Longitudinal alterations of the cisternal segment of trigeminal nerve and brain pain-matrix regions in patients with trigeminal neuralgia before and after treatment

Tai-Yuan Chen,Ching-Chung Ko,Yi-Chieh Hung,Li-Ching Lin,Ming-Chung Chou,Te-Chang Wu,Yun-Ju Shih

doi:10.1186/s12868-021-00681-w

Abstract

BackgroundTrigeminal neuralgia (TN) is the most common type of chronic neuropathic facial pain, but the etiology and pathophysiological mechanisms after treatment are still not well understood. The purpose of this study was to investigate the longitudinal changes of the cisternal segment of the trigeminal nerve and brain pain-related regions in patients with TN before and after treatment using readout segmentation of long variable echo-train (RESOLVE) diffusion tensor imaging (DTI) and transverse relaxation (T2)-weighted sampling perfection with application-optimized contrast at different flip angle evolutions (T2-SPACE).MethodsTwelve patients with TN and four healthy controls were enrolled in this study. All patients underwent assessment of the visual analog scale (VAS), and acquisition of RESOLVE DTI and T2-SPACE images before and at 1, 6, and 12 months after treatments. Regions-of-interest were placed on the bilateral anterior, middle, and posterior parts of the cisternal segment of the trigeminal nerve, the bilateral root entry zone (REZ), bilateral nuclear zone, and the center of pontocerebellar tracts, respectively. Voxel-based morphometry (VBM) analysis was conducted with T2-SPACE images, and gray matter volumes (GMV) were measured from brain pain-matrix regions.ResultsThe results demonstrated that the VAS scores, the axial diffusivity of the middle part of the affected cisternal trigeminal nerve, the fractional anisotropy of the bilateral nuclear zones, and the mean diffusivity of the center of pontocerebellar tract significantly changed over time before and after treatment. The changes of GMV in the pain-matrix regions exhibited similar trends to the VAS before and after treatment.ConclusionWe conclude that magnetic resonance imaging with RESOLVE DTI and VBM with T2-SPACE images were helpful in the understanding of the pathophysiological mechanisms in patients with TN before and after treatment.

Highlights

Trigeminal neuralgia (TN) is by far the most common type of chronic neuropathic facial pain [1] and is characterized by intermittent attacks of severe, sharp, burning or electric shock-like unilateral pain along the distribution of the trigeminal nerve branches [2]
The dif‐ fusion tensor imaging (DTI) indices in the cisternal trigeminal nerve (FA) and nuclear zone (RD and mean diffusivity (MD)) of the affected side were significantly correlated with the gray matter volumes (GMV) in specific painmatrix regions (PAG, right S1, and left thalamus) before
Consistent with a prior study [24], our findings suggested that the increased MD and radial diffusivity (RD) may be linked to neurovascular compression (NVC)-induced focal demyelination in the trigeminal nerve root entry zone (REZ) [25], neuroinflammatory processes, and/or edema [26] that affected the trigeminal system

Summary

Introduction

Trigeminal neuralgia (TN) is by far the most common type of chronic neuropathic facial pain [1] and is characterized by intermittent attacks of severe, sharp, burning or electric shock-like unilateral pain along the distribution of the trigeminal nerve branches [2]. With the application of readout segmentation of long variable echo-train (RESOLVE) DTI and parallel imaging [11, 12], susceptibility distortions could be reduced substantially to analyze more accurately subtle changes involving the symptomatic cisternal segment of trigeminal nerve, REZ, and the nuclear zone. Trigeminal neuralgia (TN) is the most common type of chronic neuropathic facial pain, but the etiology and pathophysiological mechanisms after treatment are still not well understood. The purpose of this study was to investigate the longitudinal changes of the cisternal segment of the trigeminal nerve and brain pain-related regions in patients with TN before and after treatment using readout segmentation of long variable echo-train (RESOLVE) dif‐ fusion tensor imaging (DTI) and transverse relaxation (T2)-weighted sampling perfection with application-optimized contrast at different flip angle evolutions (T2-SPACE)

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