What Is the Difference Between Acute and Chronic Pain?

Pain that hits you suddenly – after falling from a ladder, being tackled on the football field, or lifting a load that is just too heavy, for example – is acute pain. Acute pain comes on quickly and often leaves just as quickly. To be classified as acute, pain should last no longer than 6 weeks. Acute pain is the most common type of back pain.

Chronic pain, on the other hand, may come on either quickly or slowly, and it lingers a long time. In general, pain that lasts more than 3 months is considered chronic. Chronic pain is much less common than acute pain.

How Is Back Pain Treated?

Treatment for back pain generally depends on what kind of pain you experience: acute or chronic.

Acute Back Pain: Acute back pain usually gets better on its own and without treatment, although you may want to try acetaminophen, aspirin, or ibuprofen to help ease the pain. Perhaps the best advice is to go about your usual activities as much as you can with the assurance that the problem will clear up. Getting up and moving around can help ease stiffness, relieve pain, and have you back doing your regular activities sooner. Exercises or surgery are not usually advisable for acute back pain.

Chronic Back Pain: Treatment for chronic back pain falls into two basic categories: the kind that requires an operation and the kind that does not. In the vast majority of cases, back pain does not require surgery. Doctors will nearly always try nonsurgical treatments before recommending surgery. In a very small percentage of cases – when back pain is caused by a tumor, an infection, or a nerve root problem called cauda equina syndrome, for example – prompt surgery is necessary to ease the pain and prevent further problems.

Following are some of the more commonly used treatments for chronic back pain.

Nonsurgical treatments

Hot or cold: Hot or cold packs – or sometimes a combination of the two – can be soothing to chronically sore, stiff backs. Heat dilates the blood vessels, both improving the supply of oxygen that the blood takes to the back and reducing muscle spasms. Heat also alters the sensation of pain. Cold may reduce inflammation by decreasing the size of blood vessels and the flow of blood to the area. Although cold may feel painful against the skin, it numbs deep pain. Applying heat or cold may relieve pain, but it does not cure the cause of chronic back pain.

Exercise: Although exercise is usually not advisable for acute back pain, proper exercise can help ease chronic pain and perhaps reduce the risk of it returning. The following four types of exercise are important to general physical fitness and may be helpful for certain specific causes of back pain:

Flexion: The purposes of flexion exercises, which are exercises in which you bend forward, are to (1) widen the spaces between the vertebrae, thereby reducing pressure on the nerves; (2) stretch muscles of the back and hips; and (3) strengthen abdominal and buttock muscles. Many doctors think that strengthening the muscles of the abdomen will reduce the load on the spine. One word of caution: If your back pain is caused by a herniated disc, check with your doctor before performing flexion exercises because they may increase pressure within the discs, making the problem worse.

Extension: With extension exercises, you bend backward. They may minimize radiating pain, which is pain you can feel in other parts of the body besides where it originates. Examples of extension exercises are leg lifting and raising the trunk, each exercise performed while lying prone. The theory behind these exercises is that they open up the spinal canal in places and develop muscles that support the spine.

Stretching: The goal of stretching exercises, as their name suggests, is to stretch and improve the extension of muscles and other soft tissues of the back. This can reduce back stiffness and improve range of motion.

Aerobic: Aerobic exercise is the type that gets your heart pumping faster and keeps your heart rate elevated for a while. For fitness, it is important to get at least 30 minutes of aerobic (also called cardiovascular) exercise three times a week. Aerobic exercises work the large muscles of the body and include brisk walking, jogging, and swimming. For back problems, you should avoid exercise that requires twisting or vigorous forward flexion, such as aerobic dancing and rowing, because these actions may raise pressure in the discs and actually do more harm than good. In addition, avoid high-impact activities if you have disc disease. If back pain or your fitness level make it impossible to exercise 30 minutes at a time, try three 10-minute sessions to start with and work up to your goal. But first, speak with your doctor or physical therapist about the safest aerobic exercise for you.

Medications: A wide range of medications are used to treat chronic back pain. Some are available over the counter. Others require a doctor’s prescription. The following are the main types of medications used for back pain.

Analgesics: Analgesic medications are those designed specifically to relieve pain. They include over-the-counter acetaminophen (Tylenol)¹ and aspirin, as well as prescription narcotics, such as oxycodone with acetaminophen (Percocet) or hydrocodone with acetaminophen (Vicodin). Aspirin and acetaminophen are the most commonly used analgesics; narcotics should only be used for a short time for severe pain or pain after surgery. People with muscular back pain or arthritis pain that is not relieved by medications may find topical analgesics helpful. These creams, ointments, and salves are rubbed directly onto the skin over the site of pain. They use one or more of a variety of ingredients to ease pain. Topical analgesics include such products as Zostrix, Icy Hot, and BenGay.

¹ Brand names included in this booklet are provided as examples only, and their inclusion does not mean that these products are endorsed by the National Institutes of Health or any other Government agency. Also, if a particular brand name is not mentioned, this does not mean or imply that the product is unsatisfactory.

NSAIDs: Nonsteroidal anti-inflammatory drugs (NSAIDs) are drugs that relieve pain and inflammation, both of which may play a role in some cases of back pain. NSAIDs include the nonprescription products ibuprofen (Motrin, Advil), ketoprofen (Actron, Orudis KT), and naproxen sodium (Aleve). More than a dozen others, including a subclass of NSAIDs called COX-2 inhibitors, are available only with a prescription.

All NSAIDs work similarly – by blocking substances called prostaglandins that contribute to inflammation and pain. However, each NSAID is a different chemical, and each has a slightly different effect on the body.²

²Warning: NSAIDs can cause stomach irritation or, less often, they can affect kidney function. The longer a person uses NSAIDs, the more likely he or she is to have side effects, ranging from mild to serious. Many other drugs cannot be taken when a patient is being treated with NSAIDs because NSAIDs alter the way the body uses or eliminates these other drugs. Check with your health care provider or pharmacist before you take NSAIDs. Also, NSAIDs sometimes are associated with serious gastrointestinal problems, including ulcers, bleeding, and perforation of the stomach or intestine. People age 65 and older and those with any history of ulcers or gastrointestinal bleeding should use NSAIDs with caution.

Side effects of all NSAIDs can include stomach upset and stomach ulcers, heartburn, diarrhea, and fluid retention; however, COX-2 inhibitors are designed to cause fewer stomach ulcers. For unknown reasons, some people seem to respond better to one NSAID than another. It’s important to work with your doctor to choose the one that’s safest and most effective for you.

Other medications: Muscle relaxants and certain antidepressants have also been prescribed for chronic back pain, but their usefulness is questionable.

Traction: Traction involves using pulleys and weights to stretch the back. The rationale behind traction is to pull the vertebrae apart to allow a bulging disc to slip back into place. Some people experience pain relief while in traction, but that relief is usually temporary. Once traction is released, the stretch is not sustained and back pain is likely to return. There is no scientific evidence that traction provides any long-term benefits for people with back pain.

Corsets and braces: Corsets and braces include a number of devices, such as elastic bands and stiff supports with metal stays, that are designed to limit the motion of the lumbar spine, provide abdominal support, and correct posture. Although these may be appropriate after certain kinds of surgery, there is little, if any, evidence that corsets and braces help treat chronic low back pain. In fact, by keeping you from using your back muscles, they may actually cause more problems than they solve by causing lower back muscles to weaken from lack of use.

Behavioral modification: Developing a healthy attitude and learning to move your body properly while you do daily activities – particularly those involving heavy lifting, pushing, or pulling – are sometimes part of the treatment plan for people with back pain. Other behavior changes that might help pain include adopting healthy habits, such as exercise, relaxation, and regular sleep, and dropping bad habits, such as smoking and eating poorly.

Injections: When medications and other nonsurgical treatments fail to relieve chronic back pain, doctors may recommend injections for pain relief. Following are some of the most commonly used injections, although some are of questionable value:

Nerve root blocks: If a nerve is inflamed or compressed as it passes from the spinal column between the vertebrae, an injection called a nerve root block may be used to help ease the resulting back and leg pain. The injection contains a steroid medication or anesthetic and is administered to the affected part of the nerve. Whether the procedure helps or not depends on finding and injecting precisely the right nerve.

Facet joint injections: The facet joints are those where the vertebrae connect to one another, keeping the spine aligned. Although arthritis in the facet joints themselves is rarely the source of back pain, the injection of anesthetics or steroid medications into facet joints is sometimes tried as a way to relieve pain. The effectiveness of these injections is questionable. One study suggests that this treatment is overused and ineffective.

Trigger point injections: In this procedure, an anesthetic is injected into specific areas in the back that are painful when the doctor applies pressure to them. Some doctors add a steroid medication to the injection. Although the injections are commonly used, researchers have found that injecting anesthetics or steroids into trigger points provides no more relief than “dry needling” (inserting a needle and not injecting a medication).

Prolotherapy: One of the most talked about procedures for back pain, prolotherapy is a treatment in which a practitioner injects a sugar solution or other irritating substance into trigger points along the periosteum (the tough, fibrous tissue covering the bones) to trigger an inflammatory response that promotes the growth of dense, fibrous tissue. The theory behind prolotherapy is that such tissue growth strengthens the attachment of tendons and ligaments whose loosening has contributed to back pain. As yet, studies have not verified the effectiveness of prolotherapy. The procedure is used primarily by chiropractors and osteopathic doctors.

Complementary and alternative treatments: When back pain becomes chronic or when medications and other conventional therapies do not relieve it, many people try complementary and alternative treatments. Although such therapies won’t cure diseases or repair the injuries that cause pain, some people find them useful for managing or relieving pain. Following are some of the most commonly used complementary therapies.

Manipulation: Spinal manipulation refers to procedures in which professionals use their hands to mobilize, adjust, massage, or stimulate the spine or surrounding tissues. This type of therapy is often performed by osteopathic doctors and chiropractors. It tends to be most effective in people with uncomplicated pain and when used with other therapies. Spinal manipulation is not appropriate if you have a medical problem such as osteoporosis, spinal cord compression, or inflammatory arthritis (such as rheumatoid arthritis) or if you are taking blood-thinning medications such as warfarin (Coumadin) or heparin (Calciparine, Liquaemin).

Transcutaneous electrical nerve stimulation (TENS): TENS involves wearing a small box over the painful area that directs mild electrical impulses to nerves there. The theory is that stimulating the nervous system can modify the perception of pain. Early studies of TENS suggested it could elevate the levels of endorphins, the body’s natural pain-numbing chemicals, in the spinal fluid. But subsequent studies of its effectiveness against pain have produced mixed results.

Acupuncture: This ancient Chinese practice has been gaining increasing acceptance and popularity in the United States. Acupuncture is based on the theory that a life force called Qi (pronounced chee) flows through the body along certain channels, which if blocked can cause illness. According to the theory, the insertion of thin needles at precise locations along these channels by practitioners can unblock the flow of Qi, relieving pain and restoring health.

Although few Western-trained doctors would agree with the concept of blocked Qi, some believe that inserting and then stimulating needles (by twisting or passing a low-voltage electrical current through them) may foster the production of the body’s natural pain-numbing chemicals, such as endorphins, serotonin, and acetylcholine.

A consensus panel convened by the National Institutes of Health (NIH) in 1997 concluded that there is clear evidence this treatment is effective for some pain conditions, including postoperative dental pain. Although there is less convincing evidence to support using acupuncture for back pain and some other pain conditions, the panel concluded that acupuncture may be effective when used as part of a comprehensive treatment plan for low back pain, fibromyalgia, and several other conditions.

Acupressure: As with acupuncture, the theory behind acupressure is that it unblocks the flow of Qi. The difference between acupuncture and acupressure is that no needles are used in acupressure. Instead, a therapist applies pressure to points along the channels with his or her hands, elbows, or even feet. (In some cases, patients are taught to do their own acupressure.) Acupressure has not been well studied for back pain.

Rolfing: A type of massage, rolfing involves using strong pressure on deep tissues in the back to relieve tightness of the fascia, a sheath of tissue that covers the muscles, that can cause or contribute to back pain. The theory behind rolfing is that releasing muscles and tissues from the fascia enables the back to align itself properly. So far, the usefulness of rolfing for back pain has not been scientifically proven.

Surgical treatments

Depending on the diagnosis, surgery may either be the first treatment of choice – although this is rare – or it is reserved for chronic back pain for which other treatments have failed. If you are in constant pain or if pain reoccurs frequently and interferes with your ability to sleep, to function at your job, or to perform daily activities, you may be a candidate for surgery.

In general, two groups of people may require surgery to treat their spinal problems. People in the first group have chronic low back pain and sciatica, and they are often diagnosed with a herniated disc, spinal stenosis, spondylolisthesis, or vertebral fractures with nerve involvement. People in the second group are those with only predominant low back pain (without leg pain). These are people with discogenic low back pain (degenerative disc disease), in which discs wear with age. Usually, the outcome of spine surgery is much more predictable in people with sciatica than in those with predominant low back pain.

Some of the diagnoses that may need surgery include:

Herniated discs: In this potentially painful problem, the hard outer coating of the discs, which are the circular pieces of connective tissue that cushion the bones of the spine, are damaged, allowing the discs’ jelly-like center to leak, irritating nearby nerves. This causes severe sciatica and nerve pain down the leg. A herniated disc is sometimes called a ruptured disc.

Spinal stenosis: Spinal stenosis is the narrowing of the spinal canal, through which the spinal cord and spinal nerves run.

It is often caused by the overgrowth of bone caused by osteoarthritis of the spine. Compression of the nerves caused by spinal stenosis can lead not only to pain, but also to numbness in the legs and the loss of bladder or bowel control. Patients may have difficulty walking any distances and may have severe pain in their legs along with numbness and tingling.

Spondylolisthesis: In this condition, a vertebra of the lumbar spine slips out of place. As the spine tries to stabilize itself, the joints between the slipped vertebra and adjacent vertebrae can become enlarged, pinching nerves as they exit the spinal column. Spondylolisthesis may cause not only low back pain but also severe sciatica leg pain.

Vertebral fractures: These fractures are caused by trauma to the vertebrae of the spine or by crumbling of the vertebrae resulting from osteoporosis. This causes mostly mechanical back pain, but it may also put pressure on the nerves, creating leg pain.

Discogenic low back pain (degenerative disc disease): Most people’s discs degenerate over a lifetime, but in some, this aging process can become chronically painful, severely interfering with their quality of life.

Following are some of the most commonly performed back surgeries:

For Herniated Discs:

Laminectomy/discectomy: In this operation, part of the lamina, a portion of the bone on the back of the vertebrae, is removed, as well as a portion of a ligament. The herniated disc is then removed through the incision, which may extend two or more inches.

Microdiscectomy: As with traditional discectomy, this procedure involves removing a herniated disc or damaged portion of a disc through an incision in the back. The difference is that the incision is much smaller and the doctor uses a magnifying microscope or lenses to locate the disc through the incision. The smaller incision may reduce pain and the disruption of tissues, and it reduces the size of the surgical scar. It appears to take about the same amount of time to recuperate from a microdiscectomy as from a traditional discectomy.

Laser surgery: Technological advances in recent decades have led to the use of lasers for operating on patients with herniated discs accompanied by lower back and leg pain. During this procedure, the surgeon inserts a needle in the disc that delivers a few bursts of laser energy to vaporize the tissue in the disc. This reduces its size and relieves pressure on the nerves. Although many patients return to daily activities within 3 to 5 days after laser surgery, pain relief may not be apparent until several weeks or even months after the surgery. The usefulness of laser discectomy is still being debated.

For Spinal Stenosis:

Laminectomy: When narrowing of the spine compresses the nerve roots, causing pain or affecting sensation, doctors sometimes open up the spinal column with a procedure called a laminectomy. In a laminectomy, the doctor makes a large incision down the affected area of the spine and removes the lamina and any bone spurs, which are overgrowths of bone, that may have formed in the spinal canal as the result of osteoarthritis. The procedure is major surgery that requires a short hospital stay and physical therapy afterwards to help regain strength and mobility.

For Spondylolisthesis

Spinal fusion: When a slipped vertebra leads to the enlargement of adjacent facet joints, surgical treatment generally involves both laminectomy (as described above) and spinal fusion. In spinal fusion, two or more vertebrae are joined together using bone grafts, screws, and rods to stop slippage of the affected vertebrae. Bone used for grafting comes from another area of the body, usually the hip or pelvis. In some cases, donor bone is used.

Although the surgery is generally successful, either type of graft has its drawbacks. Using your own bone means surgery at a second site on your body. With donor bone, there is a slight risk of disease transmission or rejection. In recent years, a new development has eliminated those risks for some people undergoing spinal fusion: proteins called bone morphogenic proteins are being used to stimulate bone generation, eliminating the need for grafts. The proteins are placed in the affected area of the spine, often in collagen putty or sponges.

Regardless of how spinal fusion is performed, the fused area of the spine becomes immobilized.

For Vertebral Osteoporotic Fractures³

Vertebroplasty: When back pain is caused by a compression fracture of a vertebra due to osteoporosis or trauma, doctors may make a small incision in the skin over the affected area and inject a cement-like mixture called polymethylacrylate into the fractured vertebra to relieve pain and stabilize the spine. The procedure is generally performed on an outpatient basis under a mild anesthetic.

³ Used only if standard care, rest, corsets and braces, and analgesics fail.

Kyphoplasty: Much like vertebroplasty, kyphoplasty is used to relieve pain and stabilize the spine following fractures due to osteoporosis. Kyphoplasty is a two-step process. In the first step, the doctor inserts a balloon device to help restore the height and shape of the spine. In the second step, he or she injects polymethylacrylate to repair the fractured vertebra. The procedure is done under anesthesia, and in some cases it is performed on an outpatient basis.

For Discogenic Low Back Pain (Degenerative Disc Disease)

Intradiscal electrothermal therapy (IDT): One of the newest and least invasive therapies for low back pain involves inserting a heating wire through a small incision in the back and into a disc. An electrical current is then passed through the wire to strengthen the collagen fibers that hold the disc together. The procedure is done on an outpatient basis, often under local anesthesia. The usefulness of IDT is debatable.

Spinal fusion: When the degenerated disc is painful, the surgeon may recommend removing it and fusing the disc to help with the pain. This fusion can be done through the abdomen, a procedure known as anterior lumbar interbody fusion, or through the back, called posterior fusion. Theoretically, fusion surgery should eliminate the source of pain; the procedure is successful in about 60 to 70 percent of cases. Fusion for low back pain or any spinal surgeries should only be done as a last resort, and the patient should be fully informed of risks.

Disc replacement: When a disc is herniated, one alternative to a discectomy – in which the disc is simply removed – is removing the disc and replacing it with a synthetic disc. Replacing the damaged one with an artificial one restores disc height and movement between the vertebrae. Artificial discs come in several designs. Although doctors in Europe had performed disc replacement for more than a decade, the procedure had been experimental in the United States until the Food and Drug Administration approved the Charité artificial disc (http://www.fda.gov/cdrh/pdf4/p040006.html).

What Kind of Research Is Being Done?

The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) is currently supporting a number of studies to better understand and treat back pain. Goals of current research include the following:

To compare the effectiveness of surgery versus nonsurgical treatment for low back pain. Although the percentage of people having spinal surgery in the United States has increased sharply over time, there is not much information on whether back surgery is better than nonsurgical treatments. One study is comparing the most commonly used surgical treatments to the most commonly used nonsurgical treatments for three common back problems: herniated discs of the lumbar spine, spinal stenosis, and spinal stenosis from spondylolisthesis. The study, being conducted at 12 medical centers, will follow patients for at least 24 months after treatment to determine the medical and cost-effectiveness of treatments.

To identify the best treatments for certain patients with low back pain. Just as certain treatments are effective for some back problems and not others, the same treatment may be effective for some people and not others – even if those people have the same medical problem. Researchers at several centers will study more than 3,000 patients who have one of three common causes of back pain – herniated discs, spinal stenosis, and spondylolisthesis – and who respond well to specific treatments. Extensive testing and surveys will allow doctors to identify the best treatments for these patients.

To test the effectiveness of lumbar fusion and other treatments for disc-derived pain. Discogenic pain is low back pain due to the wearing away of a disc between the vertebrae. Although treatment for this condition is often lumbar spinal fusion, its effectiveness, as well as that of other treatments, has not been established. A new study will compare the results of spinal fusion with those of nonsurgical care for patients with similar disc degeneration. Researchers will also try to find out (1) what distinguishes people who choose surgery from those who do not; (2) the consequences of common complications of spinal fusion surgery and how often they occur; (3) what predicts a good response to surgical therapy but not to other treatments; and (4) what are the characteristics and outcomes of patients who have repeat back surgery for this condition.

To measure the frequency of complications in lumbar fusion surgery. Lumbar spinal fusion is a commonly performed procedure for several back problems, including disc degeneration, spondylolisthesis, spinal stenosis, and scoliosis, but the procedure can have complications. A new study will follow 1,000 people who have spinal fusion for one of these diagnoses to find out (1) how often complications occur after surgery, (2) how the rates of specific serious complications vary with different types of lumbar fusion, (3) the consequences of specific types of complications, and (4) the characteristics of treatments or patients that predict particularly severe complications. The information will help doctors better assess the benefits versus the risks of the procedure.

To better understand the relationship between the loss of motor control and low back pain. Compared to people without back problems, those with low back pain show losses in motor control, including problems with trunk muscle response and posture. Some researchers believe that losses in motor control may predispose people to falls that result in back pain. Other researchers think losses in motor control may result from damage sustained by tissue during a fall. To explore the relationship between motor control loss and back pain, scientists will study varsity athletes to determine whether poor motor control of the lumbar spine increases the risk of low back injury. They will also study changes in the lumbar spine motor control of people with low back pain after they complete rehabilitation programs that emphasize motor control training.

To develop and evaluate a psychosocial program for people with acute low back pain. Acute low back pain is a common problem that affects people’s abilities to work and function, and it contributes to high health care costs. There are few studies, however, that prove whether or not a treatment truly reduces limitation and prevents the recurrence of pain. One new project will develop a program to enhance the social support and self-efficacy of people with acute low back pain. After developing and testing the program, researchers will evaluate its effectiveness by comparing the results of 160 participants with those of 160 people receiving usual care.

To evaluate the nervous system mechanisms of low back pain. Scientists think that when a disc ruptures, material leaking from its jelly-like filling leads to inflammation and the release of chemicals that irritate cells within the spinal canal. Scientists believe that the effects of these chemicals on the nerve endings in discs and adjacent tissue lead to low back pain, while the effects on dorsal nerve roots lead to sciatica. One study will test these ideas using a variety of techniques. A better understanding of pain mechanisms related to herniated discs will allow researchers to develop better treatments.