Jeffry Marshall Neil, Presenter: Nothing to Disclose

Hong Shen PhD, Abstract Co-Author: Nothing to Disclose

Mark E. Schweitzer MD, Abstract Co-Author: Nothing to Disclose

Canal size is an important diagnostic criterion for spinal stenosis. However, it is known that most bones will enlarge in individuals of larger body habitus. One could surmise that this would impact upon the diagnosis of spinal stenosis in overweight patients. We studied this problem using cross-sectional and volumetric analysis.

10 patients receiving lumbar spine CTs were studied prospectively. Patient height, weight, and waist size were measured, body fat % was obtained using biological impedance analysis, and BMI was calculated. Symptomatology was assessed via the Oswestry questionnaire and Scranton dermatome chart. Using axial CT data, canal cross-sectional area was measured at the mid-vertebral body level of L3, L4, and L5. The volume of the right L4/L5 IVF was also measured. The canal and IVF sizes were compared to age and the body habitus variables using linear regression. Sizes were also analyzed in relation to symptomatology.

Canal area was 2.75 ± 0.67 cm2 (mean ± SD) at L3, 3.11 ± 1.09 cm2 at L4, and 3.43 ± 1.13 cm2 at L5. Right L4/L5 IVF volume was 1.36 ± 0.39 cm3. Canal area was directly related to height at L3 (p=.047) and L5 (p=.049) and directly related to weight at L3 (p=.040), L4 (p=.020), and L5 (p=.0063). There were no other significant relationships seen for canal area. No significant relationships were found for IVF volume. However, there was a tendency for both canal area and IVF volume to decrease with increasing body fat %. The mean Oswestry score of the patients with the five smallest L4 canal areas was 49 ± 10%; for those with the five largest it was 49 ± 20%. The mean score of the patients with the five smallest IVF volumes was 49 ± 19%; for those with the five largest it was 54 ± 13%.

Canal area was shown to increase with height and weight. In addition, there is a trend in the data for canal area and IVF volume to decrease with increasing body fat %. It is possible that the criteria for spinal stenosis should take into account body habitus and/or patients of varying body habitus have a variable rate of spinal stenosis. Lastly, symptoms do not seem to be correlated with canal or IVF size.

Neil, J, Shen, H, Schweitzer, M, Spinal Canal and Intervertebral Foramen Size: Cross-sectional and Volumetric Analysis and Comparison with Symptomatology and Body Habitus.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4408027.html