title: Pseudocystic degeneration of the lumbar ligamentum flavum: a little known entity.
abstract: OBJECTIVE
  The objective of this work was to investigate the clinical and histologic features of patients with pseudocystic lesions of the ligamentum flavum in the lumbar region of the spinal canal and ascertain the existence of genuine ligamentum flavum pseudocysts.
  
  
  METHODS
  Retrospective chart and histologic study of a patient cohort with lumbar radiculopathy due to a cystic intraspinal lesion and who had undergone decompressive surgery was conducted. Intraoperatively, the stenosing process had been found to be different from common etiologic entities and had been submitted for histologic examination.
  
  
  RESULTS
  The 33 patients with symptoms and signs of lumbar radiculopathy were between 48 and 85 years of age (mean 63.5 years). Twenty (61%) of them were women. All patients showed degenerative changes of the bony structures of the spine by conventional radiography. Segmental instability due to degeneration of the lumbar spine was present in 45%. Computed tomography and/or magnetic resonance imaging showed a cystic lesion. Clinical and histologic examination confirmed their origin from within the severely degenerated ligamentum flavum.
  
  
  CONCLUSIONS
  Radiologic, surgical, and histologic findings suggest that the pseudocystic degeneration of the ligamentum flavum represents a genuine entity that is associated with degenerative changes of the structures of the respective lumbar spine segment. These pseudocystic lesions may compress the adjacent nerve roots, provoking symptoms and signs of radiculopathy. The findings suggest that the surgical treatment not only must consist of removal of the pseudocyst but must also include a radical extirpation of the ligamentum flavum surrounding the pseudocyst to avoid recurrence of such a lesion.
authors.affiliation: Department of Rheumatology, University Hospital, Zürich, Switzerland.
authors.forename: Lukas M
authors.initials: LM
authors.lastname: Wildi
authors.forename: Michael O
authors.initials: MO
authors.lastname: Kurrer
authors.forename: Arnaldo
authors.initials: A
authors.lastname: Benini
authors.forename: Dominik
authors.initials: D
authors.lastname: Weishaupt
authors.forename: Beat A
authors.initials: BA
authors.lastname: Michel
authors.forename: Pius
authors.initials: P
authors.lastname: Brühlmann
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003560:Cysts / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D019299:Decompression, Surgical / Q000706:statistics & numerical data; D004547:Elastic Tissue / Q000473:pathology; D005260:Female; D006801:Humans; D017843:Ligamentum Flavum / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D017116:Low Back Pain / Q000209:etiology / Q000473:pathology / Q000601:surgery; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011843:Radiculopathy / Q000209:etiology / Q000473:pathology / Q000601:surgery; D012189:Retrospective Studies; D055502:Secondary Prevention; D013115:Spinal Canal / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D013126:Spinal Nerve Roots / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D013130:Spinal Stenosis / Q000209:etiology / Q000473:pathology / Q000601:surgery; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome