What is "injury memory"?
Injury memory is an apt term for the localized, leftover stress response that causes pain after a traumatic injury heals. (It's not a mental memory of an accident.) During tissue healing, stress response in the injury site is normal and healthy, serving immune and regenerative mechanisms. However, after tissue healing is complete (or almost complete but blocked), a stubborn stress response often remains, which may engender pain and degeneration indefinitely. Fortunately, this injury "memory" can be erased by SNS pain discharge.
Strangely, the presence of injury memory may be confirmed only retrospectively—after pain is discharged from the injury site. For example, how does one detect injury memory in a knee joint with chronic pain? Firstly, pain is always accompanied by stress response, which equals tissue contraction. Stress response is a normal response to discomfort. However, knee pain often does not involve muscle spasms that we associate with musculoskeletal pain. But then, when pain is discharged from the knee, chronic pain stops immediately. Pain relief indicates relaxation, tissue expansion, and a return to normal circulation. A stable stress response—dating back to the injury—was suddenly and permanently relaxed. But where was the stress response, if not in muscles? It was hidden inside the knee joint, in all the tissues.
The dual functions of the autonomic nervous system—expansion and contraction—exist at the cellular level, in individual cells of every solid tissue (at least), including muscle, cartilage, and bone. We know this from observation of organisms with no nervous system, e.g. the single-celled amoeba and multi-celled sea sponge, which exhibit tissue expansion and contraction, i.e. relaxation and stress response. Therefore, even inside a knee joint, we can have injury memory (chronic tissue contraction), pain discharge, and tissue expansion—basic functions of the autonomic nervous system. This point is vitally important for those with inflammation affecting the inner tissues of joints, i.e. osteoarthritis, where constricted circulation blocks normal metabolism. As suggested by permanent or prolonged pain relief, the degenerative process appears to be interrupted and/or terminated by SNS pain discharge.