A Systematic Analysis of the Reliability of Diffusion Tensor Imaging Tractography for Facial Nerve Imaging in Patients with Vestibular Schwannoma.

Surgeons need to visualize the facial nerve reliably in relation to the vestibular schwannoma (VS) in surgical planning. Diffusion tensor imaging (DTI) tractography has enabled unprecedented in vivo preoperative visualization. We collected data to measure the accuracy of DTI for an accurate location of the nerve in preoperative VS resection planning. A PubMed search for relevant studies was conducted. Inclusion criteria were gross total resection of VS, preoperative DTI identification of the facial nerve, and intraoperative cranial nerve localization by the surgeon. Exclusion criteria were tumors other than VS and unsuccessful preoperative location of the cranial nerve. Accuracy rate was calculated by comparing the intraoperative and preoperative locations detailed by DTI. The query identified 38 cases of VS that fit our inclusion criteria. Overall, 89% had surgical findings that agreed with the DTI location of the facial nerve. Of these cases, 32 patients had a postoperative House-Brackmann grade I or II. Our findings suggest that DTI is a reliable method for facial nerve imaging. Implementation of this technique may help decrease facial nerve injury during surgery. Limitations and further studies are needed to better understand what factors correlate with successful location of the facial nerve and DTI in patients with VS.