Preoperative Prediction of Facial Nerve in Patients with Vestibular Schwannomas: The Role of Diffusion Tensor Imaging—A Systematic Review

In vestibular schwannoma surgery, the preservation of facial and cochlear nerves is of paramount concern regarding to their effect on patients' quality of life. The rate of nerve function preservation has increased with advancements in surgical technique and neuroimaging and the introduction of intraoperative neuromonitoring. The preoperative depiction of anatomical issues between the nerves and tumor could help in surgical planning. Many studies investigating advanced imaging for cranial nerves detection, in particular diffusion tensor imaging, have been reported in the past decade. A systematic review of the reported data evaluating preoperative facial nerve fiber tracking, followed by intraoperative verification, was conducted. Seventeen studies with 223 patients (mean age, 47.5 years; range 17-77; male/female ratio 1:1.4) met our inclusion criteria. Preoperative facial nerve fiber tracking was obtained for 214 patients (96%), and subsequent intraoperative verification revealed a correct prediction for 187 cases (85.5%). The results from the present review have confirmed that preoperative fiber tracking for facial nerve identification during large vestibular schwannoma surgery is valuable and reliable. However, the included studies were not comparable in terms of images, acquisitions, or postprocessing elaboration. Larger series and homogenous magnetic resonance imaging parameters are required to strengthen these findings.