title: Natural course and prognostic factors in patients with mild cervical spondylotic myelopathy with increased signal intensity on T2-weighted magnetic resonance imaging.
abstract: METHODS
  A retrospective comparative study.
  
  
  OBJECTIVE
  To investigate natural course and prognostic factors in patients with mild forms of cervical spondylotic myelopathy (CSM), focusing on intramedullary increased signal intensity (ISI) on T2-weighted magnetic resonance imaging.
  
  
  BACKGROUND
  Long-term natural course of mild forms of CSM, especially with ISI on magnetic resonance imaging, remains uncertain.
  
  
  METHODS
  Patients with CSM who visited our institution between 1992 and 2004 and did not undergo surgery at first visit were retrospectively reviewed. The inclusion criteria were as follows: (1) motor function Japanese Orthopedic Association scores of 3 or more in both upper and lower extremities and (2) cervical spinal cord compression with ISI on T2-weighted magnetic resonance imaging. There were 45 patients, with a mean follow-up period of 78 months (range, 24-208). We investigated long-term natural history by setting the timing of conversion to surgery due to neurological deterioration as an end point. We further compared prognostic parameters between patients who converted to surgery and those who continued to be followed up nonsurgically.
  
  
  RESULTS
  Sixteen patients gradually deteriorated and underwent decompression surgery, whereas 27 patients did not. Apart from these, 2 patients with acute spinal cord injury after minor trauma underwent surgery. Kaplan-Meier survival analysis revealed that 82% or 56% of patients did not require surgery 5 or 10 years after the initial treatment, respectively. As for prognostic factors, Cox proportional hazard analysis revealed that total cervical range of motion (hazard ratio: 3.25), segmental kyphosis in the maximum compression segment (hazard ratio: 4.51), and local slip (hazard ratio: 4.67) were statistically significant.
  
  
  CONCLUSIONS
  Fifty-six percent of patients with clinically mild CSM with ISI had not deteriorated or undergone surgery at 10 years. Large range of motion, segmental kyphosis, and instability at the narrowest canal were considered to be adverse prognostic factors.
authors.affiliation: Department of Orthopaedic Surgery, The University of Tokyo, Bunkyo-ku, Japan. yoo-tky@umin.ac.jp
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Oshima
authors.forename: Atsushi
authors.initials: A
authors.lastname: Seichi
authors.forename: Katsushi
authors.initials: K
authors.lastname: Takeshita
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Chikuda
authors.forename: Takashi
authors.initials: T
authors.lastname: Ono
authors.forename: Satoshi
authors.initials: S
authors.lastname: Baba
authors.forename: Jiro
authors.initials: J
authors.lastname: Morii
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Oka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawaguchi
authors.forename: Kozo
authors.initials: K
authors.lastname: Nakamura
authors.forename: Sakae
authors.initials: S
authors.lastname: Tanaka
mesh_terms: D000328:Adult; D000368:Aged; D019299:Decompression, Surgical; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013118:Spinal Cord Diseases / Q000175:diagnosis* / Q000473:pathology* / Q000601:surgery; D055009:Spondylosis / Q000175:diagnosis* / Q000473:pathology* / Q000601:surgery