Chronic Pain Patients
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Chronic pain is typically defined as pain that continues in excess of 3–6 months regardless of the cause of the pain. Less commonly, chronic pain is defined as pain that persists beyond the point of any possible healing or any other useful function such as the enforcement of rest.
Major advances in the understanding of pain began with the observations of the physician Henry Beecher during World War 2. Beecher noted that seriously wounded soldiers brought from the front line requested less-pain medicine and reported less pain than he was used to seeing in his civilian patients. Beecher inferred that pain is not simply a response to physical injury or disease but also includes a cognitive and emotional component. Twenty years later, Canadian psychologist Ronald Melzack and British physiologist Patrick Wall published their gate control theory. Gate theory proposed that noxious and non-noxious sensory information interact in the spinal cord with descending influence from the brain. The theory explains pain experience as dependent upon that interaction rather than just the strength of a noxious stimulus. The precise details of the theory are less important than the dramatic impact gate control had on the understanding of pain. Gate control theory ended simplistic ideas of pain based on an isolated dedicated pathway from the periphery to the brain. It provided the first plausible physiological explanations for the influence of psychological states on pain experience through a brain-spinal cord loop. Most importantly, gate control theory shifted attention away from the stimulus and toward the spinal cord, brain, and the subjective experience of pain. After the gate it became increasingly apparent that pain cannot be reliably judged based upon an objective measure of injury or receptor activation and so assessment of pain requires subjective report – the “what it is like” to be in pain.
The shift in focus away from the noxious stimulus that triggers pain and toward the psychological experience of pain was particularly important for the understanding of chronic pain. Chronic pain conditions are often characterized by the lack of a stimulus that can explain the pain. Patients with phantom limb pain, for example, feel pain in a limb that has been amputated. Patients with causalgia suffer severe burning pain at a site of injury long after the injury has healed. Even in diseases where there is an ongoing trauma, such as patients with cancer or arthritis, the pain is typically difficult to predict based on objective measures of disease activity and continues beyond any period when cessation of activity and rest might facilitate healing. Thus, the understanding of chronic pain is not helped by a focus on injury or disease but by a focus on the experience of pain. Chronic, persistent pain is a distinct medical entity, syndrome, or disease in its own right, but it is not a disease that can be defined by objective markers such as provided by X-rays or histological tests; chronic pain is a disease defined by the subjective experience of pain. In short, chronic pain is a problem because it feels bad.
This understanding of chronic pain is further reflected in the international association for the study of pain (IASP) definition of pain, which states that pain is “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage… pain is always subjective. Each individual learns the application of the word through experiences related to injury in early life.” This definition recognizes a number of important facts about pain: (1) It is a multidimensional experience. (2) It is subjective. (3) It may or may not be associated with tissue damage.
The somewhat complex understanding of pain provided by the IASP is perhaps not especially important when considering acute pain. If someone hits their hand with a hammer, it is patently obvious that the pain was caused by the hammer and it is reasonable to assume that the pain will subside once the injury heals. Although it may be theoretically correct to point out that the pain is in the patient’s mind, not their hand, and that the experience derives from psychology, and not the hammer, such points would be overly pedantic. When faced with an obvious injury it is reasonable to depersonalize the experience as a consequence of external forces, which rapidly lose their influence with healing. For patients with chronic pain, however, there is either no external force to blame or the external force never loses its influence. Either way, the experience is deeply personal and subjective.
The personal and subjective nature of chronic pain makes treatment difficult. Traditional treatment approaches involving periods of rest and analgesic medication use are typically unsuccessful in resolving chronic pain. Physicians and patients can easily become disillusioned when multiple treatments, used sequentially or in combination, fail to provide pain relief. In many cases, physicians are left frustrated and patients dissatisfied with chronic, unremitting symptoms. Treatment approaches that focus on the patient’s experience, what they feel and how they manage their feelings, are usually more successful. Cognitive behavioral therapy, for example, aims to modify the reciprocal relationships between sensation, cognition, emotion, and behavior so as to improve mood and decrease the disability associated with the pain. Cognitive behavioral therapy emphasizes the teaching of coping skills and the active role patients have in modifying how they think, feel, and believe. The aim is to reduce the negative impact of their pain even if the pain itself is not directly reduced.
Among adults, the prevalence of chronic pain where an identifying cause is difficult to find ranges between 2% and 40% depending on the study. Unsurprisingly, chronic pain substantially reduces quality of life and also generates considerable costs. In the Netherlands, for example, the cost of back pain alone equals 1.7% of the gross national product and in the UK, back pain results in the loss of over 150 million workdays annually. There is also evidence that the problem may be increasing. In the USA, the rate of disability claims associated with low back pain has increased over the rate of population growth by 1,400% since the early 1970s. Understanding chronic pain so as to address this increase and provide better treatments remains a considerable challenge.
References and Further Reading
- Loeser, J. D. (2006). Pain as a disease. In F. Cervero & T. J. Jensen (Eds.), Handbook of clinical neurology (pp. 11–20). Edinburgh: Elsevier.Google Scholar
- McMahon, S., & Koltzenburg, M. (2005). Wall and Melzack’s textbook of pain (5th ed.). Edinburgh: Churchill Livingstone.Google Scholar
- Melzack, R., & Wall, P. D. (1996). The challenge of pain. London: Penguin.Google Scholar