Definition

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage [1]. Chronic pain is a pain status that persists beyond a reasonable expected healing period for the involved tissue. It is chronic if it persists for 6 months or more despite active treatment. It is called a syndrome because a constellation of symptoms develops in those patients facing chronic pain. The most common conditions leading to chronic pain syndrome (CPS) include headaches, repetitive stress injuries, back pain, whiplash injury, degenerative joint disorders, cancer, complex regional pain syndrome, shingles, fibromyalgia, neuropathy, central pain, and multiple surgeries [2]. In excess of 50 million Americans suffer from CPS and have a degree of impairment or disability from this condition [2]. Pain disorders cost $100 billion annually in lost work days, medical expenses, and other benefit costs [2]. Chronic pain is often a hidden problem and may be an issue that individuals are reluctant to share with family or friends. This may have an impact on the awareness of CPS in the community at large.

Chronic pain is prevalent in both adults and the pediatric population. Children suffering from chronic pain frequently continue to suffer from chronic pain as adolescents and young adults [3]. Some authors have reported a higher prevalence of CPS in individuals with a history of childhood abuse and personality disorder (borderline, narcissistic) [4]. CPS is more prevalent in women and by up to twofold in some diagnoses (e.g., fibromyalgia) [5,6]. Studies suggest a relationship between chronic pain and race as well as socioeconomic status. In a study of 3730 adults between ages 18 and 49, African Americans appear to have significantly more pain and disability and live in lower socioeconomic neighborhoods [7]. Living in a lower socioeconomic status neighborhood was associated with increased sensory, affective, pain-related disability and mood disorders [7].

Given its unclear pathophysiology and the lack of a definitive diagnostic test or successful treatment, CPS imposes a challenge to health care providers. Most patients are often unsatisfied with the treatment outcomes, leading to psychosocial stress, chronic pain behaviors, medication seeking, impairment, activity restriction, limited participation, and disability.

Symptoms

The primary symptom is a protracted pain that is out of proportion to the objective pathophysiologic process. Table 97.1 shows a list of common associated symptoms. Pain may be localized to a body segment, or it could be widespread. The measurement of pain severity is subjective and typically relies on the patient’s report as well as on functional ability (work, activities of daily living, hobbies). The numeric (0-10) or the visual analogue scale that is used to assess pain often does not properly reflect the pain intensity, and despite adjustments to medical management, the reported pain level is unchanged. Because of this, clinicians may focus on functional gains as a measure of treatment success rather than on the patient’s report of a decreased numeric or visual analogue scale score.

In CPS, there are often associated pain behaviors that help establish the diagnosis. Pain behaviors include assuming poor posture, abnormal gait (limping), facial grimacing, stiff movements, and use of assistive devices that have not been medically prescribed (canes, wheelchairs, and electric scooters). Decreasing pain behavior decreases the experience of pain. Behavioral treatments are a key component of multidisciplinary pain programs and can be effective for the relief of pain.

Mood and affect disorders including depression, anxiety, emotional instability, and anger are commonly associated symptoms in patients with CPS [8]. Some studies have reported up to fourfold increased depression in patients with chronic back pain [9]. Chronicity of the pain, lack of clear etiology, and poor treatment outcomes contribute to the emotional aspect of this disorder. Just treating pain with medications without addressing the psychosocial component will lead to poor outcomes and further suffering. Part of the reasonable success associated with the multidisciplinary pain programs is related to management of the psychosocial component of the chronic pain.

Sleep disorders are prevalent in patients with CPS. Studies have shown that severity of insomnia contributes to the prediction of pain severity [10]. The insomnia associated with chronic pain needs to be anticipated and treated. Sleep-inducing medications often combined with cognitive-behavioral therapy can help improve insomnia. Sleep education, cognitive control and psychotherapy, sleep restriction, remaining passively awake, stimulus control therapy, sleep hygiene, relaxation training, and biofeedback are part of the cognitive-behavioral approach to treatment of insomnia [11]. Clinicians should be aware of increased cognitive impairment in elderly patients treated with medications for insomnia. This may lead to falls, injury, and increased pain [12].

Physical Examination

Physical examination is directed toward finding treatable causes of CPS. One of the most important parts of the physical examination is to observe the patient’s gait, body motion, posture, and facial expression as well as abnormal pain behaviors. A systematic and detailed musculoskeletal and neurologic examination needs to be conducted. If the CPS follows an injury, focused examination of the injured body part is needed. Give-away weakness, nonmyotomal weakness, and nondermatomal numbness are often encountered on physical examination. If it is done repeatedly, there are likely to be inconsistencies in physical examination findings of a patient with CPS. Redirecting the patient’s attention while repeating the examination may alter the findings and can point to pain behaviors. For example, diffuse tender points may not be tender if the patient’s focus is diverted. Another example is a negative result of the seated straight-leg test (patients are less knowledgeable about it) versus a positive result of the supine straight-leg test in the same patient.

There are diagnosis-specific examination findings that may be noted, such as allodynia and trophic changes. These may be found in the area of the initial injury or in a different body part. Depending on the complaint, examination of other systems, including gastrointestinal, urologic, and pelvic girdle, may be indicated.

Functional Limitations

Typically, there is a disproportionate loss of function in patients with CPS when it is matched to the injury and the stated age. Fear-avoidance behavior will result in deconditioning and decline in function with activities of daily living [13]. Deconditioning leads to increased perception of pain, reduced quality of life, and further psychosocial stress and disability. If such abnormal pain behavior is reinforced by health care providers or the patient’s family, it will result in chronicity of the pain and further decline in function.

Diagnostic Studies