Unravelling the enigma of chronic pain and its treatment
By Mark Johnson
The prevalence of chronic pain in the general adult population worldwide may be as high as 30%. Yet pain is not seen as a major health care problem by politicians, probably because people do not die of pain, although many people die in pain. Chronic pain challenges our traditional beliefs about the process of diagnosis, treatment, and cure, with over 40% of individuals reporting inadequate management of chronic pain. Chronic pain is an enigma.
We have all experienced pain and we know with certainty when we have it. Yet, we may doubt others who tell us that they are in pain especially if their pain has a vague or uncertain diagnosis and is not responding to conventional treatment. The medical management of pain evolved from the view that pain is a symptom of pathology and diagnosis, and treatment of pathology will relieve pain. This approach usually works well for pains associated with recent tissue damage (acute pain) but starts to fall apart when pain becomes chronic. This is because the link between pain and tissue damage (pathology) is not quite as strong as we are led to believe. For example, soldiers seriously injured in battle often report no pain for some time after the injury occurred. The link between pathology and chronic pain is particularly variable. In fact chronic pain may uncouple from the pathology that caused the pain in the first place. In essence, pain can become a disease entity in its own right.
Life experiences teach us that pain warns of tissue damage and we adapt our behaviours to avoid pain accordingly. Body parts often become “sensitive” in the presence of tissue damage so that non-painful activities become painful. Pain makes us avoid things that may hinder tissue healing so we learn to “fear” walking on a twisted ankle for example, because it provokes pain. Sensitivity associated with pathology results from the nervous system amplifying input from the site of tissue damage increasing the input to the pain producing brain — no brain, no pain. Pain resulting from sensitivity within the nervous system fades over time as tissue heals, although occasionally the nervous system remains in a persistent sensitive state despite tissue having healed. The consequence is chronic pain that has uncoupled from the original tissue damage. Pain of this nature has limited usefulness and is detrimental to well-being and reflects a dysfunctional pain system.
In such circumstances medical tests may fail to detect appreciable pathology, diagnosis may become vague, and treatment uncertain and unsuccessful. Practitioners may start to doubt the legitimacy of the person’s pain and believe that the pain is “psychogenic” (fake). This is entirely irrational because it is impossible to prove or disprove that a person is in pain, because pain is a subjective phenomenon with no objective way of measuring. The only way to gain insight into a person’s personal pain experience is through their self-report — pain is whatever the patients says it is. If a person reports that they are experiencing pain, they should be believed.
Knowledge that pain may persist without appreciable tissue damage has shifted the focus of management strategies for chronic pain that advocate progressive return to and continuation of normal activities despite the presence of pain. The challenge for the practitioner is balancing advice about under-activity, leading to disability, with over-activity leading to further pain and harm. The challenge for the patient is being able to accept and commit to a pain management plan that encourages undertaking activities in the presence of pain, because this is counterintuitive to life experiences that have taught us to avoid pain because it warns of harm. Accepting that total resolution of pain may be unlikely and committing to integrating a painful body into normal life has been shown to have a positive impact on suffering and long-term disability. In fact inactivity is a risk factor for the development of long-term pain, suffering and disability. Easy explanations of the factors contributing to chronic pain to promote a benign view of chronic pain can help individuals to change the way they think and behave about their pain. Pain management plans offering advice about the risk of harm of daily activities and self-management techniques to find solutions for pain flare ups, medication use, sleep disturbances, depression, anger, and relationship problems are becoming available.
Exercise regimes aim to get individuals to return to normal activities through stretching, strengthening, and cardiovascular fitness with the focus on progressive return to activities. Manual therapies such as massage of soft tissue and mobilization and manipulation of joints, and electrophysical agents such as transcutaneous electrical nerve stimulation (TENS), acupuncture, low level laser therapy, and ultrasound, are all part of the multidisciplinary pain management team’s toolkit. Clinical experience suggests that these non-pharmacological interventions are beneficial and popular with patients, although the findings of clinical research have been inconsistent. This is due to the complex nature of administering some of the interventions where optimal technique (dose) is not known.
So the puzzle of chronic pain is being unravelled with the realization that a reliance on diagnosis and treatment of pathology causing pain may not be the most effective way to help patients. We need a multidisciplinary model of care that is flexible enough to shift in emphasis from a biopsychosocial model in the acute phase to a “sociopsychobio” model in the chronic phase.
Mark Johnson is Professor of Pain and Analgesia at Leeds Metropolitan University in the UK. He is author of Transcutaneous Electrical Nerve Stimulation (TENS): Research to support clinical practice.
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Image: Doctor talking with a patient by National Cancer Institute. Public domain via Wikimedia Commons.