Diffusion Tensor Tractography of the Facial Nerve

Abstract

Objective: 1) Demonstrate that preoperative diffusion tensor (DT) tractography can predict the displacement of the facial nerve in the vicinity of vestibular schwannomas. 2) Demonstrate that the course of the constructed tract consistently agreed with the surgical findings in most of the cases.

Method: Prospective study of 15 patients undergoing surgical removal of vestibular schwannomas. The course of the facial nerve, determined preoperatively by diffusion tensor tractography using the method of Taoka et al was compared with the course of the nerve determined intraoperatively by microscopic inspection and using facial nerve monitoring equipment.

Results: The displaced facial nerve was identified in 14 patients by diffusion tensor tractography in axial and coronal T1 post-gadolinium and equivalent tractography images. In 13 patients there was a precise correspondence between the course of the nerve determined preoperatively by diffusion tensor tractography and the course of the nerve found at surgery. In 1 patient the facial nerve was found anterior/cranial to the tumor while tractography seemed to depict an anterior/caudal course.

Conclusion: Diffusion tension tractography of the facial nerve is a feasible technique that can consistently predict the displacement of the facial nerve in the vicinity of vestibular schwannomas. The technique can be used preoperatively to lower the risk of facial nerve injury during acoustic neuroma surgery.