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Chronic pain: A clinician's introduction

By Mike Edgar


What is chronic pain? A lot of us feel like Sandra Bullock in Bird Box whenever the topic comes up. If you don’t know that reference, I’d recommend watching the movie. The gist behind the statement though, is that we tend to feel like we’re blind on the topic and tread cautiously when discussing it. Unlike the traditional biomechanical perspective toward rehabilitation and exercise, it lacks the certainty of a quantitative science. It isn’t wrapped nicely for us with a little bow.

In regards to chronic pain, a good place to start is with the evolution of pain theories. Moseley et al.1 highlighted several major theories, but I’ll touch on three. Firstly, the ‘Grand Poobah Pain’ theory focused on the underlying idea that pain is an unpleasant experience felt somewhere in the body. This then urges us to protect that bodily location. Pain is one of many protective mechanisms; others include movement, immune, cognitive, endocrine and autonomic function. Although this is the case, according to the theory, pain is the only protective mechanism we are necessarily aware of and compels us to do something in reaction to it.


The second theory highlighted by Moseley et al. (1) was ‘The Protectometer’ which re-conceptualized pain from nociception to a protector which allowed this model to act as a patient-centered tool for conceptualization. It was framed around the idea of DIM’s ‘danger in me’ and SIM’s ‘safety in me.’ Both could be thought of as opposite sides of a scale and when the brain perceives more credible evidence of DIM’s, pain will be perceived.


The last theory of focus is the Neuromatrix Theory which was created by Ron Melzack. This saw the brain as a neural network that would produce both a perception of pain and a matching motor command, like bracing or guarding.(1-2)

So what is the relevance of this?


Well, by this perception, we can consider pain to have a matching behavioral response and in accord, a movement-based outcome. From here, I’d like to discuss the idea of kinesiophobia. The word, in layman’s terms simply means excessive and irrational fear of physical movement. It can also relate to the idea of catastrophic thoughts and fear-avoidance belief patterns. An interesting finding of this, highlighted by Moseley et al. (3-5) was the idea of the interconnection between physiology and perception. They found that people in pain tended to modify their movements but the interesting caveat was that people who expected to be in pain also moved differently. There also tended to be a degree of decreased movement variability and therefore reductions in adaptability. The point being made here is that we can’t simply see our perceptions as a response to how our body ‘feels’ but that it is a two-way street where both affect one another. (3-5)

A systematic review by Luque-Suarez et al. (6) investigated the role of kinesiophobia on pain, disability and quality of life in people suffering from chronic musculoskeletal pain. The review highlighted 63 studies and was considered the most extensive to date. So what did they find? Well, they found a moderate association between kinesiophobia in relation to pain severity and quality of life, but the major highlight was the strong association to perceptions of disability and pain intensity (6). This may raise some questions as to the difference between pain intensity and severity but the authors noted that this was purely due to the dimensions of the measures. Pain intensity is considered a unidimensional measure while severity is considered a multidimensional measure. An interesting aspect of this systematic review was the inclusion of only studies which used the Tampa Scale for Kinesiophobia (TSK).

Based on previous research, the TSK offers good reliability and validity with a positive correlation to fear-avoidance, pain catastrophizing and pain-related disability (7-9). This was recreated in several populations including the general population and a population of chronic pain patients (7-9). Although this is the case, French et al. (9) found that in a population of chronic pain patients, the TSK did not relate to differences in standardized physical performance testing. Now at first, this may seem like a weakness of the TSK but I want you to remember our initial discussion on chronic pain. We need to realize that pain is not purely structural damage but also relates in many regards to one’s perception of their context and circumstances.

When does acute pain tend to become chronic pain? How does it relate to kinesiophobia?


For this, we can conceptualize it through operant conditioning and negative reinforcement (11). In the acute stage of pain, there tends to be a noxious stimulus which is provoked each time we perform a movement that relates to these structures. In turn, we perceive the pain signals which makes us stop the movement. Therefore, reinforcing our decision to avoid pain. Over time, we begin to pre-emptively perceive this pain response before performing the movement, which causes us to further validate this decision as pain was not experienced. The issue with this though, is the idea that while tissues have healed and structural integrity is present, we still perform these guarding responses and our confirmatory signals continue to develop despite the initial injury being removed.

How do we break this cycle?


It would be great if we could have the perfect recipe and the perfect exercise to combat this, but realistically this isn’t the case (11-14). Instead, maybe we should start to focus more on ‘why’ and ‘how’ we implement these exercises. This is why the biopsychosocial model of care is paramount.

Communication comes first: Educate the individual on the mechanisms of pain and the difference between nociception and central sensitization. Explain the potential for a nociceptive biomedical injury like cervical radiculopathy and attentional cues which may lead to a hyper-focus towards pain.

Movement and exercise: Understand the utility of directional preferences, not just from a centralization standpoint but from a movement preference standpoint to get the individual simply moving more (11-14). Focus on a gradual exposure to activity to pain provoking behaviors. After these aspects, you can focus on further loading and endurance. Understand there are many ways to implement these principles whether it be through exercise dosage, communicating safety perceptions, adherence principles and various cognitive behavioral techniques like systemic desensitization. We also need to be aware of the support networks these individuals have.

To Wrap Up:


Do not stigmatize or stereotype. Re-frame pain and treatment methods, as exercise is not a purely biomechanical endeavour. Understand the utility of proper communication, avoiding negative affirmations and the importance of support networks. Be open and adaptable to change as it occurs. Lastly, do not perceive self-report methods as an inferior form of outcome measure. Pain is a perceptual experience and the best way to understand that phenomenon is by simply asking the individual.


Mike is the founder of Original Physiques, a coaching company focused on evidence-based approaches to nutrition and training for body composition and rehabilitative purposes. Original Physiques also aims to raise awareness and organize fundraisers for various local charities.



References:


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4. Moseley GL, Nicholas MK, Hodges PW. Does anticipation of back pain predispose to back trouble?. Brain. 2004 Jul 28;127(10):2339-47.

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6. Luque-Suarez A, Martinez-Calderon J, Falla D. Role of kinesiophobia on pain, disability and quality of life in people suffering from chronic musculoskeletal pain: a systematic review. Br J Sports Med. 2019 May 1;53(9):554-9.

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10. McLeod S. Skinner-operant conditioning. Retrieved from. 2015 Jan.

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12. Cote P, Wong JJ, Sutton D, Shearer HM, Mior S, Randhawa K, Ameis A, Carroll LJ, Nordin M, Yu H, Lindsay GM. Management of neck pain and associated disorders: A clinical practice guideline from the Ontario Protocol for Traffic Injury Management (OPTIMa) Collaboration. European Spine Journal. 2016 Jul 1;25(7):2000-22.

13. Nelson A, Allen K, Golightly Y, Goode A, Jordan J. A systematic review of recommendations and guidelines for the management of osteoarthritis: the chronic osteoarthritis management initiative of the U.S. Bone and Joint Initiative. Semin Arthritis Rheum. 2014; 43(6): 701-712.

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