Diana Coffa, MD
Wolf Mehling, MD
Chronic pain is variously defined as (1) pain lasting more than 3 months, (2) pain lasting more than 6 months, and (3) pain lasting beyond the period of expected healing or persisting in the absence of injury. Chronic pain is distinguished from acute pain in a number of ways. Most concretely, it lasts longer. In many cases, though, what is genuinely unique about chronic pain is that it seems to persist even when a physical insult is not occurring, or it is out of proportion to the physical damage that has occurred.
Pain is an extraordinarily complex phenomenon. At first glance, it appears to be a simple sensation, a message passed to the brain by a peripheral nerve that has received a signal of tissue injury. Upon further examination, though, it becomes clear that what most people describe as pain is much more than a simple sensation. When people say the word “pain,” they are generally referring to the suffering that is associated with a particular physical sensation. In the case of chronic pain, when the sensation often is not an accurate signal that a physical injury is occurring, the distress or the aversion to the sensation might accurately be described as the actual problem with pain. Sensations themselves can be translated in the brain in any number of ways and can lead to a wide array of emotions. These emotions typically lead to associations and thoughts. If the evaluation of a sensation is aversive and appraised as a threat, the emotions that arise in response to it will typically be unpleasant emotions including fear, anxiety, anger, despair, frustration, or hatred. The related thoughts, which can often become catastrophic stories about the future, then perpetuate the suffering of the individual independent of the original sensation. These thoughts and emotions then lead to coping behaviors, which, in sufferers of chronic pain, often include decreased physical activity, social isolation, and avoidant behaviors, all of which deepen the suffering.
This complex web of phenomena: sensation, translation, emotion, thoughts, and behavior patterns, provides the treatment team with a multitude of potential therapeutic targets. Treatment might target the origin of the physical sensation itself, the transmission of the signal, the interpretation of the sensation in the central nervous system, the emotional reaction to that interpretation, the thought patterns that result, or the habitual behaviors. Each of these areas is an independent source of suffering, and improvements in any of them will address at least some part of the patient’s distress.
There are many kinds of chronic pain. In some disorders, the primary source of suffering appears to originate in a clear pain-generating pathophysiology. Inflammatory arthritides such as rheumatoid arthritis, or invasive cancer are examples of this category of chronic pain. In other disorders, such as somatoform disorder or conversion disorder, the primary source of suffering appears to be almost entirely emotional or cognitive. In between these extremes lie the majority of chronic pain conditions. They are frequently initiated by some injury, neurologic disorder, or pain-processing dysfunction, but they seem to evolve so that psychological processes begin to play a greater role in the patients’ suffering and in the perpetuation of pain. The distinction between psychological and neurologic phenomena blurs, especially as we learn more about the specific neurologic correlates of the chronic pain experience.
NEUROLOGY OF PAIN
Recent research into the neurology of pain has dramatically changed our understanding of pain. Pain, whether acute or chronic, has commonly been interpreted as an aspect of the somatosensory system: Either a nociceptive stimulus hitting pain-specific receptors (nociceptive pain) or a damage to the nerve (neuropathic pain) creates a bottom-up nerve impulse that is transmitted through distinct anterolateral spinothalamic pain pathways and perceived in its discriminative (location and intensity) aspects in somatosensory cortex areas (SI) and in its affective aspects in limbic brain regions (anterior cingulate cortex, ACC). The last decades of pain research have widened that view and furthered our understanding of pain and its regulation.
First, the insular cortex is not only the terminal region for the ipsilateral ascending visceral pain pathway, but it now has been described as the key organ of interoception, that is, the perception of the inner milieu of the body. Interoceptive afferents including pain signals are transmitted through a lateral spinothalamic tract to the posterior insular cortex and are filtered to reach our awareness of the entire internal milieu of the body, pleasant or unpleasant, in the anterior insula (Figure 11–1). Pain perception relies on thick transmission cables to the somatosensory cortex for discrimination and sensorimotor integration and on thin-cabled homeostatic pathways to ACC and insula. Evolution provided only humanoids with this high-definition, topographically organized anterior insular cortex for re-representation of our internal milieu, which includes the felt aspects of emotions and pain. Therefore, with the discovery of the interoceptive homeostatic pathway, it is no longer a surprise that pain shares most qualities with emotions: it has a felt, sensory quality and an affective aspect, demands our mind’s attention, and includes a strong behavioral drive toward homeostasis. The evolutionary gain of a more refined and graded emotion perception, however, comes with a price, namely the increased ability to be aware of and suffering from unpleasant emotions including pain. Pain regulation is conceptually and neurologically intriguingly similar to emotion regulation.
Figure 11–1. Pathways of pain perception. (Reproduced, with permission, from Craig AD. How do you feel? Interoception: the sense of the physiological condition of the body. Nat Rev Neurosci. 2002 Aug;3(8):655–666. Review. [PMID: 12154366].)
Second, the discovery that electrodes placed in specific cortical areas can elicit pain sensations projected into, for example, a peripheral limb, without any pain stimulus ascending from that limb itself, necessarily lead to the logical conclusion that “pain is all in your brain.” This discovery implies that we may have preformed representations in our brain only waiting to be selected or modified by afferent nociceptive stimuli. This is similar to the current conceptualization of interoception which includes pain as one of its key modalities. The human brain appears to create a simulation copy, an “as-if” loop of the integrated and organized sensations brought to the posterior insula, a simulation that is based on and, to varying degrees, analogue to the body proper, but that at the same time is under the influence of the prefrontal cortex with stored beliefs, concepts, past experiences, and appraisal and conditioning processes. The “feeling” of pain is centrally generated in our brain with preformed representations that have been evolutionary useful. This usefulness is intuitive for acute pain but much less clear for chronic pain.
Third, key elements of the long postulated descending pathways for top-down regulation of pain have been elucidated. The bottom-up transmission of nociceptive signals can be modulated from higher brain regions at several “train stations,” at the level of the entry into the spinal cord (dorsal horn), the rostral ventromedial medulla (RVM) and the nucleus cuneiformis. In the latter, specified cells have opioid receptors and perform top-down graded on or off functions on the ascending neurons, thereby decreasing or increasing the stream of bottom-up neuronal activity, filtering and modulating at each “train station” the input from the body’s periphery to the pain sensation generated in the brain.
Fourth, chronic pain has unique features. It is associated with a reduction in brain matter density over time in nucleus accumbens (NAc), insula and sensorimotor cortex (SC). Both developing chronic pain and its perceived intensity are associated with decreased negative neural connectivity of insula and SC to prefrontal (dlPFC) and thalamic regions, indicating impaired cognitive control. Patients who develop chronic pain appear to have increased connectivity between mPFC and NAc, viewed as underlying rumination and aversive reinforcement learning and positively correlated with affective pain intensity. As pain persists, pain circuits develop a hypersensitive state, with pain itself being a pain predictive conditioning cue. Pain hypersensitivity and its chronicity is an expression of neuronal plasticity, an activeprocess generated in the peripheral nerve, spinal cord and cortico-limbic brain areas, rather than the passive consequence of the bottom-up transfer of peripheral nociceptive input to a cortical pain center.
Fifth, placebo research has elucidated the interaction of complex mental activities, such as expectancy, beliefs, and values with neuronal systems and pain. Placebo analgesia from conscious expectations or unconscious conditioning functions through the top-down modulation circuit, effectively modulating pain through opiate receptors at all “train stations,” from pain-modulating cortical structures (ACC) through the brain stem, all the way down to the dorsal horn. The striking parallel between brain regions involved in the placebo response with pain and with aversive emotions (eg, depression) suggests that the placebo response is part of a neurobehavioral homeostatic self-regulation system that applies to both emotions and pain.
Sixth, opioid pain medications, in addition to their pain relief, particularly effective for acute pain, are both rewarding and behaviorally reinforcing. Repeated use can lead to molecular changes in the brain promoting continued drug taking that may become increasingly difficult for the individual to control. The change from voluntary drug use to habitual and compulsive drug use corresponds neurologically to a transition from prefrontal cortical to striatal control over drug taking behavior and from ventral (NAc) to more dorsal subregions of the striatum and depend on sensitization and the neuroplasticity in both cortical and striatal structures. The NAc is involved in responding to the motivational significance of stimuli, and the dorsal striatum is involved in the learning and execution of behavioral sequences that permit an efficient response to those cues. Opiates increase the levels of synaptic dopamine in the NAc reward circuit and thereby produce behavioral reinforcement (the tendency to repeat actions that increase synaptic dopamine). Dopamine neurons in the striatum can habituate, or learn by conditioning and then fire in response to predictive cues that are carried by projection neurons from the cerebral cortex (including insula), hippocampus, and amygdala, thus associating reward with external context and interoceptively felt emotional and physiological states. Long-term opiate use, however, dampens the reward experience associated with the medication so that an unfortunate combination of several factors weaken an individual’s behavioral control into addiction: (a) decreased reward circuit sensitivity, (b) enhanced sensitivity of memory circuits to conditioned expectations to opiates and opiate-related predictive cues, (c) stress reactivity, (d) negative mood, and (e) involvement of the interoception circuitry with increased insula sensitivity associated with craving.
Seventh, brain imaging fMRI studies have provided new insights into the neural mechanisms involved in how cognitive behavioral therapy (CBT) and mindfulness interventions (MI) are able to alter pain perception, at least in acute experimental pain. Following CBT, a verbal intervention involving evaluative attention to pain and a narrative cognitive mental process, pain patients showed increased activations in the ventrolateral prefrontal/lateral orbitofrontal cortex with experimental pain stimuli. These regions are associated with executive cognitive control. This suggests that CBT changes the brain’s processing of pain by increasing access to executive brain regions for reappraisal of pain. In MI, quite differently, an increased sensory attention to the discriminatory aspects of pain coupled with decreased evaluative thinking about pain results in decreased affective pain (less bothersome) and is neurologically associated with increased insular cortex activity for interoceptive awareness and decreased lateral prefrontal cortex activity, interpreted as decreased cognitive control and less cognitive-evaluative reactivity. CBT directs attention away from pain and increases cognitive appraisal activity (reframing), MI refines attention toward the pain region and facilitates detachment from cognitive appraisal activity.
These neurological findings may help us in the understanding of the psychosomatics of pain and its regulation and management.
PSYCHOLOGY OF PAIN
On psychological personality profile tests, patients with chronic pain have been described as expressing exaggerated concern over body feelings, developing bodily symptoms in response to stress, and either often failing to recognize their own emotional state (eg, depression) or being demanding and complaining. Clinical studies have shown that these psychological attributes can improve with reduction in pain and are seen as a consequence of chronic pain rather than antecedent and predictive to it. However, the prognosis of both acute and chronic pain is more strongly dependent on psychological and occupational than on physical or medical factors. Although studies vary widely in inclusion criteria (duration of pain, primary care, workers compensation claims) and outcome parameters (return to work, pain or disability reduction, perceived recovery), several factors stand out and are now widely accepted as risk factors for (a) the transition from acute to chronic pain and (b) the persistence of chronic pain. These factors are modifiable by the nonpharmacological interventions presented below.
Depression
Depression is more common in chronic pain patients than in healthy controls, and pain is more common in depressed patients than in nondepressed individuals. Whereas some researchers believe that depression is frequently overlooked in pain patients, others emphasize that depression is a consequence rather than an antecedent of chronic pain. Distress (complaining of physical symptoms associated with depression and anxiety), depressive mood, and somatization are all implicated in the transition to chronic low back pain. Although numerous studies show a strong cross-sectional association between pain and depression, longitudinal studies have yielded contradictory results regarding depression as a risk factor for onset of new pain or for the progression to or persistence of chronic pain. Some researchers postulate that this is because people with chronic pain can be divided into two categories. In one group pain symptoms, nonpain somatic symptoms, and symptoms of depression and anxiety tend to cluster, with heightened stress reactivity and a tendency to overwhelm self-regulatory homeostatic systems. The second category, sometimes labeled “happy endurers,” form a separate cluster by ignoring symptoms of discomfort and pain and making a nondepressed, “happy face” in response to stress or pain. These persons are equally at risk of pain chronification and longer pain duration but do not exhibit depressive symptoms.
When depression is comorbid with chronic pain, both are frequently seen as a dyad that requires a combined therapy, although systematic reviews have found no evidence that antidepressants are more effective for chronic low back pain than placebo.
Pain Catastrophizing
Catastrophizing, a maladaptive coping style, is a construct with three components: magnification or amplification of pain, ruminating thoughts about pain, and perceived helplessness in the face of pain. It appears to be the strongest and most consistent psychosocial factor associated with persistence of pain and poor function in persons with chronic pain, even after controlling for depression. Catastrophizing is modifiable and, if treated by psychosocial interventions, pain improves with a decrease in catastrophizing.
Fear Avoidance
Fear avoidance is another maladaptive coping behavior, the avoidance of work, movement, or other activities due to fear that they will damage the body or worsen pain. Pain patients high in fear avoidance have worse long-term outcomes. Fear avoidance is associated with catastrophic misinterpretations of pain, hypervigilance, increased escape and avoidance behaviors, and increased pain intensity and functional disability. Although it has not been shown that fear-avoidance leads to decreased physical fitness or deconditioning as a mediator for developing chronic pain, sufficient evidence has accumulated that pain-related fear may increase the risk for developing new-onset back pain, for its chronification, and for its persistence. The value of changing beliefs about pain early in its course has been shown in studies involving patient education in physician’s offices and over the public radio.
Job Satisfaction
Although supervisor support may be a factor in duration of sick leave, there is strong evidence that job satisfaction is not a prognostic factor for duration of sick leave. Studies assessing the effects of job demands, job control, job strain, skill discretion, decision authority, job security, coworker support, supervisory support, psychological demands, physical demands, and work flexibility on duration of work absenteeism can be summarized as inconclusive. There is strong evidence, however, that heavy work is a predictor for longer duration of sick leave. Although assignment to light duties as commonly used for a rapid return to work appears not to shorten sick leave in workers with acute LBP, staying active and modified work are supported.
Distraction
Distraction is a coping style that generally is favored by patients. It’s opposite, a hypervigilant attention style toward pain is related to anxiety and is maladaptive. In research studies, distraction appears to have no consistent proven benefits for chronic pain, though evidence does exist that music, either by providing distraction or by increasing positive affect and inducing relaxation, may diminish pain. An attention focus toward pain can be either beneficial or maladaptive, a distinction that is likely mediated by the attention style. An anxiety-driven and hypervigilant attention style is likely maladaptive, while accepting and mindful attention may be beneficial. Research on this question is underway.
Ignoring/Endurance
Ignoring pain is generally considered an adaptive coping style, particularly with the use of cognitive distraction. This represents a focused approach to diverting attention from pain and is consistent with the aims of cognitive behavioral therapy for pain. Yet, suppressing the perception of pain to avoid interruptions in daily activities, a more disorganized and nonfocused search for distraction that often fails and causes feelings of emotional distress, is a form of distressed endurance behavior and task persistence that has been shown to lead to chronic pain, possibly via physical overload. There are, however, studies indicating that the opposite of ignoring and suppression, an in vivo exposure approach such as acceptance and mindfulness training, may be effective in pain patients.
Recovery Expectation
Recovery expectation is one of the strongest predictors of work outcome for patients with pain. Recovery expectations measured within weeks of new-onset of pain can identify people at risk of poor outcome. Expectation is a complex construct composed of numerous variables such as concerns about pain exacerbations, recurrent pain, financial security, support at work, and self-confidence. Practitioners may need to further inquire why patients have beliefs of delayed recovery and address specific concerns.
Using a combination of physical and psychological variables, feasible prediction tools have been developed in the United Kingdom and Sweden (Örebro Musculoskeletal Pain Questionnaire and STarT back screening tool) for return to work as primary outcome after a first office visit for low back pain (see Chapter 7).
CHRONIC PAIN MANAGEMENT
Chronic pain is a long-term condition that can always be managed and sometimes cured. The primary goal of therapy is generally management and coping rather than complete obliteration of the pain. Patients who have realistic expectations about pain treatment tend to have better outcomes than those that do not. Pain management programs are most effective when they emphasize self-management on the part of the patient and enhance the patient’s sense of self-efficacy and confidence in their ability to cope with pain.
It is important to monitor the effectiveness of a given pain management program in order to adjust and make changes as appropriate. Unlike acute pain, which can often adequately be measured using numerical rating scales or visual analog scales, chronic pain requires more complex measurement tools. In addition to aiming to decrease the experience of pain, chronic pain treatment must also be focused on the improvement of function. Functional improvement can be measured in terms of physical function, social function, or work function. Particularly when high risk or addictive substances are being used to control pain, it is critical that the prescriber have an objective measure to show that the strategy is in fact improving the patient’s function rather than diminishing it.
Examples of tools for measuring pain and its impact on function include the pain, enjoyment, and general activity (PEG) scale (Figure 11–2) or the brief pain inventory (Figure 11–3). In general, both pain and function should be assessed at the initiation of treatment and at regular intervals as treatment progresses.
Figure 11–2. The pain, enjoyment, and general activity (PEG) scale.
Figure 11–3. Brief pain inventory. (Reproduced with permission from the University of Texas MD Anderson Cancer Center, Department of Symptom Research, Houston, TX. Copyright ©1991 Charles S. Cleeland, PhD, Pain Research Group. All rights reserved.)
Because the suffering that arises from chronic pain can have its source in the physical sensations, emotions, thoughts and believes, or coping behaviors and their consequences; each of these domains needs to be addressed by a comprehensive pain management strategy. It is no surprise that multidisciplinary and multimodal approaches to chronic pain appear to be most effective. Treatment teams that include occupational therapists, physical therapists, psychotherapists, pharmacists, complementary medicine practitioners, and a physician, nurse practitioner, or physician’s assistant are likely to be most effective.
What follows is a brief review of treatment modalities that can be effective in chronic pain. No one modality can be expected to suffice for a given patient, and an optimal treatment strategy will combine therapies from multiple categories.
Pharmacologic Therapies
In general, medications can be expected to reduce pain scores by 20–50%, depending on the type of pain and the type of medication. They are rarely sufficient alone for the management of chronic pain.
See Table 11–1 for a description of common classes of medication used to treat chronic pain.
Table 11–1. Pharmacologic pain therapies.
In the last 15 years, it has become increasingly common to treat chronic pain with opioid medications. This is despite the absence of evidence for effectiveness with opioids beyond a 6-month period and consistent evidence that they do not improve function. Simultaneously, there has been a marked increase in the number of overdose deaths from prescription opioids and the incidence of prescription opioid addiction. For most patients, the risk of developing addiction to prescribed opioids remains low but real. In addition, some people with preexisting addictions present to care stating that they are in pain and, in an attempt to treat pain, the prescriber inadvertently contributes to the disease of addiction. In recent studies, up to 60% of patients prescribed opioids do not take them as prescribed. Some opioids that are prescribed for pain are given or sold to people to whom they are not prescribed, contributing significantly to the national epidemic of opioid overdose. For this reason, specific guidelines for safe opioid prescribing have been developed. These guidelines are designed to decrease the risk of overdose of opioid misuse and to assist the clinician in identifying signs a patient may be coming to harm from the medications. These guidelines include
1. Make a clear diagnosis for the cause of pain.
2. Use nonopioid pain treatments first, including non-pharmacologic approaches.
3. A benefit-to-harm evaluation should guide initiation of opioid therapy and should be re-evaluated throughout therapy. If ever harm appears to outweigh benefit, therapy should be discontinued.
4. All patients should receive informed consent about the risks of opioids.
5. For chronic pain, opioid therapy should be initiated as a 3-month trial, not as a long term commitment. If function and pain do not improve, or if there are signs of misuse, opioids should be discontinued.
6. At the initiation of therapy, measurable functional goals should be set by the patient and clinician.
7. The patient should be reassessed periodically with documentation of pain, function, and progress toward goals. If there is no improvement in these areas, opioids should not be continued.
8. Regular monitoring for aberrant behaviors, including urine drug testing, should be performed.
9. Patients at high risk for misuse, such as those with a history of substance use disorder or psychiatric illness, should be monitored more closely with frequent visits and urine drug tests.
10. Patients who display aberrant drug related behaviors, such as early refill requests or use of multiple prescribers, should be carefully assessed for appropriateness of continued prescribing. These may be signs that the prescription is contributing to psychological and social pathology, and should be discontinued.
11. Repeated dose escalations should also be reviewed for risk-benefit assessment. They may be a sign of opioid induced hyperalgesia, opioid nonresponsive pain, or opioid misuse.
12. Patients who engage in repeated aberrant drug related behaviors, drug abuse, or diversion, or who have no progress toward their goals should be weaned off of opioids.
13. Clinicians treating patients with opioids over time should also employ psychotherapeutic interventions and interdisciplinary therapy.
Standard of practice for chronic pain is moving away from monotherapy with opioids and toward a multimodal approach. The following sections describe nonpharmacologic pain treatment options that are recommended for patients with chronic pain.
Psychologically Based Therapies
Regardless of whether a particular patient’s pain has its source in psychosocial suffering, it will inevitably result in this type of suffering. For that reason, almost all patients with chronic pain benefit from psychosocial interventions. There is evidence that these therapies reduce pain intensity, improve function and quality of life, and reduce depression. What follows is an inexhaustive list of evidence-based psychosocial interventions for chronic pain. Which approach is the appropriate for a given patient may vary.
A. Self-Management Support
Chronic pain is in many ways analogous to other chronic illnesses. It can be expected to wax and wane in severity, and the degree to which a patient tolerates the illness is related to the degree to which the patient takes responsibility for managing it. Self-management support programs can take many different forms. Some programs take the form of classes that teach patients exercises, distraction techniques or mindfulness, muscle relaxation practices, and communication skills, while other programs involve coaches assigned to help patients manage pain at home, and others involve peer led support groups. Each of these models has been found to reduce pain and some of them improve function and decrease disability. The fundamental components of a self-management program include
• Medication management training
• Emotional management, including education about the role of anger and depression and strategies for managing difficult emotions
• Social support management, including communication training and strategies for maximizing social support
• Sleep management, including sleep hygiene training and discussion of the impact of sleep on pain
• Pain coping practices, including distraction, muscle relaxation, visualization, meditation, and breathing exercises
B. Cognitive Behavioral Therapy
There is significant overlap between cognitive behavioral therapy and self-management support programs. Often, the two occur simultaneously. Cognitive behavioral therapy (CBT) is based on the understanding that habitual thoughts and beliefs, or cognition, alter patients’ behaviors in ways that can either be productive or destructive. The goal of CBT is to help patients identify destructive thought patterns and learn to generate more constructive thought patterns. The focus of pain-based CBT will generally be on restructuring the patient’s relationship with pain from one of helpless victim to one of active agent, learning to use self-management skills such as pacing, relaxation and problem solving, and fostering self-confidence and hope. On a neurological level, CBT supports neural connectivity associated with improved cognitive executive control.
CBT can be provided in both group and individual settings. Group therapy has the advantage of providing social support to patients who are often socially isolated, and also increases access to programs by allowing clinicians to see multiple patients simultaneously. Individual therapy has the advantage of being more tailored to the patient’s specific needs and may be more appropriate for patients with significant co-occurring psychopathology.
C. Acceptance and Commitment Therapy
Acceptance and commitment therapy (ACT) is different from CBT in that it teaches acceptance and “just noticing” of one’s present situation, including pain and suffering. ACT teaches patients to disentangle the perception of pain from its accompanying thoughts and emotions but does not teach patients to attempt to control these thoughts and feelings. Distraction from pain is viewed as experiential avoidance and as maladaptive, whereas mindful discrimination of pain is considered adaptive. Improved psychological flexibility is then combined with goal setting and commitment to take action. ACT has shown efficacy in the treatment of chronic pain, addiction and anxiety disorders by reducing psychological risk factors for chronic pain: catastrophizing, fear-avoidance, and expectations of poor outcome.
D. Mindfulness Meditation
Mindfulness meditation has been adapted to and studied in the treatment of chronic pain since the 1980s. It has become a popular approach to chronic pain management not only because of its impact on pain, but because it also seems to address many patients’ more global, even existential forms of suffering. Mindfulness is characterized by a nonjudgmental compassionate awareness of the present moment. Patients who are trained in mindfulness learn to minimize the narrative and emotional overlay of pain and to just experience the physical sensations of pain as more neutral, discriminate, and less personally loaded physical sensations, rather than distracting themselves with unfocussed rumination. The goal is to learn to separate and create space between sensing pain and the emotional and mental reactivity that tends to follow and is usually the source of much of a person’s suffering. “Pain is part of life, suffering is optional.” In medical settings, mindfulness meditation is usually taught in the Mindfulness Based Stress Reduction (MBSR) format pioneered by Jon Kabat-Zinn. The MBSR format has been studied extensively and found to reduce pain intensity, increase physical activity, improve quality of life, and improve mood in patients with chronic pain. On the neurological level, MBSR-related neuroplasticity changes are associated with increased interoceptive awareness (insula activation), improved attention regulation and decreased rumination and cognitive-evaluative control.
E. Hypnotherapy and Guided Imagery
Hypnotherapy begins with the induction of a deep state of relaxation. Patients who are skilled in relaxation can induce this state themselves, or they can be guided into the state by a hypnotherapist. Once the relaxed state has been induced, the hypnotherapist speaks with the patient, providing useful suggestions to the patient’s own imagery, cognitive frameworks, or narratives to help the patient develop more productive behaviors or cognitions about their pain. For example, a patient with shoulder pain might be guided to feel the hand relax and become easeful, or to see the bones and muscles of the shoulder realign in a healthful, comfortable alignment. Patients are generally taught to induce these states for themselves so that they can become part of the patient’s self-management toolkit.
F. Biofeedback
Biofeedback refers to a variety of systems designed to give patients direct, visual feedback about internal physical processes. A device can be used to provide feedback about muscle tension in target muscles, heart rate, respiratory rate, temperature, or skin conductance. The goal is to develop an awareness of these more subtle interoceptive physiologic phenomena so that they come under direct voluntary control by the patient. Biofeedback can therefore help patients learn to relax both physically and psychologically and has been shown to be effective in the management of pain conditions, particularly chronic headaches.
Movement-Based Therapies
A. Physical and Occupational Therapy
It is beyond the scope of this chapter to describe physical and occupational therapies for each chronic pain condition. Broadly speaking, the goal of physical and occupational therapy for these patients is to teach them self-management skills and assist them in learning to function within the constraints of their limited abilities. The therapist working with chronic pain patients will find that overcoming fear-avoidance and catastrophizing cognitive patterns are of paramount importance. Gentle, playful, but persistent coaching and education are critical. In studies of physical therapy for patients with pain, physical therapy is generally as effective as or more effective than pharmacologic treatments for reducing pain scores, and is clearly superior at improving function.
B. Aerobic Exercise
Even absent a formal physical therapy program, engagement in regular physical activity is beneficial for patients with chronic pain. Exercise reduces chronic inflammation, improves mood, and improves strength and mobility. Patients who exercise regularly note decreased pain scores and increased sense of self-efficacy.
C. Tai Chi and Yoga
Both approaches have become very popular and are here jointly discussed, as both are essentially complex exercise interventions with a strong focus on postural correction and kinesthetic body awareness. The development of muscular strength, positive affect, reduced catastrophizing, and improved self-efficacy occur as products of these practices. Particularly yoga has been clinically studied in patients with chronic low back pain and is included in the guideline recommendations by the American Pain Society and American College of Physicians for its treatment. Yoga exercises may need to be individualized to the particular needs of patients, as some back pain patients may be constitutionally hypermobile and experience worsened pain with extreme postures or may have either flexion or extension-sensitive back pain. Tai chi has been found to be effective for fibromyalgia pain, presumably because it is gentle enough to be tolerated by patients with significant pain sensitivity.
D. Pacing
Along with strategies for enhancing mobility and strength, patients with chronic pain can benefit from learning to pace themselves appropriately. Because of the waxing and waning nature of chronic pain, most patients will find that they have days or moments in which they feel minimal pain and other times in which they have increased pain. It is common for patients to become less physically active during periods of pain, sometimes failing to get out of bed or spending entire days sitting down. Conversely, on days with less pain, patients will often overextend themselves, rushing to complete all of the tasks and errands that they failed to accomplish on previous days. Both behavior patterns can lead to increased pain, one through increased stiffness, weakness, and depression, the other through soreness, increased inflammation, and even injury.
Pacing techniques prevent these periods of over- or under-activity by teaching to measure out task in advance and planning the amount of time intended to spend on an activity. For example, the patient may plan in advance to spend 5 minutes on dishes, rest for 5 minutes, and restart the dishes again after rest. If a patient knows that 3 minutes of loading the laundry machine causes pain, one limits laundry to 2 minutes at a time with 3 minute breaks. Pacing can feel slow at first, but allows patients to remain active. Another pacing technique involves measuring one’s pain score before starting an activity and periodically checking the pain score throughout. If the pain score rises more than 2 points, the patient is instructed to pause and rest.
Interventional Therapies
Depending on the specific source of a patient’s pain, a wide variety of mechanical or surgical interventions may be available. Joint injections with steroids are effective for arthritis, and can be performed in most medium to large joints in the body. Trigger point injections, which target points of muscular tension and aim to release them with local anesthetics, can be helpful for patients with chronic myofascial pain. Anesthesiologists and physiatrists are able inactivate offending nerves with nerve blocks. If the patient’s pain can be tracked to a single nerve or nerve plexus, nerve ablation can sometimes be performed. For intractable pain, intrathecal medication pumps or neural stimulators implanted in the spinal cord may provide relief. Finally, for some conditions, such as advanced osteoarthritis, surgical removal and replacement of the painful joint is appropriate and highly effective.
Complementary Therapies
A. Acupuncture
A Cochrane meta-analysis found that acupuncture, the insertion and manual or electrical stimulation of thin needles (Gauge 30 and higher) inserted into specific, anatomically defined acu-points chosen according to diagnostic principals from traditional Chinese medicine (TCM), adds to other conventional therapies, relieves pain and improves function better than conventional therapies alone. However, effects are small and vary. TCM is an entire system of applications including acupuncture, moxibustion, massage, exercises, herbs, and verbal counseling. How it may work on a molecular, tissue, peripheral, and central neural level is the subject of numerous recent publications. Effects are strongest when in concordance with patient expectations. When self-management strategies for pain do not help, three to six sessions of acupuncture in addition to conventional treatments (PT, nonnarcotic pain medication) can provide a reasonable trial and clarify whether the patient will benefit. Licensed nonphysician acupuncturists have a much more extensive training than physicians who have taken shorter acupuncture courses.
B. Chiropractic Therapy and Osteopathic Manipulative Therapy
Manual therapy-trained physical therapists, chiropractors, and osteopaths are three professions which can apply a variety of mobilizing and manipulating techniques to patients with musculoskeletal pain summed up under the label of “manual therapy” or, if provided by physicians, “manual medicine.” They apply highly trained palpation skills to diagnose muscle, fascia, and joint dysfunctions and assess spine function on a segmental level. In addition to numerous soft tissue and gentle manipulation techniques, they may apply high-velocity, low-amplitude manipulation impulses to spine segments and individual facet joints. The physiological effects of such spinal manipulations have been documented as increased facet gapping in human MRI studies and as reduced paraspinal muscle spindle afferents in animal studies. A Cochrane review of over 40 RCTs concluded that spinal manipulation is more effective than sham manipulation or ineffective therapies, and equally effective as other conventional therapies. Other systematic reviews found no clear evidence of it being superior to other therapies or sham for patients with acute low back pain, while a large study in the British National Health System found effectiveness for pain, function, and costs above best primary care. Studies conducted by physical therapists in the United States found that spinal manipulation appears to be most effective in a subgroup of patients with a shorter duration of back pain (<16 days), segmental hypomobility, and low fear-avoidance behavior. The guidelines by the American Pain Society, the American College of Physicians, and the National Institute for Clinical Excellence in the United Kingdom recommend spinal manipulation for acute and chronic low back pain in patients who do not improve with self-care options. A large telephone survey in the United States reported that 27% of back and neck pain patients found conventional care “very helpful,” whereas 61% felt that way with chiropractic care. High-velocity spinal manipulation at the upper cervical spine, however, is a procedure requiring informed patient consent due to a small but undeniable stroke risk from vertebral artery dissection.
C. Massage Therapy
Massage is an ages-old therapy and uses a wide variety of techniques: compression, friction, gliding/stroking (effleurage), holding, kneading (petrissage), lifting, movement and mobilization, and vibration. Although not covered by health insurances, a 2010 Cochrane review of 13 RCTs found moderate evidence for low back pain and function compared with sham in short and long term, best when combined with exercise and education. Effects are larger if concordant with patient expectations. In a large 2003 telephone survey, 65% of queried US back pain patients reported that massage was “very helpful” for neck and back pain. A meta-analysis of a variety of outcomes from massage therapy studies found that massage therapy provided by far the largest effect size for a reduction in trait anxiety. The effect on pain may, at least in part, be mediated by a reduction in catastrophizing, one of the key psychological factors associated with duration and intensity of chronic pain. On a cellular and tissue level, massage has been studied for its effect on muscular pain caused by exhaustive muscular activity, which may be applicable to specific occupational settings: massage was found to improve mitochondrial biogenesis signaling and to decrease cellular stress from myofiber injury by mitigating the production of pro-inflammatory TNF-α + IL-6 and heat shock protein 27 phosphorylation.
Mind-Body Therapies
Mind-body therapies are predicated on the understanding that mental processes impact the physical body and vice versa. Because the mind-body distinction is so clearly blurred in chronic pain, these therapies have been accepted into the mainstream of chronic pain treatment and are therefore discussed above in the section on psychologically based therapies.
Herbs & Supplements
In general, botanical therapies and nutritional supplements have not been studied as extensively as pharmacologic therapies for pain. On the other hand, many patients prefer these forms of treatment, not only because they may notice fewer side effects but because they tend to be less pathologizing for patients. Patients who take medications often see the medications as a sign of weakness or failure, whereas patients taking herbs and supplements seem to relate to them more as sources of strength and symbols of self-efficacy. So despite having less clarity about efficacy, many patients and providers prefer these therapeutic options. Common herbs and supplements used for pain are listed in Table 11–2.
Table 11–2. Common herbs and supplements used for pain.
Nutrition
Many diets are purported to have a positive impact on pain, but few have been studied sufficiently to recommend to patients. Elimination diets, in which common allergens are systematically eliminated and correlated with changes in clinical status, are frequently used for pain but not well studied. One dietary pattern supported by research is the anti-inflammatory diet. This diet appears to be useful and may be tried in inflammatory pain conditions such as rheumatoid arthritis and possibly osteoarthritis, particularly in patients motivated to make lifestyle changes. It is characterized by high vegetable, whole grain, fish, and polyunsaturated fat intake, low refined grain intake, and little to no meat or dairy.
MULTIMODAL APPROACH
Each of the above therapeutic categories addresses a different aspect of the human pain experience. Practitioners can be most effective when they design a treatment plan to impact each of those areas, particularly in cases where the physical source of pain cannot be determined or removed. This multimodal approach to pain often involves the engagement of an interdisciplinary team that either sees patients together or discusses cases regularly to generate a shared care plan. Regardless of the model, occupational medicine specialists, with their unique focus on patient function, are key members of the team.
REFERENCES
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SELF-ASSESSMENT QUESTIONS
Select the one correct answer to each question.
Question 1: Pain
a. regulation is neurologically distinct from emotion regulation
b. erases the felt aspects of emotions
c. includes a strong behavioral drive toward homeostasis
d. is unlike suffering from unpleasant emotions
Question 2: Chronic pain
a. is associated with an increase in brain matter density
b. is associated with an increase in negative neural connectivity of insula to prefrontal and thalamic regions
c. does not impair cognitive control
d. circuits develop a hypersensitive state, with pain itself being a pain predictive conditioning cue
Question 3: Opioid pain medications
a. are particularly effective for chronic pain
b. are both rewarding and behaviorally reinforcing
c. never become difficult for patients to control
d. neurologically lead to a transition from striatal to prefrontal cortical control over drug
Question 4: Depression
a. is more common in chronic pain patients than in healthy controls
b. is frequently diagnosed and overtreated in pain patients
c. is typically an antecedent of chronic pain
d. is unrelated to pain chronification
Question 5: Pharmacologic treatments for chronic pain
a. generally reduce pain scores by 80–100%
b. are usually sufficient on their own
c. are usually most effective when combined with other treatment strategies
d. rarely have side effects
Question 6: Cognitive behavioral therapy (CBT)
a. is the same as self-management support programs
b. alters patients’ behaviors whether productive or destructive
c. helps patients identify destructive thought patterns and learn to generate more constructive thought patterns
d. restructures the patient’s relationship with coworkers
Question 7: Pacing is
a. a technique for preventing patients from being overactive or underactive
b. a technique for teaching patients to remain constantly active without pause
c. a technique for getting things done more quickly
d. a technique for explaining to other people what it feels like to have chronic pain