Neurophysiological monitoring in microsurgical treatment of vestibular schwannomas

Objective To summarize the experience of acoustic neuroma removal in a minimal invasive method,and explore the technique of facial and auditory nerve preservation in microsurgery in order to improve tumor removal rate and nerve preservation rate.Methods Two hundred and ninety-three patients suffering from acoustic neuromas treated microsurgically by suboccipital retrosigrnoid transmeatus approach under neurophysiological monitoring or intraoperative navigation assistance in our hospital from January 2006 to January 2012,were chosen in our study.Neurophysiological monitoring was used in 287 patients to locate the position of facial nerve and auditory nerve,and intraoperative navigation assistance was chosen in 31 patients to locate the position of sinus and guide the removal of the posterior wall of the internal auditory meatus (IAM); their clinical data and treatment efficacy were analyzed retrospectively.Results Total resection of the tumors was achieved in 289 patients (98.6％).Facial nerve was preserved in 278 patients (94.9％) in anatomy.Three months after tumor resection,facial nerve function was preserved (Grade Ⅰ and Ⅱ by House-Brackmann facial nerve function scale) in 247 patients (84.3％); 33 patients (15.7％) was graded into Ⅲ-Ⅳ.Audition was preserved in 33 patients before the resection and 9 (27.3％) after the resection.No patient died in this series.Conclusion The application of neurophysiological monitoring in the microsurgical treatment will be helpful to ensure the safe removal,decrease invasive injure and improve the surgical outcome of acoustic neuromas; it also helps keep facial nerve anatomic intact and improve functional preservation. Key words: Acoustic neuroma;  Facial nerve;  Neuronavigation;  Electrophysiologic monitoring;  Microsurgical technique