Do K, Baker K, Praetorius M, Staecker H

International Congress Series. 2004 Nov;1273:167–70.

Objective: To develop and validate a mouse model of implantation trauma. Study design: Adult CBA mice were anesthetized and a basal turn cochleostomy created. Using a micromanipulator varying amounts of sterile phosphate-buffered saline were injected into the cochleostomy. The cochleostomy was sealed and hearing was then tested by ABR. Animals were also treated with cell death inhibitors prior to injection. Hearing was tested after 24 h allowing the elucidation of cell death pathways after cochlear trauma. Results: Volume changes under 4% of the perilymph volume of the mouse cochlea were well tolerated. Greater volume injections resulted in progressively larger hearing losses with profound hearing loss occurring at 30% of perilymph volume injection. There was a correlation between volume delivered, hearing loss, and histological findings with higher volumes resulting in tears of Reisner’s membrane and blood in the perilymph. Addition of caspase inhibitors to the injection mix significantly improved hearing outcomes in high volume injections. Conclusion: This animal model allows evaluation of a cochlear injury in a quantitative fashion. Use of cell death pathway inhibitors significantly improved hearing outcome, suggesting that these substances may play a role in cases where hearing preservation is planned in implant surgery. This mouse model of hydraulic trauma may be used to test a variety of potential protective substances.