Those suffering from chronic pain will often confess that nothing hurts more than their inability to convince their doctors that they’re hurting. Some relief may be on its way, though: Recent research has gradually begun to uncover the mechanism behind this mysterious malady.
Defined as physical discomfort of an unknown source lasting more than three to six months, chronic pain plagues more than a billion people around the world and has flummoxed scientists for decades. But researchers are now beginning to understand the role a collection of nervous-system cells, called glia, may play in the process.
Originally thought to be simple connective tissues binding neurons together, glia have since been found to be instrumental in feeding neurons, cleaning their waste, and helping them communicate. Only in the past 20 years have researchers begun to discover how glia not only respond to pain signals and other neuronal activity but often manipulate it.
As a result, the body’s normal response to the acute pain that signals an injury becomes an ongoing battle with a mysterious enemy. As Stanford University pain researcher Elliot Krane, MD, tells the New York Times, rather than acting as a warning of harm, a pain signal turns into “its own disease.”
When you stub your toe on a table leg, for instance, the message travels seamlessly toward your brain via the pain-sensitive neurons of the peripheral nervous system, sparking an instant recognition that your toe is hurting. During the transfer of signals from the peripheral to the central nervous system, however, glia can cause trouble. These cells can dysregulate the pain message, provoking the nerves to continuously sound the alarm.
Though researchers don’t yet know how to clearly identify the process in humans, they can at least point to biological evidence that chronic pain does exist. And for sufferers like Cindy Steinberg, national director of policy and advocacy at the U.S. Pain Foundation, that’s a welcome affirmation. “Learning this is enormously helpful to those of us who suffer chronic pain,” she says.