Sciatica

Sciatica is pain going down the leg from the lower back.<ref name=NIH2015>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> This pain may go down the back, outside, or front of the leg.<ref name=NEJM2015/> Onset is often sudden following activities such as heavy lifting, though gradual onset may also occur.<ref name=FowlerScadding2003>Template:Cite book</ref> The pain is often described as shooting.<ref name=NIH2015/> Typically, symptoms are only on one side of the body.<ref name=NEJM2015/> Certain causes, however, may result in pain on both sides.<ref name=NEJM2015/> Lower back pain is sometimes present.<ref name=NEJM2015/> Weakness or numbness may occur in various parts of the affected leg and foot.<ref name=NEJM2015/>

About 90% of sciatica is due to a spinal disc herniation pressing on one of the lumbar or sacral nerve roots.<ref name=Valat2010/> Spondylolisthesis, spinal stenosis, piriformis syndrome, pelvic tumors, and pregnancy are other possible causes of sciatica.<ref name=NEJM2015/> The straight-leg-raising test is often helpful in diagnosis.<ref name=NEJM2015/> The test is positive if, when the leg is raised while a person is lying on their back, pain shoots below the knee.<ref name=NEJM2015/> In most cases medical imaging is not needed.<ref name=NIH2014b/> 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.<ref name=NIH2014b/> Conditions that may present similarly are diseases of the hip and infections such as early shingles (prior to rash formation).<ref name=NEJM2015/>

Initial treatment typically involves pain medications.<ref name=NIH2014b>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> However, evidence for effectiveness of the pain medication and muscle relaxants is lacking.<ref name="pmid17585160" /> It is generally recommended that people continue with normal activity to the best of their abilities.<ref name=NEJM2015/> Often all that is required for sciatica resolution is time; in about 90% of people symptoms resolve in less than six weeks.<ref name=NIH2014b/> If the pain is severe and lasts for more than six weeks, surgery may be an option.<ref name=NIH2014b/> While surgery often speeds pain improvement, its long term benefits are unclear.<ref name=NEJM2015/> Surgery may be required if complications occur, such as loss of normal bowel or bladder function.<ref name=NIH2014b/> Many treatments, including corticosteroids, gabapentin, pregabalin, acupuncture, heat or ice, and spinal manipulation, have limited or poor evidence for their use.<ref name=NEJM2015/><ref>Template:Cite journal</ref><ref name="pmid29970367">Template:Cite journal</ref>

Depending on how it is defined, less than 1% to 40% of people have sciatica at some point in time.<ref name=Valat2010>Template:Cite journal</ref><ref name=Cook2014>Template:Cite journal</ref> Sciatica is most common between the ages of 40 and 59, and men are more frequently affected than women.<ref name=NIH2014b/><ref name=NEJM2015/> The condition has been known since ancient times.<ref name=NEJM2015>Template:Cite journal</ref> The first known modern use of the word sciatica dates from 1451,<ref>Template:Cite book</ref> although Dioscorides (1st-century CE) mentions it in his Materia Medica.<ref>Dioscorides, Materia Medica (2-184, s.v. Sinepi), p. 311</ref>

Definition

File:Sciatica.jpg

Sciatica often results in pain radiating down the leg.

The term "sciatica" usually describes a symptom—pain along the sciatic nerve pathway—rather than a specific condition, illness, or disease.<ref name=Valat2010/> Some use it to mean any pain starting in the lower back and going down the leg.<ref name=Valat2010/> The pain is characteristically described as shooting or shock-like, quickly traveling along the course of the affected nerves.<ref>Bhat, Sriram (2013). SRB's Manual of Surgery. p. 364. Template:ISBN.</ref> 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.<ref name=Valat2010/> Pain typically occurs in the distribution of a dermatome and goes below the knee to the foot.<ref name=Valat2010/><ref name="pmid17585160" /> It may be associated with neurological dysfunction, such as weakness and numbness.<ref name=Valat2010/>

Causes

Risk factors

Modifiable risk factors for sciatica include smoking, obesity, occupation,<ref name=Cook2014 /> 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.<ref name=Cook2014 />

Spinal disc herniation

{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} 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.<ref name=Valat2010/> This is particularly true in those under age 50.<ref name=tarulli_radiculopathy>Template:Cite journal</ref> Disc herniation most often occurs during heavy lifting.<ref name=":3">Template:Cite book</ref> Pain typically increases when bending forward or sitting, and reduces when lying down or walking.<ref name=tarulli_radiculopathy/>

Spinal stenosis

{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} 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.<ref name=":2" /> 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.<ref name=":2" /> This is the most frequent cause after age 50.<ref name=tarulli_radiculopathy/> 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.<ref name=tarulli_radiculopathy/><ref name=":2" /> However, pain can arise with any position or activity in severe cases.<ref name=":2" /> The pain is most commonly relieved by rest.<ref name=":2" />

Piriformis syndrome

{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} 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.<ref name=Miller2012>Template:Cite journal</ref> In 17% of people, the sciatic nerve runs through the piriformis muscle rather than beneath it.<ref name=":2" /> When the piriformis shortens or spasms due to trauma or overuse, it is posited that this causes compression of the sciatic nerve.<ref name=Miller2012/> 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.<ref name="pmid19466717">Template:Cite journal</ref><ref name="pmid17030664">Template:Cite journal</ref>

Deep gluteal syndrome

{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}} Deep gluteal syndrome is non-discogenic, extrapelvic sciatic nerve entrapment in the deep gluteal space.<ref name=":5" /> 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.<ref name=":6" /><ref name=":7">Template:Cite journal</ref> 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.<ref name=":7" /> Piriformis syndrome is now considered one of many causes of deep gluteal syndrome.<ref name=":6" />

Endometriosis

Sciatic endometriosis, also called catamenial or cyclical sciatica, is a sciatica whose cause is endometriosis. Its incidence is unknown. Diagnosis is usually made by an MRI or CT-myelography.<ref name="Gandhi Wilson Liang Weissbart pp. 3–9">Template:Cite journal</ref>

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.<ref name=":2" /> While most cases do not directly harm the woman or the fetus, indirect harm may come from the numbing effect on the legs, which can cause loss of balance and falls. There is no standard treatment for pregnancy-induced sciatica.<ref>Sciatic Nerve Pain During Pregnancy: Causes and Treatment. American Pregnancy Association. Published September 20, 2017. Accessed November 12, 2018.</ref>

Other

Pain that does not improve when lying down suggests a nonmechanical cause, such as cancer, inflammation, or infection.<ref name=tarulli_radiculopathy/> Sciatica can be caused by tumors impinging on the spinal cord or the nerve roots.<ref name=Valat2010/> 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.<ref name=":2" /> Trauma to the spine, such as from a car accident or hard fall onto the heel or buttocks, may also lead to sciatica.<ref name=":2" /> A relationship has been proposed with a latent Cutibacterium acnes infection in the intervertebral discs, but the role it plays is not yet clear.<ref name=GankoRao2015>Template:Cite journal</ref><ref name=ChenZhou2016>Template:Cite journal</ref>

Pathophysiology

The sciatic nerve comprises nerve roots L4, L5, S1, S2, and S3 in the spine.<ref>Giuffre BA, Black AC, Jeanmonod R. Anatomy, Sciatic Nerve. [Updated 2023 May 4]. In: StatPearls [Internet]. Treasure Island (Florida): StatPearls Publishing; 2023 January. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482431/.</ref> 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.<ref name=":02">Davis D, Maini K, Vasudevan A. Sciatica. [Updated 2022 May 6]. In: StatPearls [Internet]. Treasure Island (Florida): StatPearls Publishing; 2023 January. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507908/.</ref>

Intraspinal sciatica

File:728 Herniated Disk.jpg

Left: Illustration of herniated spinal disc, superior view. Right: MRI showing herniated L5-S1 disc (red arrow tip), sagittal view.

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.<ref name=":3" /><ref>Template:Cite journal</ref> Sciatica is generally caused by the compression of lumbar nerves L4 or L5 or sacral nerve S1.<ref name=":4">Template:Cite book</ref> Less commonly, sacral nerves S2 or S3 may cause sciatica.<ref name=":4" />

Intervertebral spinal discs consist of an outer anulus fibrosus and an inner nucleus pulposus.<ref name=":3" /> The anulus fibrosus forms a rigid ring around the nucleus pulposus early in human development, and the gelatinous contents of the nucleus pulposus are thus contained within the disc.<ref name=":3" /> Discs separate the spinal vertebrae, thereby increasing spinal stability and allowing nerve roots to properly exit through the spaces between the vertebrae from the spinal cord.<ref>Template:Cite book</ref> As an individual ages, the anulus fibrosus weakens and becomes less rigid, making it at greater risk for tear.<ref name=":3" /> When there is a tear in the anulus fibrosus, the nucleus pulposus may extrude through the tear and press against spinal nerves within the spinal cord, cauda equina, or exiting nerve roots, causing inflammation, numbness, or excruciating pain.<ref name=":1">Template:Cite book</ref> 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.<ref name=":3" />

Other causes of sciatica secondary to spinal nerve entrapment include the roughening, enlarging, or misalignment (spondylolisthesis) of vertebrae, or disc degeneration that reduces the diameter of the lateral foramen through which nerve roots exit the spine.<ref name=":3" /> 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.<ref name=":2" />

Extraspinal sciatica

File:Fibrovascular entrapment of the sciatic nerve undefined distribution.jpg

Illustration of fibrovascular bands restricting mobility of the sciatic nerve in multiple directions, like a splattering of glue

The sciatic nerve is highly mobile during hip and leg movements.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> 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.<ref>Template:Cite journal</ref>

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.<ref name=":02"/> Anatomic variations in nerve branching can also predispose the sciatic nerve to further compression by the piriformis muscle, such as if the sciatic nerve pierces the piriformis muscle.<ref>Template:Cite journal</ref>

The sciatic nerve can also be entrapped outside of the pelvic space and this is called deep gluteal syndrome.<ref name=":5">Template:Cite journal</ref> 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.<ref name=":6">Template:Cite journal</ref> 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.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Diagnosis

File:Straight-leg-test.gif

Straight leg test sometimes used to help diagnose a lumbar herniated disc

Sciatica is typically diagnosed by physical examination, and the history of the symptoms.<ref name=Valat2010/>

Physical tests

Generally, if a person reports the typical radiating pain in one leg, as well as one or more neurological indications of nerve root tension or neurological deficit, sciatica can be diagnosed.<ref name="pmid17585160" />

The most frequently used diagnostic test is the straight leg raise to produce Lasègue's sign, which is considered positive if pain in the distribution of the sciatic nerve is reproduced with passive flexion of the straight leg between 30 and 70 degrees.<ref name="pmid15130982">Template:Cite journal</ref> While this test is positive in about 90% of people with sciatica, approximately 75% of people with a positive test do not have sciatica.<ref name=Valat2010/> Straight leg raising of the leg unaffected by sciatica may produce sciatica in the leg on the affected side; this is known as the Fajersztajn sign.<ref name=":2">Template:Cite book</ref> The presence of the Fajersztajn sign is a more specific finding for a herniated disc than Lasègue's sign.<ref name=":2" /> Maneuvers that increase intraspinal pressure, such as coughing, flexion of the neck, and bilateral compression of the jugular veins, may transiently worsen sciatica pain.<ref name=":2" />

Medical imaging

Imaging modalities such as computerised tomography or magnetic resonance imaging can help with the diagnosis of lumbar disc herniation.<ref name="Gregory et al.">Template:Cite journal</ref> Both are equally effective at diagnosing lumbar disk herniation, but computerized tomography has a higher radiation dose.<ref name="pmid17585160">Template:Cite journal</ref> Radiography is not recommended because disks cannot be visualized by X-rays.<ref name="pmid17585160" /> The utility of MR neurography in the diagnosis of piriformis syndrome is controversial.<ref name=Miller2012/>

Discography could be considered to determine a specific disc's role in an individual's pain.<ref name=":3" /> Discography involves the insertion of a needle into a disc to determine the pressure of disc space.<ref name=":3" /> Radiocontrast is then injected into the disc space to assess for visual changes that may indicate an anatomic abnormality of the disc.<ref name=":3" /> The reproduction of an individual's pain during discography is also diagnostic.<ref name=":3" />

Differential diagnosis

Cancer should be suspected if there is previous history of it, unexplained weight loss, or unremitting pain.<ref name=tarulli_radiculopathy/> Spinal epidural abscess is more common among those who have diabetes mellitus or immunodeficiency, or who have had spinal surgery, injection or catheter; it typically causes fever, leukocytosis and increased erythrocyte sedimentation rate.<ref name=tarulli_radiculopathy/> If cancer or spinal epidural abscess is suspected, urgent magnetic resonance imaging is recommended for confirmation.<ref name=tarulli_radiculopathy/> Proximal diabetic neuropathy typically affects middle aged and older people with well-controlled type-2 diabetes mellitus; onset is sudden, causing pain, usually in multiple dermatomes, quickly followed by weakness. Diagnosis typically involves electromyography and lumbar puncture.<ref name=tarulli_radiculopathy/> 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.<ref name=tarulli_radiculopathy/><ref name=Dwo2007>Template:Cite journal</ref> Acute Lyme radiculopathy may follow a history of outdoor activities during warmer months in likely tick habitats in the previous 1–12 weeks.<ref name=NEJM2014>Template:Cite journal</ref> 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.<ref name=CDC-Lyme-Data>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name=canada_lyme_map>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The first manifestation is usually an expanding rash possibly accompanied by flu-like symptoms.<ref name=ogrinc_bannwarth>Template:Cite journal</ref> Lyme can also cause a milder, chronic radiculopathy an average of 8 months after the acute illness.<ref name=tarulli_radiculopathy/>

Management

Sciatica can be managed with a number of different treatments<ref name=Lew2015/> with the goal of restoring a person's normal functional status and quality of life.<ref name=":3" /> When the cause of sciatica is lumbar disc herniation (90% of cases),<ref name="Valat2010" /> most cases resolve spontaneously over weeks to months.<ref name="pmid21292142">Template:Cite journal</ref> Initially treatment in the first 6–8 weeks should be conservative.<ref name=Valat2010/> More than 75% of sciatica cases are managed without surgery.<ref name=":3" /> Smokers with sciatica are strongly urged to quit in order to promote healing.<ref name=":3" /> Treatment of the underlying cause of nerve compression is needed in cases of epidural abscess, epidural tumors, and cauda equina syndrome.<ref name=":3" />

Physical activity

Physical activity is often recommended for the conservative management of sciatica for persons who are physically able.<ref name="NEJM2015" /> Bed rest is not recommended.<ref name="pmid32291226">Template:Cite journal</ref> 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.<ref name="pmid26165218">Template:Cite journal</ref> The evidence for physical therapy in sciatica is unclear though such programs appear safe.<ref name=NEJM2015/> Physical therapy is commonly used.<ref name=NEJM2015/> Nerve mobilization techniques for sciatic nerve are supported by tentative evidence.<ref>Template:Cite journal</ref>

Medication

There is no one medication regimen used to treat sciatica.<ref name=Lew2015>Template:Cite journal</ref> Evidence supporting the use of opioids and muscle relaxants is poor.<ref name=Pinto2012>Template:Cite journal</ref> 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.<ref name=Pinto2012/><ref name="pmid28153830">Template:Cite journal</ref><ref name="pmid27743405">Template:Cite journal</ref> Nevertheless, NSAIDs are commonly recommended as a first-line treatment for sciatica.<ref name="Lew2015" /> In those with sciatica due to piriformis syndrome, botulinum toxin injections may improve pain and function.<ref name="pmid21249702">Template:Cite journal</ref> While there is little evidence supporting the use of epidural or systemic steroids,<ref name="pmid22495738">Template:Cite journal</ref><ref name="pmid26302454">Template:Cite journal</ref> systemic steroids may be offered to individuals with confirmed disc herniation if there is a contraindication to NSAID use.<ref name="Lew2015" /> Low-quality evidence supports the use of gabapentin for acute pain relief in those with chronic sciatica.<ref name=Pinto2012/> Anticonvulsants and biologics have not been shown to improve acute or chronic sciatica.<ref name="Lew2015" /> Antidepressants have demonstrated some efficacy in treating chronic sciatica, and may be offered to individuals who are not amenable to NSAIDs or who have failed NSAID therapy.<ref name="Lew2015" />

Surgery

If sciatica is caused by a herniated disc, the disc's partial or complete removal, known as a discectomy, has tentative evidence of benefit in the short term.<ref name=Fer2016>Template:Cite journal</ref> A modest reduction in pain is seen after 26 weeks, but not after one year (about 52 weeks).<ref name="pmid32291226" /> If the cause is spondylolisthesis or spinal stenosis, surgery appears to provide pain relief for up to two years.<ref name=Fer2016/>

For non-discogenic sciatica, the surgical treatment is typically a nerve decompression. A decompression seeks to remove tissue around the nerve that may be compressing it or restricting movement of the nerve.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Alternative medicine

Low to moderate-quality evidence suggests that spinal manipulation is an effective treatment for acute sciatica.<ref name=NEJM2015/><ref name=Leininger2011/> For chronic sciatica, the evidence supporting spinal manipulation as treatment is poor.<ref name=Leininger2011>Template:Cite journal</ref> 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,<ref name="pmid21404036">Template:Cite journal</ref> and it is contraindicated when there are progressive neurological deficits.<ref name=WHO-chiro-guidelines>WHO guidelines on basic training and safety in chiropractic. "2.1 Absolute contraindications to spinal manipulative therapy", p. 21. Template:Webarchive WHO</ref>

Prognosis

About 39% to 50% of people with sciatica still have symptoms after one to four years.<ref name=Wil2011>Template:Cite book</ref> In one study, around 20% were unable to work at their one-year followup, and 10% had surgery for the condition.<ref name=Wil2011/>

Epidemiology

Depending on how it is defined, less than 1% to 40% of people have sciatica at some point in time.<ref name=Cook2014/><ref name=Valat2010/> Sciatica is most common between the ages of 40 and 59, and men are more frequently affected than women.<ref name=NIH2014b/><ref name=NEJM2015/>

See also

• Failed back syndrome
• Low back pain
• Lumbar spinal stenosis
• Nerve compression syndrome
• Neuropathic pain
• Paresthesia
• Piriformis syndrome
• Sciatic nerve
• Spinal disk herniation
• Spondylolisthesis

External links

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