Facial Nerve Intraoperative Monitoring in Otologic Surgeries under Sedation and Local Anesthesia – A Case Series and Literature Review

Abstract

Introduction Local anesthesia with sedation has been employed for an increasingly number of otolaryngology procedures, and might be associated with lower surgical morbidity and costs. Facial nerve monitoring is often advisable in otology to minimize the risks of injuries to this cranial nerve, but the principles, techniques and parameters involved have only been studied for procedures under general anesthesia. Objective To report the preliminary outcomes of intraoperative facial nerve monitoring during otologic procedures under sedation and local anesthesia. Methods A total of five procedures and their respective intraoperative electrophysiological main findings were described. Facial neuromonitoring was performed using the same device by an electrophysiologist. The monitor sensitivity was set at 100 mV, and a stimulating probe was used whenever needed. Results Progressively decreasing low-amplitude baseline values were usually obtained as the level of anesthesia increased, with isolated oscillations possibly related to some degree of voluntary muscular activity. These oscillations could be easily distinguished from those of the surgical manipulation or electrical stimulation of the nerve, which tended to be of much greater amplitude and shorter latency, occurring during specific surgical steps. Conclusion With a surgical team with proper procedural knowledge and broad expertise regarding the technique, intraoperative facial nerve monitoring under local anesthesia with sedation seemed both feasible and reliable. Thus, the need for intraoperative neuromonitoring should not be an obstacle for otologic procedures under less aggressive anesthetic management.