Optimizing Facial Nerve Preservation in Surgery of Vestibular Schwannomas

Objective: In vestibular schwannoma (VS) treatment functional facial nerve preservation is the most important goal for most patients. Clinical data, surgical and monitoring techniques and their impact on functional outcome were the focus of this study. Methods: Total 266 patients with normal preoperative facial nerve function were selected for analysis. All underwent microsurgical tumor resection under conventional electromyography monitoring and, in the most recent 107 patients, additional motor evoked potentials (MEP) of the facial nerve. Facial nerve function was evaluated by House-Brackmann scale (HB) and photo documented. Outcome was summarized as useful in complete eye closure HB grades Ito III, and as nonuseful in missing or incomplete eye closure HB grades IV to VI. Results: Early useful function HB grades Ito III was present in 82% of patients and increased to 95% within the 1st year of follow-up. In 107 patients monitored with MEP, early function increased significantly to 86% (p < 0.01%). Patients' age and the sequence of surgical maneuvers were no relevant factors. Positive predictors were normal preoperative facial function and postoperative hearing preservation. Strong tumor adherence with the brainstem was a negative indicator. Conclusions: Combining conventional EMG monitoring with MEP improves facial nerve outcome. This feedback during meticulous microsurgical resection is a reliable support and directive for the continuation or change of the surgical procedure.