The Two Things You Need to Know About Pain: It’s Not What You Think (1 of 3 Pain Series)

The Two Things You Need to Know About Pain: It’s Not What You Think

Have you ever left a doctor’s office more confused than when you walked in? Maybe you were told you have ‘muscle pain,’ ‘nerve pain,’ or ‘spine pain,’ as if naming your discomfort would make it easier to understand or treat. We often think that pinpointing the exact source of pain will lead to a quick fix. But pain is more complex than that. It doesn’t always work the way we expect.

For example, when we feel pain in our back, it’s natural to blame it on an injury to our spine. However, many people don’t realize that our spines are incredibly strong and built to resist injury. Most of the changes we see in our spines on MRI and X-ray as we age are entirely normal and happen to everyone. These changes usually have more to do with our genetics than any injury. For instance, did you know that our spinal discs reach their largest size around age 13? After that, it’s normal for the spinal discs to start shrinking—a process doctors call “degeneration.” This might sound alarming, but it’s just a natural part of aging. You might also see things like disc bulges on a scan, but these are common and often have nothing directly to do with the pain you’re feeling.

Figure 1 – Brinjikji, et al. 2014

Yet despite these changes, there’s often little connection between what we see on scans—like an MRI, CT scan, or X-ray—and the pain we feel. Why do these scary-sounding changes sometimes result in pain and other times don’t? Pain isn’t a straightforward signal from a damaged body part.

Today, we’ll explore two critical things related to pain: first, how your body’s harm detection system plays a central role in pain, and second, how your body’s internal ecosystem influences this system.

Thing #1: The Nociceptive Apparatus AKA: The Harm Detector

To understand pain, we need to look beyond muscles and bones. Pain doesn’t originate directly from these tissues or any tissue. Instead, pain involves a system called the nociceptive apparatus, a part of your nervous system that acts as a harm detector. This system generates electrical impulses in response to potential or actual tissue injury—a process known as nociception. However, it’s important to note that while nociception is necessary for the sensation of pain, it does not guarantee the experience of pain. Nociception is related to actual or potential harm, not creating the pain you feel, and it also plays a crucial role in flexibility and movement—something we’ll explore in future blog posts.

One thing to understand about the nociceptive apparatus is that it’s a physical structure within our nervous system, made up of many nerves in your body tissues (including your skin), spinal cord, and brain. This system plays a crucial role in detecting potential harm throughout the body. Its job is to detect potential harm, like stretching, pressure, chemicals, heat, or changes in blood flow. Nearly 70% of your nerve fibers are focused on sensing harm, while the rest handle things like touch or pressure. This system evolved to help us survive by reacting quickly to possible injury, like when you pull your hand away from a hot stove. But the harm detector isn’t just a simple alarm. It’s a complex and distributed network, meaning that its components are spread throughout your body. Even if some parts of this network are damaged, others can still pick up the slack, ensuring that signals from the harm detector are transmitted reliably, even when certain pathways are injured. This is why pain can persist or even spread, making it a much more complicated experience than just feeling hurt in one place.

Figure 2 – Hierarchy of Nociceptive Apparatus – AKA The Body’s Harm Detector

The image shows three levels of how our body’s nociceptive system works to detect harm:

1. Local Level:
   This is the first level where nociceptive nerve impulses are often first generated. Nociceptors are special sensors in various tissues, such as skin, muscles, joints, ligaments, bones, and organs. These sensors detect different types of actual or potentially harmful stimuli, such as something too hot or sharp or a chemical that could cause damage.
   
   
2. The Connecting Pathways – Long Level:
   The second level is called “Connecting Pathways” or “The Long Level.” These pathways are extensions from the local level and stretch throughout the body—like the sciatic nerve in your leg and hundreds of others. Like highways, they carry nerve impulses from the local areas through the spinal cord and into the brain. It’s important to note that spontaneous nerve impulses can also be generated anywhere along the long level without any originating signal from the local level. This means that the nerves themselves can generate signals due to factors like nerve damage or other problematic neurological processes. This is part of why pain can spread and migrate around the body. This level connects local nerve activity to a more extensive network, helping the body process and respond to potential harm on a broader scale.
   
   
3. Whole Person – Global Level:
   At this level, we see how things like blood flow, hormones, immune chemistry, and stress responses can activate the harm detector anywhere throughout the body. This involves your entire body working together, including your brain and overall health, affecting how your harm detectors are activated and how you experience pain. This shows that harm detection is influenced by more than just physical injury—it’s about how your body’s overall state can activate these sensors. For example, think about how your stomach might hurt when you’re really nervous, even though there’s nothing physically wrong with your stomach itself. This happens because your emotions influence your body’s harm detection system through stimulation, such as chemicals and tension.

Pain doesn’t come straight from the nerve impulses the nociceptive apparatus generates. There is no such thing as a pain signal, system, program, or pain sensitivity!

Instead, using a term described in our Complexity Science blog post, pain can be considered an emergent phenomenon,—arising when various factors interact to create something entirely new and distinct from the individual parts, with nociception being just one essential component. Without nociception, the emergence of pain does not occur. This makes pain a unique experience for everyone. As a quick review of an emergent phenomenon, think of water, which comprises hydrogen and oxygen atoms. These atoms can’t act like water themselves—they can’t flow, freeze, or evaporate. However, when combined as a water molecule, they create something new that neither atom could do independently. Similarly, pain is experienced when things like sensation (nociception) and emotions mix in complicated ways we do not fully understand. It’s something new that can’t be fully explained by looking at any one part alone.

A fascinating example of the complexity of pain is phantom limb pain, where someone feels pain in an amputated limb. Even though the limb is no longer there, the nociceptive apparatus can still generate and transmit signals without the missing limb’s nerves. Even if local sensors—like nerves in the skin, muscles, joints, or bones—are gone, the remaining nerves related to those original nerves, such as the “long branches” of the long level, can still send nerve impulses through the nociceptive system. These pathways connect the local areas to the spinal cord and brain. Studies show that parts of the nociceptive apparatus in the brain can still be activated by remaining nerve structures, even if the connections from the rest of the body are cut. This illustrates how deeply embedded and adaptable the nociceptive apparatus is and how pain can emerge even without direct signals from the harm detector in the specific body part where the pain is felt.

People have tried different ways to understand the complex idea of pain. One common way is to think of the brain like a computer that makes guesses about what’s happening in the body and adjusts those guesses with new information. In this view, pain can sometimes seem like the brain’s prediction that something is wrong, even if there’s no real harm. Another idea is that pain acts like a protector, warning us to be careful and avoid more injury. But these ideas have their flaws—while nociception can result in an immediate withdrawal action, pain often shows up too late to act as protection against sudden or slow damage. We also risk looking at pain like a “thing” when looking at it like a computer program when, in reality, it is far more complex of an experience than that.

As discussed earlier, we at IOCH embrace an evolutionary emergent perspective of pain—seeing pain as a complex experience essential for survival. This perspective suggests that pain isn’t just about protecting the body from immediate harm; it’s more about signaling that something within us needs attention and care. While we may not always be able to provide exactly what our body needs, by opening ourselves up to pain and striving to understand what requires attention, we increase the odds of improving our relationship with pain in a practical and meaningful way.

Thing #2: The Body’s Ecosystem

The second important thing to understand is that your harm detector—the nociceptive apparatus—doesn’t work alone. It’s part of a larger system we can think of as your body’s internal ecosystem. This ecosystem includes everything from blood flow and hormone levels to immune responses and stress levels, all of which not only influence but can also directly activate your harm detector throughout the body. But it doesn’t stop there—our internal ecosystem constantly interacts with the broader environmental, social, and cultural systems around us. These interactions occur on multiple levels and dimensions, which we will explore in more detail in future posts.

This is where the connection between spinal changes, our harm detector, and the body’s ecosystem becomes crucial. Remember how earlier on, we discussed that spinal changes seen on imaging scans, like disc bulges or degeneration, are often normal and don’t always cause pain? Here’s where the ecosystem plays a role: pain doesn’t always arise directly from the spinal changes but from how our harm detector interacts with your body’s internal environment.

For instance, when someone has an acute spinal disc herniation, it’s easy to assume the disc material is directly pressing on nerves and causing pain. However, this is rarely the case—less than 1% of the time does the disc material mechanically activate the harm detector. Instead, what usually happens is that disc herniation causes localized inflammation. This inflammation releases chemicals that irritate the local branches of the nociceptive apparatus in the spine, making these nerves much more sensitive to movement and positioning. Even though the spinal tissues aren’t directly causing mechanical damage, the chemical irritation from inflammation can trigger the harm detector to generate nerve impulses and nociception, which may result in experiencing pain with movement and positioning.

Additionally, factors like stress, anxiety, or hormonal changes can further heighten the sensitivity of your harm detector. For example, when you’re stressed, your body releases hormones like cortisol, which, along with chemistry like adrenalin, can make your nerves more sensitive. This means that even if there’s no direct injury, or the injury is minor, the pain can be intense because your body’s ecosystem indirectly increases the number of signals from our harm detector.

This shows that the pain you feel in your back isn’t just about the physical state of your spine but also about how your body’s ecosystem is behaving. The interaction between spinal changes, chemical irritation, and overall body chemistry is what makes the pain experience so complex.

At this “Global Level” of the harm detector, we see how the entire body works together—your nervous system, immune responses, endocrine chemistry, and even your emotional state—contributing to the emergence of pain. It’s not just about the mechanical aspects of your spine, or any other tissue, but how your body’s internal environment, influenced by health, emotions, and external factors, shapes your pain experience.

Conclusion

Understanding how your body’s harm detector works gives us a clearer picture of why pain isn’t just about where it hurts. Pain arises from a complex mix of harm detection, chemistry, emotions, and overall health. Pain is unique to each person and can be influenced by various factors, making it a more complex experience than we might realize. But that’s only part of the story. Pain doesn’t happen in isolation; it’s influenced by the entire body’s ecosystem, which includes factors like blood flow, hormones, stress, and immune responses. This interconnected system plays a critical role in shaping how we experience pain, especially when it becomes chronic.

In the next part, we’ll explore how your body’s ecosystem affects your harm detector and how this can lead to chronic pain. We’ll explore why pain sometimes sticks around even after an injury has healed and why your alarm system might go into overdrive, reacting too strongly or too often. Understanding these dynamics can help us see chronic pain not just as a lingering injury but as a condition shaped by the complex interactions between our body’s ecosystem and the broader ecosystem of the world.