Pain from degenerative disc disease
Low back pain from a degenerated disc
The lumbar disc is a unique and well-designed
structure in the spine. It is strong enough to
resist terrific forces in multiple different planes
of motion, yet it is still very mobile. The disc
has several functions, including acting as a shock
absorber between the vertebral bodies.
The lumbar
disc has been likened to a jelly donut. It
is comprised of a series of bands that form a
tough outer layer and soft, jelly-like material
contained within:
Annulus fibrosus—the disc’s
firm, tough outer layer
Nerves to the disc space only penetrate into
the very outer portion of the annulus fibrosus.
Even though there is little innervation to the
disc, it can become a significant source of back
pain if a tear in the annulus reaches the outer
portion and the nerves become sensitized. With
continued degeneration, the nerves on the periphery
of the disc will actually grow further into the
disc space and become a source of pain.
Nucleus pulposus—the jelly-like inner disc
material
The nucleus pulposus
contains a great
deal of very inflammatory
proteins. If this
inner disc material
comes in contact
with a nerve root,
it will inflame the
nerve root and create
pain down the leg
(sciatica or radiculopathy).
In the same manner,
if any of the inflammatory
proteins within the disc space leak out to the
outer annulus and
touch the pain fibers
in this area, it
can create a lot
of low back pain.
Source of the pain
Generally, the pain associated with degenerative
disc disease is thought to stem from two different
factors:
The proteins in the disc space can cause a lot
of inflammation, and inflammation in the disc
space can lead to low back pain radiating to
the hips. The associated pain can also
travel down the back of the legs.
If the annulus—the
outer rings of the intervertebral disc - becomes
damaged or worn down, it is not as effective
in resisting motion in the spine. This condition
has been termed “micromotion” instability
because it is usually not associated with gross
instability (such as a slipped vertebral body
or spondylolisthesis).
Both the inflammation
and micromotion instability can cause muscular
spasm in the low back. The
muscle spasm is the body’s attempt to stabilize
the low back. It is a reflex, and although
the body’s response of muscle spasm is
not necessary for the safety of the nerve roots,
it can be quite painful. |
