Intratympanic immunosuppressives for prevention of immune-mediated sensorineural hearing loss.

Hypothesis: Round window membrane application of immunosuppressives reduces cochlear inflammation and hearing loss in a guinea pig model of sterile labyrinthitis.

Background: Systemic immunosuppressives are used to treat sensorineural hearing loss due to inflammation (autoimmune, bacterial, viral), which in animal models causes hearing loss. Transtympanic application of drugs is an attractive and possibly efficacious method of treatment that avoids systemic toxicities.

Methods: Sterile labyrinthitis was created using keyhole limpet hemocyanin (KLH). Dexamethasone (0.048 mg/day and 0.288 mg/day), cyclosporine (0.5%), prednisolone acetate (1%), fluorouracil, (5%), and FK506 (0.01%) were delivered to the round window membrane with one injection (filling middle ear space) or osmotic minipumps. Efficacy was evaluated by auditory brainstem response and histology.

Results: No drug was effective at reducing hearing loss or inflammation.

Conclusion: Local application of immunosuppressives did not suppress inner ear inflammatory infiltrates and hearing loss in KLH-induced labyrinthitis in a guinea pig model.