Assessment and Diagnosis of Chronic Pain Conditions
Christopher Vije
Michael A. Ashburn
The patient with chronic pain comes to the physician with the hope that he can help her find relief from pain and suffering. The initial evaluation starts this process, and what occurs during this evaluation goes a long way toward setting the stage for success or failure. What occurs during the evaluation will impact on the physician’s ability to optimize treatment. This interaction plays an important role in establishing the physician–patient relationship, and this relationship is an important contributor to patient outcomes. Therefore, it is reasonable to think of the evaluation process as one that includes several steps, including collection of information, the conduct of a physical examination, the establishment of a physician–patient relationship, the establishment of the initial diagnosis and treatment plan, and the establishment of patient (and family) agreement to the proposed treatment plan.
In this chapter, we review the process of information collection in some detail. However, other chapters in this text also provide valuable information on what data to collect regarding specific disease states. Likewise, this chapter will provide an overview of the physical examination, but other chapters will provide more detailed information regarding the conduct of specific examination techniques related to specific disease states (see Chapters 31, 38, 43,44,45,46,47,48,49). We will discuss outcome measurement instruments, as these instruments, when integrated into the care of the pain patient, provide a unique opportunity to track outcomes in a particular patient as well as in populations of patients over time.
Overview of the Process
In as much as possible, the process for the conduct of the initial evaluation, including the documentation of the visit, should be standardized. Although each patient has her own unique story to tell, the use of a standardized process to collect information will improve the likelihood that all necessary information is collected and will lower the chances that valuable information will be overlooked. In addition, as the practice of medicine appropriately moves toward the use of electronic health records, a standardized format will be necessary for data entry. Standardization can include the use of a preprinted initial evaluation form to guide the collection and documentation of information.
The traditional format for the conduct of the patient evaluation, which includes the history of present illness, past medical and surgical history, family history, current medications, drug allergies, review of systems, past radiologic and laboratory studies, physical examination, counseling and coordination of care, impression, and treatment plan, is appropriate. Enhancement can be made, however, to ensure appropriate pain-specific information is collected on the chronic pain patient (detailed history of current pain).
The physician’s interactive style has an important impact on the patient’s perception of the quality of the care received, and appears to be linked to quality of care (1). An interactive style described as patient-centered is associated with better quality (2). Patient-centeredness involves focusing the dialog on the biopsychosocial model of care, rather than a biomedical model of care (3). A patient-centered dialog includes active patient engagement in the medical dialog, with the physician being open and responsive to the patient’s agenda and perspective. In this model, the physician also seeks to learn the patient’s concerns, expectations, and preferences for treatment, and he makes an effort to establish an emotional rapport with the patient (1).
It is important to note that it is not only what physicians say to their patients, but how they say it that matters (4). A patient extracts meaning from her physician’s tone of voice, facial expression, and body cues (5). This nonverbal communication plays an important role in the establishment of trust, liking, and respect, factors deemed by patients to be important parts of the physician–patient relationship (6).
The physician should understand early in the evaluation what the patient hopes to accomplish during the visit. Patients may come to the physician seeking a single, specific therapy. Wasted time and frustration on both the physician and patient’s part can be avoided if this expectation is identified and addressed early. Frank, open discussion of whether the physician can meet the patient’s expressed goals may avoid frustration later on and allow for education of the patient regarding available treatment options. Such a discussion early may allow patients to make more informed decisions regarding their treatment, thus leading to improved compliance, efficacy, and satisfaction.
At the completion of the visit, treatment goals should be clearly stated and agreed upon. Treatment goals often include improvement in physical and mental function, as well as improvement in pain. Expectations should be reasonable and based on evidence whenever possible. Physicians need to clearly understand what treatment options the patient is willing to consider. For example, medications will not be effective if the patient refuses to take drugs from certain drug classes, or cannot afford to pay for the medications offered. Likewise, physical therapy will not be effective if the patient cannot afford the therapy, or if transportation to the therapist for frequent visits is not possible.
Conduct of the Initial Evaluation
History of Present Illness
Physicians often form their initial diagnosis from the information collected during this part of the evaluation. As this is usually done first, this also is the part of the evaluation that provides both the physician and the patient with the critical first impression that has a significant impact on the physician–patient relationship going forward. It is important to allow the patient to tell her story as much as possible. Physicians often interrupt the patient very soon after she starts to speak. Such interruptions can be perceived in a negative way by the patient, probably do not allow for more rapid information sharing, and may result in the physician making conclusions based on incomplete information. Therefore, it is important for the physician to develop and practice active listening, especially early in the evaluation.
It is important to collect detailed information regarding the pain experience (Table 37-1). After allowing the patient to “tell her story,” gaps in the story should be filled in, so that the physician has complete information regarding the patient’s pain. This should include information regarding the circumstances surrounding the onset of the pain, a detailed description of the pain (e.g., site, radiation, character, intensity, precipitating and associated factors; Table 37-1), and past interventions, including the impact of these interventions on the pain experience.
Character of pain refers to the nature of the pain, such as burning, stabbing, dull, aching, tingling, pricking, and many others. The character of the pain can help distinguish the etiology of the pain. A few scales have attempted to assess pain character with numerical scoring, notably the Neuropathic Pain Scale (NPS) (7) and the McGill Pain Questionnaire (MPQ) (8).
The NPS asks respondents to rate their pain based on 10 different characteristics (two global ratings of pain and eight terms common to neuropathic conditions) (9). The advantages of the NPS include its brevity and ability to help discriminate neuropathic pain conditions (10). The main disadvantage of the NPS is that it was developed specifically for neuropathic conditions. Several other neuropathic pain scales are now available, and the two most efficient in detecting neuropathic pain are the PainDetect and S-LANSS (11) (Table 37-2).
The McGill Pain Questionnaire (MPQ), introduced by Melzack and Torgerson, continues to be a standard in assessing pain character. It is more comprehensive than the NPS. The MPQ attempts to score and characterize the character of pain by assigning rank values to different terms used to describe the pain (8). These terms are grouped together and placed in order of intensity. A final score is given to the patient based on different subgroupings of the endorsed terms (sensory, affective, evaluative, and miscellaneous). Although it is difficult to quantify and score an individual’s pain experience, the MPQ has been shown to be reproducible, sensitive, and responsive to therapeutic interventions. There is also some evidence that the MPQ can be used to aid in the differential diagnosis of certain pain syndromes. Melzack, largely because of the large amount of time needed to administer the MPQ, developed the short-form MPQ (SF-MPQ) in 1987 (12). It consists of only 15 possible terms to describe the pain, but still correlates well with the pain rating index (PRI) from the original MPQ (13). So, although the quantity of pain is a more common outcome measurement, assessment of character guides important treatment decisions in neuropathic conditions (14).
Table 37-1 History taking in patients with persistent pain | |
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Patient report of pain intensity can be descriptive (“mild” or “severe”) or numerical (on a scale of 0–10). Patient report of pain intensity can be highly variable among patients for a variety of reasons, including differences in perception, demographics, and behavioral patterns (15). Pain intensity can be reported using the Verbal Rating Scales (VRS), Numerical Rating Scales (NRS), or Visual Analogue Scales (VAS), among others (16). The NRS is a commonly used pain intensity measurement
tool in clinical practice. The NRS is a 11-point categorical scale, where 0 = No Pain, and 10 = Worst Possible Pain. The NRS is easy to administer, and its validity has been well documented (17).
tool in clinical practice. The NRS is a 11-point categorical scale, where 0 = No Pain, and 10 = Worst Possible Pain. The NRS is easy to administer, and its validity has been well documented (17).
Table 37-2 Neuropath pain screening tools | ||||||||||||||||||||||||
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Timing (temporal pattern) refers not only to the duration of the pain, but also time-related qualities (constant versus intermittent) and day or seasonal relationships of the pain. In a patient who has a long history of chronic pain, questioning should attempt to uncover periods of time when pain was absent or much improved. Often, therapy will be less efficacious if the pain is longstanding and progressive in nature (18). Appropriate understanding of timing can help establish realistic treatment goals with the patient. Intermittent, very sudden, spontaneous bursts of pain that may last only seconds to minutes are referred to as paroxysmal pain. Such pain is usually of neuropathic origin.
The history of present illness should include an assessment of other key aspects of the patient’s life experience that often are altered by the presence of chronic pain. This includes an assessment of the patient’s mood, sleep, and functional status.
Patients with chronic pain may suffer from depression, anxiety, or other psychological disturbances (19). These conditions may pre-date the onset of the painful condition or present after the onset of chronic pain. It is important that the pain physician look for and identify psychiatric illness, as these illnesses may have profound impact on outcomes, especially if these illnesses are not properly treated.
Multiple chronic pain conditions have an increased incidence of comorbidity with depressive and anxiety disorders. For example, patients with fibromyalgia have up to a threefold increase risk of developing depression and up to a fivefold increase risk of anxiety disorders (20,21). Increased incidence of mood disorders can also be found in patients with chronic pelvic pain, chronic low back pain, myofascial pain syndrome, and many other conditions seen by the pain specialist. Clearly, mood disturbances can be secondary to chronic impairment from pain, can increase the perception of pain as a somatic condition, and could have developed independently from the primary pain process.
Patients with chronic pain often report disruptions in their sleep (22). Sleep disorders can manifest as insomnia, frequent awakening, early awakening, or restless and disturbed sleep. Sleep disturbances may be due to poorly controlled pain, associated depression, a side effect of the patient’s medications, or due to other existing disease. In the United States, the incidence of obstructive sleep apnea appears to be growing as obesity becomes more prevalent (23). It is important for sleep disturbances and their underlying cause(s) to be identified and treated as part of an integrated pain treatment plan.
Patients with chronic pain often have compromise of their mental and physical functioning (24). Alterations in function may range from an inability to engage in specific activities that are important to the patient to an inability to engage in the activities necessary for daily living. It is important to note that alterations in function include both physical functioning (i.e., inability to raise their arms over their head), and mental functioning (i.e., inability to engage in meaningful conversations with friends and family).
Impairment of function and a diminished ability to perform activities of daily living (ADLs) are often associated with chronic pain conditions (25). This can be related to the pain that causes decreased physical activity and inability to perform social and occupational duties. However, it can also be related to psychosocial and behavioral changes that may impair the mood and motivation of the patient.
An assessment of function begins by establishing baseline lifestyle activities. From this baseline, changes (or percentage changes) in activity can be assessed before and after the pain condition. It is important to include multiple categories in the assessment. Usually, employment status and stability is assessed first. The patient’s ability to perform their occupation in a meaningful fashion, perceived job performance, and frequency of job changes can provide insight into the impact of the pain.
Assessment of mental functioning can start with an assessment of the patient’s ability to complete family and social responsibilities. If the patient was responsible for dependents, then the patient’s ability to provide the usual care for the dependents should be assessed before and after the onset of pain. Social activities in which the patient was involved may also have taken a lesser role in the patient’s life coincidental with the onset of pain. In addition, personal recreational activities are often sacrificed secondary to pain.
Basic evaluation of function may include an assessment of physical functioning using a 4-point categorical scale, where 1 = inability to independently complete ADLs, 2 = able to do ADLs, but physical activity severely limited, 3 = unable to independently complete selected tasks important to the patient, and 4 = able to do tasks important to the patient. Detailed assessment of physical functioning can be completed as part of a formal functional capacity evaluation, (FCE) (26). Likewise, a basic assessment of the patient’s mental functioning can be completed by questioning the patient regarding any limitations they are experiencing regarding their ability to mentally
perform their work (or work equivalent) and interact with their friends and family.
perform their work (or work equivalent) and interact with their friends and family.
Past Medical History
It is important for the physician to collect complete information regarding past medical and surgical history. Special attention should be paid to medical conditions that can contribute to or be the underlying cause(s) of the painful condition. Prior surgeries can predispose to chronic pain states (for example, the incidence of chronic pain after inguinal herniorrhaphy can range from 10%–54%) (27), and certain medical conditions can either cause pain or mimic a chronic pain state. Important categories include endocrine dysfunction, anatomic abnormalities, cancerous processes, inflammatory conditions, and infectious diseases. Endocrine conditions, such as diabetes, could present with symptoms indicative of peripheral neuropathy. Glycemic control and the presence of other end-organ complications are positively correlated with diabetic neuropathy (28), and this history should be elicited from the patient. Anatomic abnormalities such as cervical syrinx may mimic symptoms of discogenic radicular pain (29), but would require completely different treatment. Clearly, chronic inflammatory conditions, cancer, and chronic infection (e.g., HIV neuropathy) are associated with chronic pain. Treatment of chronic pain in these conditions may be related to success in treating the primary condition (30).
In addition to conditions that may directly affect the patient’s pain, the patient’s general medical history is important (such as cardiac history, kidney dysfunction, allergies, pulmonary history) because this information will help determine what therapies would be safe and effective in certain population groups.
Past medical history should include documentation of the results of previous evaluations and treatment for the painful condition. This should include all imaging and other tests, as well as response to medical and interventional therapy. It is important to have a clear understanding of what analgesic medications have been tried in the past, and this information should include the dose and duration of therapy, as well as the patient’s response to this therapy, including adverse effects and allergies. Because an unlimited number of treatment options does not exist, the physician may miss an opportunity for successful therapy if an assumption is made that a prior attempt at therapy with a particular drug was done appropriately.
It is critical that the physician collect accurate, reliable information regarding the use of all medications, not just what analgesic medications the patient is taking. Often, the patient will be taking medications that can interact with analgesic medications, and an accurate medication history is critical to guiding therapy. Case reports of near fatal interactions of medications with opioids, such as methadone and meperidine, have been reported (31,32). Finally, the physician must obtain information regarding drug allergies, and this information must be clearly documented in the health record.
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