title: Neurovascular compression anatomy and pain outcome in patients with classic trigeminal neuralgia treated by radiosurgery.
abstract: OBJECTIVE
  To study the influence of the anatomy of neurovascular compression (NVC) on pain outcome in patients with classic trigeminal neuralgia treated by radiosurgery.
  
  
  METHODS
  Analysis of the anatomy of the trigeminal nerve, brainstem, and vessels was performed in 89 consecutive patients treated by Leksell gamma knife (Elekta Instruments, Stockholm, Sweden) for classic trigeminal neuralgia. One-millimeter axial magnetic resonance imaging slices (T1-weighted, T1-weighted enhanced, and T2-weighted selected partial inversion recovery) with coronal, sagittal, and three-dimensional reconstructions were viewed. The end point for outcome was total pain remission and no medication. The follow-up period ranged between 6 and 42 months.
  
  
  RESULTS
  In 82 patients (92%), a vascular structure in contact with the nerve was observed. In four patients, the NVC was produced by a large vessel (basilar or vertebral artery) and in 78 by a smaller vessel. The superior cerebellar artery was the cause of the NVC in 64 patients (78%). The NVC was proximal (<3 mm to the brainstem) in 34 patients (41%) and distal in 43 patients (52%). Nerve dislocation was present in 29 patients (33%), and nerve atrophy was present in 21 (24%) patients. Visualization of NVC on magnetic resonance imaging scans was not associated with outcome. The two variables associated with poor outcome were a large vessel contacting the nerve with brainstem deformation and proximal NVC. Nerve atrophy and nerve dislocation were not associated with outcome.
  
  
  CONCLUSIONS
  The visualization of NVC, nerve atrophy, and nerve dislocation on magnetic resonance imaging scans was not associated with pain outcome. A large vessel compressing the nerve and deforming the brainstem and proximal NVC were associated with a lesser pain control.
authors.affiliation: Department of Neurosurgery, School of Medicine, Pontifica Universidad Católica de Chile, Santiago, Chile. jglorenzoni@hotmail.com
authors.forename: Josè G
authors.initials: JG
authors.lastname: Lorenzoni
authors.forename: Nicolas
authors.initials: N
authors.lastname: Massager
authors.forename: Philippe
authors.initials: P
authors.lastname: David
authors.forename: Daniel
authors.initials: D
authors.lastname: Devriendt
authors.forename: Francoise
authors.initials: F
authors.lastname: Desmedt
authors.forename: Jacques
authors.initials: J
authors.lastname: Brotchi
authors.forename: Marc
authors.initials: M
authors.lastname: Levivier
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001808:Blood Vessels / Q000473:pathology; D001933:Brain Stem / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009408:Nerve Compression Syndromes / Q000209:etiology / Q000473:pathology / Q000601:surgery*; D010146:Pain / Q000601:surgery*; D016634:Radiosurgery; D016896:Treatment Outcome; D014276:Trigeminal Nerve / Q000473:pathology; D014277:Trigeminal Neuralgia / Q000473:pathology* / Q000601:surgery*