Benefit of sequential bilateral cochlear implantation in children between 5 to 18 years old: A prospective cohort study.

OBJECTIVE: To determine the benefit of sequential cochlear implantation after a long inter-implantation interval in children with bilateral deafness receiving their second implant between 5 and 18 years of age. STUDY DESIGN: Prospective cohort-study. SETTING: Tertiary multicenter. PATIENTS: 85 children with bilateral deafness and unilateral implantation receiving a contralateral cochlear implant at the age of 5 to 18 years. METHOD: The primary outcomes were speech recognition in quiet and noise (CVC) scores. The secondary outcomes were language outcomes and subjective hearing abilities, all measured before and 12 months after sequential bilateral cochlear implantation. Medians of the paired data were compared using the Wilcoxon signed-rank test. Univariable linear regression analyses was used to analyze associations between variables and performance outcomes. RESULTS: A significant benefit was found for speech recognition in quiet (96% [89-98] vs 91% [85-96]; p < 0.01) and noise (65% [57-75] vs 54% [47-71]; p = 0.01) in the bilateral CI condition compared to unilateral (n = 75, excluded 10 non-users). No benefit was seen for language outcomes. The subjective sound quality score was statistically significant higher in bilateral compared to the unilateral CI condition. Pre-operative residual hearing level in the ear of the second implant, the inter-implant interval and age at time of second implantation was not significantly associated with performance scores. CONCLUSION: After 12 months of use, sequential bilateral cochlear implantation showed improved speech perception in quiet and noise and improved subjective sound quality outcomes in children despite a great inter-implantation interval (median of 8 years [range 1-16 years]).

Evaluating hearing performance with cochlear implants within the same patient using daily randomization and imaging-based fitting - The ELEPHANT study.

BACKGROUND: Prospective research in the field of cochlear implants is hampered by methodological issues and small sample sizes. The ELEPHANT study presents an alternative clinical trial design with a daily randomized approach evaluating individualized tonotopical fitting of a cochlear implant (CI). METHODS: A single-blinded, daily-randomized clinical trial will be implemented to evaluate a new imaging-based CI mapping strategy. A minimum of 20 participants will be included from the start of the rehabilitation process with a 1-year follow-up period. Based on a post-operative cone beam CT scan (CBCT), mapping of electrical input will be aligned to natural place-pitch arrangement in the individual cochlea. The CI's frequency allocation table will be adjusted to match the electrical stimulation of frequencies as closely as possible to corresponding acoustic locations in the cochlea. A randomization scheme will be implemented whereby the participant, blinded to the intervention allocation, crosses over between the experimental and standard fitting program on a daily basis, and thus effectively acts as his own control, followed by a period of free choice between both maps to incorporate patient preference. With this new approach the occurrence of a first-order carryover effect and a limited sample size is addressed. DISCUSSION: The experimental fitting strategy is thought to give rise to a steeper learning curve, result in better performance in challenging listening situations, improve sound quality, better complement residual acoustic hearing in the contralateral ear and be preferred by recipients of a CI. Concurrently, the suitability of the novel trial design will be considered in investigating these hypotheses. TRIAL REGISTRATION: ClinicalTrials.gov: NCT03892941. Registered 27 March 2019.

The occurrence of tinnitus after CI surgery in patients with severe hearing loss: A retrospective study.

OBJECTIVE: An often reported side-effect of a cochlear implant (CI) is suppression of tinnitus. However, induction of tinnitus is also a known complication of CI surgery. To date, it remains unclear why some CI recipients experience larger tinnitus complaints due to CI surgery while most others do not. The goal of this study was to investigate the effect of deterioration of residual hearing due to CI surgery on tinnitus. DESIGN: In this retrospective database study, pre- and postoperative audiometric hearing thresholds were retrieved from patients' clinical files. Furthermore, tinnitus questionnaires were sent to all patients who fitted inclusion criteria. STUDY SAMPLE: Of the 512 CI patients who were implanted within the last ten years, 197 patients fitted the inclusion criteria and returned the questionnaires. RESULTS: We identified 39 cases (19.8%) who suffered from a newly developed (25) or deteriorated (14) tinnitus following CI surgery. No statistically significant association between perioperative deterioration of hearing thresholds measured by pure-tone audiometry and the development or deterioration of tinnitus was found. CONCLUSIONS: There is a small risk for deteriorated residual hearing after cochlear implantation. However, for patients with preoperative residual hearing, there appears to be no increased risk of developing chronic tinnitus after hearing deterioration due to cochlear implantation.