The Nature of Chronic Pain

The exact pathophysiology underlying many common pain problems (e.g. back pain, headache) is largely unknown. Conversely, 30% of asymptomatic individuals who reveal structural abnormalities on imaging studies suggestive of pain do not report pain. These observations suggest factors other than detectable physical pathology contribute to the report of pain. Thus, comprehensive assessment of the patient with chronic pain requires examination of psychosocial and behavioural factors as well as physical pathology (Figure 3.1).

Figure 3.1 A biopsychosocial model of chronic pain. Many factors contribute to the pain experience and associated distress. These are closely inter-related: a dichotomous view of pain as being ‘physical’ or ‘psychological’ is not helpful.

The busy clinician may be concerned that a comprehensive assessment will require an excessive amount of time. There is no way around the problem. However, the assessment may be performed over several brief appointments and components involving patient completion of self-report questionnaires do not require clinician time beyond scoring and interpretation. The initial time for assessment may reduce the amount of time required throughout treatment.

Medical and Physical Evaluations

History and Physical Examination

Medical assessment of a patient with persistent pain begins with a current and past history and physical examination. In addition to a general medical history, the healthcare provider should inquire in some detail about the pain (Figure 3.2). A physical examination should not only include a review of systems but also an assessment of physical functioning.

Figure 3.2 Important areas to cover when taking a pain history.

Laboratory testing and imaging procedures can rule out structural or biochemical abnormalities. However, physicians must not over-interpret either the presence or absence of objective findings unless they are consistent with the history and physical examination.

Psychological Assessment

The healthcare provider should consider and evaluate the ‘whole’ patient, not just reported symptoms. Regardless of a documented organic cause for pain, the evaluation process can be helpful in identifying how biopsychosocial factors interact to influence the nature, severity, persistence of pain and disability, and response to treatment. This assessment is also helpful in treatment planning and anticipation of responses to treatment. General assessment considerations are illustrated in Box 3.1.

Box 3.1 General Assessment Considerations

Three central questions should guide assessment of people who report pain:

1. What is the extent of the patient’s disease or injury (physical impairment)?

2. What is the magnitude of the illness? That is, to what extent is the patient suffering, disabled and unable to enjoy usual activities?

3. Does the individual’s behaviour seem appropriate to the disease or injury or is there any evidence of amplification of symptoms for any of a variety of psychological or social reasons or purposes?

Interviews

Semi-structured interviews can be used to assess the myriad of psychosocial factors related to pain and disability. Not all patients require a detailed psychosocial evaluation. Outlined in Box 3.2 is a range of points that can be used as pre-screening questions with patients who report chronic pain and as a basis for determining whether a more thorough psychological evaluation is warranted.

Box 3.2 Screening Questions

If there is a combination of more than six ‘Yes’ answers to the first 13 questions and ‘No’ to the last three questions, or if there are general concerns in any one area (e.g. substance abuse), a referral for a detailed psychological assessment should be considered.

1. Has the patient’s pain persisted for three months or longer despite appropriate interventions and in the absence of progressive disease? [Yes]

2. Does the patient repeatedly and excessively use the healthcare system, persist in seeking invasive investigations or treatments after being informed these are inappropriate, or use opioid or sedative–hypnotic medications or alcohol in a pattern of concern to the patient’s physician (e.g. escalating use)? [Yes]

3. Does the patient come in requesting specific opioid medication (e.g. dilaudid, oxycontin)? [Yes]

4. Does the patient have unrealistic expectations of the healthcare providers or the treatment offered (i.e. ‘total elimination of pain and related symptoms’)? [Yes]

5. Does the patient have a history of substance abuse or is he or she currently abusing mind altering substances? [Yes]

6. Does the patient display are large number of pain behaviours that appear exaggerated (e.g. grimacing, rigid or guarded posture)? [Yes]

7. Does the patient have litigation pending? [Yes]

8. Is the patient seeking or receiving disability compensation? [Yes]

9. Does the patient have any other family members who had or currently suffer from chronic pain conditions? [Yes]

10. Does the patient demonstrate excessive depression or anxiety? [Yes]. Straightforward questions such as, ‘Have you been feeling down?’ or ‘What effect has your pain had on your mood?’ can clarify whether this area is in need of more detailed evaluation.

11. Can the patient identify a significant or several stressful life events prior to symptom onset or exacerbation? [Yes]

12. If married or living with a partner, does the patient indicate a high degree of interpersonal conflict? [Yes]

13. Has the patient given up many activities (recreational, social, familial, in addition to occupational and work activities) due to pain? [Yes]

14. Does the patient have any plans for renewed or increased activities if pain is reduced? [No]

15. Was the patient employed prior to pain onset? [No] If yes, does he or she wish to return to that job or any job? [No]

16. Does the patient believe that he or she will ever be able to resume normal life and normal functioning? [No]

History of and current controlled- and illicit-substance use is important as some patients use opioid analgesics to manage their mood, and some have side effects that mimic the symptoms of depression (e.g. mood changes, altered sleep). Psychological dependence and aberrant behaviours related to prescribed pain-relieving medications and illicit drugs should be evaluated. A record of prescribed controlled substances and urine toxicology screening should be obtained and documented.

Referral for further evaluation may be indicated when the following are present:

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