Facial Nerve Preserving Subtotal Excision for Large Vestibular Schwannoma: An Institution-Based Functional Outcome Study

Background: The ideal goal of treatment for medium to large vestibular schwannoma is complete tumor removal with preservation of all cranial nerves. However, despite the advancements in microsurgery and intraoperative monitoring, the risk of facial nerve dysfunction following total resection varies between 31% and 57%. Currently, the goal of treatment for large tumors is shifting from total excision to facial nerve preservation. Objective: To evaluate the facial nerve outcome in patients who underwent subtotal excision with or without subsequent gamma knife radiosurgery for large vestibular schwannomas in our institute. Methods and Material: All patients who underwent primary surgery for large vestibular schwannomas between January 2012 and December 2016 were analyzed retrospectively. Cases where total excision was not done and a residue was left behind to prevent facial nerve injury during surgery were included in the study. Results: A total of 52 patients who met the inclusion criteria were analyzed. At final follow-up, 70% of patients had good facial nerve function (H-B grade 1 and 2). In patients with normal facial nerve function preoperatively, 81% (25/31) of them had good facial nerve outcomes (H-B grade 1 and 2), whereas in patients with preexisting facial nerve deficits, nearly 62% (13/21) of them either maintained or had improvement in their facial nerve grades. Conclusion: Good facial nerve outcomes and tumor control rate is obtained by subtotal excision of VS followed by upfront or delayed GKRS; however, there is a need for long-term follow-up to detect recurrences in these slow-growing tumors.