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As the chronic pain epidemic continues to pour over into the opioid epidemic, new research continues to break down the complexity of chronic pain. Just a few short years ago, chronic pain was viewed completely from a biomechanical perspective. When the medical community realized that treating only the injury was not only not working, but the epidemic of chronic pain continued to worsen they realized they needed to take a step back and look at the whole person. What has been discovered has been an eye-opening look at how chronic pain involves factors beyond what is happening within body tissue. Now, we take a broader look at the whole person and understand chronic pain has a multitude of origins.
Over time, physicians and other professionals realized the amount of tissue damage being seen on an MRI and the amount of pain a person was experiencing just weren't matching up. Beyond that, those who underwent surgical procedures were showing objective improvements in imaging but not meaningful improvements in pain levels and quality of life. Over time, physicians and therapists noted that some people with chronic pain had no substantial injury on an MRI that would explain their pain. On the other hand, others had extensive arthritis and changes in the tissue without pain. This does not mean that the pain is not real, just that it's not correlating with tissue damage.
This observation led researchers to dive deeper into differences in the overall lives of those with pain and those without. What they found was that factors such as lifestyle choices, diets full of inflammatory foods, smoking, anxiety, depression, occupation, education level, and socioeconomic status all had a stronger correlation with level of pain than any severity of injury or disease did (with rare exceptions). These results were initially surprising and led to further study into where pain was coming from.
So you might be wondering what they found...
Our nervous system consists of nerves that run to and from the brain for communication with the body. Nerves communicate through the use of electrical signaling. The nerves that communicate information from our tissues to the brain are called sensory nerves. These relay information such as pain, touch, pressure, and temperature. Sensory nerves send information to the brain constantly.
Motor nerves run from the brain to the muscles work to control muscles. These can work on a conscious or subconscious level. For instance, you can make a conscious choice to focus on your breathing and take deeper breaths. However, the minute you stop consciously focusing on your breathing your subconscious mind continues to communicate with your breathing muscles, causing them to run on autopilot. The brain and spinal cord store information on our regular movement patterns, such as breathing and walking. This stored information is called a motor program.
The brain is the center of all of this communication. It has a designated area dedicated to each body part to store information about how each part is used. The area dedicated to the hands takes up more space than the area dedicated to the back because the hands are involved in much more intricate movements and fine motor control.
Our brain decides what incoming information from sensory nerves needs to be acted on immediately, what can wait, and what does not need to be dealt with at all. For example, when you first put a sock on you may be initially aware that your foot feels different. Usually after the first few seconds you are no longer consciously aware of the sock as the sensory nerves have adapted to the continuous compression of the sock.
This also means your brain dictates whether or not you will feel pain. Suppose you are running across the street to get out of the way of a bus when you roll your ankle. Your brain delays you sensing pain because the threat of a bus coming at you is much greater in that moment. Once you are safely out of harms way, the adrenaline rush keeps you from feeling pain from the ankle sprain likely for a few more hours.
An acute pain response is normal and is your body’s way of sounding an alarm in response to a threat to your system. In the case of an acute ankle sprain, we feel ankle pain which keeps us from moving around too much until the tissue has had time to heal. However in cases of chronic pain, the nervous system is unable to calm down and continues sending an alarm even though there is no longer a threat. Pain at certain times in normal, however chronic pain is not.
Our body is also capable of sensing pain even without tissue damage. For example, if you get your hand to close to a hot stove you quickly pull your hand away likely before you realized what was happening. Many of these responses are reflexive for our body and can act without some level of conscious thought process. Sometimes the alarm system continues to go off even though there was no actual damage.
Chronic pain is an indicator of changes within the nervous system more than it is an indicator of tissue damage. Studies have shown actual changes throughout the nervous system in cases of chronic pain including:
Additional Resources for Further Exploration:
Greg Lehman’s Recovery Strategies
David Hanscom MD: Back in Control: A Surgeon’s Roadmap Out of Chronic Pain
Adrian Louw: Why Do I Hurt?