Kevin
T. Foley, M.D.
Maurice M. Smith, M.D.
Semmes-Murphey Clinic University of Tennessee
Memphis, TN |
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A shooting, stabbing pain that
shoots from your back or buttocks into your leg is called sciatica
or radiculopathy. It can be associated with numbness or weakness
of your leg and foot. The most frequent cause of this condition
is a ruptured disc in the lower back. In this article, we review
disc problems of the lower back, also known as lumbar disc disease.
Most ruptured discs respond to nonsurgical treatment. When this
does not work, back surgery may be necessary.
The content of this article
addresses the anatomy, pathology, diagnosis, treatment options,
and care for the patient who suffers from pain secondary to lumbar
disc herniation.
Anatomy of the Lowback
The lumbar spine is made up of
the last five vertebrae of the spine. The vertebrae are the bones
of the spine. Their function is to provide support and protection
to the spinal cord. The facet joints allow the vertebrae to be
linked. They provide mobile connections between each vertebra.
An intervertebral disc sits between each individual vertebra.
The annulus is the outer ring and is the strongest part of the
disc. It is responsible for connecting the vertebrae. The nucleus
pulposus is the soft, inner portion. This material is about the
consistency of crabmeat and is responsible for the shock absorption
properties of the spine.
The nerve roots of the spine
carry signals between the lower extremities and the brain that
allow us to move our legs and perceive sensations such as touch,
temperature, and pain. To better understand how the parts of
the spine affect each other, we sometimes focus on a spinal segment.
A spinal segment is composed of two vertebra, the intervertebral
disc between, and the two nerve roots that exit from that spinal
level, one from each side.
The intervertebral discs have
cartilaginous endplates at the top and bottom and are surrounded
by the annulus. Through degeneration or injury, the fibrous tissue
(annulus fibrosus) constraining the soft disc material (nucleus
pulposus) may tear. This may result in bulging (protrusion) of
the disc or even extrusion of disc material into the spinal canal
or neural foramen. This condition has been called herniated disc,
ruptured disc, herniated nucleus pulposus, or prolapsed disc.
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Understanding the anatomy
in cross section is helpful as well |
Herniated Discs
One of the more common problems
of the lumbar spine is a herniated disc. In this condition, a
tear in an annulus fibrosus allows the nucleus pulposus to squeeze
into the spinal canal. If a nerve root is compressed by the disc
material, there can be pain, numbness, and weakness in the areas
supplied by the nerve (often down the back of a leg). It is not
unusual for the back itself to be painless, or nearly so. Accordingly,
a herniated lumbar disc characteristically produces buttock and
leg pain but not back pain per se. This pain is termed radiculopathy
or sciatica.
If sensory function of the impinged
nerve root is impaired, numbness will result. The exact area
of numbness is determined by the particular root, and may be
in the big toe, the heel, the outer ankle, the outer leg, or
a combination of these. Impairment of motor function of the root
will cause weakness which again depends on the particular root.
| Disc
Level |
Root
Comp. |
Weakness |
Reflex Involvement |
Sensory Loss |
Pain
Distribution |
|
L3-L4 |
L4 |
quadriceps, tibialis anterior |
knee jerk |
medial knee and shin |
anterior thigh |
|
L4-L5 |
L5 |
extension of big toe |
no significant |
big toe |
back of thigh, lateral calf |
|
L5-S1 |
S1 |
gastrocnemius (ankle plantar
flexion) |
Achilles |
lateral foot and heel |
back of thigh and calf |
In disc herniations, the L5-S1
disc is involved 45% to 50% of the time, L4-5 40% to 45%, and
L3-4 about 5%. Disc herniation at the other lumbar levels is
rare.
The root compressed is the one
exiting the level below the disc in the vast majority
of cases. However, if the herniation is lateral, i.e.,
into the foramen, then the root compressed will be
the one exiting above. This is known as a far lateral
disc herniation and occurs in about 3% to 10% of cases.
It is also important to note that while the signs
outlined in Table 1 are helpful in the diagnosis and
decision making regarding type of treatment, not all
of the signs and symptoms associated with a root may
be present in an individual, and multiple root signs
may even be present.
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SpineUniverse
Editorial Board Comment:
"This is a good review article. However, there
is a little too much emphasis on the "MED System"
as a way of treating lumbar disc herniations.
Readers should note that the authors were extensively
involved with the design of the MED System and
thus the article reflects their own personal
bias. While some surgeons choose to use the
MED System, other experienced surgeons choose
not to use it."
Iain
Kalfas, M.D. - Editorial Board, SpineUniverse
|
Treatment
Options for Ruptured Discs in the Low Back (cont.)
Anterior
Lumbar Fusion
Sciatica
More
on Herniated Discs
Discectomy
Laminectomy
What Should I Know About
Lumbar Fusion?
Technology
Treatment
Options |