Effect of Local Corticosteroid on Electrical Impedances after Cochlear Implantation in children: A Prospective Double-Blind Randomized Clinical Trial.

Abstract

Objectives: The primary aim of this study is to determine the effects of associating local and systemic corticosteroids on electrical impedance of electrode contacts during the 6 months following cochlear implantation in children. We assessed the effect of this association along the electrode array to evaluate its impact on both basal and apical electrodes.

Methods: In 2 different patient groups, the evolution of electrical impedances was investigated during 6 months post-implantation. Children in Group 1 received systemic corticosteroids (1 ml injection of 4 mg/ml Dexamethasone (DXM) intravenously 12 hours before the procedure followed by an injection of 1 ml of 4 mg/ml de DXM during the induction of anesthesia). Group 2 received the same systemic corticosteroids with local corticosteroid (intratympanic injection [ITI] of Methylprednisolone (MP) 40 mg/1 ml given at the start of the procedure). Impedances were assessed perioperatively, on the third post-operative day, at 1 week, 1 month, 2 months, 3 months, and 6 months after implantation. We compared the mean impedance values and the average impedance at the apical and basal electrodes between both groups.

Results: Impedances in Group 1 were significantly higher than those in Group 2, both perioperatively (P = .037) and on the third post-operative day (P = .027). Starting from the first week and throughout the 6 months post-implantation, the difference between both groups was not significant. When comparing impedances at the apical and basal electrodes between both groups, the mean impedance at the basal electrodes was significantly higher in Group 1 compared to Group 2 at 1 month (P = .042).

Conclusion: The association of intratympanic and intravenous corticosteroids results in significantly reduced impedances during the early postoperative period. The basal electrodes have a more pronounced effect from this association. Based on these findings, this protocol is effective in lowering impedances in the short term but not in the medium term following cochlear implantation.