Sciatica is pain going down the leg from the lower back. This pain may extend down the back, outside, or front of the leg. The onset is often sudden following activities such as heavy lifting, although it may also occur gradually. The pain is often described as shooting. Typically, symptoms occur on only one side of the body; certain causes, however, may result in pain on both sides. Lower back pain is sometimes present. Weakness or numbness may occur in different parts of the affected leg and foot. About 90% of sciatica is due to a spinal disc herniation pressing on one of the lumbar or sacral nerve roots. Spondylolisthesis, spinal stenosis, piriformis syndrome, pelvic tumors, and pregnancy are other possible causes of sciatica. The straight-leg-raising test is often helpful in diagnosis. The test is positive if, when the leg is raised while a person is lying on their back, pain shoots below the knee. In most cases medical imaging is not needed. However, imaging may be obtained if bowel or bladder function is affected, there is significant loss of feeling or weakness, symptoms are long standing, or there is a concern for tumor or infection. Conditions that can present similarly are diseases of the hip and infections such as early shingles (prior to rash formation). Initial treatment typically consists of pain medications. However, evidence for effectiveness of pain medication, and of muscle relaxants, is lacking. It is generally recommended that people continue with normal activity to the best of their abilities. Often all that is required for resolution of sciatica is time; in about 90% of cases, symptoms resolve in less than six weeks. If the pain is severe and lasts for more than six weeks, surgery may be an option. While surgery often speeds pain improvement, its long term benefits are unclear. Surgery may be required if complications occur, such as loss of normal bowel or bladder function. Many treatments, including corticosteroids, gabapentin, pregabalin, acupuncture, heat or ice, and spinal manipulation, have only limited or poor evidence supporting their use. 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. The condition has been known since ancient times. The first known modern use of the word sciatica dates from 1451, although Dioscorides (1st-century CE) mentions it in his Materia Medica.
Definition
The term "sciatica" usually describes a symptom—pain along the sciatic nerve pathway—rather than a specific condition, illness, or disease. Some use it to mean any pain starting in the lower back and going down the leg. The pain is characteristically described as shooting or shock-like, quickly traveling along the course of the affected nerves. 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, and physical sports where back muscles and heavy weights are involved. Non-modifiable risk factors include increasing age, being male, and having a personal history of low back pain.
Spinal disc herniation
Spinal disc herniation pressing on one of the lumbar or sacral nerve roots is the most frequent cause of sciatica, being present in about 90% of cases. This is particularly true in those under age 50. Disc herniation most often occurs during heavy lifting. Pain typically increases when bending forward or sitting, and reduces when lying down or walking.
Spinal stenosis
Other compressive spinal causes include lumbar spinal stenosis, a condition in which the spinal canal, the space the spinal cord runs through, narrows and compresses the spinal cord, cauda equina, or sciatic nerve roots. This narrowing can be caused by bone spurs, spondylolisthesis, inflammation, or a herniated disc, which decreases available space for the spinal cord, thus pinching and irritating nerves from the spinal cord that become the sciatic nerve. This is the most frequent cause after age 50. Sciatic pain due to spinal stenosis is most commonly brought on by standing, walking, or sitting for extended periods of time, and reduces when bending forward. However, pain can arise with any position or activity in severe cases. The pain is most commonly relieved by rest.
Piriformis syndrome
Piriformis syndrome is a condition that, depending on the analysis, varies from a "very rare" cause to contributing up to 8% of low back or buttock pain. In 17% of people, the sciatic nerve runs through the piriformis muscle rather than beneath it. When the piriformis shortens or spasms due to trauma or overuse, it is posited that this causes compression of the sciatic nerve. Piriformis syndrome has colloquially been referred to as "wallet sciatica" since a wallet carried in a rear hip pocket compresses the buttock muscles and sciatic nerve when the bearer sits down. Piriformis syndrome may be suspected as a cause of sciatica when the spinal nerve roots contributing to the sciatic nerve are normal and no herniation of a spinal disc is apparent.
Deep gluteal syndrome
Deep gluteal syndrome is non-discogenic, extrapelvic sciatic nerve entrapment in the deep gluteal space. Piriformis syndrome was once the traditional model of sciatic nerve entrapment in this anatomic region. The understanding of non-discogenic sciatic nerve entrapment has changed significantly with improved knowledge of posterior hip anatomy, nerve kinematics, and advances in endoscopic techniques to explore the sciatic nerve. 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. Piriformis syndrome is now considered one of many causes of deep gluteal syndrome.
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