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 Discs
are the pads between the vertebrae of the spine.
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There are 24 mobile
vertebrae and 5 that are fused together to form the sacrum.
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The disc has 2
functions: it transmits the weight of the body from the bone above
to the bone below and it allows the spine to be flexible.
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The strong outer ring
or annulus, is firmly attached to the vertebrae above and below the
disc.
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The nucleus pulposis
is located inside the annulus. This is a soft gelatin-like cartilage
with a very high water content which provides cushioning while
evenly supporting the weight of the body. This cartilage transmits
the load from bone to bone.
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There is a delicate
balance between the forces trying to push the gelatin-like nucleus
out to the sides and the tension of the outer ring holding it in
place.
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Discs are vulnerable
to injury because they have the job of being flexible enough to
move, but strong enough to take enormous stress.
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The discs between the
lower lumbar vertebrae are the most commonly injured because they
support the weight of the entire upper body plus whatever is being
carried.
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Because the body's
center of gravity is in front of the discs, loads on the disc are
increased by leverage. Research has shown that picking up a 20 lb.
weight may increase pressures inside the disc by more than 8 times
the body's weight. The job of the disc is to transmit this load
efficiently and evenly to the vertebra below.
What is
a herniated lumbar disc?
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Disc herniation,
rupture, protrusion, and extrusion are all
terms that describe this injury. There are subtle differences
between these terms, but they all refer to a tear in the outer ring,
which allows some of the inner core to escape.
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A herniation occurs
when a portion of the soft inner core (nucleus pulposis)
escapes through the outer ring (annulus).
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 The
outer ring of the disc is subject to continuous stresses that
sometimes cause small tears to develop.
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If one of these tears
is large enough and the stresses inside the disc strong enough, some
of the pulposis can leak through the tear.
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The disc is most
vulnerable to injury at the weakest parts of the outer ring, where
nerves pass through the spinal canal and exit toward the legs.
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A disc can herniate
due to either a sudden load or an accumulation of minor injuries
over time. At least 50% of patients can't recall a specific event
that caused the ruptured disc. When an event can be identified, it
often involved lifting and twisting; activities that place severe
stresses on the disc.
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Discs are named for
the bones above and below them. For example, the L4-5 disc is
between the 4th and 5th lumbar bones. The L5-S1 disc is between the
5th lumbar and 1st sacral bones. These two discs do the most work
and are the most frequently injured.
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Paralysis rarely
occurs with disc herniation. The spinal cord proper ends at the
first lumbar vertebra (L1), well above these frequently injured
discs.
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Other conditions that
cause back and leg pain can mimic a ruptured lumbar disc. Some of
these conditions are:
1. arthritis of the hip or knee area
2. pulled muscles in the back (lumbar strain)
3. pulled muscles in the leg and other conditions that cause
irritation of the spinal nerves.
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People with common
herniated lumbar discs experience some combination of back and leg
pain such as numbness, tingling, and/ or weakness along the
compressed nerve. At first, most people experience severe back pain
in conjunction with muscle spasm.
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Because these are also
symptoms of pulled back muscles, at first it is difficult to distinguish
between a ruptured disc and a lumbar strain. After a few days, the
back pain usually subsides, and pain in one leg takes over. This
pain is often described as an "electric shock", or burning
sensation, that follows the nerve from the buttock, down the back of
the thigh and into the calf or foot. This type of pain is called sciatica
for the sciatic nerve that runs in the same area.
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The muscles controlled
by the nerve may weaken because they are not getting normal signals
from the brain and spinal cord. Eventually, these muscles may atrophy
because they are not being used.
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Although these are the
most common symptoms, there may be any combination of back and leg
pain in varying degrees of severity, from a very mild ache to
unbearable pain requiring a visit to a hospital emergency room.
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The physician will use a
combination of history:
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how the pain began,
how long it has been going on and how severe it is.
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if an accident or fall
preceded the pain.
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The the state of the
patient's general health.
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which medications the
patient is taking (both prescription and over the counter).
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other treatments that
have been tried and whether any of them have been helpful.
The doctor will check
several functions in the physical examination:
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Gait
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Range of motion
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The back will be
checked for curvatures, muscle spasm, and tenderness.
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Other conditions such
as hip problems, leg length differences, circulation problems and
injuries to the legs must be checked.
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Nerve root tension
signs: The doctor may stretch the legs in various ways to see if
stretching a nerve will reproduce the pain. This helps determine if
a nerve is compressed. The most common of these tests is the
"straight leg raise".
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Neurological
examination: The doctor will evaluate as many nerve functions as
possible in the patient's legs. This will include checking the sense
of touch using a pin prick and evaluating the strength in several
leg muscles. The reflexes at the knee and ankle will also be tested.
It is often necessary to
obtain an X-ray, MRI, bone scan, or myelogram. Since many people recover
completely in a short time, most doctors suggest waiting until the
condition has failed to respond to several weeks of conservative
(non-operative) treatment before getting imaging studies.
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X-rays: are
best suited for looking at the bones. Fractures, disc degeneration,
arthritis and spinal deformities are also visible on regular X-rays.
Abnormal movements of the vertebrae can be identified if X-rays are
made while the patient is bending forward or leaning backward.
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Computed Tomography
(CT scan): This is a special type of X-ray that shows soft
tissues (disc, nerve, muscle and ligament) more clearly than a
regular X-ray. CT scans are about 83% accurate at diagnosing a
herniated disc.
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MRI (Magnetic
Resonance Imaging): The MRI is ordered only after a period of
unsuccessful conservative treatment. The MRI is extremely good at
showing the discs, nerves, spinal cord, spinal fluid, muscles and
ligaments. It is about 93% accurate at finding herniated discs.
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Myelogram and Post
Myelogram CT Scan: During a myelogram the radiologist injects
dye into the spinal fluid. A series of X-rays is followed by a CT
scan. The dye outlines the nerves and makes them easier to see. This
method is also about 93% accurate at identifying herniated discs,
but most doctors prefer an MRI because it does not require an
injection. A myelogram and post myelograin CT scan is often done
when an earlier MRI was not conclusive.
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Non-operative
treatment for the first 4-6 weeks:
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General: Except
in a few special circumstances, initial treatment for herniated
discs should be conservative. People with back pain and sciatica are
treated alike, with emphasis on pain relief and early mobilization.
Fortunately, herniated discs improve without surgery about 80% of
the time. It usually takes 4-6 weeks of conservative treatment
before a patient can resume normal activities.
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Narcotics: If
the first few days are extremely painful, narcotic pain medicines
are often prescribed. Some of these are safe for short periods, but
have worrisome side effects when used for a long period of time.
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Anti-Inflammatories:
Since inflammation of the spinal nerves and back muscles contribute
to the problem, anti-inflammatory medicines are frequently
prescribed. Often called "arthritis medicines" or
"NSAIDs" (non steroidal anti inflammatory drugs) it
usually takes several days of treatment before NSAIDs are fully
effective. Some NSAIDs may cause acid stomach so they should
generally be taken with food.
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Muscle Relaxers:
These medicines are given to help ease muscle spasm. Their
usefulness is controversial, and they tend to make patients drowsy.
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Oral
corticosteroids: These powerful anti-inflamatories have many
side effects so their use is limited. The side effects of upset
stomach, mood swings and changes to the endocrine system are
minimized if the length of treatment is limited to a week. These
medicines are often given in tapering doses daily for 7 to 10 days
and then stopped.
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Physical therapy:
Physical therapists have several treatments that can help loosen
cramped muscles and ease pain. One very important contribution they
make is to get the patient started on a specific exercise program to
strengthen the stomach and back muscles after the initial spasms
have subsided. An ongoing commitment to a home exercise program is
the best way to protect against a recurrence of back problems.
Non-operative
treatment after the first 4-6 weeks:
Most people improve
steadily and gradually for several weeks, then hit a plateau. When this
plateau is still unacceptably painful, the following treatments may be
considered.
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It is important to
determine whether the pain is more in the leg or more in the back.
Patients with leg pain predominating (sciatica) may have the
diagnosis confirmed by an MRI of the lumbar spine or a myelogram/CT
scan. Two non-surgical treatments that can be helpful:
1. Epidural steroid injection (ESI): The MRI may suggest that
an injection of corticosteroid (sometimes known as
"cortisone") directly around the spinal nerves, may be
helpful. This is a special procedure. ESIs are very safe, but the
decision to have one should only be made after a discussion with the
physician.
2. A selective nerve root block (SNRB) is an injection which
treats only one nerve. Frequently, epidurals and selective nerve
root blocks are done with X-ray control to make sure the medicine is
placed exactly where it is needed.
Herniated
Disc Patients With Back Pain Predominating:
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Exercise: The
mainstay of treatment for back pain is a good self directed home
exercise program to increase abdominal and back muscle strength, and
flexibility. There are many theories on which exercises are best.
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Anti-inflammatory
medicines (NSAIDs): These are often called arthritis medicines.
It is important for the patient to give them a full 3-4week trial
since it takes this length of time for them to become fully
effective. There are many types, and each individual can probably
find one or two that work well.
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Bracing: If
symptoms persist over a long period of time, and exercise and NSAIDs
have not improved the condition, a brace may be worn to provide
additional support to the painful disc.
Operative
Treatment for patients with Back Pain Predominating
Surgery is the final option, and should be used only if all other
treatments have failed over several months. The back pain is often due
to degeneration of the disc itself rather than a compressed nerve. When
back pain is the main symptom, the surgery most often recommended is a fusion.
In this operation, the vertebrae are fused together to limit motion.
Operative
Treatment for Patients with Leg Pain Predominating
The 20% who do not respond to treatment after at least 4-6 of
non-surgical treatment and a few who have special problems may benefit
from surgery, such as a microdiscectomy: a microscopic removal of
the disc rupture to decompress the pinched nerve.
The indications for surgery include:
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Intense leg pain.
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MRI shows a ruptured
disc compressing a nerve which is consistent with the distribution
of the leg pain.
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Testing the nerve by
stretching it ("nerve root tension signal") reproduces the
leg pain.
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There are no factors
that would make surgery a risk for the patient.
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Progressive worsening
of nerve function, such as any loss of bowel or bladder function.
The Surgical Procedure:
Microdiscectomy: The operation usually lasts 1-2 hours and provides
good or excellent results in 95% of cases. Leg pain does not disappear
immediately after surgery, but gradually disappears over several weeks.
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A general anesthetic
is used
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The patient is placed
in the prone or kneeling position on a specially padded frame.
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A small incision is
made directly over the disc, and a microscope is then used to find
the compressed nerve and move it aside so that the ruptured portion
of the disc can be seen and removed. Only the ruptured portion and
loose pieces within about ½ inch of the hole are removed.
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The space around the
nerve is then thoroughly examined to make sure no small pieces of
disc material might still compress the nerve.
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Finally, antibiotic
solutions are washed through the disc and incision to reduce the
chances of infection. An absorbable suture is used to close the
incision so that there are no stitches to be removed later.
What types of
complications may occur? All surgeries have risks, but complications
with this procedure are few. Nevertheless, it is important for the
patient to have a thorough discussion of these and other potential risks
with the doctor before making a decision to have surgery.
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Scar tissue
formation (a 5% chance): When this surgery fails, it is due to
an overgrowth of scar tissue around the nerve. Most people form some
scar tissue in the area of a surgery, but for unknown reasons, some
individuals form an extraordinary amount of scar which surrounds and
irritates the nerve. It can form along the spinal nerve inside the
spinal canal, or where the nerve exits the spine.
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Infection (a 3-5%
chance): Wound infection can happen any time an incision is
made. The bacteria can come from the skin around the incision, the
air in the operating room, or the bacteria that circulate in the
bloodstream. The steps taken in the operating room to avoid
infection are many. A dose of intravenous antibiotics right before
surgery reduces the risk of infection even more. Persistent drainage
from the wound 4-7 days after surgery usually means an infection is
present. The patient might also have fever or chills, but this is
not a reliable indication of an infection. Antibiotics are usually
successful, but sometimes it is necessary to return to the operating
room to wash out the incision. An infection does not usually
cause the operation to fail, but may slow the healing process.
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Spinal fuid leak
(approximately 1%): Spinal fluid bathes the spinal cord and is
contained inside a sac called the dura mater. Sometimes scar tissue
forms between this sac and the ruptured disc. A hole can develop in
the dura when the surgeon is looking for or removing the ruptured
disc, allowing spinal fluid to leak out. When a spinal fluid leak is
encountered, the hole is immediately repaired. Sometimes artificial
blood clot is added to form a seal around the repair. Usually the
patient is kept flat for 24 hours to allow the hole to heal before
resuming a normal recovery.
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Nerve damage at
surgery (<1% chance): A nerve that has been compressed by a
ruptured disc can be very fragile. Just moving the nerve to get at
the disc behind it might cause this fragile nerve to be damaged.
Fortunately, this is very rare, as is other surgical damage to the
nerve
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Bleeding (rare):
Blood loss is a rare complication . People whose blood does not clot
blood normally are at increased risk. The large blood vessels in
front of the spine may be damaged while removing disc material from
within the disc. This is extremely rare (perhaps one in ten thousand
cases) and requires emergency abdominal surgery to repair the
bleeding vessel.
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Recurrence (7%):
Though technically not a complication of surgery, there is about a
seven percent chance that the same disc will rupture again, most
likely in the first six weeks after surgery when the hole in the
disc annulus is healing. Even after six weeks the disc continues to
be prone to injury. This is why the maximum weight a patient should
lift is 8-10 pounds for six weeks after surgery. Abdominal
strengthening exercises are recommended for life, since strong
stomach muscles are good insurance against recurring disc problems.
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