Audiometric Outcomes and Longitudinal Trends of Sequential Cochlear Implantation in Adults with Bilateral Deafness: A 20-Year Single-Center Study

Background Examine the outcomes and trends of second-side cochlear implant (CI) in adults as measured by change in speech perception scores with a focus on those meeting age-requirements for Medicare. Methods: This is a retrospective cohort study at a tertiary academic center including adult patients with bilateral hearing loss receiving a sequential, bilateral CI between 2001-2020. Bilateral speech perception scores under best-aided conditions were compared following first- and second-side CI using Arizona Biomedical (AzBio) Sentence Test, Consonant-Nucleus-Consonant word (CNC-W), and Hearing in Noise Test (HINT). Individual Changes in audiometric scores and trends in implant age and inter-implant interval were evaluated. Results 162 individuals were included in this study. 50 patients with AzBIO scores, 40 patients with HINT scores, and 72 patients with CNC-W scores demonstrated mean improvements of 11.8 (95%CI: [5.7 - 17.9]), 6.7 (95%CI: [0.4 - 13.7]), 12.0 (SD: 25.3), and 11.5 (95%CI: [7.3-15.7]) points respectively following second-sided CI. Patients aged 65 and older experienced similar magnitude of improvement as younger patients. (t-tests: AzBio: 95% CI [-16.7, 17.4]; HINT: 95% CI [-34.6,0.5]; CNC-W: 95% CI [-10.7,13.1]). Longer time interval between implants was associated with reduced improvement in CNC-W in the overall population (β: -2.9, 95%CI:[-5.5 - -1.2]) and the elderly population ((β: -4.24, 95%CI:[-6.1 - -2.8]) specifically. Over time, there were no significant changes in age of CI-1 implant or audiometric scores after bilateral CI, but there was a decrease in inter-implant interval. Conclusions Intervention with a second-sided cochlear implant was associated with improved speech recognition scores and this benefit extended to patients aged 65 and over. Decreased inter-implant interval is associated with an increase in audiometric improvement between first- and second- CI.