title: Spontaneous reduction in ossification of the posterior longitudinal ligament of the thoracic spine after posterior spinal fusion without decompression: a case report.
abstract: METHODS
  Case report.
  
  
  OBJECTIVE
  We report on a patient with thoracic myelopathy caused by ossification of the posterior longitudinal ligament (OPLL) of the spine.
  
  
  BACKGROUND
  Surgery for thoracic OPLL (T-OPLL) is associated with a high rate of complications. Posterior spinal instrumentation (PSI) with decompression is a relatively safe procedure with satisfactory results. However, the mechanisms by which PSI with decompression produces neurological recovery in patients who undergo T-OPLL have not been elucidated fully, and no reports have described the radiographical progress after PSI.
  
  
  METHODS
  The patient was a 78-year-old female with a 4-month history of gait disturbance and paresthesia of the lower extremities who had continuous OPLL at T1-T4. The spinal cord was impinged by beak-type OPLL with a nonossified area at T3-T4. PSI without decompression of C7-T6 was performed.
  
  
  RESULTS
  After surgery, the patient showed clear improvement in neurological symptoms. She recovered fully after 2 years, by which time, the point of the beak-type OPLL at T3-T4 had become a mild protuberance and the nonossified area was fused through the remodeling process. This reduced the size of the ossified lesion that had caused severe compression of the spinal cord before surgery.
  
  
  CONCLUSIONS
  The remaining mobility at the nonossified lesion, where the point of the beak-type OPLL compressed the spinal cord, might have caused the myelopathy in this patient. We propose that stabilization with PSI stimulates bone remodeling of nonossified lesions, leading to a reduction of OPLL. This finding provides a clue about the mechanisms responsible for neurological improvement after PSI for T-OPLL.
authors.affiliation: From the Department of Orthopedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kimura
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Fujibayashi
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Takemoto
authors.forename: Bungo
authors.initials: B
authors.lastname: Otsuki
authors.forename: Shuichi
authors.initials: S
authors.lastname: Matsuda
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D017887:Ossification of Posterior Longitudinal Ligament / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D020127:Recovery of Function; D013123:Spinal Fusion; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome