Introduction:
Most patients with low back and leg pain can be treated in a conservative
fashion with excellent resolution of their pain. This communication,
however, is directed to those so afflicted who have failed a conservative
course of treatment and are still bothered by an unacceptable level
of low back and leg pain. We hope this provides you with sufficient
anatomical information and different treatment modes, enabling you
to make a more informed decision regarding appropriate treatment for
you.
Anatomy:
Your spine consists of seven vertebrae in the neck, twelve in the
thoracic portion and five vertebrae in the lumbar portion. Your spinal
cord is the electrical conduit between your brain and your arms and
legs. Electrical impulses emanating from the brain descend through
the brain stem into the spinal cord and out peripheral nerve roots
to activate the appropriate portion of your motor system. Similarly,
sensory receptors in your extremities convey sensations such as touch
and pain up the peripheral nerves into the spinal cord. From there
the impulses travel into various parts of the brain to help you perceive
light touch, pain and higher forms of sensation. The spinal cord actually
terminates at approximately the first lumbar vertebra in the spinal
canal. From that point downward, the canal is filled with nerve roots
(cauda equina) going to various portions of the body (Fig. 1).
Figure 1. Side View of Lumbar Spine
One nerve root exits the spinal canal both right and left at each
segment. Thus, the first lumbar nerve root exits in the foramen (side
outlet) between L1 and L2. Likewise, the fourth lumbar nerve root
exits between the fourth and fifth vertebrae. The intervertebral disc
sits between two vertebral bodies. It is composed of a thick and tough
annulus fibrosis which surrounds the central portion of the disc space.
The central portion of the disc space is occupied by the nucleus pulposus,
which has a rubbery consistency similar to crab meat (Fig. 3). Areas
of weakness develop in the back (posterior) portion of the annulus,
predisposing one to later disc herniation. When a disc herniates (Fig.
4) it protrudes through the crack in the annulus, thereby compressing
one or several nerves at that particular level. Most discs herniate
between L4 and 5 or between L5 and the first sacral level. Your physician
can usually tell which level is herniated from a good description
of the pain distribution and the neurological examination. His/her
suspicions are then corroborated with an appropriate diagnostic test.
Generally, a lumbar MRI scan is the most desirable. However, on occasion,
a CT scan or myelogram combined with a contrast CT scan might be ordered.
Occasionally, a discogram is also performed if the other studies are
inconclusive. Disc herniations in the lumbar spine can be named for
the area in which they are present (Fig. 5). A central disc herniation
(1) is one in which the disc protrudes straight back in the midline.
This causes prominent back pain and may or may not involve leg pain.
A posterrolateral disc herniation, (2) the most common, occurs to
one side of the midline and produces prominent leg pain with perhaps
some back pain. Discs can also present in the foramen (3) (side port)
or in the far lateral disc space are (4). These typically cause severe
leg pain with little or no back pain.
Treatment: The initial treatment for disc herniation is nonsurgical.
This consists of time, appropriate medications and physical therapy.
Sometimes a change in one's work environment is helpful. Other treatments
such as epidural blocks may be appropriate as well. It is assumed,
however, that you have gone through those modes of treatment without
significant benefit.
One form of surgical treatment is the traditional laminectomy (Fig.
6). The surgeon makes an open incision in the midline of the back.
Muscle is separated from bone and ligament and a portion of your lamina
and ligaments forming the roof of the spinal canal is removed. The
surgeon then uses instruments (retractors) to gently pull the nerve
root off of the disc herniation so that he might first visualize the
herniation before removing it. Laminectomy is very effective with
success rates approaching 85% in properly selected patients.
This procedure, however, may be associated with two types of scarring
(arachnoiditis, epidural fibrosis) which have been implicated as possible
reasons for failure to relieve pain in a small percentage of patients.
A laminectomy usually requires a one to two day stay in the hospital
and a fairly slow convalescence. Time for return to work is usually
in the range of four to six weeks. Two forms of minimally invasive
lumbar discectomy (percutaneous lumbar discectomy, laser disc decompression)
are utilized by some surgeons. These two methods, however, do not
effectively treat the disc herniation proper. Although performed on
an outpatient basis, these procedures are only 50% effective in long-term
follow-up studies.
Meld:
Microscopic extraforamenal lumbar discectomy has been devised by Dr.
Obenchain as another form of less invasive lumbar discectomy. It treats
the disc herniation directly, taking pressure off the nerve root or
nerve root sac. This procedure can be carried out under either local
or general anesthesia. The average patient is discharged from the
recovery room three hours after surgery. Less bone and ligament is
removed via this approach and the extent of post surgical scar formation
is less. Perhaps more importantly, the two nerve roots involved at
that particular level can be directly visualized and do not have to
be retracted (pulled on) to remove the disc herniation. This reduces
the potential for injury to the nerve root. Because your postoperative
pain is less than with the traditional laminectomy, reactivation occurs
more quickly. Most individuals can return to work within one to three
weeks after surgery. It is important that you follow instructions
provided by your surgeon in your early postoperative period. Reactivation
to prior levels of physical activity should be done on a gradual basis
as your discomfort and energy level dictate. Medications will be diminished
with time as judged appropriate by your physician.
It is important that you develop a positive attitude and adopt a
lifestyle that fosters a well- conditioned back. This consists of
a healthy diet and maintaining or attaining a normal body weight.
Conditioning and strengthening exercises to your abdominal muscles,
quadriceps, hamstrings, glutei and low back extensor muscles are important.
These well-conditioned muscles, in effect, stabilize the spine, making
you less prone to develop recurrent back problems in the future. Certain
environmental changes important to your convalescence should be discussed
further with your physician.
Theodore G. Obenchain, M.D., Inc.
355 East Grand Avenue, Escondido, CA 92025
Phone: (760) 741-9550 ~ FAX: (760) 741-9552
Email: Information@DrObenchain.com