Effectiveness of preoperative facial nerve diffusion tensor imaging tractography for preservation of facial nerve function in surgery for large vestibular schwannomas: Results of a prospective randomized study

Background: The goal of surgery in case of a large vestibular schwannoma is complete excision of tumor and preservation of facial nerve function. The identification and preservation of facial nerve is very difficult during surgery, particularly in case of large tumors. This prospective randomized study was conducted to find out the effectiveness of preoperative facial nerve diffusion tensor imaging tractography (DTI) to predict location of the nerve and preservation of facial nerve function in surgery for large vestibular schwannomas. Materials and Methods: In this prospective randomized study, we recruited 100 patients with a large vestibular schwannoma(> 3cm). After initial scrutiny, 94 patients were randomized based on a computer generated chart. In group I, preoperative DTI was done and the operating surgeon was informed about the position of facial nerve preoperatively. In group II, DTI was not done. The facial nerve preservation rates and clinical outcome at follow up was compared between the two groups. Results: Out of 94 patients, there were 47 patients in group I (DTI group) and 47 patients in group II (Non DTI group). In DTI group, 40 patients were left for comparison after the exclusion criteria was applied. Preoperative DTI predicted that the facial nerve position was concordant with its intraoperative position in 39 patients (97.5% concordance). Facial nerve preservation rates were statistically significant in group I (DTI group) (P value = 0.002). Conclusion: The study establishes the role of preoperative DTI tractography for better facial nerve preservation in surgery for large vestibular schwannomas (>3 cm).