title: Morphologic changes in the cervical neural foramen due to flexion and extension: in vivo imaging study.
abstract: METHODS
  Dimensional measurement of cervical neural foramen at various positions, using reformatted computed tomography.
  
  
  OBJECTIVE
  To examine the morphologic changes in the neural foramen during flexion and extension of the cervical spine in vivo.
  
  
  BACKGROUND
  Previous cadaveric studies have shown the effect of cervical spinal motion on dimensions of the neural foramen. However, little information is available about dynamic morphologic changes in the cervical neural foramen in vivo.
  
  
  METHODS
  Cervical CT images of seven healthy volunteers were taken at the neutral position, maximum extension, and maximum flexion, and were reconstructed in the oblique plane perpendicular to the long axis of each neural foramen from the C3-C4 to C6-C7 level. Measured parameters included foraminal height, width, cross-sectional area, and segmental sagittal rotation at each spinal level. Differences in neural foraminal dimensions among these positions were analyzed. Correlations of segmental sagittal rotation with differences in dimensions between flexion and extension were analyzed.
  
  
  RESULTS
  Flexion significantly increased the foraminal height (by 1.0 mm; 11%), foraminal width (by 1.0 mm; 16%), and foraminal area (by 12 mm2; 28%) (P < 0.01). Extension significantly decreased the foraminal height (by 0.9 mm; 10%), foraminal width (by 1.4 mm; 22%), and foraminal area (by 8.0 mm2; 17%) (P < 0.01). Segmental sagittal rotation significantly positively correlated with % change in foraminal height (r = 0.434, P < 0.01) and area (r = 0.504, P < 0.01).
  
  
  CONCLUSIONS
  The present results are consistent with those of previous in vitro studies and may explain the clinical observation that cervical extension aggravates symptoms in patients with cervical radiculopathy and that flexion often relieves them.
authors.affiliation: Department of Orthopedics, Dokkyo University School of Medicine, Shimotsuga, Japan. tki@sea.plala.or.jp
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Kitagawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Fujiwara
authors.forename: Naoki
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Saiki
authors.forename: Kazuya
authors.initials: K
authors.lastname: Tamai
authors.forename: Koichi
authors.initials: K
authors.lastname: Saotome
mesh_terms: D000328:Adult; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging* / Q000502:physiology; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology*; D012399:Rotation; D013116:Spinal Cord / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D013117:Spinal Cord Compression; D014057:Tomography, X-Ray Computed / Q000379:methods*; D021801:Zygapophyseal Joint / Q000033:anatomy & histology* / Q000502:physiology