BackgroundDiffusion tensor imaging (DTI) may demonstrate microstructural changes in diseased trigeminal nerves. Few prognostic indicators for long-term pain freedom after microvascular decompression (MVD) of the trigeminal nerve have been identified. The present study aimed to determine whether microstructural changes from DTI are present in the trigeminal nerve of patients with classical trigeminal neuralgia (cTN) due to arterial compression or deformation and whether they may be used to predict surgical success.MethodsPatients with a diagnosis of cTN due to arterial compression or deformation that underwent MVD from October 2013 until December 2020, with high resolution 3T magnetic resonance imaging DTI, and over two years of post-surgical follow-up were included in this study. The microstructural metrics of the symptomatic and asymptomatic trigeminal nerve were compared using a paired, two-sided Student's t-test. Differences between the microstructural metrics of the symptomatic nerve between treatment responders and treatment non-responders were assessed using Welch's t-test due to unequal variances and/or unequal sample sizes.ResultsEighty-eight patients met inclusion criteria and were analyzed. There was no significant difference in fractional anisotropy (FA) (p = 0.3658), mean diffusivity (MD) (p = 0.1734) and radial diffusivity (RD) (p = 0.6586) between the symptomatic and asymptomatic nerve. There was a significant difference in AD (p = 0.0186). However, after the sequential modified Bonferroni correction, the difference in AD no longer reached significance. There was no significant difference in FA (p = 0.7556), MD (p = 0.8915), RD (p = 0.4324) and AD (p = 0.9918) in the symptomatic nerve between the treatment responders and non-responders.ConclusionsDTI may not reliably predict outcomes of microvascular decompression in patients with cTN due to arterial compression or deformation.
Keywords: DTI; classical; directions; fractional anisotropy; microstructural metrics; trigeminal neuralgia.