Beyond the Nervous System: Rethinking Nociplastic Pain
We’re slowly learning that not all pain has a neat cause.
Sometimes there’s no injured tissue to heal, no damaged nerve to trace. And yet the pain is there — persistent, exhausting, and real. This is where the term nociplastic pain emerged as a way to describe pain that isn’t due to ongoing tissue damage (nociceptive) or nerve injury (neuropathic), but still arises from changes in how the body processes signals of threat and protection.
This relatively new descriptor — formally recognised by the International Association for the Study of Pain (IASP, 2017) — reflects a growing awareness among clinicians and researchers that a third category of pain is needed to account for a wide range of chronic pain conditions. Fibromyalgia, some forms of persistent low back pain, chronic pelvic pain, and irritable bowel syndrome are often cited as examples. These conditions frequently show no structural pathology and are poorly explained by conventional biomedical models.
Yet, despite its promise, nociplastic pain is still often interpreted narrowly. Most definitions — and much of the current clinical language — frame it as a dysfunction of the central nervous system: sensitised spinal circuits, hyperactive nociceptive pathways, faulty descending inhibition, and maladaptive brain patterning. Whilst this framing is not wrong — I feel it is incomplete, and not able to explain “unexplainable pain” properly. Leading patients to continually be gaslit and invalidated when their pain can be explained away as a “problem of the brain” by ignorant clinicians.
Pain does not emerge solely from the nervous system. It is a dynamic, emergent property of an entire organism in context. A person’s immune system, endocrine regulation, metabolic function, sleep quality, past experiences, social environments, and stress reactivity all shape how pain is perceived and sustained. These aren’t mere modifiers — they’re integral components of the pain experience.
Chapman et al. (2008) articulated this beautifully in their systems model of pain and stress, highlighting the recursive interactions between neural, endocrine, and immune processes. Pain, in this view, is not a static input-output phenomenon but an emergent state of the whole body system under threat. Similarly, Mick Thacker and colleagues have argued for a move away from reductionist models of pain and toward an enactive, embodied perspective — one that acknowledges the lived experience of the person in pain, embedded within biological, psychological, and sociocultural systems (Kiverstein et al., 2022).
A narrow focus on sensitisation alone can lead to inadvertently invalidating care — reducing the person’s experience to a brain glitch or a nervous system misfire. Worse, it may perpetuate the very frustration and mistrust that people with chronic pain so often face.
Instead, an ecological perspective invites us to see nociplastic pain as a pattern of system dysregulation — not just within the CNS, but across the interacting loops of the nervous, immune, and endocrine systems, all shaped by environment and history. We see this in the altered stress responses of people with long-term pain, in the cytokine profiles of those with fibromyalgia, and in the way trauma imprints itself across physiology over time.
This isn’t about throwing out the neuroscience — it’s about expanding our lens. Understanding nociplastic pain through a systems lens doesn't make it any less real or biological. It makes our explanations more adequate — and our care more humane.
This doesn’t mean the pain is “all in the head.” It means it's in the whole system. And that’s exactly where recovery must begin.
References
Chapman, C. R., Tuckett, R. P., & Song, C. W. (2008). Pain and stress in a systems perspective: reciprocal neural, endocrine, and immune interactions. The Journal of Pain, 9(2), 122–145. https://doi.org/10.1016/j.jpain.2007.09.006
International Association for the Study of Pain (IASP). (2017). IASP Terminology. Retrieved from https://www.iasp-pain.org/resources/terminology/
Kiverstein, J., Kirchhoff, M. D., & Thacker, M. (2022). An embodied predictive processing theory of pain experience. Review of Philosophy and Psychology, 13(5), 973–1000. https://doi.org/10.1007/s13164-022-00616-2
Thacker, M., & Moseley, L. (2017). Pathophysiological mechanisms of chronic pain. In The Routledge Handbook of Philosophy of Pain (pp. 157–172). Routledge.