using MedEl Flex 20 mm (n=46), MedEl Flex 24 mm (n=34), MedEl Flex 28 mm (n=40), Nucleus Hybrid-L24 (n=97) and Nucleus CI422 (n: 100) electrodes. Pre- and postoperative (initial fitting, 12 and 24 months) pure tone audiometry (125 Hz – 1500 Hz) was performed and median hearing loss was determined.

Results: At initial fitting, median hearing loss of 17.5 dB (Flex 20), 20 dB (Flex 24), 24 dB (Flex 28), 10 dB (Hybrid-L24) and 14.6 dB (CI422) was observed. After 24 months, stable 20 dB and 17.5 dB median hearing loss was observed for Flex 20 and Flex 24 patients. 26.5 dB median HL was reached for the Flex 28 patients, 15 dB for Hybrid -L24 and 30 dB for CI422.

Conclusions: HP is possible in patients, up to 24 month postoperativeley, after CI with atraumatic electrodes of different lengths (MEDL-EL Flex 20 mm^®, MEDL-EL Flex 24 mm^®, MEDL-EL Flex 28 mm^®, Nucleus Hybrid-L24 and Nucleus CI422). Lowest median hearing lost was found in patients in patients with shorter electrodes over time. To obtain the best clinical outcomes and performance, further research and longer follow up times are necessary to identify specific factors that impact on hearing preservation outcomes.