Pathophysiology of Degenerative Disc
Disease
- One theory hypothesizes that small, posttraumatic peripheral tears
of the anulus fibrosus lead to an acceleration in the dehydration of the
intervertebral disk, with resultant fraying of the nucleus pulposus.8
Studies using
annular trauma in a sheep model support this theory.9
8. Osti OL, Vernon-Roberts B,
Moore R, Fraser
RD: Annular tears
and disc degeneration in the lumbar spine: A post-mortem study of 135 discs. J Bone Joint Surg Br 1992;74:678-682.
9. Osti OL, Vernon-Roberts B, Fraser RD: Anulus tears and intervertebral disc degeneration: An
experimental study using an animal model. Spine 1990;15: 762-767.
- In the normal intervertebral disk, sensory
nerves do not penetrate beyond the outer one third of the anulus fibrosus.11-13
11. Bogduk N, Tynan W, Wilson
AS: The nerve supply to the human lumbar intervertebral discs. J Anat 1981;132(pt 1):39-56.
12. Freemont AJ, Peacock TE,
Goupille P, Hoyland JA, O’Brien J, Jayson MI: Nerve ingrowth into diseased intervertebral
disc in chronic back pain. Lancet 1997;350:178-181.
13. Coppes MH, Marani E,
Thomeer RT, Groen GJ: Innervation of “painful” lumbar discs. Spine 1997;22:2342-2350.
- Vascular ingrowth also has been observed in peripheral tears of the
anulus.10 Nociceptors may accompany this vascular growth
and account for the presence
of sensory nerve supply in the inner anulus.
10. Hirsch C, Schajowicz F:
Studies on structural changes in the lumbar annulus fibrosus. Acta Orthop Scand 1953;
22:184-231.
- In degenerative disk disease (DDD) an association has been
demonstrated between ingrowth of nerves expressing substance P and disk
degeneration. The extent of neoneuralization has been shown to be greatest
at the painful levels.12
12. Freemont AJ, Peacock TE,
Goupille P, Hoyland JA, O’Brien J, Jayson MI: Nerve ingrowth into diseased
intervertebral disc in chronic back pain. Lancet 1997;350:178-181.
- Coppes et al13 noted that disk degeneration and perhaps disk injury are
associated with centripetal
growth of nerve fibers in the disk, which would provide a
morphologic basis for true discogenic pain. The findings of these
histologic studies agree with those of clinical studies identifying the
anulus fibrosus as a common source of the back pain.14,15
13. Coppes MH, Marani E,
Thomeer RT, Groen GJ: Innervation of “painful” lumbar discs. Spine 1997;22:2342-2350.
14. Wiberg G: Back pain in
relation to the nerve supply of the intervertebral disc. Acta Orthop Scand 1950;19:211-221.
15. Kuslich SD, Ulstrom CL,
Michael CJ: The tissue origin of low back pain and sciatica: A report of pain
response to tissue stimulation during operations on the lumbar spine using
local anesthesia.
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