DTI for Facial Nerve Preoperative Prediction of Position and Course

Abstract

The current strategy in vestibular schwannoma surgery dictates early intraoperative identification of the facial nerve by means of intraoperative monitoring. Imaging studies designed to trace the course of the facial nerve preoperatively should theoretically enhance surgical safety. The use of diffusion tensor tractography (DTT) for nerve tracking has evolved as a reliable technique in this regard. The latest systematic review available in the literature showed that complete tracking of the nerve’s course was obtained in 96.6% of cases and that surgical concordance with the preoperative DTT findings was obtained in 90.7%. The authors deemed preoperative DTT for facial nerve identification a useful adjunct in the surgical planning for large tumors (>2.5 cm). The application of tractography to detailed morphological reconstruction of the cranial nerves is a recent technology; therefore, it has potential limitations. These include a limited ability to distinguish the fibers of VII and VIII nerves, which could be overcome by combining DTT with specific MRI sequences.