title: The cross-sectional area of the cervical spinal canal in patients with cervical spondylotic myelopathy. Correlation of preoperative and postoperative area with clinical symptoms.
abstract: METHODS
  Retrospective analysis of routine computed tomography investigations.
  
  
  OBJECTIVE
  To investigate whether the extent of clinical symptoms in patients undergoing surgery for cervical spinal myelopathy depends on the transsectional area of the cervical spinal canal.
  
  
  METHODS
  Forty-five patients underwent surgery using different techniques to enlarge the width of the spinal canal. For clinical evaluation before and after surgery, a modified score of the Japanese Orthopedic Association was used (mean follow-up period, 19.6, 9.1 months). The cross-sectional area of the spinal canal in computed tomography scans (C4-C6) was quantified 1 day before and 1 week after surgery using pixel-dependent area calculation software for three different density ranges given in Hounsfield units.
  
  
  RESULTS
  After surgery, a significant enlargement of the cervical spinal canal of 78.2 +/- 55.9% could be achieved. The Japanese Orthopedic Association score increased significantly by 3.7 +/- 2.2 points from a median preoperative score of 10 to a score of 14 after surgery. Patients with a preoperative Japanese Orthopedic Association score > or = 10 achieved a significantly better outcome after surgery. Conversely, no patient with a postoperative area larger than 1.6 cm2 achieved a score of less than 12 Japanese Orthopedic Association-points. No significant linear correlation, however, was found between the postoperative transsectional area and the postoperative Japanese Orthopedic Association score of all patients.
  
  
  CONCLUSIONS
  The preoperative clinical presentation of the patient was found to be the only prognostic hint for improvement after surgery. Preoperative area measurements of the spinal canal cannot be used as a prognostic tool for surgical outcome. Further, the postoperative measurements do not correlate with the clinical outcome. These data, however, which refer to C4 to C6, provide evidence that every surgical procedure to enlarge the cervical spinal canal should result in an area of 1.6 cm or more.
authors.affiliation: Department of Neurosurgery, Grosshadern University Hospital, Ludwig-Maximilians-University of Munich, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Hamburger
authors.forename: A
authors.initials: A
authors.lastname: Büttner
authors.forename: E
authors.initials: E
authors.lastname: Uhl
mesh_terms: D002574:Cervical Vertebrae; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D013115:Spinal Canal / Q000000981:diagnostic imaging; D013117:Spinal Cord Compression / Q000000981:diagnostic imaging / Q000209:etiology; D013128:Spinal Osteophytosis / Q000150:complications* / Q000000981:diagnostic imaging / Q000601:surgery; D013130:Spinal Stenosis / Q000000981:diagnostic imaging / Q000209:etiology; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome