title: MR assessment of the normal position of the spinal cord in the spinal canal.
abstract: OBJECTIVE
  To investigate intradural geometry, which strongly influences the effects of epidural spinal cord stimulation.
  
  
  METHODS
  Axial MR images with turbo spin-echo were made of 26 healthy subjects at C-4 through C-6, T-5 and T-6, and T-11 and T-12, at T-11 and T-12 both in the supine and the prone position. Measurements were made of the dorsomedial and the ventromedial cerebrospinal fluid layer and the anteroposterior and transverse sizes of both the spinal cord and the dural sac. The samples of all variables were analyzed statistically. The distance between spinal and vertebral midline was also determined.
  
  
  RESULTS
  The dorsal cerebrospinal fluid layer was 1.5 to 4.0 mm at C-4 through C-6 and 4.0 to 8.5 mm at T-5 and T-6. At T-11 it was 2.0 to 6.0 mm in the supine position and was increased by approximately 2.2 mm in the prone position. At T-12 these values were 1.5 to 4.5 mm and approximately 3.4 mm, respectively. Differences between the spinal and vertebral midline up to 1.5 to 2.0 mm occurred in approximately 40% of the images.
  
  
  CONCLUSIONS
  Because there are variations of the dorsal cerebrospinal fluid layer among subjects by more than a factor of 2, and significant variations of the mediolateral position of the spinal cord, information on these parameters in patients will be essential for the optimal application of epidural spinal cord stimulation.
authors.affiliation: Institute for Biomedical Technology, University of Twente, Enschede, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Holsheimer
authors.forename: J A
authors.initials: JA
authors.lastname: den Boer
authors.forename: J J
authors.initials: JJ
authors.lastname: Struijk
authors.forename: A R
authors.initials: AR
authors.lastname: Rozeboom
mesh_terms: D000328:Adult; D004388:Dura Mater / Q000033:anatomy & histology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D016684:Prone Position / Q000502:physiology; D012016:Reference Values; D013116:Spinal Cord / Q000033:anatomy & histology*; D013131:Spine / Q000033:anatomy & histology*; D016683:Supine Position / Q000502:physiology