WHAT HAPPENS TO OUR PAIN CIRCUITS WHEN THE NERVES CONNECTING MUSCLES AND THE SPINAL CORD GET INJURED?

In 1984, while I was studying the effects of a nerve injury where an injured nerve was unable to repair itself and reestablish its former connections inside of muscles, it became apparent that, in addition to the injured nerve cells, the nerve cells that they connected to inside the spinal cord were also getting injured. This discovery indicated that the effects of nerve injury were much more serious and widespread than previously appreciated because they extended to the entire pain circuit of the injured nerve. This finding in part provides an explanation for why so often a chronic pain experience will long outlast an initial injury or traumatic event. 

Since that time, many other changes in pain circuits following nerve injuries have been discovered. For example, injured nerve cells release several different chemicals like substance p and nerve growth factor into their affected muscles as well as from their endings in the spinal cord. In addition, the environment surrounding pain neurons in the spinal cord that transmit pain messages to the brain also changes. For example, glial cells surrounding injured spinal cord neurons start releasing chemicals around these neurons that increase their activity. All of these effects contribute to the continuation of the activity of nerve cells in pain pathways that contribute to the sustained, unrelenting quality of the chronic pain experience.

After nerves have been injured, there are two kinds of activities that contribute to this relentless quality of chronic pain. First, the nerve cells inside of the injured nerves begin to respond to events that were previously not considered painful, like light touch or pressure. They also begin to respond to new areas of the body that previously lied beyond the more limited areas that they used to respond to. These changes fall under what scientists call allodynia, i.e., injured nerve cells that now respond to events that were not previously painful but now are.

The second activity involves nerve cells inside the spinal cord and brain pain pathways that receive inputs from the injured nerves. These nerve cells now maintain their activity longer than they used to. They will often exhibit a behavior called windup where they will respond to successive inputs with higher and higher firing rates. Such changes are referred to as neuropathic pain by scientists, i.e., sustained activity in brain and spinal cord pain pathways that long outlast the injurious event that caused them.

Such sustained activities in altered pain pathways have a disastrous effect on the muscles of the body that they activate. What happens is that the sustained activity in the pain pathways  is also maintained by the nerve cells exiting the spinal cord (motor nerve cells) that control these muscles. Because of the sustained activity, the affected muscles cells cannot fully relax. They develop contraction spots, shorten, are placed under excessive tension and cannot move comfortably through their normal, full range of motion. The result is chronic pain that comes from these muscles. If it goes on long enough, the joints that they are attached to will also get damaged and also become sources of chronic pain. At this point, all the elements of a full blown chronic pain experience are now in place. Without confronting such a chronic pain situation and taking some kind of corrective action, the chronic pain will continue for months and many times for years.

Is there a way out of this dilemma? There is. It involves a two part solution; first, stopping the affected muscles from continually sending painful messages along their nerves into the spinal cord and second, altering the pain circuits in the spinal cord and brain so that they stop firing continuously.

The first part involves identifying the muscles that have been affected, applying sustained pressure to all of the contraction spots in those muscles using the trapped ball method (detailed in The Book [https://store.bookbaby.com/book/A-Way-Out-Of-Chronic-Pain]) and applying sustained stretches of the affected muscles to relieve excess tension in them and recapture their lost range of motion. The second part involves returning each day to confront the contraction spots for at least two to four weeks to get them to stop their destructive effects on the brain and spinal cord pain pathways. If this can be accomplished, it will give them a chance to change their activity patterns and allow them to heal. Along with their healing, will come relief from the chronic pain.

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