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C H A P T E R 2 3

Multidisciplinary Assessment of Patients with Chronic Pain

DENNIS C. TURK and JAMES P. ROBINSON

This chapter deals with the multidisciplinary assessment of patients with chronic noncancer pain. In order to be specific, especially with regard to the medical evaluation of chronic pain patients, we organize the discussion around a typical and com- mon chronic pain problem (e.g., persistent cervical spine pain). We note, though, that many of the concepts in the chapter are relevant to the assessment of virtually any chronic pain patient. In particular, concepts related to the assessment of psychologi- cal factors, social factors, and functional limitations have wide applicability. A key premise in this chapter is that multiple factors influ- ence the symptoms and functional limitations of patients with chronic pain. As a consequence, we believe that evaluation along multiple dimensions, performed by professionals with a variety of skills, provides important insights into the factors governing the reports of these patients and assists in treatment planning. Conceptual Issues CONUNDRUMS IN THE ASSESSMENT OF PAIN How we think about symptoms such as pain influences the way in which we go about evaluating patients. Physicians and the lay public alike tend to assume that some underlying pathol- ogy is both a necessary and a sufficient cause of the symptoms reported and experienced by patients. Consequently, medical assessment usually begins with taking a thorough history and performing a physical examination, followed by, when deemed appropriate, laboratory tests and diagnostic imaging procedures in an attempt to identify or confirm the presence of an under- lying pathology that causes the symptom (see later). However, over the years, research has revealed puzzling observations that challenge the presumed isomorphism between pain and organic pathology. For example, the exact pathophysiology underlying some of the most common and recurring acute (e.g., primary headache) and chronic (e.g., back pain, fibromyalgia [FM]) pain problems is largely unknown. Thus, it is common for pa- tients to have pain that cannot be attributed unambiguously to an organic pathologic process. Conversely, many people have abnormalities on diagnostic tests but no pain. For example, studies using plain radiography, computed tomography (CT), and magnetic resonance imaging (MRI) reveal that more than 30% of asymptomatic individuals have structural abnormal- ities such as herniated disks, spinal stenosis, joint space nar- row in degenerative knees, and torn rotator cuffs that would be accepted as valid explanations of pain if the individuals had been symptomatic. 1–3 Thus, we are confronted with a rather strange set of circumstances: people with no identified organic pathology who report severe pain and, conversely, others with significant pathology who are apparently pain-free. When health care providers are unable to identify organic pathology that reasonably accounts for a patient’s reports of pain, they may assume that the reports reflect psychological factors such as personality characteristics, psychopathology, and malingering. A psychological evaluation may be requested to detect the psychological factors that underlie the patient’s reports. Thus, there is a duality where the report of symptoms

is attributed to either somatic or psychogenic mechanisms. This dualistic perspective dates back at least to the 17th cen- tury and the philosopher René Descartes. The assumption that symptoms that cannot be explained by medical findings must originate from psychological distress is, albeit unfortunately common, overly simplistic and inconsistent with current scien- tific understanding. The dichotomous view is incomplete and, as described throughout this chapter, is not compatible with available research evidence or the current understanding of chronic pain. 4 A CONCEPTUAL MODEL FOR ASSESSING PAIN The conundrums described suggest that multiple factors likely contribute to persistent pain and related disability. There is a growing consensus that these consist of (1) genetic composi- tion 5 ; (2) physical pathology associated with trauma or disease; (3) alterations in the peripheral and central nervous system (CNS) attributable to the initial insult (peripheral and central sensitization); (4) psychological contributors including various types of psychopathology, prior learning history, and available coping resources (e.g., emotional support, financial resources, acquired coping skills); and (5) environmental influences (e.g., response by significant others, disability compensation, fea- tures inherent in the workplace) that all likely interact. A com- prehensive evaluation should provide information about each of these factors. Examination of unique genetic contributions is in its infancy at this time and is generally not performed in clinical settings, although it will likely be gaining attention in the coming years. Thus, in this chapter, we describe a general strategy for assessing factors 2 to 5. Pain Behavior It is useful to begin a discussion of assessment of patients with chronic pain with the concept of pain behaviors. Pain is a sub- jective perception, and there is currently no objective way to know about the experience of pain other than by patients’ behavior. Pain behaviors include verbal behaviors (i.e., state- ments about pain). They also include nonverbal behaviors such as limping or wincing. 6 These pain behaviors are sources of communication; they convey to others the presence and sever- ity of pain. The challenge for an examiner is how to interpret patients’ pain behaviors. Although these behaviors are sometimes de- termined entirely by an abnormal biologic process in the area of injury, they are typically also influenced by changes in ner- vous system encoding and processing of nociceptive signals; by a patient’s beliefs and appraisals, emotional status, and coping strategies; and by the social environment. Classes of Variables Underlying Pain Behavior We will return to more formal assessment of pain behaviors later in this chapter. For now, a useful way to conceptualize this challenge is to think of a prediction equation with multiple unknowns: PB 5 f(Xa 1 , Xa 2 . . . Xa an ; Xb 1 , Xb 2 . . . Xb bn ; Xc 1 , Xc 2 . . . Xc cn ; Xd 1 , Xd 2 . . . Xd dn ). Where PB 5 the pain behavior that a patient demonstrates, and predictor variables are organized into four categories, such

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