When pain becomes chronic, it takes on a life of its own in the body and needs special treatment. (MASTERFILE) Acute pain comes on quickly, often following an injury or infection. And it usually goes away quickly with painkillers or antibiotics. Chronic pain persists. For some people it can occur out of the blue, with no evident triggering injury or illness. It can be experienced as headaches, back pain, joint pain, nerve pain, or a myriad of other localized conditions. And it's much more common than many realize: One 2004 study estimated that approximately one-third of Americans had experienced chronic pain in the past year.
Scientists now believe that one cause of chronic pain is a dysfunction of the nervous system. Neurons (cells in the nervous system that communicate with each other) become overexcited and keep firing, even after the original cause (injury or illness, in some cases) has long since passed. The person receives persistent pain signals.
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At the same time, scientists believe that the cells that normally inhibit these neurons from firing either die off, begin to degenerate, or are overpowered and become less effective.
"These very excitable neurons don't have the intrinsic mechanism to keep them under control," explains Robert Yezierski, PhD, director of the Comprehensive Center for Pain Research at the University of Florida, in Gainesville, "so wham, they just start firing out of control."
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"We're beginning to appreciate that chronic pain is a disease in its own right and a disease that can be very sneaky and very difficult to manage," says Sean Mackey, MD, chief of the Division of Pain Management at Stanford University School of Medicine, in Palo Alto, Calif.
"It causes fundamental changes to our nervous system. It rewires our brains and our spinal cords and when it does that it's very challenging to reverse that wiring and bring it back to normal," says Dr. Mackey. "And that's what a lot of us are doing research to do right now."
Andrea Cooper, 52, a fibromyalgia sufferer from Phoenix, Md., is intimately acquainted with the phenomenon: "In someone who has a normal pain response, the pain will stop. But [with chronic pain] it's like the brain never gets the signal back that it doesn't hurt anymore. The alarm just keeps going off."
Why is this happening to me?
Pain teaches all creatures who suffer it not to do things that caused them injury the first time around—a useful evolutionary tool. Wracked by chronic pain, though, the human sufferer may well wonder, What is the point of this? When chronic pain is understood as a disease, rather than a warning sign, it becomes clear that there is no point, only a poorly understood mechanism. But as science better understands that mechanism, new pain strategies are being developed to help bring the pain under control.