Sciatica

Source: Wikipedia, the free encyclopedia.
Sciatica
Other namesSciatic neuritis, sciatic neuralgia, lumbar radiculopathy, radicular leg pain
physical rehabilitation
Frequency2–40% of people at some time[4]

Sciatica is

Lower back pain is sometimes present.[3] Weakness or numbness may occur in various parts of the affected leg and foot.[3]

About 90% of sciatica is due to a

tumor or infection.[2] Conditions that may present similarly are diseases of the hip and infections such as early shingles (prior to rash formation).[3]

Initial treatment typically involves

limited or poor evidence for their use.[3][7][8]

Depending on how it is defined, less than 1% to 40% of people have sciatica at some point in time.[4][9] Sciatica is most common between the ages of 40 and 59, and men are more frequently affected than women.[2][3] The condition has been known since ancient times.[3] The first known use of the word sciatica dates from 1451.[10]

Definition

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.[4] Some use it to mean any pain starting in the lower back and going down the leg.[4] The pain is characteristically described as shooting or shock-like, quickly traveling along the course of the affected nerves.[11] 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.[4] Pain typically occurs in the distribution of a dermatome and goes below the knee to the foot.[4][6] It may be associated with neurological dysfunction, such as weakness and numbness.[4]

Causes

Risk factors

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

Main article: Spinal disc herniation

sacral nerve roots is the most frequent cause of sciatica, being present in about 90% of cases.[4] This is particularly true in those under age 50.[12] Disc herniation most often occurs during heavy lifting.[13] Pain typically increases when bending forward or sitting, and reduces when lying down or walking.[12]

Spinal stenosis

Main article: Lumbar spinal stenosis

Other compressive spinal causes include

herniated disc, which decreases available space for the spinal cord, thus pinching and irritating nerves from the spinal cord that become the sciatic nerve.[14] This is the most frequent cause after age 50.[12] 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.[12][14] However, pain can arise with any position or activity in severe cases.[14] The pain is most commonly relieved by rest.[14]

Piriformis syndrome

Main article: 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.

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.[16][17]

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.[18]

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.[14] 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.[19]

Other

Pain that does not improve when lying down suggests a nonmechanical cause, such as cancer, inflammation, or infection.[12] Sciatica can be caused by tumors impinging on the spinal cord or the nerve roots.[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.[14] Trauma to the spine, such as from a car accident or hard fall onto the heel or buttocks, may also lead to sciatica.[14] A relationship has been proposed with a latent Cutibacterium acnes infection in the intervertebral discs, but the role it plays is not yet clear.[20][21]

Pathophysiology

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

The sciatic nerve comprises nerve roots L4, L5, S1, S2, and S3 in the spine.[22] 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.[23]

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

sacral nerves S2 or S3 may cause sciatica.[25]

Intervertebral spinal discs consist of an outer

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.[27] 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.[13]

Other causes of sciatica secondary to spinal nerve entrapment include the roughening, enlarging, or misalignment (

radiculitis when accompanied by an inflammatory response.[14]

Extraspinal sciatica

The sciatic nerve is highly mobile during hip and leg movements.[28][29] 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.[30]

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.[31] 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.[32]

The sciatic nerve can also be entrapped outside of the pelvic space and this is called deep gluteal syndrome.[33] 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.[34] 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.[35][36]

Diagnosis

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.[4]

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.[37]

The most frequently used diagnostic test is the

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.[38] While this test is positive in about 90% of people with sciatica, approximately 75% of people with a positive test do not have sciatica.[4] 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.[14] The presence of the Fajersztajn sign is a more specific finding for a herniated disc than Lasègue's sign.[14] Maneuvers that increase intraspinal pressure, such as coughing, flexion of the neck, and bilateral compression of the jugular veins, may transiently worsen sciatica pain.[14]

Medical imaging

Imaging modalities such as

computerised tomography or magnetic resonance imaging can help with the diagnosis of lumbar disc herniation.[39] The utility of MR neurography in the diagnosis of piriformis syndrome is controversial.[15]

Discography could be considered to determine a specific disc's role in an individual's pain.[13] Discography involves the insertion of a needle into a disc to determine the pressure of disc space.[13] Radiocontrast is then injected into the disc space to assess for visual changes that may indicate an anatomic abnormality of the disc.[13] The reproduction of an individual's pain during discography is also diagnostic.[13]

Differential diagnosis

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.[42][43] The first manifestation is usually an expanding rash possibly accompanied by flu-like symptoms.[44] Lyme can also cause a milder, chronic radiculopathy an average of 8 months after the acute illness.[12]

Management

Sciatica can be managed with a number of different treatments

lumbar disc herniation (90% of cases),[4] most cases resolve spontaneously over weeks to months.[46] Initially treatment in the first 6–8 weeks should be conservative.[4] More than 75% of sciatica cases are managed without surgery.[13] In persons that smoke who also have sciatica, smoking cessation should be strongly considered, in order to promote healing.[13] Treatment of the underlying cause of nerve compression is needed in cases of epidural abscess, epidural tumors, and cauda equina syndrome.[13]

Physical activity

Physical activity is often recommended for the

conservative management of sciatica for persons who are physically able.[3] However, the difference in outcomes between physical activity compared to bed rest have not been fully elucidated.[3][47] The evidence for physical therapy in sciatica is unclear though such programs appear safe.[3] Physical therapy is commonly used.[3] Nerve mobilization techniques for sciatic nerve is supported by tentative evidence.[48]

Medication

There is no one medication regimen used to treat sciatica.

NSAIDs do not appear to improve immediate pain, and all NSAIDs appear to be nearly equivalent in their ability to relieve sciatica.[49][50][51] Nevertheless, NSAIDs are commonly recommended as a first-line treatment for sciatica.[45] In those with sciatica due to piriformis syndrome, botulinum toxin injections may improve pain and function.[52] While there is little evidence supporting the use of epidural or systemic steroids,[53][54] systemic steroids may be offered to individuals with confirmed disc herniation if there is a contraindication to NSAID use.[45] Low-quality evidence supports the use of gabapentin for acute pain relief in those with chronic sciatica.[49] Anticonvulsants and biologics have not been shown to improve acute or chronic sciatica.[45] 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.[45]

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.[55] If the cause is spondylolisthesis or spinal stenosis, surgery appears to provide pain relief for up to two years.[55]

Alternative medicine

Low to moderate-quality evidence suggests that spinal manipulation is an effective treatment for acute sciatica.[3][56] For chronic sciatica, the evidence supporting spinal manipulation as treatment is poor.[56] 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,[57] and it is contraindicated when there are progressive neurological deficits.[58]

Prognosis

About 39% to 50% of people with sciatica still have symptoms after one to four years.[59] In one study, around 20% were unable to work at their one-year followup, and 10% had had surgery for the condition.[59]

Epidemiology

Depending on how it is defined, less than 1% to 40% of people have sciatica at some point in time.[9][4] Sciatica is most common between the ages of 40 and 59, and men are more frequently affected than women.[2][3]

See also

References

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External links

  • "Sciatica". MedlinePlus. U.S. National Library of Medicine.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Sciatica&oldid=1213066392"