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Is Sciatica a Disorder or a
Symptom?
The term sciatica is commonly used to describe
pain traveling in the distribution of the sciatic nerve. Sciatica is
a symptom caused by a disorder occurring in the lumbar spine. The
sciatic nerve is the largest nerve in the human body, about the
diameter of a finger.
Sciatic nerve fibers begin at the 4th and 5th lumbar vertebra
(L4, L5) and the first few segments of the sacrum. The nerve passes
through the sciatic foramen just below the Piriformis muscle
(rotates the thigh laterally), to the back of the extension of the
hip and to the lower part of the Gluteus Maximus (muscle in the
buttock, thigh extension). The sciatic nerve then runs vertically
downward into the back of the thigh, behind the knee branching into
the hamstring muscles (calf) and further downward to the feet.
Sciatica
Fig 2
1 Sciatic Nerve (yellow) 2 Sacrum 3 Hip
Bone
Yellow = Nerves
Red = Arteries
Blue = Veins
Sciatica Symptoms
Usually sciatica affects one side of
the body. The pain may be dull, sharp, burning, or accompanied by
intermittent shocks of shooting pain beginning in the buttock
traveling downward into the back or side of the thigh and/or leg.
Sciatica then extends below the knee and may be felt in the feet.
Sometimes symptoms include tingling and numbness. Sitting and trying
to stand up may be painful and difficult. Coughing and sneezing can
intensify the pain.
The Cause: Nerve Compression
Compression of the sciatic
nerve can cause any of the above-cited symptoms. Rarely is nerve
damage permanent and paralysis is seldom a danger as the spinal cord
ends before the first lumbar vertebra. However, increasing trunk or
leg weakness, or bladder and/or bowel incontinence is an indication
of Cauda Equina Syndrome, a serious disorder requiring emergency
treatment.
Lumbar spine disorders known to cause sciatic nerve
compression include the following:
- Herniated Discs are the most common cause of sciatica
in the lumbar spine.
- Degenerative Disc Disease, a natural biological
process associated with aging, is known to cause disc weakness that
can be a precursor to a disc herniation.
- Lumbar Spinal Stenosis is a narrowing of one or more
neural passageways due to disc degeneration and/or facet arthritis.
The sciatic nerve may become impinged as a result of these changes.
- Isthmic Spondylolisthesis results from a stress
fracture often at the 5th lumbar vertebra (L5). The fracture
combined with disc space collapse may allow the vertebra to slip
forward on the first sacral segment (S1). The slippage may cause the
L5 nerve root to become pinched as it leaves the spine.
- Spinal Tumors and Infections are other disorders that
may compress the sciatic nerve, but this is rare.
There are other conditions, which may occur, and may mimic
true sciatica, but these are difficult to diagnose.
Diagnosis of Sciatica
The physician's examination includes the
patient's medical history, a review of current medications, a
physical and neurologic examination and, if warranted, x-rays, CT
scan and/or MRI. A proper diagnosis requires an analysis of the
patient's pain. The patient is often provided a Pain Diagram to
illustrate pain distribution and sensation (eg, tingling and
burning).
The physician's questions may include:
- "How did the pain develop?"
- "On a scale from 1 to 10, with 10 being the worst pain
imaginable, rate your pain."
- "Is the pain worsened by walking uphill or downhill?"
- "How does the pain affect activities of daily living?"
- "What type of treatment has been tried and what was
effective?"
The patient's range of motion is observed. Reflexes and muscle
strength are tested. The physician may use one or more movement
tests to determine the source or cause of the pain.
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