Identification of the Facial Nerve in Relation to Vestibular Schwannoma Using Preoperative Diffusion Tensor Tractography and Intraoperative Tractography-Integrated Neuronavigation System

BACKGROUND: Preoperative visualization of the facial nerve could help neurosurgeons to prevent facial nerve injury during vestibular schwannoma surgery. Some studies have addressed diffusion tensor tractography (DTT) for preoperative identification of the facial nerve. However, few studies have focused on tractography-integrated neuronavigation for DTT verification. This study aimed to explore the appropriate DTT tracing parameters and evaluate the effect of intraoperative facial nerve tractography-integrated neuronavigation for verifying the DTT accuracy. METHODS: Patients who underwent vestibular schwannoma surgery between September 2013 and August 2015 were included. Clinical features were recorded. All patients underwent preoperative DTT with 2 seed regions of interest and a variable fractional anisotropy threshold. Intraoperatively, the facial fiber tract guided by the neuronavigation was compared with the real location of facial nerve so that the accuracy of DTT was verified. Postoperative facial nerve function of each patients was followed up. RESULTS: Nineteen patients were enrolled in this study. Successful facial fiber tracts was obtained in 18 patients. In 17 of the 18 patients, intraoperative navigation confirmed DTT accuracy. The facial nerves were located on the anterior middle third of the tumor in 9 patients. Twelve months after surgery, facial nerve function was classified as grade I in 10 patients and grade II in 8 patients. CONCLUSIONS: We consider preoperative DTT with intraoperative tractography-integrated neuronavigation to be a useful method for identifying the location of the facial nerve. This method might improve facial nerve preservation.