Chronic pain is the worst houseguest ever, sticking around long after it arrives and making it tough to carry on with your life and activities. The difference is you can send your houseguest home. Sending chronic pain packing isn’t as easy.

Most people view pain as having an underlying cause; treat the cause, and the pain should disappear. According to this theory, getting rheumatoid arthritis, RA, under control should get pain under control. And replacing a joint damaged by osteoarthritis, OA, should eliminate pain in that joint.

Often, these measures work. Taking disease-modifying drugs and having joints replaced can give people their lives back, eliminating or drastically reducing pain.

But as too many people with well-controlled RA and/or artificial joints know, pain often lingers. And because it’s not well understood why that happens, effective treatment can be elusive.

“Chronic pain is a very difficult problem for doctors to [help patients] with,” says David Borenstein, MD, clinical professor of medicine at The George Washington University Medical Center in Washington, D.C., and head of the Pain Management Task Force for the American College of Rheumatology. “If you have acute pain – a broken bone, say – you can diagnose and treat it. But if you’ve had the same pain for five years and nothing has worked, the pain has become ingrained in your psyche and physiology. Its home isn’t in the various [body parts] that may have been the pain’s initial starting point.”

That may be because chronic pain turns independent, essentially becoming its own disease. “If you have inflammation in RA that hurts over long periods, that pain message is always being sent to the brain,” says psychologist Afton L. Hassett, an associate research scientist at the Chronic Pain and Fatigue Research Center, University of Michigan Medical School in Ann Arbor. “Because of the plastic nature of the central nervous system [CNS], those very neurons that carry the message begin to change, and probably become more efficient messengers.”

The upshot? Your brain may begin to misread a small message of pain as a big one. Doctors call this “centralized pain.”

A Quest For Answers

Hassett and other researchers are trying to figure out which patients will have this kind of pain response and why, and OA is a good basis for study. “Cartilage doesn’t have [nerves], so a key area of damage – the cartilage – is not directly causing pain,” says Jacqueline Hochman, MD, assistant professor of rheumatology at the University of Toronto. In OA, damage to joints doesn’t always correlate with symptoms;

X-rays can show significant joint damage, but a person may feel little pain – or vice versa.

Hassett is studying patients with OA who have had their knee or hip replaced. “About 20 percent continue to have chronic pain. The pain has likely become centralized – they no longer need to have outside input from inflammation or injury. The pain is driven by dysfunction in the central nervous system,” Hassett says.

Fibromyalgia pain, once thought to be in the ligaments and soft tissues, is now believed to be directed by the CNS as well.

According to a 2010 review in the journal Pain, brain changes that result from chronic pain appear to be specific to each type of chronic pain. The brain changes in someone with chronic back pain, for instance, might look different from changes that originated from OA. And pain “looks” different in each brain, depending on how it is perceived. In other words, understanding pain’s imprint on the brain isn’t easy, and is far from complete.

As for whether chronic pain and resulting brain changes can be reversed, no one knows for sure – but small studies suggest it’s possible. A 2010 study in Arthritis & Rheumatism of 16 patients with hip pain found that gray matter in the thalamus, part of the brain involved in sensory perception, decreased during chronic pain. Nine months after hip replacement, the gray matter had normalized.

“The presumption was that the ongoing input from the damaged joint led to reversible changes in the thalamus that contributed to chronic pain,” says Dr. Hochman. “The researchers’ impression was that the abnormalities in pain processing normalized after the removal of the damaged joint and the chronic input into the CNS. But there may be a subset of people in which changes are irreversible.”

Make Pain A Priority

Despite the sobering data about widespread chronic pain, the good news is that, as scientists embrace chronic pain as its own disease, they can begin to explore treatments addressing the CNS instead of – or in addition to – treating whatever condition jump-started your pain. But they can’t treat what they don’t know, so here are ways to help doctors help you.

Don’t Tough It Out. Experts define “chronic pain” as pain that has lasted three months or longer, or pain that persists beyond the expected healing time of an injury. Take steps to stop pain before it becomes chronic.

Immediate, short-term pain is much easier to treat, says Dr. Borenstein. “Patients say, ‘I don’t want medications,’ but I try to convince them to take enough so that the nervous system does not get pain signals,” he says.

Give Your Doctor Details. “If a patient doesn’t bring pain up as priority, the physician may not focus on it,” saysYvonne C. Lee, MD, assistant professor of medicine at Brighamand Women’s Hospital in Boston and co-author of an October2011 editorial on pain in The Rheumatologist. “Tell him where the pain is and what it prevents you from doing – for instance, ‘I can’t brush my hair, or shower.’ And if it doesn’t make you focus too much on pain, keep a pain diary so that you can go to appointments informed.”

Ask About CNS Meds. “A major breakthrough is the use of antidepressant medications such as duloxetine [Cymbalta] for chronic [pain] conditions,” says Dr. Borenstein. “Chemicals called norepinephrine and serotonin populate the body’s pain-inhibition system. If you increase those chemicals, you stimulate the pain-inhibition pathways so you have less pain.”

Another breakthrough is the use of certain epilepsy drugs, such as pregabalin, brand name Lyrica, which was the first FDA-approved drug for treating fibromyalgia. “In people with fibromyalgia, it modifies the way pain signals are processed,” Dr. Borenstein says. (Learn more about fibromyalgia drugs in the Drug Guide, page 66.)

Consider A Pain Center. If you’re not getting pain relief, ask your doctor to refer you to a pain center, says Dr. Lee. “Look for a center that is multidisciplinary. You want a mix of physicians, like an anesthesiologist, a physiatrist and a psychiatrist, plus physical therapists and psychologists.”

The bottom line: Push to understand and control your pain. Don’t let it rob you of a life you love.