title: Influence of intramedullary stress on cervical spondylotic myelopathy.
abstract: METHODS
  A cross-sectional analysis.
  
  
  OBJECTIVE
  To examine whether intramedullary stress is related to the appearance of symptoms in cervical spondylotic myelopathy (CSM).
  
  
  METHODS
  Japan.
  
  
  METHODS
  Thirty-three consecutive patients with CSM and 30 consecutive patients without CSM were enrolled. A total of 99 disc levels from C3 to C6 in 33 patients with CSM were divided into two groups: 33 disc levels with high signal intensity (HSI) on T2-weighted magnetic resonance image (HSI group) and 66 disc levels without HSI (Non-HSI group). Ninety disc levels from C3 to C6 in patients without CSM were set up in a control group. Intramedullary stress value at each level was analyzed using the finite element method. Stress was compared among the three groups. A cutoff value of stress to present HSI was investigated from receiver operator characteristics (ROC) curve.
  
  
  RESULTS
  In all the patients with CSM, the disc level with HSI presented the highest stress among the three disc levels evaluated. The stress was 3.16 ± 0.86 kPa (mean ± s.d.) in the HSI group, 1.81 ± 0.72 kPa in the Non-HSI group and 1.01 ± 0.37 kPa in the control group. The stress differed significantly among the three groups (P<0.0001). The qualified cutoff value derived from the ROC curve was 2.30 kPa (sensitivity 78.8%, specificity 91.9%). None of the disc levels in the control group exceeded 2.30 kPa.
  
  
  CONCLUSIONS
  HSI was strongly associated with intramedullary stress. Threshold of intramedullary stress to present HSI that related closely to the symptoms of myelopathy was revealed.
authors.affiliation: 1] Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan [2] Department of Orthopaedic Surgery, Senboku Kumiai Hospital, Akita, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Takahashi
authors.forename: H
authors.initials: H
authors.lastname: Ozawa
authors.forename: N
authors.initials: N
authors.lastname: Sakamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Minegishi
authors.forename: M
authors.initials: M
authors.lastname: Sato
authors.forename: E
authors.initials: E
authors.lastname: Itoi
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D019299:Decompression, Surgical / Q000379:methods; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D013118:Spinal Cord Diseases / Q000209:etiology / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D013119:Spinal Cord Injuries / Q000150:complications / Q000473:pathology / Q000601:surgery*; D013312:Stress, Physiological; D016896:Treatment Outcome