[3] About 90% of sciatica is due to a spinal disc herniation pressing on one of the lumbar or sacral nerve roots.

[4] Spondylolisthesis, spinal stenosis, piriformis syndrome, pelvic tumors, and pregnancy are other possible causes of sciatica.

[3] The test is positive if, when the leg is raised while a person is lying on their back, pain shoots below the knee.

[2] 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.

[2] Conditions that may present similarly are diseases of the hip and infections such as early shingles (prior to rash formation).

[2] Many treatments, including corticosteroids, gabapentin, pregabalin, acupuncture, heat or ice, and spinal manipulation, have limited or poor evidence for their use.

[4] Modifiable risk factors for sciatica include smoking, obesity, occupation,[9] 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.

[9] 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.

[13] 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.

[15] 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.

[15] When the piriformis shortens or spasms due to trauma or overuse, it is posited that this causes compression of the sciatic nerve.

Deep gluteal syndrome was created as an improved classification for the many distinct causes of sciatic nerve entrapment in this anatomic region.

[22] 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.

[4] Severe back pain extending to the hips and feet, loss of bladder or bowel control, or muscle weakness may result from spinal tumors or cauda equina syndrome.

[15] Trauma to the spine, such as from a car accident or hard fall onto the heel or buttocks, may also lead to sciatica.

[15] A relationship has been proposed with a latent Cutibacterium acnes infection in the intervertebral discs, but the role it plays is not yet clear.

[30] As an individual ages, the anulus fibrosus weakens and becomes less rigid, making it at greater risk for tear.

[14] When sciatica is caused by compression of a dorsal nerve root, it is considered a lumbar radiculopathy or radiculitis when accompanied by an inflammatory response.

[20] 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.

[15] Maneuvers that increase intraspinal pressure, such as coughing, flexion of the neck, and bilateral compression of the jugular veins, may transiently worsen sciatica pain.

[39] Both are equally effective at diagnosing lumbar disk herniation, but computerized tomography has a higher radiation dose.

[13] If cancer or spinal epidural abscess is suspected, urgent magnetic resonance imaging is recommended for confirmation.

[13] Shingles is more common among the elderly and immunocompromised; typically, pain is followed by the appearance of a rash with small blisters along a single dermatome.

[13][40] Acute Lyme radiculopathy may follow a history of outdoor activities during warmer months in likely tick habitats in the previous 1–12 weeks.

[41] 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.

[13] Sciatica can be managed with a number of different treatments[45] with the goal of restoring a person's normal functional status and quality of life.

[45] In those with sciatica due to piriformis syndrome, botulinum toxin injections may improve pain and function.

[47] If the cause is spondylolisthesis or spinal stenosis, surgery appears to provide pain relief for up to two years.

[57][58][59] Low to moderate-quality evidence suggests that spinal manipulation is an effective treatment for acute sciatica.