Pain processing is how our body’s nervous system detects, sends, and understands pain signals. It involves different parts of our body, like nerves, the spinal cord, and the brain, working together. And before we continue, I want to mention that I am not a medical professional and what follows is not medical advice. I was intrigued with this information, and I hope you will get some value from it, too.
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When we get hurt or have tissue damage, special nerve endings called nociceptors get activated. These nociceptors send signals through our nerves to the spinal cord, which then sends the information to the brain. The brain processes these signals and makes us feel pain. Ouch!
Neuroinflammation, on the other hand, is how our immune system in the central nervous system responds to injury, infection, or disease. It involves certain immune cells called microglia and astrocytes, as well as the release of molecules that cause inflammation, like cytokines and chemokines.
In terms of pain, neuroinflammation can affect both short-term and long-term pain conditions. In short-term pain (aka acute pain), neuroinflammation is a normal part of the body’s healing process. It helps clean up damaged tissue and promote tissue repair. However, in long-term pain (aka chronic pain) conditions, neuroinflammation can last longer and make pain signals stronger and longer lasting.
In chronic pain conditions, neuroinflammation can persist for extended periods of time, which means it lasts longer than usual. This prolonged neuroinflammation can have significant effects on pain signals within the body.
Firstly, neuroinflammation can intensify or amplify pain signals. Normally, when we experience pain, the nociceptors send signals to the brain to indicate the presence of a painful stimulus (aka something that hurts!). However, in chronic pain conditions accompanied by neuroinflammation, the inflammatory molecules released during the neuroinflammatory response can sensitize or heighten the sensitivity of nociceptors. As a result, these nociceptors become more responsive to pain, meaning that even mild or non-painful stimuli (i.e., things that do not cause pain) can be perceived as painful.
Secondly, the persistence of neuroinflammation can lead to the prolonged transmission of pain signals. Ordinarily, when acute pain occurs, the neuroinflammatory response serves a protective function by helping the body heal and recover from the injury or damage. Once the healing process is complete, the neuroinflammation subsides, and pain signals diminish. However, in chronic pain conditions, the neuroinflammatory response persists even after the initial injury has healed. This ongoing neuroinflammation keeps pain signals active and continually transmitted to the brain, resulting in a prolonged experience of pain.
In summary, in chronic pain conditions, neuroinflammation can both increase the intensity of pain signals and prolong their duration. The persistent neuroinflammatory response sensitizes the nociceptors, making them more sensitive to pain, while also sustaining the transmission of pain signals to the brain. These combined effects contribute to the heightened and prolonged experience of pain often associated with chronic pain conditions.
If you want to take a deeper dive on this topic, here are some references that should provide you with a good foundation for understanding pain processing and neuroinflammation:
- Pain. Glia and pain: Is chronic pain a gliopathy?
- Neuron. Current challenges in glia-pain biology
- Nature Reviews Immunology. Pathological pain and the neuroimmune interface
To Your Success & Freedom,
Glenn Shimabukuro
