Cochlear Implantation Via the Middle Fossa Approach

Abstract

To report the results of cochlear implantation via the middle fossa approach in 4 patients, discuss the complications, and present a detailed description of the programming specifications in these cases. Retrospective case review. Tertiary-care referral center with a well-established cochlear implant program. Four patients with bilateral canal wall down mastoid cavities who underwent the middle fossa approach for cochlear implantation. Cochlear implantation and subsequent rehabilitation. A middle fossa approach with cochleostomy was successfully performed on the most superficial part of the apical turn in 4 patients. A Nucleus 24 cochlear implant system was used in 3 patients and a MED-EL Sonata Medium device in 1 patient. The single electrode array was inserted through a cochleostomy from the cochlear apex and occupied the apical, middle, and basal turns. Telemetry and intraoperative impedance recordings were performed at the end of surgery. A CT scan of the temporal bones was performed to document electrode insertion for all of the patients. Complications, hearing thresholds, and speech perception outcomes were evaluated. Neural response telemetry showed present responses in all but 1 patient, who demonstrated facial nerve stimulation during the test. Open-set speech perception varied from 30% to 100%, despite the frequency allocation order of the MAP. Cochlear implantation via the middle cranial fossa is a safe approach, although it is a challenging procedure, even for experienced surgeons.