An animal model of cochlear implantation with an intracochlear fluid delivery system.

Abstract

CONCLUSION: An animal model of cochlear implantation with a local intracochlear fluid through a microcatheter included in the array has been developed. It is suitable for evaluation of putative therapeutic agents to decrease cochlear trauma after cochlear implantation. OBJECTIVES: The purpose of this study was to design an animal model of cochlear implantation with an intracochlear fluid delivery system to demonstrate the stability of the device and study the patterns of hearing loss. MATERIALS AND METHODS: Eleven guinea pigs were implanted with a prototype array that comprised one electrode and a microcatheter connected to an osmotic minipump containing saline serum. Three animals were implanted with the same electrode carrier without any connection to the minipump. Preoperative and postoperative audiometry was assessed by means of auditory brainstem response (ABR, clicks). Morphological analyses were performed with imaging and histological techniques. RESULTS: In the saline serum perfusion group an initial ABR threshold shift of 33+/-3.0 dB was observed and remained stable over time. In the unconnected group a similar threshold shift was observed at day 7. At day 30 CT scanning showed that the implants remained in a stable position. Histological analysis revealed fibrosis around the implant in the basal turn but preservation of inner ear structures in apical turns.