title: Cervical myelopathy due to degenerative spondylolisthesis.
abstract: OBJECTIVE
  To investigate clinical-radiological features of cervical myelopathy due to degenerative spondylolisthesis (DSL).
  
  
  METHODS
  A total of 448 patients were operated for cervical myelopathy at Nishitaga National Hospital between 2000 and 2003. Of these patients, DSL at the symptomatic disc level was observed in 22 (4.9%) patients. Clinical features were investigated by medical records, and radiological features were investigated by radiographs.
  
  
  RESULTS
  Disc levels of DSL were C3/4 in 6 cases and C4/5 in 16 cases. Distance of anterior slippage was 2 to 5 mm (average 2.9 mm) in flexion position. Space available for the spinal cord (SAC) was 11 to 15 mm (average 12.8 mm) in flexion position and 11 to 18 mm (average 14.6 mm) in extension position; 11 cases were reducible and 11 cases were irreducible in extension position. Myelograms demonstrated compression of spinal cord by the ligamentum flavum in extension position. Compression of spinal cord was not demonstrated in flexion position. C5-7 lordosis angle was lower than control. C5-7 range of motion (ROM) was reduced compared to controls. These alterations were statistically significant.
  
  
  CONCLUSIONS
  DSL occurs in the mid-cervical spine. Lower cervical spine demonstrated restricted ROM and lower lordosis angle. Pathogenesis of cervical myelopathy due to DSL is compression of spinal cord by the ligamentum flavum in extension position and not by reduced SAC in flexion position.
authors.affiliation: Department of Orthopaedic Surgery, Nishitaga National Hospital, Sendai, Japan. koakutsu@med.tohoku.ac.jp
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Koakutsu
authors.forename: Junko
authors.initials: J
authors.lastname: Nakajo
authors.forename: Naoki
authors.initials: N
authors.lastname: Morozumi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hoshikawa
authors.forename: Shinji
authors.initials: S
authors.lastname: Ogawa
authors.forename: Yushin
authors.initials: Y
authors.lastname: Ishii
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography; D013118:Spinal Cord Diseases / Q000000981:diagnostic imaging / Q000209:etiology*; D013168:Spondylolisthesis / Q000150:complications*