Abstract
Chronic pain syndrome is a common and challenging disorder. It is often a constellation of presenting symptoms that develop and persist beyond a reasonable expected healing period for the involved tissue. Given its unclear pathophysiology and lack of definitive diagnostic tests or successful symptom resolution, this disorder poses a challenge to healthcare providers.
Systematic examination and diagnostic testing are performed by healthcare providers to identify treatable causes of chronic pain or to find alarming neurologic signs or symptoms. In most cases, such examination does not lead to a specific target for procedural or surgical treatment; therefore, the hallmark of treatment becomes education, symptom management, and supportive care. Although the primary complaint is pain, associated symptoms including poor sleep, depression, behavioral disorders, and mood and affect disorders need to be recognized and treated concurrently. Both pain and any associated symptoms are ideally treated in a multimodal and multidisciplinary approach. The goal of treatment should be improved quality of life and improvement in function.
Definition
Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage. 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, back pain, neuropathy, fibromyalgia, whiplash injury, repetitive stress injuries, degenerative joint disorders, cancer, complex regional pain syndrome, shingles, central pain, and pain following multiple surgeries.
Statistics and Demographics : In excess of 50 million Americans suffer from CPS and have a degree of impairment or disability from this condition. 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. Pain disorders cost $100 billion annually in lost work days, medical expenses, and other benefit costs. In the United States, nearly $20 billion per year is spent on caring for chronic pain in adolescents. Chronic pain is prevalent in all ages. Children suffering from chronic pain frequently continue to suffer from chronic pain as adolescents and young adults. Some authors have reported a higher prevalence of CPS in individuals with a history of childhood abuse and personality disorder (borderline, narcissistic). CPS is more prevalent in women and by up to twofold in certain diagnoses (e.g., fibromyalgia). Studies suggest a relationship between chronic pain, race, and socioeconomic status. These studies show that African Americans between ages 18 and 49 have a significantly higher prevalence of pain and disability and also live in lower socioeconomic neighborhoods. Living in a lower socioeconomic status neighborhood is associated with increased sensory, affective, pain-related disability, and mood disorders.
Given its unclear pathophysiology and the lack of a definitive diagnostic test or successful treatment, CPS imposes a challenge to healthcare 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 98.1 shows a list of symptoms that present along with pain complaint. Chronic pain may be localized or 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 pain scale (0 to 10) or the visual analog scale (VAS) 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 VAS score.
| Depression | Sleep disorders |
| Anxiety | Irritable bowel |
| Emotional lability | Cognitive difficulty (memory, concentration) |
| Chronic fatigue | Pain behaviors |
| Medication seeking | Dramatization of symptoms |
| Doctor shopping | Legal action—secondary gain |
In CPS, there are often associated pain behaviors that help establish the diagnosis. Pain behaviors include assuming poor posture, intentional limping or facial grimacing, stiff movements, and use of assistive devices that have not been medically prescribed (canes, wheelchairs, and electric scooters). Behavioral treatments aiming to address pain behaviors are a key component of multidisciplinary pain programs and can be effective in reducing pain.
Mood and affect disorders including depression, anxiety, emotional instability, and anger are commonly associated with CPS. Chronicity of the pain, lack of clear etiology, and poor treatment outcomes contribute to the emotional aspect of this disorder. Some studies have reported up to fourfold increased depression in patients with chronic back pain. Simply treating pain 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 correlates with pain severity. In patients with CPS, the insomnia needs to be anticipated and treated. Sleep-inducing medications 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. 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. Recent use of medical marijuana in chronic pain may also address the insomnia aspect of patients with CPS.
Physical Examination
Physical examination is directed toward finding a treatable cause for the chronic pain condition. A systematic and detailed musculoskeletal and neurologic examination needs to be conducted. Depending on the complaint, examination of other systems, including gastrointestinal, urologic, and pelvic girdle, may be indicated. If the CPS follows an injury, focused examination of the injured body part is needed. An important part of the physical examination is to observe patient’s gait, body motion, posture, and facial expression and to look for abnormal pain behaviors. Give-away weakness, non-myotomal weakness, and non-dermatomal numbness are often encountered on physical examination. There are likely to be inconsistencies in physical examination findings of a patient with CPS if exact physical exam is repeated. 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.
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. 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 healthcare providers or the patient’s family, it will result in chronicity of the pain and further decline in function.
Diagnostic Studies
In CPS, diagnostic studies are performed to find treatable causes that can lead to protracted pain. The results of such studies are often inconclusive or normal. Diagnostic testing may include laboratory work, electrodiagnostics, and imaging. Unless the presenting symptoms have clearly changed, repeating costly tests is of no value. Equally important is psychological testing. The Minnesota Multiphasic Personality Inventory is the most common psychological test used in patients with chronic pain and has been shown to help understand pain behaviors and the psychological impact on individuals with chronic pain ( Table 98.2 ).
Somatoform disorder
Somatization disorder
Conversion disorder
Hypochondriasis
Factitious disorder
Malingering
| Disorder | Description |
|---|---|
| Somatoform disorder | Group of psychiatric disorders, including somatization disorder, conversion disorder, hypochondriasis, and factitious disorder, that cause unexplained physical symptoms |
| Somatization disorder | Chronic physical symptoms that involve more than one part of the body, but no physical cause can be found Pain complaint is often associated with gastrointestinal, pseudoneurologic, and sexual complaints Symptoms are not intentionally fabricated |
| Conversion disorder | Dramatic loss of voluntary motor or sensory function (e.g., inability to walk, sudden blindness, paralysis) No evidence that the symptom is feigned or intentionally produced; loss of function is not due to medical illness |
| Hypochondriasis | Excessive preoccupation or worry about having a serious illness in absence of an actual medical condition |
| Factitious disorder | Deliberately produces or falsifies symptoms of illness for the sole purpose of assuming the sick role |
| Malingering | Fabricating or exaggerating the symptoms of mental or physical disorders for a variety of secondary gain motives |
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