1078 Limitations of Diffusion Tensor Imaging in Predicting Outcomes of Patients With Classical Trigeminal Neuralgia

INTRODUCTION: Microvascular decompression (MVD) is an effective treatment for patients with classical trigeminal neuralgia (cTN). Several predictors of long-term pain freedom after MVD have been identified (e.g. response to medication, degree of neurovascular compression, and symptom description). Studies on diffusion tensor imaging (DTI) in patients with trigeminal neuralgia have noted microstructural changes in the centrally myelinated portion of the trigeminal nerve. However, rigorous and reproducible methods have not been consistently applied. METHODS: Patients who underwent MVD as their initial surgical procedure for cTN with arterial compression or deformationbetween March 2013 and December 2020 were analyzed. ExploreDTI software was used to correct for signal drift correction, Gibbs ringing, subject motion, and eddy currents. Mean diffusivity, radial diffusivity, axial diffusivity, and fractional anisotropy (MD, RD, AD, FA) were extracted from the bilateral cisternal segments of the trigeminal nerve immediately adjacent to the root entry point on diffusion tensor imaging. We compared the symptomatic vs. asymptomatic side and the symptomatic side in responders vs. non-responders to MVD using a paired, two-sided student t-test with a sequential modified Bonferroni correction. RESULTS: Eighty-eight patients with cTN and 3T magnetic resonance images were included in this study. When comparing the symptomatic nerve to the asymptomatic nerve, no difference in MD (q= 0.1734), RD (q= 0.6586), AD (q= 0.0186), FA q=0.3658) were noted. Furthermore, there was no difference in MD (p= 0.8915), RD (p= 0.4324), AD (p= 0.9918), FA (p= 0.7556) between patients that responded to MVD and those that did not. CONCLUSIONS: Diffusion tensor imaging, as it has been utilized in the past decade, may not have the prognostic implications for TN that it is believed to have.