title: Microstructural alterations in trigeminal neuralgia determined by diffusion tensor imaging are independent of symptom duration, severity, and type of neurovascular conflict.
abstract: OBJECTIVE
  In this prospective study diffusion tensor imaging (DTI) was used to evaluate the influence of clinical and anatomical parameters on structural alterations within the fifth cranial nerve in patients with trigeminal neuralgia (TN) due to neurovascular compression.
  
  
  METHODS
  Overall, 81 patients (40 men and 41 women; mean age 60 ± 5 years) with typical TN were included who underwent microsurgical decompression. Preoperative 3.0-T high-resolution MRI and DTI were analyzed in a blinded fashion. The respective fractional anisotropy (FA) and apparent diffusion coefficient values were compared with the clinical, imaging, and intraoperative data. This study was approved by the institutional review board, and written informed consent was obtained from all patients.
  
  
  RESULTS
  DTI analyses revealed significantly lower FA values within the vulnerable zone of the affected trigeminal nerve compared with the contralateral side (p = 0.05). The DTI analyses also included 3 patients without clear evidence of neurovascular conflict on preoperative MRI. No differences were seen between arterial and venous compression. Lower FA values were found 5 months after symptom onset; however, no correlation was found with the duration of symptoms or severity of compression.
  
  
  CONCLUSIONS
  DTI analysis allows the quantification of structural alterations, even in those patients without any discernible neurovascular contact on MRI. Moreover, our findings support the hypothesis that both the arteries and veins can cause structural alterations that lead to TN. These aspects can be useful for making treatment decisions.
authors.affiliation: Departments of 1 Neuroradiology.
authors.forename: Juergen
authors.initials: J
authors.lastname: Lutz
authors.affiliation: Neurosurgery, and.
authors.forename: Niklas
authors.initials: N
authors.lastname: Thon
authors.affiliation: Radiology, Hospital of the University of Munich, Campus Grosshadern, Munich, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Stahl
authors.affiliation: Departments of 1 Neuroradiology.
authors.forename: Nina
authors.initials: N
authors.lastname: Lummel
authors.affiliation: Neurosurgery, and.
authors.forename: Joerg-Christian
authors.initials: JC
authors.lastname: Tonn
authors.affiliation: Departments of 1 Neuroradiology.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Linn
authors.affiliation: Neurosurgery, and.
authors.forename: Jan-Hinnerk
authors.initials: JH
authors.lastname: Mehrkens
mesh_terms: D000368:Aged; D016880:Anisotropy; D019299:Decompression, Surgical; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008866:Microsurgery; D008875:Middle Aged; D009408:Nerve Compression Syndromes / Q000175:diagnosis* / Q000209:etiology* / Q000601:surgery; D011446:Prospective Studies; D014277:Trigeminal Neuralgia / Q000150:complications / Q000473:pathology* / Q000601:surgery
keywords: AD = axial diffusivity; ADC = apparent diffusion coefficient; AICA = anterior inferior cerebellar artery; CE = contrast enhanced; CN = cranial nerve; DTI = diffusion tensor imaging; FA = fractional anisotropy; FIESTA = fast imaging employing steady-state acquisition; MRA = MR angiography; MVD = microsurgical decompression; PICA = posterior inferior cerebellar artery; RD = radial diffusivity; REZ = root entry zone; ROI = region of interest; SCA = superior cerebellar artery; TN = trigeminal neuralgia; diagnostic and operative techniques; diffusion tensor imaging; microvascular decompression; neurovascular compression syndrome; pain; trigeminal neuralgia