title: Correlation of spinal canal dimensions to efficacy of epidural steroid injection in spinal stenosis.
abstract: OBJECTIVE
  To determine a critical canal dimension in patients with spinal stenosis that predicts response to epidural steroid injections (ESI).
  
  
  METHODS
  Lumbar spinal stenosis patients with a computed tomography scan before ESI were identified through ICD-9/CPT codes. Using a digital caliper, canal dimensions on axial cuts of each lumbar intervertebral level were recorded: the transverse canal diameter in line with the facets including the soft tissues, TC; the transverse osseous canal diameter, OS; and the mid-sagittal anteroposterior diameter, MS. Minimum and maximum measurements were determined. Patients who improved after ESI and those that required a decompression after ESI were differentiated.
  
  
  RESULTS
  Eighty-four patients were included in the study. Fifty required surgical decompression after ESI and 34 patients improved after ESI. There were no statistically significant differences in the demographics between the 2 groups. Mean minimum dimensions in the surgical group were 9.47 mm (TC), 16.53 mm (OS), and 12.40 mm (MS); and 9.75 mm (TC), 16.65 mm (OS), and 12.39 mm (MS) in the nonsurgical group. Mean ratio between the maximum and minimum dimensions in the surgical group was 1.76 (TC), 1.35 (OS), and 1.57 (MS); and 1.86 (TC), 1.47 (OS), and 1.63 (MS) in the nonsurgical group. There was no statistically significant difference in the minimum measurement in any dimension between the surgical and the nonsurgical group. There was also no statistically significant difference in the ratio between the minimum and maximum measurement in any dimension between the surgical and the nonsurgical group.
  
  
  CONCLUSIONS
  Spinal canal dimension is not predictive of success or failure of ESI in patients with spinal stenosis.
authors.affiliation: Department of Orthopaedic Surgery, University of Louisville School of Medicine, Louisville, Kentucky, USA.
authors.forename: Mitchell J
authors.initials: MJ
authors.lastname: Campbell
authors.forename: Leah Y
authors.initials: LY
authors.lastname: Carreon
authors.forename: Steven D
authors.initials: SD
authors.lastname: Glassman
authors.forename: Mark D
authors.initials: MD
authors.lastname: McGinnis
authors.forename: Brian S
authors.initials: BS
authors.lastname: Elmlinger
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019412:Anatomy, Cross-Sectional / Q000379:methods; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007268:Injections, Epidural; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011379:Prognosis; D011856:Radiographic Image Enhancement / Q000379:methods*; D013130:Spinal Stenosis / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D013223:Statistics as Topic; D013256:Steroids / Q000008:administration & dosage*; D016896:Treatment Outcome
chemical_list: D000893:Anti-Inflammatory Agents; D013256:Steroids