Pain Response Not Always Normal One

Category: Fibromyalgia (FMS) Published on Monday, 01 August 2005 Written by Yong Tsai, MD

Do you live with constant pain, but are told that everything is normal? Do you have fibromyalgia or chronic back pain and feel there is no answer in sight? Like many other fibromyalgia patients, you too may have CSS (central sensitivity syndrome). Defined as hyper-excitability of the central nervous system due to harmful stimuli, CSS creates an exaggerated response to painful stimulus (hyperalgesia), prolonged length of response after brief stimulus (persistent pain), and pain after the simple act of touching or rubbing (allodynia). When injury, disease, or inflammation occurs, pain receptors in our skin, muscles, ligaments, and joints are able to detect tissue damage.

In turn, numerous neurotransmitters, located in each nerve cell, work together and transmit electrical impulses from the pain receptor to the peripheral nerve and up the spinal cord. Finally, these impulses are relayed to the brain whose role is to process and interpret pain signals.

During a gout flare-up, you would experience acute pain because of immediate, usually severe, inflammation. Fortunately, acute pain usually resolves itself in a matter of time, depending on the severity of the injury or illness. Further characteristics of acute pain are the fact that you know exactly from where the pain stems and its course is usually predictable.

Unlike acute pain, chronic pain can occur without any indication of injury, as a result of improper healing of an acute injury such as an improperly treated back injury, or due to a chronic illness such as spinal stenosis or rheumatoid arthritis. The duration of chronic pain is far from being predictable and periods can last from several weeks, months, or years.

The culprit in this instance is that of abnormal pain processing by the brain, which makes chronic pain much more complex than acute pain. When the brain receives repetitive and sustained electrical impulses from the pain receptors for a prolonged period of time it becomes hyper excited and its pain signals are amplified. But pain signals become automatically relayed, even in the absence of electrical impulses, which is known as the “wind-up” phenomenon. Even though the original injury may be healed, the sensation of pain can persist and even intensify. A typical example of abnormal pain processing is fibromyalgia. Patients suffer with chronic widespread, generalized muscle pain, along with headaches, irritable bowel syndromes, chronic fatigue, hyperalgesia, allodynia, and persistent pain, but lack muscle or joint inflammation.

Many fibromyalgia patients report on onset of symptoms following events like repetitive injury, which is associated with the “wind-up” phenomenon. The continual tissue insult amplifies pain peripheral impulses, thus distracting the normal course of pain perception.

Fortunately, times have changed and the belief that most central sensitivity syndromes are “all psychological” is fading. Hopefully, with further understanding of pain processing, we can develop some medications specially targeting the problems of central sensitization.

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