title: Circulatory dynamics of the cauda equina in lumbar canal stenosis using dynamic contrast-enhanced magnetic resonance imaging.
abstract: BACKGROUND
  There has been no study regarding the cauda equina circulation of patients with neurogenic intermittent claudication (NIC) in lumbar spinal canal stenosis (LSCS) using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).
  
  
  OBJECTIVE
  The mechanism responsible for the onset of NIC was investigated using DCE-MRI to examine changes in cauda equina blood flow in patients with LSCS.
  
  
  METHODS
  This was a retrospective longitudinal registry and magnetic resonance imaging study.
  
  
  METHODS
  The subjects consisted of 23 patients who had LSCS associated with NIC (stenosis group). Ten asymptomatic volunteers who did not have NIC served as controls (control group). In the LSCS group, the cross-sectional area of the dural sac was <75 mm2 at the site of most severe stenosis. These patients were further divided into single and double stenosis subgroups.
  
  
  METHODS
  The main measures we used were the signal intensity (S-I) ratio and the shape and size of the time intensity (T-I) curves. We compared these between the stenosis and control groups.
  
  
  METHODS
  At first, plain T1-weighted MR images were obtained and the lumbar dural sac cross-sectional area was measured using a digitizer. For DCE-MRI, sagittal T1-weighted images of the same slice were acquired continuously for 10 minutes after administration of gadolinium as an intravenous bolus to observe the distribution of contrast medium (gadolinium) in the cauda equina. To objectively evaluate changes in contrast enhancement of the cauda equina at the site of canal stenosis, regions of interest were established. The signal intensity (SI) ratio was calculated to compare the signal intensities before and after contrast enhancement, and time-intensity curves were prepared to investigate changes over time.
  
  
  RESULTS
  The static imaging findings and the changes of gadolinium uptake showed striking differences between the study and control patients. In the stenosis group, abnormal intrathecal enhancement showed around the site of stenosis on enhanced MR imaging. The SI ratio at the site of canal stenosis had a slower increase in the arterial phase when compared with that in the control group and remained high in the venous phase for up to 10 minutes. Finally, abnormal intrathecal enhancement was visible around the site of stenosis on enhanced MR imaging in all patients.
  
  
  CONCLUSIONS
  These clinical data indicate that cauda equina nerve roots in the LSCS patients are pathologic even when symptoms are not elicited in the supine position, suggesting that intraradicular venous congestion and edema themselves do not influence the existence of radicular symptoms.
authors.affiliation: Department of Orthopaedics and Rehabilitation Medicine, Faculty of Medicine, University of Fukui, 23-3, Shimoaizuki, Matsuoka, Eiheiji, Fukui 910-1193, Japan; Research and Education Program for Life Science, University of Fukui, Fukui, Japan. Electronic address: kshigeru@u-fukui.ac.jp.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kobayashi
authors.affiliation: Suzuki Orthopaedic Clinic, 5-1, Tokiguchi, Nakamati, Toki, Gifu, 509-5124, Japan.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Victor Horsley Department of Neurosurgery, The National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK.
authors.forename: Adam
authors.initials: A
authors.lastname: Meir
authors.affiliation: Victor Horsley Department of Neurosurgery, The National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK.
authors.forename: Naji
authors.initials: N
authors.lastname: Al-Khudairi
authors.affiliation: Department of Radiology and Orthopaedics, Aiko Orthopaedic Hospital, 1221, Sinmei, Okehazama, Midori, Aichi, 458-0911, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakane
authors.affiliation: Department of Radiology and Orthopaedics, Aiko Orthopaedic Hospital, 1221, Sinmei, Okehazama, Midori, Aichi, 458-0911, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Hayakawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002420:Cauda Equina / Q000098:blood supply / Q000473:pathology*; D003251:Constriction, Pathologic / Q000175:diagnosis; D005260:Female; D005682:Gadolinium; D006801:Humans; D008161:Lumbosacral Region / Q000098:blood supply / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D013130:Spinal Stenosis / Q000175:diagnosis*
chemical_list: D005682:Gadolinium
keywords: Blood-nerve barrier; Cauda equina; Dynamic contrast-enhanced MR imaging; Edema; Lumbar spinal canal stenosis; Neurogenic intermittent claudication