Objectives: The aim of this study was to determine whether the dexamethasone-eluting electrode (DEXEL) has a protective anti-inflammatory effect in a normal hearing implanted cochlea, as well as its performance and safety. Design: Ten healthy and normal hearing cynomolgus macaques (Mf) were divided into two cohorts: DEXEL group (DG) (CONCERTO CI device containing a DEXEL) and conventional CI group (CG) (unmodified CONCERTO CI device). The electrode was inserted into the scala tympani via the round window with an angle of insertion of 270 degrees. Auditory, impedance, electrically evoked compound action potential (eCAP), and recovery of function measurements were recorded monthly until sacrifice at 6 months post-implantation. A histologic analysis was also performed. Results: At 6 months, measurement of auditory brainstem responses revealed a mean threshold shift, as well as a mean impedance value, lower in the DEXEL group. The minimum eCAP for the remaining active contacts in the DEXEL group was 68% of that in the conventional CI group. Also at 6 months, the eCAP amplitude produced by a stimulating current of 800 cu (eCAP800) was almost 2.5-fold higher in the DEXEL group than in the conventional CI group (1338.86 +/- 637.87 mu V versus 545.00 +/- 137.37 mu V; p = 0.049). Tissue reactions, in particular fibrosis and ossification, were more common in the conventional CI group. Conclusions: The CI electrode array equipped with a dexamethasone-eluting component tested in ...

OBJECTIVES: To determine the feasibility of progressive insertion (two sequential surgeries: partial to full insertion) of an electrode array and to compare functional outcomes. MATERIAL AND METHODS: 8 normal-hearing animals (Macaca fascicularis (MF)) were included. A 14 contact electrode array, which is suitably sized for the MF cochlea was partially inserted (PI) in 16 ears. After 3 months of follow-up revision surgery the electrode was advanced to a full insertion (FI) in 8 ears. Radiological examination and auditory testing was performed monthly for 6 months. In order to compare the values a two way repeated measures ANOVA was used. A p-value below 0.05 was considered as statistically significant. IBM SPSS Statistics V20 was used. RESULTS: Surgical procedure was completed in all cases with no complications. Mean auditory threshold shift (ABR click tones) after 6 months follow-up is 19 dB and 27 dB for PI and FI group. For frequencies 4, 6, 8, 12, and 16 kHz in the FI group, tone burst auditory thresholds increased after the revision surgery showing no recovery thereafter. Mean threshold shift at 6 months of follow- up is 19.8 dB ranging from 2 to 36dB for PI group and 33.14dB ranging from 8 to 48dB for FI group. Statistical analysis yields no significant differences between groups. CONCLUSION: It is feasible to perform a partial insertion of an electrode array and progress on a second surgical time to a full insertion (up to 270º). Hearing preservation is feasible for both procedures. Note that a minimal threshold deterioration is depicted among full insertion group, especially among high frequencies, with no statistical differences.