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MAY / JUNE 2013 :: 74(3)
Chronic Pain

This issue focuses on the challenge of managing chronic pain. Commentaries present various treatment options, including opioids, nonopioid medications, surgery, and alternative therapies. Authors also address the problems of opioid misuse and abuse and discuss ways to lessen these risks. Original articles examine health professionals’ communication with adolescents about smoking, as well as children's immunization status as verified by practice records and by the North Carolina Immunization Registry.

INVITED COMMENTARY

Chronic Pain and Mental Health: Moving Beyond the Conceptualization of Pain as the Fifth Vital Sign

Elizabeth N. Lima

N C Med J. 2013;74(3):229-231.PDF | TABLE OF CONTENTS



Current approaches to the assessment and treatment of chronic pain continue to rely predominantly on the medical model. However, the comorbidity of chronic pain with psychiatric conditions underscores the need for a biopsychosocial and interdisciplinary approach to pain that can bridge the gap between scientific understanding and medical practice.

We must never forget that we may also find meaning in life even when confronted with a hopeless situation, when facing a fate that cannot be changed. For what then matters is to bear witness to the uniquely human potential at its best, which is to transform a personal tragedy into a triumph, to turn one’s predicament into human achievement. When we are no longer able to change a situation—just think of an incurable disease such as inoperable cancer—we are challenged to change ourselves.
—Viktor Frankl, Man’s Search for Meaning

The costs of chronic pain have been estimated in terms of pain’s financial, occupational, emotional, and social impacts, and all such calculations lead to the conclusion that societies and individuals continue to pay too high a price for the effects of chronic pain. The literature suggests that, despite advances in our understanding of pain, health care providers tend to rely heavily on the medical model when assessing and treating pain [1]. However, the evidence points toward the importance of taking an interdisciplinary, biopsychosocial approach to chronic pain. Patients therefore need to expand the set of tools they use to manage chronic pain, and health care providers need to evolve beyond the overly simplistic medical model toward a more comprehensive approach to assessment and treatment of pain.

Models of Pain from Descartes to the Neuromatrix Model
In Traité de l’homme, which had been written by 1633 but was not published under that title until 1664, René Descartes advanced a medical model of pain that theorized that pain is directly proportional to the amount of tissue damage in the body [2]. Although there is now good evidence to the contrary, the medical model continues to exert great influence on the assessment and treatment of chronic pain. Descartes’s stance led to the assumption that any pain occurring in the absence of discernible and diagnosable tissue damage must be psychogenic. The ineffective distinction between “organic” and psychogenic pain has created a chasm between these 2 entities that is not only frustrating—both to patients and to health care providers—but that also negatively impacts the care provided and received. Patients feel they are being told that “the pain is all in their head,” and providers struggle to balance the necessity of relieving pain against the known risks of available pharmacological interventions.

In 1965, Melzack and Wall advanced the gate control theory of pain, which called attention to the role of the central nervous system [3]. This theory accounted for the role that psychological and social factors play in either ameliorating or exacerbating the experience of pain. More recently, Melzack’s conceptualization of pain evolved into the pain neuromatrix concept [4], which accounts for the fact that pain is an alarm that signals potential tissue damage. This model takes the position that these signals are a “false” alarm in patients with chronic pain. Melzack proposed the pain neuromatrix model because no other model could explain the phantom-limb pain experienced by paraplegic patients.

Chronic Pain and Comorbid Psychiatric Conditions
Anxiety and depressive disorders are quite prevalent in patients with chronic pain. The question of which comes first has been debated; however, prospective studies suggest a bidirectional relationship in which baseline anxiety or depression predicts susceptibility to chronic pain, and chronic pain prospectively predicts anxiety and depression [5-7]. Once both diagnoses are established, having anxiety or depression as a comorbidity in addition to chronic pain tends to produce reports of greater intensity of pain as well as greater disability [8, 9]. Patients with chronic pain have also been found to suffer from generalized anxiety symptoms. Finally, the role of trauma and posttraumatic stress disorder (PTSD) in chronic pain has been substantiated in the literature [10, 11].

The brain’s role in pain may help to account for these common comorbidities. There is not one particular place in the brain that serves as a “pain center.” Rather, pain neurophysiology is represented by the spinal cord and multiple regions of the brain that are not only involved in pain but also specialize in other functions. These structures include the premotor/motor cortex (organizes and prepares movement), the cingulate cortex (concentration and focusing), the prefrontal cortex (problem solving and memory), the amygdala (fear, fear conditioning, and addiction), the sensory cortex (sensory discrimination), the hypothalamus and thalamus (stress responses, autonomic regulation, and motivation), the cerebellum (movement and cognition), and the hippocampus (memory, spatial recognition, and fear conditioning) [12].

An Integrated Biopsychosocial Approach to the Assessment of Chronic Pain
Simply measuring pain using a Likert scale provides only a glimpse of the impact that pain has on an individual patient. Comorbid psychiatric conditions also deserve attention; if left untreated, they may serve as barriers to successful treatment. Rather than exploring only the biomedical causes of pain, a biopsychosocial approach also examines how psychological and social influences affect pain. Thus, an informative pain assessment goes beyond the measurement of pain severity. For example, the West Haven–Yale Multidimensional Pain Inventory [13] assesses the extent to which pain interferes with marital, social, occupational, and recreational aspects of life. It further considers the current presence of support, life control over pain, affective distress, the patient’s ability to perform common activities, and the responses of the patient’s significant other. It is relevant to assess how the patient’s significant other responds to the patient’s pain because the reactions of a solicitous spouse—someone who is overly vigilant about the patient’s pain and who responds in ways that reinforce pain-related behaviors (for example, by doing household chores for the patient)—have been shown to lead to increases in pain experience [14].

The presence of comorbid anxiety symptoms can be assessed using instruments such as the State-Trait Anxiety Inventory [15]. Similarly, symptoms of depression in patients with chronic pain have been investigated using the Beck Depression Inventory [16]. For assessing symptoms of PTSD, the PTSD Checklist has been used in primary care settings [17]. Given the intractable nature of chronic pain, evidence suggests that the patient’s level of functioning—as assessed by a shortened version of the World Health Organization Quality of Life instrument (WHOQOL-BREF), for example [18]—may be more responsive to treatment than is the reported pain severity. Finally, substance use disorders represent an increasingly problematic challenge during treatment and assessment of chronic pain, with opioid addiction and misuse warranting national attention. Miotto and colleagues provide a guide to assessing and managing chronic pain conditions in patients with comorbid substance use [19].

In addition to evaluating pain and comorbid conditions, it is also important to consider predictors of treatment outcomes. Among the strongest predictors of treatment outcomes are patients’ perceptions, beliefs, and attitudes about chronic pain and their ability to influence it. These beliefs and attitudes can respond to treatment. The Pain Catastrophizing Scale measures patients’ attitudes and beliefs by having the patient rate items in 3 different categories: rumination about pain, magnification of pain, and sense of helplessness about pain [20].

An Interdisciplinary Biopsychosocial Approach to Treatment
The pain literature demonstrates that single-modality approaches to chronic pain result in poor outcomes or have only small effect sizes [21]. Response to medications, for example, may be bimodal, with only a minority of individuals responding very well [22]. Complicating matters is a lack of predictive power. Specifically, it is not possible to prospectively identify which patients will respond optimally to which treatments, although there has been promising work using the West Haven–Yale Multidimensional Pain Inventory to categorize patients and assign them to specific treatments [23]. An interdisciplinary approach in which psychosocial approaches are used in conjunction with pharmacological or physiological interventions therefore remains a better choice for treating patients with chronic pain. Psychological therapies that can be beneficial include cognitive behavioral therapy (CBT), acceptance and commitment therapy, and dialectical and behavioral therapy. Of these 3 types of therapy, CBT has been the subject of the most research, and no other psychological therapy has shown incrementally superior results in patients with chronic pain.

CBT for chronic pain focuses on replacing maladaptive patterns of thought and behavior—those that contribute to the experience of pain—with more beneficial patterns. John Otis [24] has developed a CBT approach for treating chronic pain that involves specific steps. These steps include providing information about pain (eg, an explanation of gate control theory), teaching relaxation skills (eg, progressive muscle relaxation, visual imagery, diaphragmatic breathing), increasing levels of behavioral activation by scheduling pleasant activities, reducing fear of movement with time-based pacing, and encouraging sleep modification [24]. CBT programs can be successfully delivered in either individual therapy or group therapy settings. CBT for chronic pain has been shown to have positive effects on patients’ attitudes and beliefs about pain and mood.

Most patients with chronic pain experience some fear of movement (ie, kinesiophobia), which contributes to avoidance of physical activity. This results in further deconditioning through disuse, increased levels of pain, and negative social and emotional impacts. Combining patient education and therapies with an active movement or walking program has positive effects not only on physical functioning but also on mood. However, patients with chronic pain should be guided through this lifestyle change; otherwise, they will typically engage in periods of overactivity that cause soreness and discomfort, resulting in physical inactivity for days afterward. To help the patient to establish a baseline for physical activity, clinicians can ask: “How many minutes can you walk without stopping, without causing a pain flare-up or without having to take a pill right before or after walking?” However, keep in mind that patients tend to overestimate how much they can do without triggering a pain flare-up. Encourage the patient to consistently maintain their baseline level of activity and to increase it slowly over an extended period of time. Patients with chronic pain are also increasingly using other therapies with a specific focus (eg, mindfulness, biofeedback), as well as complementary and alternative medicine approaches.

For patients who have psychiatric comorbidities, treatments targeting these comorbidities should be recommended. Psychological therapies, such as cognitive processing therapy and prolonged exposure, have been validated in patients with PTSD. CBT therapies for anxiety and depression are also well validated. Individuals with comorbid substance use disorders should be encouraged to undergo treatment for addiction (eg, Alcoholics Anonymous, Narcotics Anonymous, detoxification).

Overall, the nature of chronic pain underscores the need to bridge the gap between scientific knowledge and clinical practice. A biopsychosocial approach to the assessment and treatment of chronic pain is consistent with scientific developments that point to the essential role of the brain in the experience of pain. Adopting a biopsychosocial approach will require changes in beliefs and attitudes, not just on the part of patients, who need to be willing to try nonpharmacological interventions for chronic pain, but also on the part of health care providers, who must move beyond the medical model of chronic pain.

Acknowledgments
The author appreciates the feedback and support provided by the following colleagues: Matthew Bain, MaryLynn Barrett, Sherry Hall, Valerie Krall, Molly McGaughey, Brian Peek, and Jeremy Walters.

Potential conflicts of interest. E.N.L. has no relevant conflicts of interest.

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Elizabeth N. Lima, PhD clinical psychologist, Charles George VA Medical Center, Asheville, North Carolina.

Address correspondence to Dr. Elizabeth N. Lima, Charles George VAMC, 1100 Tunnel Rd,
MHS-116 Bldg 70, Asheville, NC 28805 (elizabeth.lima@va.gov).