title: Postsurgical ossified extradural cyst of the lumbar spine: a case report.
abstract: METHODS
  An extremely rare case of postsurgical ossified extradural cyst is reported. The imaging and intraoperative findings are described and compared with those in cases previously reported in the literature.
  
  
  OBJECTIVE
  To draw attention to this rare but dangerous condition that can develop after lumbar surgery.
  
  
  BACKGROUND
  Only six cases of postsurgical ossified extradural cyst have hitherto been reported.
  
  
  METHODS
  A 65-year-old man who had undergone surgery for a herniated lumbar intervertebral disc 20 years earlier complained of leg pain. From the imaging and intraoperative findings an ossified cyst with closed communicating aperture was diagnosed. The ossified cyst was surgically resected.
  
  
  RESULTS
  Postoperatively, this patient was discharged and experienced alleviation of his symptoms.
  
  
  CONCLUSIONS
  This case showed an extremely rare postsurgical ossified extradural cyst, and was of particular interest because in contrast to the previously reported cases the communicating aperture between the cyst and subarachnoid space was closed.
authors: Department of Orthopaedic Surgery, Meijo hospital, Nagoya, Japan.
authors: H
authors: H
authors: Saito
authors: N
authors: N
authors: Kawakami
mesh_terms: D000368:Aged; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D009192:Myelography; D009999:Ossification, Heterotopic / Q000175:diagnosis*; D011183:Postoperative Complications / Q000175:diagnosis*; D013122:Spinal Diseases / Q000175:diagnosis; D013581:Synovial Cyst / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed