Article: Sciatica

Sciatica is a pain in the leg due to irritation of the sciatic nerve. The pain generally goes from the back of the thigh to the back of the calf, and may also extend upward to the hip and down to the foot. In addition to pain, there may be numbness and difficulty moving or controlling the leg. Typically, the symptoms are only felt on one side.

Although sciatica is a relatively common form of low back pain and leg pain, the true meaning of the term is often misunderstood. Sciatica is a set of symptoms rather than a diagnosis for what is irritating the nerve root and causing the pain. This is an important point because treatment for sciatica or sciatica-type symptoms will often be different depending on the underlying cause of the symptoms.

The first cited use of the word occurs in 1450 ^[1].

Causes of sciatica

Sciatica is generally caused by compression of a nerve root in the lumbar spine, and far less commonly by compression of the sciatic nerve itself. "True" sciatica, therefore is caused by compression at the nerve root from a "slipped disc" (a herniated disc in the spine), roughening and enlarging and/or misalignment of the vertebrae (spondylolisthesis), or degenerated discs[1].

Sciatica may also be experienced in late pregnancy either as the result of the uterus pressing on the sciatic nerve, or secondarily from muscular tension or vertebral compression associated with the extra weight and postural changes inherent in pregnancy.

"Pseudo-sciatica", which causes symptoms similar to spinal nerve root compression, is caused by compression of more peripheral sections of the nerve, usually from soft tissue tension in the piriformis or other related muscles. The most predominant form of this condition is known as piriformis syndrome. With this condition the piriformis muscle, which is located beneath the gluteal muscles, contracts in spasm and strangles the sciatic nerve, which is located beneath the muscle. Another cause of sciatica-type symptoms is sacroiliac joint dysfunction. Unhealthy postural habits such as excessive sitting in chairs and sleeping in the fetal position, along with insufficient stretching and exercise of the relevant myofascial areas, can lead to both the vertebral and soft tissue problems associated with sciatica.

Yet another source of sciatica symptoms is caused by active trigger points in the lower back or gluteal muscles. In this case, the referred pain is not, in fact, coming from compression of the sciatic nerve, though the pain distribution down the buttocks and leg can be quite similar. Trigger points occur when muscles become ischemic (low blood flow) due to injury or chronic muscular contraction. The muscles most commonly associated with trigger points causing sciatica symptoms are the quadratus lumborum, the gluteus medius and minimus, and the deep hip rotators.

One major cause of sciatica is a disc herniation which has placed pressure on the sciatic nerve. The discs are composed of a spongy-type cartilage material with a liquid filled center. The discs separate the vertebrae and thereby allow room for the sciatic nerve to properly exit through the sacral portion of the pelvis into the leg. The discs will cushion the spine from compressive forces, but have weakness with regards to the pressure applied during rotational movements. That is why a person who bends over to one side at a bad angle to pick up a piece of paper may be more likely to herniate the disc than a person falling off a ladder and landing on their back. Compression of the sciatic nerve from a disc herniation occurs when the center of the disc bulges outward, tearing the outside ring of fibers and ballooning itself onto the root and thus causing sciatica.

Other compressive spinal type of causes include Spinal Canal Stenosis, a condition in which the canal that the spine runs through narrows to compress the cord itself. This canal narrowing can lead to a decreased space for the sciatic nerve to exit, and thus cause a pinching and friction irritation. The sciatic nerve runs through a muscle in the buttocks region called the piriformis. When the muscle shortens or spasms due to trauma, it can compress the sciatic nerve. This cause of sciatica symptoms is known as Piriformis Syndrome. The approach to treating Sciatica is to reduce the compressive forces that are causing the pressure on the nerve. This can be accomplished through traction and realignment therapeutic procedures in the case where it is spinal related. Manual muscle stretching, massage and mobilization techniques should be utilized when it is piriformis related. General goals include helping the muscles to loosen up and thereby lessen the pain and to minimize any inflammation.

Diagnosis and Treatment

Because of the many conditions that can compress nerve roots and cause sciatica, treatment options often differ from patient to patient. Treatment of the underlying cause of the compression is often the most effective course. When the cause is due to a prolapsed or lumbar disc herniation research has shown that with supportive treatment to help relieve pain 90% of disc prolapse will recover with no specific intervention. Genetics appear to influence the risk of developing disc herniation.

Imaging methods such as MRI neurography may help diagnosis and treatment of sciatica. MR neurography is a modified MRI technique using MRI software to provide better pictures of the spinal nerves and the effect of compression on these nerves. MR neurography may help diagnose piriformis syndrome which is another cause of sciatica that does not involve disc herniation. MR neurography is considered experimental and is not covered by insurances.

Most cases of sciatica can be effectively treated by physical therapy or massage therapy and appropriate changes in behavior and environment (for example cushioning, chair and desk height, exercise, stretching). Other conservative treatment options include anti-inflammatory medications (i.e. NSAIDs or oral steroids), pain medications, and epidural steroid injections (however the latter carries the risk of possible side effects and complications from the needle puncture and medications used).

"Alternative" and "complementary" treatments include chiropractic manipulation (although there is no scientific consensus for chiropractic's effectiveness) and somatics. Acupuncture has no effect beyond placebo in treating sciatica.

See also

• Lumbar disc herniation
• Back pain