Evaluation of the hearing preservation and tissue response of dexamethasone and hyaluronic acid delivery during cochlear implantation on cats in a three-month period study.

OBJECTIVE:To evaluate the effects of DX and HA on hearing preservation and tissue response with cochlear implantation in a cat mode. METHODS:11 cats were bilaterally implanted with Nurotron electrode. According to the different treatment, 22 ears were subdivided into four following groups: Electrode (E) only, Electrode +HA (E+H), Electrode + DX (E+DX), and Electrode +HA +DX (E+H+DX). Auditory brainstem responses (ABR) thresholds were recorded before and 3 months after surgery. After 3 months of cochlear implantation histopathological assessment of all cochleae were performed . RESULTS:At low frequencies, the mean ABR thresholds shift in animals treated with E+H+DX demonstrated a statistically significant difference. The proportion of cochleae showing fibrous tissue and new bone formation was 50% in E+H+DX group, 66.7% in E+DX group, 83.3% in E+H group and 100% in E group. CONCLUSION:United HA and DX local delivery could provide better protection against hearing loss at low-frequency threshold and could more effectively reduce the trauma related to electrode insertion and the fibrous tissue formation around the electrode.