What really decides the facial function of vestibular schwannoma surgery?

Objectives. To find the main cause of facial nerve dysfunction in vestibular schwannoma (VS) surgery and review the prognosis of facial function in relation to tumor size, preoperative facial function and surgical approach. Methods. We reviewed the surgical outcome of 134 patients with VS treated in our department between 1994 and 2008. All patients included in the study had postoperative facial paralysis after surgical management of their VS. There were 14 women and 7 men. The mean age was 48.5 years, with a mean follow-up period of 57 months. Results. Twenty-one patients (sustained facial palsy, 4; newly developed facial palsy, 17) had facial nerve paralysis after surgery: ten patients in large VS and eleven patients in small VS. In large VS group, 4 patients had facial nerve function of HB grade II, 3 patients had HB grade III, and 3 patients had HB grade IV. In small VS group, 9 patients had HB grade II and 2 patients had HB grade IV. Middle cranial fossa approach rather than translabyrinthine approach for the preservation of hearing, led to facial nerve deterioration and the patients who had facial nerve paralysis perioperatively, had resulted in permanent facial paralysis. Conclusion. The tumor size in VS is certainly one of the most important prognostic factors. However, VS tumor size alone should not be considered a unique prognostic indicator. The surgical approach used, which may be related to tumor size, based on the surgeon's experience, can be a deciding factor, and the status of the facial nerve injured by the tumor can influence postoperative facial nerve function.