Effects of Preoperative Postauricular Glucocorticoid Injection on Electrode Impedance in Cochlear Implantation

Objectives: We aimed to investigate the short-term effects of preoperative postauricular glucocorticoid (GC) injection on electrode impedance in cochlear implant (CI) recipients. Methods: A total of 69 participants were enrolled: 44 children (<18 years) and 25 adults (18-85 years). Using a pre-specified non-randomized alternating assignment strategy, they were respectively assigned to either the treatment group (preoperative postauricular methylprednisolone injection and intraoperative intratympanic betamethasone) or the control group (intraoperative intratympanic betamethasone alone). Electrode impedance was measured intraoperatively and at 1, 3, and 6 months postoperatively. Owing to the use of different implant systems in pediatric and adult patients, the two cohorts were analyzed separately. Longitudinal impedance data across cochlear turns (apex, middle, base) were analyzed using linear mixed-effects models adjusted for baseline values. This study was registered on Chictr.org.cn (ChiCTR2400081024). Results: In the pediatric cohort, a significant interaction between group and time was observed (F = 8.34, p < 0.001); however, post hoc analyses did not demonstrate statistically significant differences between groups at individual postoperative time points (all p > 0.05). In the adult cohort, a significant interaction between group and turn was identified (F = 3.07, p = 0.049); post hoc analysis demonstrated statistically significant differences in impedance in the middle turn between groups (intervention effect = 1.355 kΩ; 95% CI, 0.115 to 2.596; p = 0.033). Conclusions: Preoperative postauricular GC administration, when combined with intraoperative intratympanic steroid therapy, may be associated with differences in postoperative electrode impedance dynamics and the electrode-tissue interface.