title: Risk factors for acute cervical spinal cord injury associated with ossification of the posterior longitudinal ligament.
abstract: METHODS
  Retrospective review.
  
  
  OBJECTIVE
  To identify risk factors for traumatic cervical spinal cord injury (SCI) associated with ossification of the posterior longitudinal ligament (OPLL) by comparing patients with SCI and those with cervical myelopathy (CM) associated with OPLL.
  
  
  BACKGROUND
  Although the prevalence of OPLL among patients with cervical SCI is high, little is published about the risk factors for SCI associated with OPLL.
  
  
  METHODS
  We evaluated 3 groups of patients: 34 with SCI associated with OPLL, 32 with CM associated with OPLL, and 32 normal controls. Developmental canal diameter, spinal canal stenosis, type of OPLL, and presence of ossification of the anterior longitudinal ligament (OALL) were evaluated using 3-dimensional computed tomography.
  
  
  RESULTS
  The mean age of the SCI group was 71.5 years, significantly more than that of the CM group (63.3 years). The SCI and CM groups had significantly smaller developmental canals than controls. Canal stenosis caused by OPLL was significantly more severe in the CM group than in the SCI group. There were no significant differences in sex distribution or the type of OPLL. Mixed or segmental types of OPLL were the main cause of SCI and CM. The SCI group showed a significantly higher incidence of OALL (56%) than the CM group (22%). Cervical SCI occurred at the edge of the OPLL or OALL in 20 patients (59%). If limited to mixed or continuous types of OPLL, 18 of the 19 patients (95%) sustained SCI at the edge of the OPLL or OALL.
  
  
  CONCLUSIONS
  Risk factors for cervical SCI associated with OPLL were being elderly, having a mixed or segmental type of OPLL, and presence of OALL. Most instances of SCI occurred at edges of the OPLL or OALL. Severe spinal canal stenosis caused by OPLL was not an essential risk factor for developing SCI.
authors.affiliation: Department of Orthopaedic Surgery, Kurashiki Central Hospital, Okayama, Japan. eo10957@kchnet.or.jp
authors.forename: Eijiro
authors.initials: E
authors.lastname: Onishi
authors.forename: Akira
authors.initials: A
authors.lastname: Sakamoto
authors.forename: Sohei
authors.initials: S
authors.lastname: Murata
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Matsushita
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging; D019299:Decompression, Surgical; D005260:Female; D006801:Humans; D007796:Laminectomy; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D017887:Ossification of Posterior Longitudinal Ligament / Q000150:complications* / Q000000981:diagnostic imaging / Q000601:surgery; D011859:Radiography; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D012306:Risk; D012307:Risk Factors; D013119:Spinal Cord Injuries / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery; D013123:Spinal Fusion; D013130:Spinal Stenosis / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery; D016896:Treatment Outcome