title: Microstructural abnormalities in the trigeminal nerves of patients with trigeminal neuralgia revealed by multiple diffusion metrics.
abstract: OBJECTIVE
  To investigate microstructural tissue changes of trigeminal nerve (TGN) in patients with unilateral trigeminal neuralgia (TN) by multiple diffusion metrics, and correlate the diffusion indexes with the clinical variables.
  
  
  METHODS
  16 patients with TN and 6 healthy controls (HC) were recruited into our study. All participants were imaged with a 3.0 T system with three-dimension time-of-flight (TOF) magnetic resonance angiography and fluid attenuated inversion recovery (FLAIR) DTI-sequence. We placed regions of interest over the root entry zone of the TGN and measured fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD). The mean values of FA, MD, AD and RD were compared between the affected and unaffected sides in the same patient, and to HC values. The correlation between the side-to-side diffusion metric difference and clinical variables (disease duration and visual analogy scale, VAS) was further explored.
  
  
  RESULTS
  Compared with the unaffected side and HC, the affected side showed significantly decreased FA and increased RD; however, no significant changes of AD were found. A trend toward significantly increased MD was identified on the affected side comparing with the unaffected side. We also found the significant correlation between the FA reduction and VAS of pain (r=-0.55, p=0.03).
  
  
  CONCLUSIONS
  DTI can quantitatively assess the microstructural abnormalities of the affected TGN in patients with TN. Our results suggest demyelination without significant axonal injury is the essential pathological basis of the affected TGN by multiple diffusion metrics. The correlation between FA reduction and VAS suggests FA as a potential objective MRI biomarker to correlate with clinical severity.
authors.affiliation: Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053, PR China.
authors.forename: Yaou
authors.initials: Y
authors.lastname: Liu
authors.forename: Jiping
authors.initials: J
authors.lastname: Li
authors.forename: Helmut
authors.initials: H
authors.lastname: Butzkueven
authors.forename: Yunyun
authors.initials: Y
authors.lastname: Duan
authors.forename: Mo
authors.initials: M
authors.lastname: Zhang
authors.forename: Ni
authors.initials: N
authors.lastname: Shu
authors.forename: Yongjie
authors.initials: Y
authors.lastname: Li
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Zhang
authors.forename: Kuncheng
authors.initials: K
authors.lastname: Li
mesh_terms: D000465:Algorithms; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014276:Trigeminal Nerve / Q000473:pathology*; D014277:Trigeminal Neuralgia / Q000473:pathology*