Objective: This study was conducted to investigate the usefulness of multimodal intraoperative facial nerve monitoring in predicting facial functional outcome following vestibular schwannoma surgeries.
Methods: This study represents a retrospective analysis of 200 cases of vestibular schwannoma operated through the retrosigmoid approach. The intraoperative electrophysiological records were retrospectively analysed and correlated with the facial nerve functional outcome immediate postoperative and at the last follow-up. Facial nerve function was classified according to the House-Brackmann grading scale, the results of free-running Electromyography (EMG) were graded according to the occurrence and the frequency of A-Trains, however Facial motor evoked potential (FMEP) was graded according to the degree of amplitude loss at the end of surgery both for orbicularis oculi and orbicularis oris muscles.
Results: The immediate as well as late postoperative facial function correlated significantly with FMEP amplitude loss of 80% for orbicularis oculi muscle (p = 0.005 and