Sciatica

The term "sciatica" usually describes a symptom—pain along the sciatic nerve pathway—rather than a specific condition, illness, or disease. Others use the term as a diagnosis (i.e. an indication of cause and effect) for nerve dysfunction caused by compression of one or more lumbar or sacral nerve roots from a spinal disc herniation. Pain typically occurs in the distribution of a dermatome and goes below the knee to the foot. It may be associated with neurological dysfunction, such as weakness and numbness. ==Causes==

Risk factors Modifiable risk factors for sciatica include smoking, obesity, occupation, Disc herniation most often occurs during heavy lifting. Pain typically increases when bending forward or sitting, and reduces when lying down or walking. In 17% of people, the sciatic nerve runs through the piriformis muscle rather than beneath it. Deep gluteal syndrome Deep gluteal syndrome is non-discogenic, extrapelvic sciatic nerve entrapment in the deep gluteal space. There are now many known causes of sciatic nerve entrapment, such as fibrous bands restricting nerve mobility, that are unrelated to the piriformis in the deep gluteal space. Deep gluteal syndrome was created as an improved classification for the many distinct causes of sciatic nerve entrapment in this anatomic region. Pregnancy Sciatica may also occur during pregnancy, especially during later stages, as a result of the weight of the fetus pressing on the sciatic nerve during sitting or during leg spasms. Other Pain that does not improve when lying down suggests a nonmechanical cause, such as cancer, inflammation, or infection. ==Pathophysiology==

The sciatic nerve comprises nerve roots L4, L5, S1, S2, and S3 in the spine. These nerve roots merge in the pelvic cavity to form the sacral plexus and the sciatic nerve branches from that. Sciatica symptoms can occur when there is pathology anywhere along the course of these nerves. Intraspinal sciatica Intraspinal, or discogenic sciatica refers to sciatica whose pathology involves the spine. In 90% of sciatica cases, this can occur as a result of a spinal disc bulge or herniation. Sciatica is generally caused by the compression of lumbar nerves L4 or L5 or sacral nerve S1. Less commonly, sacral nerves S2 or S3 may cause sciatica. As an individual ages, the anulus fibrosus weakens and becomes less rigid, making it at greater risk for tear. Inflammation of spinal tissue can then spread to adjacent facet joints and cause facet syndrome, which is characterized by lower back pain and referred pain in the posterior thigh. Any pathology which restricts normal movement of the sciatic nerve can put abnormal pressure, strain, or tension on the nerve in certain positions or during normal movements. For example, the presence of scar tissue around a nerve can cause traction neuropathy. A well known muscular cause of extraspinal sciatica is piriformis syndrome. The piriformis muscle is directly adjacent to the course of the sciatic nerve as it traverses through the intrapelvic space. Pathologies of the piriformis muscle such as injury (e.g. swelling and scarring), inflammation (release of cytokines affecting the local cellular environment), or space occupying lesions (e.g. tumor, cyst, hypertrophy) can affect the sciatic nerve. The sciatic nerve can also be entrapped outside of the pelvic space and this is called deep gluteal syndrome. Surgical research has identified new causes of entrapment such as fibrovascular scar bands, vascular abnormalities, heterotropic ossification, gluteal muscles, hamstring muscles, and the gemelli-obturator internus complex. In almost half of the endoscopic surgery cases, fibrovascular scar bands were found to be the cause of entrapment, impeding the movement of the sciatic nerve. ==Diagnosis==

Sciatica is typically diagnosed by physical examination, and the history of the symptoms. While this test is positive in about 90% of people with sciatica, approximately 75% of people with a positive test do not have sciatica. The presence of the Fajersztajn sign is a more specific finding for a herniated disc than Lasègue's sign. Both are equally effective at diagnosing lumbar disk herniation, but computerized tomography has a higher radiation dose. Radiography is not recommended because disks cannot be visualized by X-rays. Acute Lyme radiculopathy may follow a history of outdoor activities during warmer months in likely tick habitats in the previous 1–12 weeks. In the U.S., Lyme is most common in New England and Mid-Atlantic states and parts of Wisconsin and Minnesota, but it is expanding to other areas. The first manifestation is usually an expanding rash possibly accompanied by flu-like symptoms. Lyme can also cause a milder, chronic radiculopathy an average of 8 months after the acute illness. ==Management==

Sciatica can be managed with a number of different treatments Initially treatment in the first 6–8 weeks should be conservative. Although structured exercises provide small, short-term benefit for leg pain, in the long term no difference is seen between exercise or simply staying active. The evidence for physical therapy in sciatica is unclear though such programs appear safe. Medication There is no one medication regimen used to treat sciatica. Evidence supporting the use of opioids and muscle relaxants is poor. Low-quality evidence indicates that NSAIDs do not appear to improve immediate pain, and all NSAIDs appear to be nearly equivalent in their ability to relieve sciatica. Nevertheless, NSAIDs are commonly recommended as a first-line treatment for sciatica. While there is little evidence supporting the use of epidural or systemic steroids, systemic steroids may be offered to individuals with confirmed disc herniation if there is a contraindication to NSAID use. A modest reduction in pain is seen after 26 weeks, but not after one year (about 52 weeks). Alternative medicine Low to moderate-quality evidence suggests that spinal manipulation is an effective treatment for acute sciatica. Spinal manipulation has been found generally safe for the treatment of disc-related pain; however, case reports have found an association with cauda equina syndrome, and it is contraindicated when there are progressive neurological deficits. ==Prognosis==

About 39% to 50% of people with sciatica still have symptoms after one to four years. In one study, around 20% were unable to work at their one-year followup, and 10% had surgery for the condition. ==Epidemiology==

Depending on how it is defined, less than 1% to 40% of people have sciatica at some point in time. Sciatica is most common between the ages of 40 and 59, and men are more frequently affected than women. == See also ==