title: Intrathecal volume changes in lumbar spinal canal stenosis following extension and flexion: An experimental cadaver study.
abstract: BACKGROUND
  The spinal canal stenosis is a common disease in elderly. The thecal sac narrowing is considered as the anatomical cause for the disease. There is evidence that the anatomical proportions of the lumbar spinal canal are influenced by postural changes. The liquor volume shift during these postural changes is a valuable parameter to estimate the dynamic qualities of this disease.
  
  
  OBJECTIVE
  The aim of this human cadaver study was the determination of intrathecal fluid volume changes during the lumbar flexion and the extension. A special measuring device was designed and built for the study to investigate this issue under controlled conditions.
  
  
  METHODS
  The measuring apparatus fixed the lumbar spine firmly and allowed only flexion and extension. The dural sac was closed water tight. The in vitro changes of the intrathecal volumes during the motion cycle were determined according to the principle of communicating vessels. Thirteen human cadaver spines from the Institute of Anatomy were examined in a test setting with a continuous adjustment of motion. The diagnosis of the lumbar spinal stenosis was confirmed by a positive computer tomography prior testing. The volume changes during flexion and extension cycles were measured stepwise in a 2 degree distance between 18° flexion and 18° extension. Three complete series of measurements were performed for each cadaver.
  
  
  RESULTS
  Two specimens were excluded because of fluid leaks from further investigation. The flexion of the lumbar spine resulted in an intrathecal volume increase. The maximum volume effects were seen in the early flexion positions of 2° and 4°. The spine reclination resulted in a volume reduction. The maximum extension effect was seen between 14° and 16°.
  
  
  CONCLUSIONS
  According to our results, remarkable volume effects were seen in the early movements of the lumbar spine especially for the flexion. The results support the concept of the spinal stenosis as a dynamic disease and allow a better understanding of the pathophysiology of this nosological entity. Under clinical aspects our data support the value of a body upright position under avoiding of extended spinal inclination and reclination.
authors.affiliation: Department of Orthopaedics, Ruhr-University Bochum, Bochum, Germany.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Teske
authors.affiliation: Institute for Spine Research, Bochum, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schwert
authors.affiliation: Institute for Spine Research, Bochum, Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Zirke
authors.affiliation: Department of Orthopaedics, Ruhr-University Bochum, Bochum, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: von Schulze Pellengahr
authors.affiliation: Institute for Spine Research, Bochum, Germany.|Royal Orthopaedic Hospital, Birmingham, UK.
authors.forename: Matthias
authors.initials: M
authors.lastname: Wiese
authors.affiliation: Department of Orthopaedics, Ruhr-University Bochum, Bochum, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Lahner
mesh_terms: D000368:Aged; D002102:Cadaver; D003251:Constriction, Pathologic / Q000473:pathology*; D006801:Humans; D008159:Lumbar Vertebrae / Q000473:pathology*; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D016059:Range of Motion, Articular; D013116:Spinal Cord / Q000473:pathology*; D013130:Spinal Stenosis / Q000473:pathology*; D014057:Tomography, X-Ray Computed
keywords: Lumbar spinal canal stenosis; dural sac volume determination; lumbar flexion and extension