Effects of systemic administration of methylprednisolone on residual hearing in an animal model of cochlear implantation.

Abstract

CONCLUSION: Delivery of intramuscular injection of methylprednisolone around the implantation surgery improved the hearing threshold shift induced by cochlear implantation. OBJECTIVES: During electroacoustic cochlear implantation surgery, the residual hearing is not preserved in about 15% of cases. In this study, we tested the effects of intramuscular administration of methylprednisolone on the hearing loss induced by cochlear implantation in a model of guinea pig cochlear implantation. METHODS: Eleven guinea pigs with normal hearing were implanted with a 254 μm diameter silicone array through a cochleostomy, and the effects on hearing of longstanding array insertion (21 days) were assessed. Six of the implanted animals received intramuscular administration of methylprednisolone. Auditory brainstem response recordings were performed before and up to 21 days after the cochlear implantation. CT scans were performed in some animals 1 month after implantation. RESULTS: CT scans confirmed that the array was well positioned in tested animals. From days 3 to 21, a hearing loss of about 30 dB on all frequencies was observed in the implanted nontreated group. This hearing loss remained stable during the whole follow-up period. Compared with implanted nontreated animals, the hearing threshold shift decreased by 12 dB in animals treated with methylprednisolone.