Publication Date

2017-05-28

Availability

Open access

Embargo Period

2017-04-28

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Biomedical Engineering (Engineering)

Date of Defense

2017-03-21

First Committee Member

Suhrud M. Rajguru

Second Committee Member

Abhishek Prasad

Third Committee Member

Jorge Bohorquez

Fourth Committee Member

Esperanza Bas

Fifth Committee Member

Fred F. Telischi

Sixth Committee Member

W. Dalton Dietrich

Abstract

Objective: Cochlear implants are the most successful neuroprostheses. Unfortunately, the trauma caused during cochlear implant insertion can lead to a loss of residual hair cells in the cochlea. Localized therapeutic hypothermia has the potential to be the standard of clinical care for neuroprotective intervention. This study demonstrates the design, operation and protocols, in an animal and a cadaver temporal bone model, for efficacious delivery of mild therapeutic hypothermia to the cochlea that can be translated to clinical practice in patients undergoing surgical cochlear implantation to preserve residual hearing. Main Results: The study found that localized hypothermia protects cochlear hair cells and residual hearing function against surgical and implantation trauma in an in-vivo rat model. A significant loss of residual hearing was observed in the normothermic animal implant group after one month. Comparatively, the residual hearing in the animal cochleae receiving therapeutic hypothermia was significantly conserved. Histology confirmed a significant loss of outer hair cells in normothermic cochleae receiving the surgical trauma when compared to the hypothermia treated group. The results were repeated and extended for an additional two months and the hypothermia induced recovery was still present while the untreated cochleae remained impaired. To achieve a clinical translation of the hypothermic therapy, we conducted finite element modeling and experimental studies in human cadaver temporal bones. The model simulations showed uniformly-distributed cooling across the human cochlea. Significance: Collectively, these results indicate that therapeutic hypothermia during cochlear implantation reduces the traumatic effects of electrode insertion and improve conservation of residual hearing.

Keywords

Therapeutic hypothermia; cochlear implant; residual hearing; auditory; electrode trauma protection; finite element analysis; COMSOL; hypothermic device; temporal bone model; auditory system model

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