Analysis of dural sac thickness in human spine - Cadaver study with confocal infrared laser microscope

Background context: The thickness of the human spine dural sac can show differences between individuals and levels, and these differences can alter clinical outcomes. Purpose: To analyze spinal cord dural sac thicknesses. Study design: Anatomical study of human cadavers. Methods: The subjects of this study were 19 human cadavers with no prior history of spinal surgery or deformity. Seventeen specimens from T1/T2 to L5/S1 were obtained from each of 19 cadavers, a total of 323 specimens. Multiple sections were prepared from these specimens. Microscopic measurements were taken with an infrared laser-based confocal microscope to determine the mean dural sac thickness at each level. In addition, a magnetic resonance image of the lumbar spine was obtained from each subject. Relations between dural sac thicknesses at different levels were analyzed with respect to gender, age, and stenosis level. Results: Overall mean dural sac thickness was 0.307±0.122 mm in this human cadaver series. Dura thicknesses differed significantly at different levels (p=.046). Overall, dural thickness was highest at T9/T10 and lowest at L2/L3 (p=.0007) as well as highest at the lower thoracic level followed by the upper thoracic and lumbar levels (p=.003). In addition, dural sac thickness was found to increase slightly but significantly with age (p=.019). However, dural thickness was similar between men and women (p=.123). And, no significant dural thickness differences were found for stenotic and nonstenotic lesions (p=.885). Conclusion: Dural sac thickness was found to be significantly dependent on spinal level and age in human cadavers. An appreciation of dural sac thickness differences can be useful in the clinical field, and it is hoped that this encourages further study of dural physiology.