More than 350 years ago, Rene Descartes presented a theory that shaped the way we understood pain for centuries. At the time, the widespread idea was that pain stemmed from outside of the body, existing as a kind of divine test—something that could only be addressed through spiritual means. Descartes suggested that pain originated from within the body, starting from the injured area and moving to the brain. For a long time, this general concept of pain prevailed. However, research over the past few decades has led to a new theory: that pain originates not in the injured area of the body, but in the brain itself.
Imagine that you accidentally touch a hot stove. Your nervous system immediately begins sending messages from your hand to your brain. These messages aren’t pain itself, but rather signals to your brain letting it know that your body has encountered a danger. Once your brain receives these signals, it activates its pain center, causing your hand to start hurting. And once you start feeling pain, you’ll pull away from the stove and prevent further damage to your hand. In this sense, pain isn’t inherently a bad thing—it often allows us to avoid more serious injuries by encouraging us to address the danger immediately.
Let’s imagine, however, that once you pull your hand away from the stove, you don’t really give it enough time to rest before using it again. Maybe you use it when doing the dishes or taking out the trash or typing—all for weeks on end, while the original burn is healing. When your brain perceives these new, ongoing threats, it adapts by making the nervous system better able to send danger messages, in the hope that you will eliminate the danger if the pain gets louder or more persistent. We see this situation all the time: an individual will, for example, injure the back and then continue to do all sorts of physical labor while it’s still healing, causing reoccurring and escalating amounts of pain.
This leads us to an imperfection in this system. Let’s say it has been several months since you burned your hand. The injury itself has completely healed. However, at this point, your nervous system has gotten very good at sending danger messages to your brain, and your brain has gotten very good at turning these messages into pain. And now, your body might interpret any number of things as dangerous and signal your brain to activate its pain centers. Stress, allergies, an ache in another part of the body, gastrointestinal upset, memories of previous trauma, anxiety—even things as innocuous as temperature, pressure, or weather changes—may now cause pain in your hand, or even in other parts of your body. Your brain still perceives danger (however misguided this may be), and it is doing its best to get your attention.
If you are one of the 25.3 million adults who suffers from chronic pain—that is, pain that lasts more than three months—this might sound both familiar and frustrating. After all, how do you treat pain after the injury itself has healed? Fortunately, the brain and the nervous system are both incredibly adaptive. When it comes to treating chronic pain, we simply need to treat your brain in addition to your body.
So what does this mean for physical therapy? Generally speaking, when your medical team suspects that your chronic pain may be a result of these amplified danger messages, it is very important that any treatments do not worsen your pain. Increasing pain is a sign that your brain perceives danger, which will perpetuate this pain cycle. This is absolutely not a time for a “no pain, no gain” approach. Rather, your physical therapist will guide you through repeated, gentle movements—ones that your brain will perceive as “safe.” This will allow your brain to “recalibrate” its pain processing system, so that it can more accurately warn you of true danger and cease to perceive danger where there is none.
This type of treatment has proven incredibly effective for chronic pain. The nervous system can adapt in just a few minutes, and the amplified danger signals can diminish in as little as a few days. What’s more, studies have shown that education on chronic pain can immediately alleviate pain, as it targets the brain and calms the anxiety that can accompany a painful experience.
If you’re experiencing chronic pain even after an injury has healed, please do not feel as though there’s nothing more you can do. Reach out to your physical therapist for an assessment. We’d be happy to help you find relief from your pain—in your body and in your brain.