1 / 21

The “Dehydrated” Lumbar Intervertebral Disk on MR, its anatomy, biochemistry and biomechanics

The “Dehydrated” Lumbar Intervertebral Disk on MR, its anatomy, biochemistry and biomechanics. Victor Haughton MD University of Wisconsin. The defining feature is diminished signal intensity in the nucleus pulposus on T2 weighted images.

pearl
Download Presentation

The “Dehydrated” Lumbar Intervertebral Disk on MR, its anatomy, biochemistry and biomechanics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The “Dehydrated” Lumbar Intervertebral Disk on MR, its anatomy, biochemistry and biomechanics Victor Haughton MD University of Wisconsin

  2. The defining feature is diminished signal intensity in the nucleus pulposus on T2 weighted images. Meets criteria for a stage III degenerated disk in the Pfirrmann or the Thompson scales Stage III is distinguished from stage I and II disks by decreased T2 signal "dehydrated", "desiccated" or "dark" disks.

  3. Background: • The terms “dehydrated” or “dessicated disk” have not been adequately defined. • Used in radiologic reports, the terms suggest a process different from degeneration and perhaps less significant clinically.

  4. Methods: • Scientific reports were reviewed • Anatomical, biochemical, and biomechanical properties of dark disks summarized

  5. Conclusions: • The dehydrated or dessicated disk, because of its morphological, biochemical and biomechanical features warrants the designation of early disk degeneration.

  6. High intensity zone in annulus fibrosus Minority of Dark Disks Dark disks: HIZ on MR

  7. Dark Disk: Discography (100% sensitivity) Concordant pain at L4-5 on discography, No pain at L3-4 or L5-S1. Disposition: L4-5 interbody fusion; pain free following surgery

  8. Dark Disk: Anatomic correlation.Radial tear in all cases

  9. Radial tear in anatomic sections of cadaver disks

  10. Radial tear: axial MR and anatomic sections

  11. Anatomic section demonstrating granulation tissue in the radial tear

  12. Staging of intervertebral disk degeneration (MR) Pfirrmann

  13. Differential diagnosis: annular tears Transverse tear Concentric tear

  14. Biochemistry of dark disk • Diminished glycosaminoglycans • Increased collagen content • Change in Glucosulfonates • Increase in aggregated proteins

  15. Water content, GAG content diminished in dark disk

  16. “Dark Disk” responds abnormally to forces and torques Diminished resistance to rotagtory torque Behaves as a biomechanically failed disk Biomechanics

  17. Biomechanical Testing • Increase torque incrementally • Measure rotation of vertebrae for each torque increment • Calculate stiffness • Small changes for aging disks • Significantly larger changes in dark disks

  18. Rotations of dark disks and control disks measured in vivo

  19. Dark disk: Degenerating disk • Type III in Pfirrmann grading on morphology • Radial tear of the annulus fibrosus • Abnormal biochemically: water and GAG content diminished • Abnormal biomechanically : mechanical failure of intervertebral disk • Early disk degeneration • Early disk degeneration

  20. Radial tear: Sagittal section

More Related