WebMD Health - Pain Management

Mar 11, 2011 4:26 PM

Top Causes of Chronic Pain

People with persistent pain often think of themselves as suffering from a specific ailment, whether it's arthritis, back pain, migraines, or something else. But anyone who has experienced pain for several months or longer also happens to be among the millions of Americans with a condition known as chronic pain.

Chronic pain is a complex condition that affects 42 million-50 million Americans, according to the American Pain Foundation. Despite decades of research, chronic pain remains poorly understood and notoriously hard to control. A survey by the American Academy of Pain Medicine found that even comprehensive treatment with painkilling prescription drugs helps, on average, only about 58% of people with chronic pain.

What causes chronic pain, and what can you do about it?

Some cases of chronic pain can be traced to a specific injury that has long since healed -- for example, an injury, a serious infection, or even a surgical incision. Other cases have no apparent cause -- no prior injury and an absence of underlying tissue damage. However, many cases of chronic pain are related to these conditions:

  • Low back pain
  • Arthritis, especially osteoarthritis
  • Headache
  • Multiple sclerosis
  • Fibromyalgia
  • Shingles
  • Nerve damage (neuropathy)

Treating your underlying condition is, of course, vitally important. But often that does not resolve chronic pain. Increasingly, doctors consider chronic pain a condition of its own, requiring pain treatment that addresses the patient's physical and psychological health.

Understanding the Psychological Impact of Chronic Pain

At a fundamental level, chronic pain is a matter of biology: Errant nerve impulses keep alerting the brain about tissue damage that no longer exists, if it ever did. But complex social and psychological factors are also at play, and they seem to help determine who fares well despite even severe chronic pain -- and whose lives quickly unravel.

Negative emotions, including sadness and anxiety, seem to aggravate chronic pain. For example, people who dwell on their discomfort tend to be more disabled by chronic pain than people who try to take their pain in stride. And among people with chronic pain stemming from a work-related injury, those who report poor job satisfaction fare worse than those who say they like their jobs.

But negative emotions can be a result of chronic pain as well as a cause. "If you had always been an active person and then you developed chronic pain, you might become depressed," says Roger Chou, MD, associate professor of medicine at Oregon Health & Science University in Portland and a leading expert on chronic pain. "Depression is common in chronic pain patients, but people who think chronic pain is 'all in the head' are not being realistic."

Because chronic pain affects all aspects of your life, it's important to treat chronic pain both medically and emotionally.

"People with chronic pain shouldn't assume that they have to tough it out," says Russell K. Portenoy, MD, chairman of pain medicine and palliative care at Beth Israel Hospital in New York City and past president of the American Pain Society. "And they should not be satisfied with a doctor who doesn't want to treat it aggressively."

Drugs Used to Control Chronic Pain

A wide variety of over-the-counter and prescription medicines have been shown to help ease chronic pain, including:

Pain relievers. Many pain patients get some relief from common pain medicines such as acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), and analgesics like aspirin, ibuprofen, ketoprofen, and naproxen. These drugs are considered safe, but they are not risk-free. For example, taking too much acetaminophen can cause liver damage or even death, especially in people with liver disease. NSAIDs can cause ulcers and raise the risk for heart attack and kidney trouble.

Antidepressants. Several drugs approved by the FDA to treat depression are also prescribed by doctors to help relieve chronic pain. These include tricyclic antidepressants such as amitriptyline (Elavil), imipramine (Tofranil), clomipramine (Anafranil), desipramine (Norpramin), doxepin (Sinequan), and nortriptyline (Pamelor). The pain-relieving effect of tricyclics appears to be distinct from the mood-boosting effect, so these drugs can be helpful even in chronic pain patients who are not depressed.

Other antidepressants used to treat pain include venlafaxine (Effexor) and duloxetine (Cymbalta), which the FDA has approved to treat fibromyalgia and diabetic nerve pain. These drugs are members of a class of medications known as serotonin and norepinephrine reuptake inhibitors (SNRIs). They seem to be about as effective at treating chronic pain as tricyclics, but are less likely to cause dry mouth, sedation, urinary retention, and other side effects.

When used at appropriate doses with careful monitoring, these drugs can be safe and effective treatment for chronic pain. But be sure to discuss the risks, benefits, and research behind any drug with your doctor.

Anticonvulsants. Several drugs originally developed to treat epilepsy are also prescribed for chronic pain. These include first-generation drugs like carbamazepine (Tegretol) and phenytoin (Dilantin), as well as second-generation drugs like gabapentin (Neurontin), pregabalin (Lyrica), and lamotrigine (Lamictal). Gabapentin and Lyrica are FDA-approved to treat pain.

The first-generation drugs can cause an unstable gait (ataxia), sedation, liver trouble, and other side effects. Side effects are less of a problem with second-generation drugs.

Opioids. Codeine, morphine, oxycodone, and other opioid medications can be very effective against chronic pain, and they can be administered in many different ways, including pills, skin patches, injections, and via implantable pumps.

Many pain patients and even some doctors are wary of opioids (also known as narcotics) because they have the potential to be addictive. Except for patients with a history of addictive behavior, pain experts say the potential benefit of narcotic therapy for chronic pain often outweighs the risk.

"It's a matter of balance," says Chou. "People do need to be concerned about the risk posed by opioids. But as a physician, I think it is inappropriate not to use medications that can help people, if the risks can be managed."

Generally, doctors who prescribe opiod treatment monitor patients with chronic pain carefully.

Nondrug Treatments for Chronic Pain

In addition to drug therapy, several nondrug treatments can be helpful for chronic pain, including:

Alternative remedies. Although doctors don't know exactly how it works, there is good scientific evidence that acupuncture can offer significant relief from chronic pain. Other alternative remedies proven to work against pain include massage, mindfulness meditation, spinal manipulation by a chiropractor or osteopath, and biofeedback, in which a patient wearing sensors that record various bodily processes learns to control the muscle tension and other processes that can contribute to chronic pain.

Exercise. Low-impact forms of exercise like walking, bicycling, swimming, and simply stretching can help relieve chronic pain. Some people find it particularly helpful to participate in a structured exercise program given by a local hospital.

Physical therapy. Pain patients who work with a physical therapist or occupational therapist can learn to avoid the particular ways of moving that contribute to chronic pain.

Nerve stimulation. Tiny jolts of electricity can help block the nerve impulses that cause chronic pain. These jolts can be delivered through the skin via transcutaneous electrical nerve stimulation (TENS) or via implantable devices.

Psychological therapies. A form of psychotherapy known as cognitive behavioral therapy is particularly helpful for many people with chronic pain. It helps them find ways to cope with their discomfort and limit the extent to which pain interferes with daily life.

Unlike some traditional forms of psychotherapy, which focus on personal relationships and early life experiences, cognitive behavioral therapy aims to help people think realistically about their pain and find ways to work around physical limitations.

"Cognitive behavioral therapy helps people overcome the mistaken belief that they need to lie in bed until their pain is gone, or that if they go back to work they will cause permanent damage to their body," Says Chou.

Picking the Right Treatment for Chronic Pain

Given all the ways chronic pain can be treated, how is one to know which treatment, or combination of treatments, makes the most sense for your chronic pain?

"We don't have enough evidence from studies to know just which approach is right for which patient," says Portenoy. "Picking the right treatment is a matter of clinical judgment, and it involves talking with the patient" about the specific nature of the pain and the effectiveness of any treatments that have already been tried.

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