Pain disorder is one of several somatoform disorders described in the revised, fourth edition of the mental health professional's handbook, the Diagnostic and Statistical Manual of Mental Disorders (known as DSM-IV-TR). The term "somatoform" means that symptoms are physical but are not entirely understood as a consequence of a general medical condition or as a direct effects of a substance, such as a drug. Pain in one or more anatomical sites is the predominant complaint and is severe enough to require medical or therapeutic intervention . Pain disorder is classified as a mental disorder because psychological factors play an important role in the onset, severity, worsening, or maintenance of pain.
Earlier names for this disorder include psychogenic pain disorder and somatoform pain disorder. There is some overlap in the meaning of these terms, but views regarding the nature of pain have been changing and they are, therefore, not equivalent diagnostic categories. Sometimes pain disorder is referred to as somatization, but this is an imprecise term and is easily confused with somatization disorder .
In 1994, the International Association for the Study of Pain (IASP) defined pain as an unpleasant sensory or emotional experience arising from real or probable tissue damage. In other words, the perception of pain is, in part, a psychological response to noxious stimuli. This definition addresses the complex nature of pain and moves away from the earlier dualistic idea that pain is either psychogenic (of mental origin) or somatogenic (of physical origin). The contemporary view characterizes pain as multidimensional; the central nervous system, emotions, cognitions (thoughts), and beliefs are simultaneously involved.
When a patient's primary complaint is the experience of pain and when impairment at home, work, or school causes significant distress, a diagnosis of pain disorder may be warranted. The diagnosis is further differentiated by subtype; subtype is assigned depending on whether or not pain primarily is accounted for by psychological factors or in combination with a general medical condition, and whether the pain is acute (less than six months) or chronic (six months or more). The classification of pain states is important since the effectiveness of treatment depends on the aptness of the diagnosis of pain disorder and its type.
Causes and symptoms
Common sites of pain include the back (especially lower back), the head, abdomen, and chest. Causes of pain vary depending on the site; however, in pain disorder, the severity or duration of pain or the degree of associated disability is unexplained by observed medical or psychological problems.
The prevailing biopsychosocial model of mental disorders suggests that multiple causes of varying kinds may explain pain disorder, especially when the pain is chronic. There are four domains of interest:
- The underlying organic problem or medical condition, if there is one. For example, fibromyalgia (a pain syndrome involving fibromuscular tissue), skeletal damage, pathology of an internal organ, migraine headache, and peptic ulcer all have characteristic patterns of pain and a particular set of causes.
- The experience of pain. The severity, duration, and pattern of pain are important determinants of distress. Uncontrolled or inadequately managed pain is a significant stressor.
- Functional impairment and disability. Pain is exacerbated by loss of meaningful activities or social relationships. Disruption or loss may lead to isolation and resentment or anger, which further increases pain.
- Emotional distress. Depression and anxiety are the most common correlates of pain, especially when the person suffering feels that the pain is unmanageable, or that the future only holds more severe pain and more losses.
In sum, there are multiple causes of pain disorder. A therapist or team of health professionals will weigh the relative causal contributions, assign priorities for therapeutic intervention, and address the several domains in a multimodal fashion. For example, the design of a treatment plan in a pain clinic may involve a physician, psychotherapist, occupational therapist, physical therapist, anesthesiologist, psychologist , and nutritionist.
Symptoms vary depending on the site of pain and are treated medically. However, there are common symptoms associated with pain disorder regardless of the site:
- negative or distorted cognition, such as feeling helpless or hopeless with respect to pain and its management
- inactivity, passivity, and/or disability
- increased pain requiring clinical intervention
- insomnia and fatigue
- disrupted social relationships at home, work, or school
- depression and/or anxiety
There is very little information regarding rates of pain disorder. A major difficulty is that the diagnostic categories for psychogenic pain disorder in DSM-III , somatoform pain disorder in DSM-III-R , and pain disorder in DSM-IV and DSM-IV-TR are not equivalent. Furthermore, many criticize the somatoform disorder group (which includes pain disorder) as being an aggregate of disorders that are not truly distinct from one another. This lack of distinctiveness suggests to some researchers that a more appropriate system of classification should be dimensional rather than categorical. In other words, if shared dimensions or characteristics of the several somatoform disorders exist, differences among disorders should be a matter of degree along the possible dimensions. The critics of the DSM categorical approach would prefer a dimensional or multiaxial system because when classification systems are improved, the reliability and validity of measures assessing disorder improve, and better estimates of rates are possible.
Nevertheless, some researchers find the DSM-IV category for pain disorder useful. For example, in one study of psychiatric pain clinic outpatients, 79% met the criteria for pain disorder of the subtype where psychological factors and a general medical condition co-exist; 9% of the outpatients met the criteria for pain disorder with psychological factors and no medical condition. In another study of patients at a psychiatric clinic, 38% of the patients at admission and 18% of the outpatients reported significant pain. In comparison, 51% in a study of general medical and surgical inpatients met the criteria for pain disorder.
Currently, there are no good estimates for rates of pain disorder in the general population.
A psychiatrist or mental health professional arrives at the diagnosis of pain disorder after considering several questions. An important preliminary question is whether the pain is entirely accounted for by a general medical condition. If so, the diagnosis of pain disorder is ruled out; and if not, the psychiatrist considers whether the pain is feigned. If the psychiatrist believes the patient is pretending to be in pain, the patient is diagnosed as malingering for external rewards, such as seeking mood-altering drugs, or as having a factitious disorder that reflects the patient's need to adopt a sick role. Neither malingering nor factitious disorder is in the somatoform group.
The psychiatrist may employ a variety of methods to assess the severity of pain and the contribution of psychological factors to the experience of pain. These include structured interviews (where the questions asked are standardized), open or unstructured interviews, numerical rating scales, visual analog scales (where the patient makes a mark along a line to indicate severity of pain, or if the patient is a child, or is illiterate, selects a face to represent the degree of pain), and instruments such as the McGill Pain Questionnaire or the West Haven-Yale Multidimensional Pain Inventory.
There are several conditions that rule out a diagnosis of pain disorder:
- Dyspareunia. (The patient's primary complaint relates to the experience of painful sexual intercourse.)
- Somatization disorder. (The patient has a long history of pain that began prior to age 30 and involves the gastrointestinal, reproductive, and nervous systems.)
- Conversion disorder. (In addition to pain, there are other symptoms associated with motor or sensory dysfunction.)
- Mood, anxiety, or psychotic disorder. (Any one of these more fully accounts for the pain. This last exclusion rests upon a very subjective opinion. Subjectivity reduces inter-rater reliability and is one of the points raised by critics of the DSM category for pain disorder.)
A final consideration is whether the pain is acute or chronic.
Depending on whether the pain is acute or chronic, management may involve one or more of the following: pharmacological treatment (medication); psychotherapy (individual or group); family, behavioral, physical, hypnosis, and/or occupational therapy. If the pain is acute, the primary goal is to relieve the pain. Customary agents are acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs); if opioid analgesics are prescribed, they often are combined with NSAIDs so that the dosage of opioids may be reduced. Psychotherapy is less important for the treatment of acute pain as compared to chronic pain disorder. In comparison, treatment of chronic pain disorder usually requires some sort of psychotherapy in combination with medication.
Tricyclic antidepressants (TCAs) reduce pain, improve sleep, and strengthen the effects of opioids (such as codeine and oxycodone), as well as moderate depression. Relief of pain may occur in a few days while lessening of depression may take several weeks. Usually, TCAs for pain are prescribed at doses 33% to 50% lower than when prescribed for depression. TCAs are particularly effective for neuropathic pain, headache, facial pain, fibromyalgia, and arthritis.
Treatment of sleep dysfunction
Pain and depression diminish the restorative quality of sleep. When the cycle of pain, depression, insomnia, and fatigue is established, it tends to be self-perpetuating. Treatment may include antidepressants, relaxation training, and education regarding good sleep hygiene.
Many people who suffer chronic pain experience isolation, distress, frustration, and a loss of confidence regarding their ability to cope; subsequently, they may adopt a passive, helpless style of problem solving. The goal of cognitive-behavioral therapy (CBT) is to restore a sense of self-efficacy by educating patients about the pain-and-tension cycle, by teaching them how to actively manage pain and distress, and by informing them about the therapeutic effects of their medications. CBT is time-limited, structured, and goal-oriented.
Some tension-reducing techniques include progressive muscle relaxation, visual imagery, hypnosis, and biofeedback . Pain diaries are useful for describing daily patterns of pain and for helping the patient identify activities, emotions, and thoughts that alleviate or worsen pain. Diaries also are useful in evaluating the effectiveness of medication. Patients may be taught pacing techniques or scheduling strategies to restore and maintain meaningful activities.
The cognitive aspect of CBT is based on cognitive-social learning theory. The focus is on helping the patient to restructure his or her ideas about the nature of pain and the possibility of effective self-management. In particular, the patient is taught to identify and then modify negative or distorted thought patterns of helplessness and hopelessness.
The principles of operant conditioning are taught to the patient and family members so that activity and non-pain behaviors are reinforced or encouraged. The goal is to eliminate pain behaviors, such as passivity, inactivity, and over-reliance on medication.
Other treatments effective in the management of pain include acupuncture , transcutaneous electrical nerve stimulation (TENS), trigger point injections, massage, nerve blocks, surgical ablation (removal of a part or pathway), meditation , exercise, yoga , music and art therapy.
The prognosis for total remission of symptoms is good for acute pain disorder and not as promising for chronic pain disorder. The typical pattern for chronic pain entails occasional flare-ups alternating with periods of low to moderate pain. The prognosis for remission of symptoms is better when patients are able to continue working; conversely, unemployment and the attendant isolation, resentment, and inactivity are correlates of a continuing pain disorder. Additionally, if reinforcement of pain behavior is in place (for example, financial compensation for continuing disability, an overly solicitous spouse, abuse of addictive drugs), remission is less likely.
The results of outcome studies comparing pain disorder treatments point to cognitive-behavioral therapy in conjunction with antidepressants as the most continually effective regimen. However, people in chronic pain may respond better to other treatments and it is in keeping with the goal of active self-management for the patient and health professional(s) to find an individualized mix of effective coping strategies.
Pain disorder may be prevented by early interventioni.e., at the onset of pain or in the early stages of recurring pain. When pain becomes chronic, it is especially important to find help or learn about and implement strategies to manage the distress before inactivity and hopelessness develop. Most patients in pain first contact their primary care physician who may make a referral to a mental health professional or pain clinic. Many physicians will reassure the patient that a referral for psychological help is not stigmatizing, does not in any way minimize the experience of pain or the medical condition, and does not imply that the physician believes the pain is imaginary. On the contrary, the accepted IASP definition of pain fully recognizes that all pain is, in part, an emotional response to actual damage or to the threat of damage.
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American Academy of Pain Medicine. 4700 W. Lake, Glenview, IL 60025. (847) 375-4731. <http://www.painmed.org> .
The American Chronic Pain Association. PO Box 850, Rocklin, CA 95677. (916) 632-3208. <http://www.theacpa.org> .
Tanja Bekhuis, Ph.D.