Sciatica is a set of symptoms including pain caused by general compression or irritation of one of five spinal nerve roots of each sciatic nerve—or by compression or irritation of the left or right or both sciatic nerves. Symptoms include lower back pain, buttock pain, and pain, numbness or weakness in various parts of the leg and foot. Other symptoms include a "pins and needles" sensation, or tingling and difficulty moving or controlling the leg. Typically, symptoms only manifest on one side of the body. The pain may radiate below the knee, but does not always.
Sciatica is a relatively common form of low back and leg pain, but the true meaning of the term is often misunderstood. Sciatica is a set of symptoms rather than a diagnosis for what is irritating the root of the nerve to cause the pain. Treatment for sciatica or sciatic symptoms often differs, depending on underlying causes and pain levels. Causes include compression of the sciatic nerve roots by a herniated (torn) or protruding disc in the lower back.
Spinal disc herniation pressing on one of the lumbar or sacral nerve roots is the primary cause of sciatica, being present in about 90% of cases.
Sciatica caused by pressure from a disc herniation and swelling of surrounding tissue can spontaneously subside if the tear in the disc heals and the pulposus extrusion and inflammation cease.
Evidence suggests that spinal manipulation is an effective treatment for acute sciatica.