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Cochlear implant (CI) surgery is one of the most utilized treatments for severe hearing loss. Though CI surgery is proven to improve patients’ quality of life, results are variable as damage to very delicate inner ear tissues can be difficult to avoid. However, even the effects of optimal scala tympani insertions on the mechanics of hearing are not yet fully understood. This project presents two finite element models of the inner ear to study the interrelationship between the mechanical function of the cochlea and the insertion of a cochlear implant electrode, one derived from the chinchilla inner ear and one derived from the rhesus monkey inner ear. These subjects were chosen due to their wide usage in inner ear research as designs of the typical device tend to progress from chinchilla animal studies, to rhesus animal studies, and finally to human trials. Both FE models include a three-chambered cochlea and full vestibular system, rarely seen in prior studies. The procedure used to create these models is low-cost, rapid, and reproducible, and results in a highly detailed model using μMRI imaging as the data source.
In the chinchilla model’s unimplanted state, data indicative of the tuning effect of the cochlea closely matched results obtained in In Vivo studies. In its implanted state, the chinchilla model found minimal loss of residual hearing or alteration of the cochlea’s tuning effect regardless of CI insertion angle. Its results suggest that an emphasis should be put on developing CI’s with maximal insertion angles and minimal trauma during insertion. The more detailed rhesus model is presented with its preliminary results and plans for its continued development. In the future, both models can be reused with minimal alteration to study a broad range of phenomena such as vestibulo-cochlear interaction, the results of vestibular implant surgery, and the effects of various pathologies on hearing function.