Basal turn cochleostomy via the middle fossa route for cochlear implant insertion

Objective: The current article describes the surgical technique and the ver y preliminary results of insertion of a cochlear implant, via the middle fo ssa (RIF), in patients with middle ear disease. Study Design: The study design was a case report and a description of surgi cal technique. Setting: The study was conducted at an ENT Department, University of Verona , Verona, Italy. Patients: Two subjects with profound bilateral hearing loss, the first one presenting a bilateral radical mastoidectomy cavity and the second one with fibroadhesive otitis media, were operated on via the current technique. Intervention: After adequate exposure of the MF floor, a triangular bony ar ea between the greater superficial petrous nerve and the projection of the labyrinthine portion of the facial nerve was drilled out. The basal cochlea r turn facing the middle cranial fossa floor was easily encountered, a smal l cochleostomy measuring 1 1/2 mm in diameter was performed on the most sup erficial Dart of the basal turn, and the electrode carrier was inserted int o the fenestrated cochlea. The receiver-stimulator was positioned on a bone well drilled previously in the temporal squama. Main Outcome Measures: The activity of the inserted electrodes was tested b y means of telemetry and intraoperative recording of the electrically evoke d auditory responses. Speech perception tests, performed 15 and 30 days aft er cochlear implant activation, showed a remarkable improvement in the outc omes versus the preoperative values that are provided for comparison. Conclusions: This new surgical approach to cochlear implant insertion via t he MF route allows stimulation of part of the basal and the middle and apic al areas of the cochlea, where greater survival rates of spiral ganglion ce lls are observed. Cochlear implant insertion via the MF approach represents a promising technique for auditory rehabilitation of subjects with a bilat eral radical mastoidectomy cavity, patients suffering from middle ear malfo rmations or chronic middle ear disease due to eustachian tube dysfunction, or subjects with doubtful responses to promontory stimulation.