(Ivanhoe Newswire) -- New research from the United Kingdom reveals what causes ongoing spontaneous pain is undamaged nerve fibers -- not those fibers that are injured.

It's an unexpected finding, say researchers from the University of Bristol in England. Previous research focused on the damaged nerve fibers after injury or disease. The nerve fibers that remain intact are overlooked, but this study shows these intact nerve fibers are the culprit when it comes to ongoing pain. The finding could help pharmaceutical companies come up with new pain killers and bring relief to pain sufferers everywhere.

Professor Sally Lawson, from the University of Bristol, says, "The cause of this ongoing pain and why it arises spontaneously was not understood before. Now that we know the type of nerve fibers involved, and especially that it is the undamaged fibers that cause this pain, we can examine them to find out what causes them to continually send impulses to the brain. This should help in the search for new analgesics that are effective for controlling ongoing pain."

Ongoing pain is defined as a burning or sharp stabbing or shooting pain that happens spontaneously after injury to the nerve. Unlike pain caused by stubbing your toe, for example, or slamming your finger in a door, ongoing pain is difficult to live with because it's usually impossible to treat with pain killers that are currently available.

Here's what the new study reveals about why ongoing pain persists: Researchers found the nerve cells responsible for the pain are 'nociceptors' or damage detectors. Each one of these nerve cells (there are thousands of them) have a long nerve fiber coming from it. Those fibers run through the nerves and connect the skin or other tissues to the spinal cord.

When an injury or disease activates these fibers, they fire electrical impulses to the spinal cord -- from where information is sent to the brain. The quicker those "undamaged" nerve fibers fire, the stronger the ongoing pain becomes.

Authors of the study say more research is now needed to establish how this mechanism may contribute to ongoing pain associated with a wide variety of diseases such as back pain or shingles.

SOURCE: Journal of Neuroscience, 2006;26:1281-1292