Chronic persistent pain is a sensory processing disorder and maladaptive neuroplasticity. Today I’ll talk about the latter. Generally, neuroplasticity is attributed to recovery from a neurological insult such as a stroke. We evoke change by using these principles of practice: repetition via massed and random practice, novelty, and intensity. This is true long after injury as well, though becomes more difficult with time. In rehabilitation we operate from the premise that neuroplasticity is a positive thing that helps us get better. And it is. But the same principles hold true for everyone even if the result is not positive, The most practiced pattern becomes dominant. Practice does not make perfect, it makes permenant-ish. It’s why musicians and athletes train for countless hours, including mental practice (more on that another day). So if an individual’s brain is constantly throwing pain volleys, it will get better at throwing pain volleys.
Moseley et al 2009 noted that when individuals with CRPS crossed their upper extremities, the unaffected extremity became cooler than the involved limb. It wasn’t the limb, but the hemispace that was relevant. This is very much like a stroke with hemispatial neglect (an inattention to the environment on the involved side.) And what do we do with individuals who experience neglect, even extreme forms of it including anosognosia (denying the limb is theirs)? We help them attend to the limb and environment. We involve the limb in care and therapy. We apply stimulus to the limb to help the brain “tune in” to it and we encourage attention to the hemispace in which the limb resides. We do this to drive neuroplastic change.
Individuals with persistent pain are rightfully very guarded and fearful over their involved body part(s). They are vigilant to threat, effectively reinforcing threat from the constant practice of identifying it. They may avoid involving the painful body part in their mobility, and sometimes may limit all activity. Fear avoidance is the logical result of the amplified perception of threat. And the ongoing effects of cortical neglect of the body part, propagated by disuse. It’s the ultimate self protection, “if I don’t do ‘xyz’, then it can’t hurt me.” The result is that individuals literally practice not attending to the body part. If the brain doesn’t have a clear construct of a body part, how can it know what to do with input related to that body part? It can’t. The net result is “I don’t know what this is, so I’m going to categorize this input as ‘danger’ so I can protect myself.” What is intended as a helpful phenomenon, becomes a debilitating one. The repetition further strengthens the pattern. Suffering increases and function and joy decline. I’d say it’s pretty clearly maladaptive.
But it is not hopeless. When I work with a patient, I want to facilitate the practice of “safety” not “danger.” I do this at the outset by focusing on self management strategies, not just for short term ability to get through their day, but more importantly, for long term neuroplastic retraining of the dominant pattern. Neuroplastic change requires a lot of repetition. By repeating self-management strategies A LOT, we aim to change the brain’s dominant pattern to “i’m okay” instead of “I’m in danger.” I think there is a misconception that self management strategies are solely about coping. There is very much a coping element to it, but more importantly it is about massed practice of “safety” to promote neuroplastic change away from persistent pain.
Büntjen, L., Hopf, J., Merkel, C., Voges, J., Knape, S., Heinze, H., & Schoenfeld, M. A. (2017). Somatosensory Misrepresentation Associated with Chronic Pain: Spatiotemporal Correlates of Sensory Perception in a Patient following a Complex Regional Pain Syndrome Spread. Frontiers in Neurology,8.
Eller-Smith, O. C., Nicol, A. L., & Christianson, J. A. (2018). Potential Mechanisms Underlying Centralized Pain and Emerging Therapeutic Interventions. Frontiers in Cellular Neuroscience,12. doi:10.3389/fncel.2018.00035
Flor, H. (2003). Cortical reorganisation and chronic pain: Implications for rehabilitation. Journal of Rehabilitation Medicine,35(0), 66-72.
Moseley, G. L., Gallace, A., & Spence, C. (2009). Space-based, but not arm-based, shift in tactile processing in complex regional pain syndrome and its relationship to cooling of the affected limb. Brain,132(11), 3142-3151.
Nudo, R. J., Plautz, E. J., & Frost, S. B. (2001). Role of adaptive plasticity in recovery of function after damage to motor cortex. Muscle & Nerve,24(8), 1000-1019.