Sciatica is caused by compression of the sciatic nerve in the lumbar (lower) spine. The sciatic nerve is the largest single nerve in the body. It begins in the lumbar spine and runs through the buttock, down the back of the leg, and into the foot. When the root of the sciatic nerve is compressed at its exit from the spinal cord, the symptoms can radiate along the entire length of the nerve.
The technical term for compression of a nerve root is radiculopathy. Sciatica is one type of radiculopathy.
Sciatica can cause a variety of symptoms, which may include:
- Constant pain in one side of the buttock or leg (rarely occurs in both legs)
- Burning or tingling pain in the leg, usually worse when sitting
- Weakness, numbness or difficulty moving the leg or foot
- “Foot drop”–the inability to bend the foot upwards at the ankle
- A sharp pain that may make it difficult to stand up or walk
Causes and Risk Factors
Sciatica describes pain that comes from a problem with the lumbar and sacral nerve roots that make the sciatic nerve. Sciatica is always caused by something–it is a symptom of another problem.
A common cause of sciatica is a herniated disc in the lumbar spine. A herniated disc occurs when the fibrous outer portion of the disc ruptures or tears and the soft cartilage core herniates out. The protruding section of the disc can compress the sciatic nerve root.
Sciatica can also be caused by lumbar spinal stenosis, which is a narrowing of the spinal canal in the lumbar spine. This narrowing can also compress the sciatic nerve root.
The chances of developing sciatica are highest in middle age. After 50 years old, the chances of developing sciatica declines.
Tests and Diagnosis
If a patient presents with symptoms associated with sciatica, the doctor may order any of the following diagnostic procedures:
- X-ray – test that uses invisible electromagnetic energy beams to produce images of bones.
- Magnetic resonance (MR) imaging – a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body. This procedure can help identify herniated discs.
- CT myelogram – a diagnostic imaging procedure that provides images of bones and nerve roots.
- Electromyography (EMG) – a diagnostic imaging procedure that provides information on the health of muscles and the nerve cells that control them.
For the most part, symptoms of sciatica go away in a few weeks with conservative (non-operative) treatment.
Nonoperative treatments include:
- pain medication
- heat/ice packs
- steroid injections
- massage therapy
- stretching and strengthening exercises
However, surgery may be considered if sciatic pain does not respond to nonoperative measures, if pain is severe, or if a patient experiences progressive numbness or weakness.
If sciatica is due to a herniated disc, the surgeon will perform a procedure known as a microdiscectomy.
If sciatica is due to lumbar stenosis, the surgeon will perform a procedure known as a laminectomy.
In some cases, the surgeon may need to perform a combination of microdiscectomy and laminectomy. The surgeon will tailor the treatment to each patient and each condition.