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Can we untangle the mystery of Chronic Pain?


What does “pain” mean for an individual? How should we evaluate it? How can we untangle “chronic” pain?

These questions have challenged pain physicians, researchers and ultimately chronic pain sufferers since “pain” was recognised as a sensory input that sometimes we would prefer not to have.

Over the years, particularly since Wall & Melzack proposed their “Gate theory” in 1964, we have defined and redefined what pain means, always trying to adapt to current knowledge. While we struggle at times to understand the precise biochemical rationale for pain we have grown to respect the emotional, cognitive and more recently the social impact on individuals.

The challenges, when attempting to define pain were highlighted by Professor Joanna Bourke, PhD, Professor of History, at Birkbeck, University of London: while acknowledging that pain is difficult to both describe and define, she argues that the sensation of pain refers to the experience, not what is experienced.

Therefore the injury or noxious stimulus, in by themselves may not cause pain, but that the sensation of pain might rather be caused by the way in which the injury or stimulus is individually evaluated.

What is “Pain”?

Dr. Hegarty, Clinical Director, Pain Relief Ireland, suggests that this question may best be answered by noting that pain can evoke complex emotions, adding that “so-called ‘noxious stimuli' can excite a vast array of emotions, including distress (e.g, face-to-face with a torturer), fear or panic (e.g, crashing through the car windscreen), anticipation or surprise (e.g, the moments after a knife or heart attack), relief (e.g, self-cutting), or inspire joy (e.g, childbirth)”.

The context of the pain is as important as the cause of the pain.

What is the evidence?

In the era of evidence-based medicine and multimodal and assessment-centered pain management, a clear definition of pain is essential. This should guide us to structure the management of pain aiming to use of the available pain treatment options to untangle the mystery.

Despite an improved understanding of pain pathophysiology, clinical decisions continue to be made based on the International Association for the Study of Pain (IASP) 1994 definition of pain, which remains the current internationally recognized definition of pain.

In fact the core elements of the 1994 definition are rooted in the seminal work dating from 1964. The IASP 1994 definition of pain states that  “Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.”

According to this definition, pain is associated with actual or potential tissue damage. The definition focuses on patient self-report, and clearly acknowledges that pain in the absence of tissue injury or a pathophysiological cause, is simply psychological, and can therefore not be considered ‘true pain'.

As an example, pricking of a finger does not lead to a pain sensation, as “it is an experience” that resembles pain, but is not unpleasant. The focus on self-report in the IASP definition does not accommodate individuals who are unable to experience or describe their pain because of language barrier or impaired cognitive capacities, oversight which led to a revision of the definition in 2002.

The current definition of pain focuses on a unidimensional physical cause that must include tissue and/or physiological injury, thus excluding cognitive and social factors known to often be associated with chronic pain. Some have argued that the current definition of pain is outdated and partly redundant.

At Pain Relief Ireland we consider pain is multidimensional.  Therefore management relies on considering all these aspects and constructing plans to target and support individuals in a holistic fashion. A solid pain management structure should also have the flexibility to recognize that, with time the role of each element can vary, and the plan should be able to adapt.

Researchers have proposed a revised definition of pain, so as to “better capture the essence of what we presently understand to be pain and how it would better equip those who try to control pain.” In this definition, it is stated that:

 Pain is a distressing experience associated with actual or potential tissue damage with sensory, emotional, cognitive, and social components.”

Dr. Hegarty believes that this revised definition acknowledges the importance of the subjective experience and accommodates social interactions, sensations and emotions. Incorporating a broad range of verbal and non-verbal behaviors as part of the pain assessment, in order to adequately capture the complexity of the pain experience is also important.

Finally, at Pain Relief Ireland we “care about your pain”. We appreciate that the context of the pain is as important as the cause of the pain. We will strive to understand that chronic pain means for individuals at each time of their life. Contact us today to see how we can help.

References

  1. Treede RD, Rief W, et al. A classification of chronic pain for ICD-11. Pain. 2015;156(6):1003-1007. 
  2. Classification of chronic pain. Descriptions of chronic pain syndromes and definitions of pain terms. Second Edition. Prepared by the Task Force on Taxonomy of the International Association for the Study of Pain. © 1994 IASP Press (Reprinted 2002) International Association for the Study of Pain. Available at: http://www.iasp-pain.org/files/Content/ContentFolders/Publications2/FreeBooks/Classification-of-Chronic-Pain.pdf. Accessed November 21, 2016.
  3. Lindley R. The Complex History of Pain: An Interview with Joanna Bourke. Published online February 1, 2015. Available at: http://historynewsnetwork.org/article/158076. Accessed November 21, 2016.
  4. Katz J, Rosenbloom BN. The golden anniversary of Melzack and Wall's gate control theory of pain: Celebrating 50 years of pain research and management. Pain Res Manag 2015;20:285-286.
  5. Williams AC, Craig KD. Updating the definition of pain. Pain. 2016;157(11):2420-2423.
  6. Makin S. Imaging: Show me where it hurts. Nature. 2016;535(7611):S8-S9.

 

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