title: A case of symptomatic extra-foraminal lumbosacral stenosis ("far-out syndrome") diagnosed by diffusion tensor imaging.
abstract: METHODS
  Case report.
  
  
  OBJECTIVE
  Diagnosis of symptomatic extra-foraminal lumbosacral stenosis using diffusion tensor imaging (DTI).
  
  
  BACKGROUND
  Conventional magnetic resonance imaging (MRI) has sometimes proved inadequate for evaluating symptomatic spinal nerve lesions. DTI has been developed to visualize anisotropy of nerve-fiber tracts to evaluate nerve degeneration. We report a case of nerve compression causing a far-out lesion diagnosed using DTI.
  
  
  METHODS
  A 68-year-old patient presented with an 8-month history of severe right-sided sciatica. Computed tomography and MRI showed right L5-S1 foraminal stenosis and contact of the L5 transverse process and S1 ala without canal stenosis at the L4-L5 level. We evaluated the fractional anisotropy (FA) of the right L5 spinal nerve and compared it with bilateral L3-S1 spinal nerves to determine the L5 spinal nerve compression site.
  
  
  RESULTS
  DTI revealed narrowing of the right L5 spinal nerve between the L5 transverse process and S1 ala. FA was significantly decreased in the right L5 spinal nerve between the L5 transverse process and S1 ala. There was no significant difference in the FA of spinal nerves between the right and left sides at L3, L4, or S1. The right L5 spinal nerve from the central spinal canal to the extra-foraminal lumbosacral lesion was exposed during surgery and found to be severely compressed by the L5 transverse process and S1 ala. Postoperatively, the patient's symptoms disappeared immediately.
  
  
  CONCLUSIONS
  We used DTI to diagnose a symptomatic lesion as an extra-foraminal lumbosacral lesion caused by compression of the L5 spinal nerve at the foramina. Because DTI can quantitatively measure damage to nerve fibers, it may be advantageous for the diagnosis of far-out syndrome.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Inohana, Chuo-ku, Chiba, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kitamura
authors.forename: Yawara
authors.initials: Y
authors.lastname: Eguchi
authors.forename: Gen
authors.initials: G
authors.lastname: Inoue
authors.forename: Sumihisa
authors.initials: S
authors.lastname: Orita
authors.forename: Masashi
authors.initials: M
authors.lastname: Takaso
authors.forename: Nobuyasu
authors.initials: N
authors.lastname: Ochiai
authors.forename: Shunji
authors.initials: S
authors.lastname: Kishida
authors.forename: Kazuki
authors.initials: K
authors.lastname: Kuniyoshi
authors.forename: Yasuchika
authors.initials: Y
authors.lastname: Aoki
authors.forename: Junichi
authors.initials: J
authors.lastname: Nakamura
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Gen
authors.initials: G
authors.lastname: Arai
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miyagi
authors.forename: Hiroto
authors.initials: H
authors.lastname: Kamoda
authors.forename: Miyako
authors.initials: M
authors.lastname: Suzuki
authors.forename: Takeo
authors.initials: T
authors.lastname: Furuya
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Toyone
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Takahashi
authors.forename: Seiji
authors.initials: S
authors.lastname: Ohtori
mesh_terms: D000368:Aged; D056324:Diffusion Tensor Imaging / Q000379:methods*; D006801:Humans; D008159:Lumbar Vertebrae / Q000473:pathology* / Q000601:surgery; D008161:Lumbosacral Region; D008279:Magnetic Resonance Imaging; D008297:Male; D009408:Nerve Compression Syndromes / Q000175:diagnosis / Q000601:surgery; D012447:Sacrum / Q000473:pathology* / Q000601:surgery; D012585:Sciatica / Q000175:diagnosis / Q000601:surgery; D013127:Spinal Nerves / Q000473:pathology / Q000601:surgery; D013130:Spinal Stenosis / Q000175:diagnosis* / Q000601:surgery; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome