Utilization of Nerve Integrity Monitor for Promontory Stimulation Testing Prior to Cochlear Implant

Objective: To demonstrate the feasibility of a nerve integrity monitor as a tool for promontory stimulation testing in patients with profound sensorineural hearing loss considering cochlear implantation. Patients: Adult patients considered for cochlear implantation with no auditory response on audiometric testing Intervention: Promontory stimulation testing using the nerve integrity monitor. Main Outcome Measure: By using a facial nerve stimulator and the nerve integrity monitor, transtympanic promontory stimulation testing was performed to assess auditory nerve function and determine candidacy for cochlear implantation. Patients indicated if they heard the stimulus. Results: Of the four patients completing the promontory stimulation tests, three patients heard the stimulus and one patient did not hear the stimulus. Of the three patients with a positive stimulation test, two patients have a history of progressive profound sensorineural hearing loss and one patient had a history of severe blunt temporal bone trauma. Two of these patients proceeded with cochlear implantation. The patient who had a negative promontory stimulation test has a history of neurofibromatosis type 2. Conclusion: The nerve integrity monitor is a convenient tool that can be used in the clinic setting to perform promontory stimulation tests and aid in determining cochlear implant candidates, specifically in those patients who require verification of auditory nerve function. This tool is a feasible and reasonable method for promontory stimulation testing.