Sciatica

Definition

Sciatica refers to pain or discomfort associated with the sciatic nerve. This nerve runs from the lower part of the spinal cord, down the back of the leg, to the foot. Injury to or pressure on the sciatic nerve can cause the characteristic pain of sciatica: a sharp or burning pain that radiates from the lower back or hip, possibly following the path of the sciatic nerve to the foot.

Description

The sciatic nerve is the largest and longest nerve in the body. About the thickness of a person's thumb, it spans from the lower back to the foot. The nerve originates in the lower part of the spinal cord, the so-called lumbar region. As it branches off from the spinal cord, it passes between the bony vertebrae (the component bones of the spine) and runs through the pelvic girdle, or hip bones. The nerve passes through the hip joint and continues down the back of the leg to the foot.

Sciatica is a fairly common disorder and approximately 40% of the population experiences it at some point in their lives. However, only about 1% have coexisting sensory or motor deficits. Sciatic pain has several root causes and treatment may hinge upon the underlying problem.

Of the identifiable causes of sciatic pain, lumbosacral radiculopathy and back strain are the most frequently suspected. The term lumbosacral refers to the lower part of the spine, and radiculopathy describes a problem with the spinal nerve roots that pass between the vertebrae and give rise to the sciatic nerve. This area between the vertebrae is cushioned with a disk of shock-absorbing tissue. If this disk shifts or is damaged through injury or disease, the spinal nerve root may be compressed by the shifted tissue or the vertebrae.

This compression of the nerve roots sends a pain signal to the brain. Although the actual injury is to the

nerve roots, the pain may be perceived as coming from anywhere along the sciatic nerve.

The sciatic nerve can be compressed in other ways. Back strain may cause muscle spasms in the lower back, placing pressure on the sciatic nerve. In rare cases, infection, cancer , bone inflammation, or other diseases may be causing the pressure. More likely, but often overlooked, is the piriformis syndrome. As the sciatic nerve passes through the hip joint, it shares the space with several muscles. One of these muscles, the piriformis muscle, is closely associated with the sciatic nerve. In some people, the nerve actually runs through the muscle. If this muscle is injured or has a spasm, it places pressure on the sciatic nerve, in effect, compressing it.

In many sciatica cases, the specific cause is never identified. About half of affected individuals recover from an episode within a month. Some cases can linger a few weeks longer and may require aggressive treatment. In some cases, the pain may return or potentially become chronic.

Demographics

A common disorder, sciatica affects about 40 percent of the population. It is found more frequently in people 30 to 50 years old, but occurs often in the elderly due to degenerative spinal disorders. Most often, sciatica is seen as a result of general wear and tear on the lower lumbosacral spine.

Causes and symptoms

Causes

The most common cause of sciatic pain is pressure on the nerves in the lumbosacral spine. Injury to the pelvis or other trauma can cause sciatica. However, it is most often a disc (a pad of shock-absorbing tissue between each vertebra) that bulges or is herniated, usually near the L4 or L5, and presses on the sciatic nerve and causes pain, numbness, or tingling. This is often called a slipped disc. Degenerative disc disease, a condition where the discs begin to break down or crumble, can irritate the nerves, too. Sometimes, a disc may rupture, causing a jelly-like substance to seep out and press on the sciatic nerve. A bulging disc can form slowly over time. A ruptured disc may be caused by an injury, bone spurs growing from the spine, or aging.

Spondylolisthesis, a condition when one vertebra slips forward over another, can press against the sciatic nerve. This action is similar to a slipped disc, except here it is a vertebra that has moved. Spondylolisthesis is the result of degenerative disc disease.

Back strain can cause the muscles in the lower back to spasm and swell. This can also put pressure against the sciatic nerve.

Some medical disorders can also cause sciatic pain. Lumbar spinal stenosis , a narrowing of the spinal canal, is found in adults over 60 years old. This condition can put pressure on the sciatic nerve. Other diseases that can cause sciatica are spinal arthritis, diabetes, and cancer.

Pregnancy can also cause sciatic pain. The growing fetus can shift internal structures so that pressure is placed on the sciatic nerve.

Other conditions such as sacroiliac joint dysfunction or piriformis syndrome can mimic sciatica symptoms, but are not actually sciatica. An irritation of the sacroiliac joint can irritate the nerve at L5 and can cause sciatic-like pain. Piriformis syndrome is a spasm of the piriformis muscle that is located near the sciatic nerve. In some cases, the sciatic nerve runs through the muscle itself. If the piriformis muscle is injured or spasms, it can press against the sciatic nerve. Runners, race walkers, and people who sit for long periods can experience piriformis syndrome.

In a number of cases, no specific cause for the sciatic pain or numbness is discovered.

Symptoms

Pain is the most pronounced symptom of sciatica. It is often accompanied by numbness or a burning or tingling sensation. Often, the pain is felt even during sitting, but may be more pronounced when attempting to stand. Some patients feel pain increase when they walk any distance.

Where that pain is felt, however, is largely a factor of where the sciatic nerve is compressed. Each region affects different parts of the lower extremities and produces characteristic symptoms.

If the nerve is affected in the region of L3-L4, the patient will have pain and/or numbness in the lower leg and foot and can have problems trying to walk on the heel of the foot. The patient may also have reduced knee-jerk reflex.

A sciatic nerve compression near L4-L5 results in pain and/or numbness in the top of the foot, especially near the area between the big toe and the second toe. The patient may present with weakness in the ankle that causes the foot to drop or drag.

Patients who have sciatic compression near L5-S1 experience pain and/or numbness in the outside regions of the foot. The patient has reduced ankle-jerk reflex and has trouble walking on tip toe.

Pressure on the sacral nerves from sacroiliac joint dysfunction produces a deep ache inside the leg, rather than pain in a specific area as in true sciatica. Piriformis syndrome causes pain or numbness most commonly in the buttocks and can radiate downward, mimicking true sciatica.

Diagnosis

Before treating sciatic pain, as much information as possible is collected. The individual is asked to recount the location and nature of the pain, how long it has continued, and any accidents or unusual activities prior to its onset. This information provides clues that may point to back strain or injury to a specific location. Back pain from disk disease, piriformis syndrome, and back strain must be differentiated from more serious conditions such as cancer or infection. Lumbar stenosis, an overgrowth of the covering layers of the vertebrae that narrows the spinal canal, must also be considered. The possibility that a difference in leg lengths is causing the pain should be evaluated; the problem can be easily be treated with a foot orthotic or built-up shoe.

Often, a straight-leg-raising test is done, in which the person lies face upward and the health-care provider raises the affected leg to various heights. This test pinpoints the location of the pain and may reveal whether it is caused by a disk problem. Other tests, such as having the individual rotate the hip joint, assess the hip muscles. Any pain caused by these movements may provide information about involvement of the piriformis muscle, and piriformis weakness is tested with additional leg-strength maneuvers.

Further tests may be done depending on the results of the physical examination and initial pain treatment. Such tests might include magnetic resonance imaging (MRI) and computed tomography scans (CT scans ). Other tests examine the conduction of electricity through nerve tissues, and include studies of the electrical activity generated as muscles contract (electromyography), nerve conduction velocity, and evoked potential testing. A more invasive test involves injecting a contrast substance into the space between the vertebrae and making x-ray images of the spinal cord (myelography), but this procedure is usually done only if surgery is being considered. All of these tests can reveal problems with the vertebrae, the disk, or the nerve itself.

Treatment

Returning the patient to mobility and independence is the goal of treatment. Since pain must be managed before further options are considered, the doctor will prescribe over-the-counter NSAIDS (non-steroidal anti-inflammatory drugs ) such as naproxen and ibuprofen. Oral steroids may also be prescribed for herniated discs. Muscle relaxants may be prescribed, especially for piriformis syndrome.

If a patient is in severe pain, the doctor may inject steroids directly into the area around the sciatic nerve. This decreases inflammation and offers temporary pain relief. Some patients experience relief for up to a year; others are pain-free for a week. Though this procedure does not work for everyone, it can be necessary relief for the patient to be able to complete the physical therapy necessary for recovery.

Bed rest is discouraged, though the doctor may recommend frequent rest periods when the patient can apply heat to the lower back to treat the inflammation of sciatica. Moist heat is the most effective.

The doctor may also begin to treat any underlying condition that may have caused or contributed to the bout of sciatica. Depending on the cause, specific treatment may be postponed until the current sciatic episode has passed.

Once the pain is under control, the doctor often will refer the patient to a physical therapist for a regime of exercise and education specific to the patient's type of sciatica. Ultrasound, transcutaneous electrical stimulation (TENs), biofeedback , and deep tissue massage may also be ordered by the physical therapist.

Braces, splints, or orthopedic shoes may help some patients accommodate for lost impairment. However, these are not permanent solutions. They may help a patient continue to work or go about daily activities until they can strengthen the muscles necessary to support the back.

Occupational therapy may also be helpful to educate patients about proper body alignment when doing daily tasks or work requirements. Other behavioral education may be necessary.

Surgery is only used in extreme cases when the sciatic nerve creates significant weakness or loss of bladder or bowels. However, surgery (diskectomy) is often used to remove part of a herniated disc. This procedure can be done with a microscope (microdisketomy). Surgery for degenerative disc disease does not stop the progression of this disease; it merely relieves the immediate problem. A study in 2007 reported that though disc surgery patients may receive immediate relief, they had similar positive outcomes a year later as those of patients who chose conservative treatment over surgery.

Alternative treatments

The doctor may also recommend alternative treatments to help a patient either manage the pain or treat the underlying cause.

Acupuncture is the Eastern practice of balancing the body's natural energies by inserting thin sterilized needles into specific parts of the body. The procedure is relatively painless, and many patients experience peaceful relaxation during the process. The National Institutes of Health has noted that acupuncture is effective in relieving the pain of sciatica and other back discomfort.

QUESTIONS TO ASK YOUR DOCTOR

• What is the cause of my sciatica pain?
• What can be done to treat that condition?
• What tests will I have to take?
• How long will I need to take pain medication?
• What can I expect from the physical therapist?
• What alternative treatments do you recommend?
• What home care do you suggest?
• How long before I can go back to my regular activities?
• Will I have to have surgery?

Though massage cannot help remove the pressure of a disc against the sciatic nerve, it can relax tense muscles in the lower back and buttocks and stimulate blood flow. This is especially helpful for patients suffering from piriformis syndrome. Massage also is relaxing and can help release endorphins, the body's natural pain relievers.

Chiropractic manipulations can help align the spine. They may be helpful for some disc problems.

Further, yoga has been found to be useful for keeping the muscles stretched and the spine flexible. However, care may need to be taken regarding some postures that put stress on the lower back. Those include any type of sitting cross legged or extreme stretches of the spine.

Nutrition/Dietetic concerns

There are no dietietic concerns regarding sciatica.

Therapy

Physical therapy is essential to successful recovery from sciatica. Inactivity, especially bed rest, has been found to make sciatic pain worse. Consistent movement keeps the body supple and strengthens critical muscles that support the lower back and legs. Walking and swimming, including pool therapy, are essential long-term exercises necessary to prevent sciatica recurrence.

Prognosis

Most cases of sciatica are treatable with pain medication and physical therapy. After 4–6 weeks of treatment, an individual should be able to resume normal activities.

KEY TERMS

Disc —A tissue between two vertebrae that cushions the spine.

Diskectomy —Surgery to remove part of a herniated disc.

CT —Computerized tomography, a test that uses a dye and a computer to image parts of the body

Coccyx —The tail bone or last four vertebrae of the spine.

Electromyography —An electrical activity test of the nerves and muscles.

Lumbosacral spine —The lower portion of the spine, including the sacrum and the coccyx.

MRI —Magnetic resonance imaging, a test that uses magnets to film parts of the body.

Microdisketomy —Adisketomyusing a microscope.

Piriformis —A muscle in the pelvic area near the sciatic nerve.

Radicuolpathy —Another name for sciatica.

Sciatic nerve —The largest and longest nerve in the body, running from the lower back to the foot.

Spondylolisthesis —A condition when one vertebra slips forward over another.

Vertebrae —Structures that compose the spine that protect the spinal chord.

Prevention

Some sources of sciatica are not preventable, such as disk degeneration, back strain due to pregnancy, or accidental falls . Other sources of back strain, such as poor posture, overexertion, being overweight, or wearing high heels, can be corrected or avoided. Cigarette smoking may also predispose people to pain, and should be discontinued.

General suggestions for avoiding sciatica, or preventing a repeat episode, include sleeping on a firm mattress, using chairs with firm back support, and sitting with both feet flat on the floor. Habitually crossing the legs while sitting can place excess pressure on the sciatic nerve. Sitting a lot can also place pressure on the sciatic nerves, so it's a good idea to take short breaks and move around during the work day, long trips, or any other situation that requires sitting for an extended length of time. If lifting is required, the back should be kept straight and the legs should provide the lift. Regular exercise, such as swimming and walking, can strengthen back muscles and improve posture. Exercise can also help maintain a healthy weight and lessen the likelihood of back strain.

Caregiver concerns

Special care should be taken to determine the underlying cause of sciatica and to treat that as well as the presenting symptoms.

Resources

periodicals

Barry, Henry. “Bed rest is bad for back pain, ineffective for sciatica.” American Family Physician (July 2005):329

Gupta, Sanjay. “Two fixes for bad backs.” Time (July 2007):74 “How can I treat sciatica.” Natural Health. (October 2006:30

Markova, Tsveti; Dhilion, Baldev Singh, and Martin, Sandra. “Treatment of acure sciatica.” American Family Physician. (January 2007):99-100

“Observation is an option for patients with sciatica >6 weeks.” Journal of Family Practice. (September 2007):704

other

“Sciatica” Mayo Clinic. 2008. http://www.mayoclinic.com/health/sciatica/DS00516

Eidelson, Stewart G. “Sciatic Nerve and Sciatica.” Spine Universe 2008. http://www.spineuniverse.com/displayarticle.php/article2524.html

“Sciatica.” Medline Plus 2008. http://www.nlm.nih.gov/medlineplus/ency/article/000686.htm

“Sciatica.” eMedicineHealth 2008. http://www.emedicine-health.com/script/main/art.asp?articlekey=59259&pf=3&page=1

other

Spine Health. http://www.spine-health.com

organizations

American Academy of Orthopaedic Surgeons, 6300 North River Rd, Rosemont, IL, 60018-4262, 847-823-7186, 800-346-2267, 847-823-8125, http://www.aaos.org.

Janie F. Franz