Low Back Pain and Sciatica - Patient Information

27 Jul 2007

What Are Low Back Pain and Sciatica?

The Spine.

The spine is a column of small bones, or vertebrae, that supports the entire upper body. The column is grouped into three sections: the cervical vertebrae are the five spinal bones that support the neck; the thoracic vertebrae are the twelve spinal bones that connect to the rib cage; and the lumbar vertebrae are the five lowest and largest bones of the spinal column. Most of the body's weight and stress falls on the lumbar vertebrae. Below the lumbar region is the sacrum, a shield-shaped bony structure that connects with the pelvis at the sacroiliac joints. At the end of the sacrum are two to four tiny partially fused vertebrae known as the coccus or "tail bone".

Vertebrae in the spinal column are separated from each other by small cushions of cartilage known as intervertebral discs. Inside each disc is a jelly-like substance called the nucleus pulposus, which is surrounded by a fibrous structure. The disc is 80% water, which makes it very elastic. It has no blood supply of its own, however, but relies on nearby blood vessels to keep it nourished.

Each vertebra in the spine has a number of bony projections, known as processes. The spinal and transverse processes attach to the muscles in the back and act like little levers, allowing the spine to twist or bend. The articular processes form the joints between the vertebrae themselves, meeting together and interlocking at the facet joints.

Each vertebra and its processes surround and protect an arch-shaped central opening. These arches, aligned to run down the spine, form the spinal canal, which encloses the spinal cordthe central trunk of nerves that connects the brain with the rest of the body. Each nerve root passes from the spinal column to other parts of the body through small openings bounded on one side by the disc and the other by the facets. When the spinal cord reaches the lumbar region, it splits into four bundled strands of nerve roots called the cauda equina (meaning horsetail in Latin).

Low Back Pain.

Low back pain is usually defined as either acute or chronic. Physicians diagnose low back pain as acute if it lasts less than a month and is not caused by serious medical conditions. Some cases clear up in a few days without medical attention, although recurrence after a first attack is common. If the pain persists beyond six months, it is considered chronic low back pain; this constitutes only 1% to 5% of all low back pain cases.

Back pain may be triggered by various problems that occur along the ridge of bone and disc. Injuries and small fractures can occur. Muscle spasms can cause pain. Pressure on a weakened disc may cause it to rupture so the nucleus pulposus protrudes out from the spinal column, a condition known as a herniated disc. The facets can become misaligned or deteriorate. The spinal canal itself can become narrowed, a disorder called spinal stenosis. If any of these conditions occur, the nerve roots passing between the discs and facets may be stretched or pinched, causing pain usually the pain known as sciatica.

Sciatica.

The nerve most likely to cause trouble is the sciatic nerve; at some time, up to 40% of people experience pain caused by compression of this nerve, which branches from the nerve roots that descend off the spinal cord in the lumbar and sacral areas. Each of the two branches of the sciatic nerve is about as wide as a thumb and threads through the pelvis and deep into the buttocks, then down the hip and along the back of the thigh to the foot. Sciatica usually occurs on one side when a sciatic nerve has been stretched or pinched, usually by a herniated disc, although spinal stenosis or other vertebral abnormalities can also cause this pain. The sensation of sciatica can vary widely from a mild tingling to pain severe enough to cause immobility. Some people experience sharp pain in one part of the leg or hip and numbness in other parts. The pain increases after prolonged standing or sitting and is aggravated by sneezing, coughing, or laughing. If spinal stenosis is causing sciatica, patients may also experience it after bending backwards or walking more than 50 to 100 yards.

What Causes Low Back Pain or Sciatica?

The causes of 85% of back pain cases are unknown. Most often, pain begins with an injury (such as in an automobile crash), after lifting a heavy object, or after making an abrupt movement. A number of conditions may make people more susceptible to low back pain.

Disc Abnormalities.

A herniated disc, sometimes but incorrectly called a slipped disc, is the most common cause of severe sciatica. A disc in the lumbar area becomes herniated when it ruptures or when the gelatin within the disc protrudes outward. If the material breaks off or extends far enough out to press against the nerve root, sciatic pain can occur. Disc material that extrudes (that is, it balloons into the area outside the vertebrae or breaks off from the disc) most likely is a cause of pain. Sciatic pain is also sometimes present when there is no bulging or extruding of the discs. Some cases of chronic low back pain may be caused by inward growth of nerve fibers into intervertebral discs. Some evidence also exists that nerves in the outer ring of the disc may be the source of pain.

Spinal Stenosis.

Spinal stenosis, the narrowing of the spinal canal, is usually caused by bone overgrowth, which occurs mostly in the elderly who have degenerative osteoarthritis, but it can sometimes be caused by other problems, including infection and birth defects. Pain from spinal stenosis can occur in both legs.

Spondylolisthesis.

Spondylolisthesis, another cause of sciatica, is a condition in which one vertebra has slipped forward over the other.

Osteoporosis.

Osteoporosis is a disease of the skeleton in which the amount of calcium present in the bones slowly decreases to the point where the bones become fragile and prone to fracture. Spinal fractures can occur simply as a result of pressure that compresses the vertebrae together. If the vertebrae collapse suddenly, pain is often severe.

Osteoarthritis.

Osteoarthritis occurs in joints where cartilage is damaged and then destroyed; in reaction to this destruction, the bones associated with the joints develop abnormalities. (Rheumatoid arthritis, which is an arthritic condition caused by inflammation in the joints, can damage joints throughout the body, but rarely effects the lower back.) When osteoarthritis affects the spine, it may damage the cartilage in the discs, the moving joints of the spine, or both. The nerves may become pinched, causing pain and, in advanced cases, numbness and muscle weakness. The patient may also experience muscle spasms and diminished mobility.

Ankylosing Spondylitis.

Ankylosing spondylitis is a chronic inflammation of the spine that may gradually result in a fusion of the spine causing the patient to stoop over. It can be quite mild, however, and it rarely affects a person's ability to work. Symptoms include a slow development of back discomfort, with pain lasting for more than three months. The back is usually stiff in the morning; pain improves with exercise. It occurs mostly in young Caucasians in their mid-twenties. The disease is more common in men, but about 30% of the cases are in women. About 20% of people with inflammatory bowel disease and about 20% of people with psoriasis develop a form of ankylosing spondylitis. Researchers believe that it is probably hereditary.

Genetic Factors.

Hereditary problems that can affect the back at any age are enteropathic arthropathy and reactive arthropathy.

Miscellaneous Causes.

Sciatica can also be caused by other problems, including inflammation, abscesses, blood clots, and tumors. Some experts believe that one cause of sciatica is the piriformis syndrome entrapment of the sciatic nerve deep in the buttock by the piriformis muscle.

Sometimes back pain can be caused by problems in other organs, usually near the spine, which is then called referred pain. These conditions can include ulcers, kidney disease, and blocked arteries. Chronic uterine or pelvic infections can cause low back pain in women.

Arthritic back pain may also be caused by infections that include Lyme disease, septic arthritis, bacterial endocarditis, Reiter's syndrome, mycobacterial and fungal arthritis, and viral arthritis.

Atherosclerosis (commonly called hardening of the arteries) may occasionally cause chronic low back pain, because the condition reduces the supply of blood. When it blocks arteries in the legs it may cause pain that resembles sciatica caused by spinal stenosis. Fibromyalgia is also a cause of back pain as is injury to the muscles and other soft tissues that support the spine.

Long-Term Outlook.

Recurrence is common after a first episode of back pain. In one survey, over a one-year period following treatment only 21% of patients had no back pain; over four years, less than half were symptom-free.

Effects on Work.

One study found that although severe back pain comprised only 10% of workers compensation cases it accounted for 86% of compensation costs. Studies have found that when people stay home because of back injury, about 65% are back within a week, 86% are back by one month, and, by three months, 91% return to work. Another study found that if someone is on disability for a year or longer, there is only a 25% chance that the patient will return.

How Is Low Back Pain or Sciatica Diagnosed?

Medical History.

Because back pain can have so many different causes, it is very important to first rule out any other medical conditions. A complete medical and family history should be taken that includes heart problems, cancer, arthritis, and any other serious conditions. The patient should report previous episodes of back pain as well as any history of injuries or accidents involving the neck, back, or hips. The physician will generally ask about frequency, duration, and the nature of the pain, e.g., whether it is dull, piercing, throbbing, or burning. The patient should describe its onset and whether the pain was triggered by an event, such as lifting a heavy object or an automobile crash. The physician will need to know what worsens the pain (for example, coughing, exercise, straining during bowel movements, walking) and what relieves the pain (lying down, exercise). Other important symptoms may include morning stiffness, problems with urination or defecation, and weakness or numbness in the legs.

Physical Examination.

Patients are asked to sit, stand, and walk in different ways: flat-footed, on the toes, and on their heels. They will be requested to bend forward, backward, and sideways, to twist, and to lift their leg straight up while lying down (which tests the tension of the sciatic nerve). The physician will also move the patient's legs in different positions and bend and straighten the knees. To test nerve function and reflexes, physicians will tap the knees and ankles with a rubber hammer. The circumference of the calves and thighs may be measured to look for muscle deterioration. The physician may touch parts of the body lightly with a pin, cotton swab, or feather to test for numbness and nerve sensitivity.

Imaging Techniques.

People with low back pain should have x-rays or scans done under certain circumstances, such as pain that lasts more than a month, very severe pain, numbness, muscle weakness, accidents that might involve the vertebrae, a history of cancer or smoking, or the presence of fever. If these conditions exist, usually an x-ray is used first, and then, if results are inconclusive, either a CT or MRI scan. (Ultrasound is not useful.)

Myelogram. A myelogram is an x-ray of the spine which requires a spinal injection and the need to lie still for several hours to avoid a very painful headache. It has largely been replaced by CT and MRI scans.

Discography. A discography uses an x-ray of the disc and employs injections into discs suspected of being the source of pain and discs nearby. It can be more painful than a myelogram and is generally used for patients who are undergoing back surgery to identify the location of the injured disc. Some experts believe that discography is not at all useful in identifying the source of pain, because it requires expert execution and analysis for any degree of accuracy. Others argue that it is the only procedure that can reveal the shape of the disc and identify nerve structures in the disc, which may play a role in some cases of sciatica.

CT and MRI Scans. MRI and CT scans are not painful, nor invasive. They are expensive and, therefore, are not generally used as part of a routine work-up. When necessary, however, they provide views of the structures and pathology of the spine that are not available through any other imaging technique.

Other Tests.

Blood and urine samples may be used to test for infections, arthritis, or other conditions. Injecting a drug that blocks pain into the nerves in the back helps locate the level in the spine where problems occur. A procedure called a facet block is also useful in locating areas of specific damage. Provocative discometry is a test that uses an injection of saline solution into the suspected disc to reproduce the pain, which is then followed by injection of an anesthetic to dull the pain.

What Are Nonsurgical Treatments for Low Back Pain or Sciatica?

Back pain attributed to medical conditions, such as arthritis, osteoporosis, or pregnancy, either resolves when the condition does or is treated as part of the overall therapeutic plan. Treatment for back pain is available from a variety of health care practitioners; a recent study of patients treated by primary care practitioners, chiropractors, and orthopedic surgeons reports similar recovery rates. When low back pain is not caused by a medical condition, about 90% of people recover within a month without any treatment at all. In spite of this encouraging statistic, back pain is the third most common reason for surgery and costs the country up to $50 million each year in medical and disability benefits. For most patients very moderate treatment options are the correct course for low back pain. It should be noted, however, that for certain patients with sciatica and spinal stenosis, surgery may be the most effective approach.

Immediate Treatment of Acute Low Back Pain.

At the onset of acute low back pain, the patient should take an over-the-counter pain reliever and lie down in a comfortable position. Lying on the side or back with knees bent supported by a pillow relieves the stress on the back. Many people find that alternating ice packs and heating pads at about twenty-minute intervals is helpful in relieving the pain. Ice packs should be applied first. Supportive back belts, braces, or corsets may help some people temporarily, but they can reduce muscle tone over time and should be used only briefly.

Home Care.

Rest. Most experts recommend staying in bed no longer than a couple of days. One study reported, however, that people who avoided bed rest altogether and simply tried to resume normal activities, without strain or stretching exercises, recovered more quickly than those who were in bed for even as short a period as two days. People who stay in bed a week or longer do even worse. Long-term bed rest results in loss of muscle tone and bone strength, increases susceptibility to blood clots, and causes depression and lethargy. Traction probably has no benefit and may be harmful.

Getting adequate amounts of sleep, however, is very important and many physicians feel that healthy sleep patterns play a vital role in recovery from back pain. It is often difficult to get a good night's sleep when suffering from back pain, particularly because the pain can intensify at night. Lying curled up in a fetal position with the pillow between the knees or lying on the back with pillow under the knees may help. To help promote sleep, avoid caffeine in the afternoon and evening, take a warm bath before bedtime, and practice relaxation techniques. It may be necessary to take medication to help manage nighttime pain or treat sleeplessness.

Resuming Normal Activity Levels and Exercise. At the other extreme, exercising to treat acute back pain may be equally unhelpful. In one study, recovery from acute back pain was slower for patients who exercised to improve flexibility than for those who gradually resumed normal activity, simply letting pain be the guide for how much movement they achieved. In general, normal activity should be resumed in a gradual fashion as soon as the patient feels ready, reserving therapeutic exercises until after the acute pain has resolved. An incremental aerobic exercise program is less stressful than stretching or exercises strengthening the trunk muscles. Experts suggest that walking, stationary biking, swimming, and even light jogging may begin within two weeks of symptoms, but patients should never force themselves to exercise if, by doing so, pain increases. People usually recover from a strained back or a mildly herniated disc in a few days. It may take as long as six weeks, however, to fully recover from back pain, particularly if it is due to sciatica. At that time, if the pain has not been relieved, additional measures may be needed.

Exercise appears to be important in treating chronic low back pain. In one study, for example, patients with back pain lasting for an average of 18 months were assigned 8 one-hour exercise sessions over four weeks. They showed greater improvement in nearly every area, including reduced pain and increased capacity, compared to patients who did not

Medication.

NSAIDs and Acetaminophen. The most common pain-relievers are the nonsteroidal anti-inflammatory drugs (NSAIDs). These drugs block prostaglandins, the substances that dilate blood vessels and cause inflammation and pain. There are dozens of NSAIDs. Some of the most common are aspirin, ibuprofen, naproxen, and ketoprofen, but many others are now available [see below]. Taking NSAIDs with food can reduce stomach discomfort, although it may slow down the pain-relieving effect. All NSAIDs are capable of damaging the mucous layer and causing ulcers and gastrointestinal (GI) bleeding when taken for long periods. The elderly are at special risk for ulcers; younger nonsmoking adults are at lower risk. Bleeding and ulcers can occur at any time, with or without symptoms. The risk for bleeding is constant as long as a patient is on these drugs and may even persist for about a year after taking them. No NSAIDs should be used for long-term pain relief except under a physician's direction. Ibuprofen has a lower risk than naproxen and ketoprofen for GI bleeding. Aspirin has a risk similar to that of ibuprofen. Buffered aspirin (aspirin coated with an antacid) is not protective against ulcers. Other side effects include dizziness, ringing in the ear, headache, skin rash, and possibly depression. Kidney damage has been reported in people taking NSAIDs, which resolves when the drugs are withdrawn. (Aspirin has little or no risk for this side effect.) People with high blood pressure, severe circulation disorders, kidney or liver problems, and those taking diuretics or oral hypoglycemics must be closely monitored if they need to take long-term NSAIDs. Because NSAIDs reduce the clotting of the blood, anyone undergoing surgery should stop taking the medication a week before the operation. Taking NSAIDs after fusion procedures may reduce the chances for success; more research is needed on this potential problem.

COX-2 Inhibitors. New, aspirin-like drugs, including celecoxib (Celebra) and another (Vioxx), are being developed to target a specific prostaglandin-producing enzyme called cyclooxygenase 2 (COX 2) without affecting COX 1, another enzyme that generates stomach-protective prostaglandins and which other NSAIDs block. Such drugs may allow high doses without the accompanying gastrointestinal side effects.

Acetaminophen (Tylenol, Anacin-3, Panadal, Phenaphen, Valadol, and other brands) is the most common alternative to NSAIDs, although many patients report less pain relief with acetaminophen than with an NSAID. It is not an anti-inflammatory agent. Acetaminophen can be used alone or in combination with NSAIDs with some success. Liver and kidney damage are potential serious side effects of acetaminophen. Alcohol use increases the risk for liver damage. Experts recommend taking no more than 8 extra-strength tablets each day.

Corticosteroids. A one-time injection of a corticosteroid into the area around the spinal column is sometimes administered to short-cut sciatic pain until the body heals itself. Corticosteroids are useful only for temporarily reducing inflammation. They are not a cure, and they offer no long-term benefits. Oral steroids are not recommended.

Opioids. Unless the pain is very severe, experts advise against routinely prescribing pain killers containing opioids, such as morphine and codeine, meperidine (Demerol), or oxycodone-release (Oxycontin), which they believe do more harm than good. Injections of local anesthetics are occasionally used and can be helpful for temporary relief of severe pain. A skin patch containing an opioid called transdermal tentanyl (Duragesic) may relieve chronic back pain more effectively than oral opioids. Side effects for all opioids include drowsiness, impaired judgment, nausea, and constipation. Addiction is a major risk and physicians should monitor patients periodically for the possibility of withdrawing from the medications.

Muscle Relaxants. Physicians may prescribe muscle relaxants such as cyclobenzaprine (Flexeril), diazepam (Valium), carisoprodol (Soma), or methocarbamol (Robaxin).

Spinal Manipulation and Chiropracty.

Spinal manipulation by a trained chiropractor may be effective in reducing back pain.

Transcutaneous Electric Nerve Stimulation.

Transcutaneous electric nerve stimulation (TENS) uses low-level electrical pulses to suppress back pain and can be particularly helpful for patients with spinal stenosis.

Alternative Treatments.

Acupuncture, which involves inserting small pins or exerting pressure on certain points in the body, has relieved pain in some people. One well-conducted study found significant benefits from acupuncture for chronic low back pain, although another reported few benefits for sciatica. Stress management and biofeedback techniques may also be helpful, although studies have not yet confirmed any benefits.

What Are Surgical Procedures for Low Back Pain or Sciatica?

The most common reasons for surgery for low back pain are sciatica and spinal stenosis. One study reported that 71% of people who had surgery for sciatica experienced pain relief compared to 43% who did not have surgery. For those with spinal stenosis, 55% of surgical patients reported pain relief compared with 28% who chose not to have surgery. The best spinal stenosis candidates are those with a condition known as block spinal stenosis. Surgery does not always improve outcome for low back pain and in some cases can make it worse.

Evidence of a herniated disc and nerve compression is not an automatic indication for surgery; surgery is advised only for selected patients with sciatica and spinal stenosis. Emergency surgery may be needed for sciatic pain if it is accompanied by incontinence, which indicates that the bundle of nerves at the end of the spinal cord known as the cauda equina are being pinched. In such cases, an operation should be performed as soon as possible to avoid permanent damage. Other indications include a progressive weakening in the legs and evidence of some physical abnormality of the spine, such as a bone spur or spinal stenosis due to bone growth. A patient should be sure that the surgeon has had significant experience with any procedure to be performed.

Discectomy.

Discectomy is the surgical removal of the diseased disc, thereby relieving pressure on the disc. In spite of the fact that the procedure has been done for 40 years, few studies have been conducted to determine its real effectiveness. Scar tissue may develop after discectomy, which, in some cases, can cause continued pain. A variation called percutaneous discectomy (PAD) uses endoscopy (the use of a catheterthin tubethat employs tiny cameras and surgical instruments.) The tube has a device at the tip that cuts away some of the nucleus pulposus and a vacuum that then sucks this gelatinous matter out. Other endoscopic procedures are also under investigation. Lasers have been investigated for use with discectomy, but results to date are unimpressive.

Laminectomy or laminotomy.

Operations that shave off part of a vertebra (laminotomy) or remove all of it (laminectomy) may be used in spinal stenosis or spondylolisthesis to decompress the nerve or they may be used to remove benign tumors on the spine. Laminectomy requires general anesthesia and a two or three day hospital stay. Recuperation takes up to six weeks. Although it often brings immediate relief from pain, there are small risks to the operation and it is not always successful. Some recurrence of back pain and sciatica occurs in half to two-thirds of postoperative patients.

Spinal Fusion.

In cases where abnormal positioning or vertebrae movement puts pressure on the nerves, such as spinal stenosis or spondylolisthesis, surgeons may fuse vertebrae together. Fusion employs a bone graft or some other device to join the vertebrae together. One medical device called the BAK Interbody Fusion System uses a tiny hollow metal cage, which is implanted into the disc space. Bone is removed from the patient and packed inside the cage; over time the bone grows through the holes and around the device, fusing the vertebrae. In one study, the device was successful in 72% of patients, who experienced decreased pain without any loss of muscle strength or function.

Postoperative Period: Complications and Outlook.

Complications of spinal surgery can include nerve and muscle damage, infection, scarring, and the need for reoperation. Patients now often remain in bed only three or four days after disc surgery; studies indicate that such patients have the same or even fewer complications than those who stay in bed for weeks. It may take four to six weeks for full recovery. Gentle exercise may be recommended.