title: Gas-filled intradural cysts of the lumbar spine and the possible pathogenesis.
abstract: BACKGROUND
  There have only been four reports of gas-filled intradural cysts, and the pathogenesis is unknown.
  
  
  OBJECTIVE
  To document the radiologic and histopathologic features of gas-filled intradural cysts and to discuss the pathogenesis with a review of the literature.
  
  
  METHODS
  Case report.
  
  
  METHODS
  A 67-year-old woman, admitted to our institute, presented with severe right thigh pain. On admission to the institute, enhanced magnetic resonance imaging, showed a cystic lesion in the spinal canal at the L2-L3 level, with an intensity suggesting the presence of gas. An enhanced region around the cyst was noted. Computed tomography after discography also revealed a water-soluble contrast filled the subarachnoid space and area around the cyst, but not inside.
  
  
  RESULTS
  The cyst was surgically resected. One of the nerve roots was firmly adherent to the gas-filled cyst. The cyst wall comprised fibrous tissue, including small granulations and herniated disc material.
  
  
  CONCLUSIONS
  Gas-filled intradural cysts are rare. The pathogenesis appears to involve gas in a degenerated intervertebral disc, and spontaneous absorption of herniated disc material.
authors.affiliation: Department of Orthopaedic and Neuro-Musculoskeletal Surgery, Kumamoto University, Honjo, Japan. a1203ki@fc.kuh.kumamoto-u.ac.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Sei
authors.forename: Masaya
authors.initials: M
authors.lastname: Mizutamari
authors.forename: Toru
authors.initials: T
authors.lastname: Fujimoto
authors.forename: Takuya
authors.initials: T
authors.lastname: Taniwaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mizuta
mesh_terms: D000368:Aged; D003560:Cysts / Q000209:etiology* / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000150:complications* / Q000601:surgery; D008159:Lumbar Vertebrae / Q000473:pathology* / Q000601:surgery; D008279:Magnetic Resonance Imaging