Cochlear Electrical Impedance and the Effect of Topical Dexamethasone on Cochlear Implant Surgery

Hearing is the ability to perceive sounds through the ear. If the transmission of sound is defective, the person suffers some degree of hearing loss. Cochlear Implants (CI) provide partial hearing by stimulating auditory nerve cells. The evaluation of the functionality of the CI is facilitated by several analysis tools, such as the clinical calibration software. This offers the possibility of measuring electrical impedances in the cochlea. The electrical impedance is the opposition to the current flow between two electrodes. It is composed of two main elements: resistance and reactance. The impedances in a cochlear implant are not stable over time. The value is minimal immediately after surgery, and increases progressively in the first 2 to 3 weeks after the procedure due to the immune response of the organism against a foreign body and the trauma of the array insertion. Several authors have suggested the use of topical or intravenous corticosteroids to decrease intracochlear fibrosis. The use of Dexamethasone could have a protective effect by reducing the initial inflammatory response, apoptosis, and delayed fibrosis, which could impact the impedance. There is limited evidence on the effect of intra-surgical topical corticosteroids on the impedance of the cochlear implant. The aim of this clinical trial is to evaluate the impact of topical dexamethasone on the electrical impedance of the cochlear implant, with special attention to the analysis of the capacitive component. It will be carried out through an experimental, prospective, randomized and double-blind study. Objective To determine whether the use of topical dexamethasone in a single dose applied in the tympanic cavity (middle ear) during cochlear implant surgery modifies the capacitive component of the electrical impedance of the electrodes in the cochlea before the activation of the cochlear implant. Material and methods A phase 3 clinical trial will be conducted. The design is a parallel, randomized,