Explain Pain Section 4: Altered Central Nervous System Alarms

This is a summary of section 4 of “Explain Pain” by David Butler and Lorimer Moseley. CNS Alarms While much of talk in rehab deals with tissue injury and tissue pain, realize that the brain always makes the final decision as to whether or not you should feel pain. No brain, no pain. This sentiment does not mean that pain is not real. All pain is real. However, pain is a construct that the brain creates in order to ensure your survival. Spinal Cord Alarms When an injury occurs and the DRG receives impulses from peripheral structures or the brain, the spinal cord neurons must adapt to better uptake all these signals. In essence, the DRG becomes better at sending danger messages up to the brain. This change leads to short term increases in sensitivity to excitatory chemicals. Those stimuli that didn’t hurt before now do (allodynia) and those that used to hurt now hurt more (hyperalgesia). In persistent pain, this change continues occurring to the point where neurons that do not carry danger messages start growing into space where danger messages are taking place. Now innocuous stimuli such as grazing the skin begin hurting. The pain may be normal, but the underlying processes become abnormal. When these spinal cord alarm systems become unhealthy, the brain no longer receives an accurate message of what is going on. The alarms become magnified and distorted.  The brain is told there is more damage in the tissues than is actually present. What is good is

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Explain Pain Section 2: The Alarm System

This is a summary of section 2 of “Explain Pain” by David Butler and Lorimer Moseley. Alarm Signals Our body’s alarm system alerts us to danger or potential danger. This alarm system is composed of sensors throughout the body, the eyes, nose, and ears. It is these sensors that are our first line of defense against harm. If one sensor fails the others take over. Most of these sensors are located in the brain and respond to various stimuli. Some to mechanical movement, some to temperature change; the sensors in the brain particularly respond to chemical activity. What is important to know with sensors is that they have a very short life expectancy of a few days. This cycling means our body’s sensitivity is constantly changing. It is with these life cycles that there is hope for those with chronic pain. Moreover, the rate at which sensors are made is normally stable but can change very quickly in regards to a particular stimulus. So if we take for example one with persistent pain, the rate at which pain sensitivity occurs can be changed. Nociception We lack pain receptors in our bodies. Instead, the various tissues have special neurons that respond to different stimuli. These receptors are called nociceptors, which translates into “danger receptors.” Nociception is occurring all the time, but only sometimes will it end in pain. Nociception is neither necessary nor sufficient for pain. The sensors correspond to particular neurons. In order for these neurons to become excited and

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