Chronic Noncancer Pain Basics for the Primary Care Physician
Chronic Noncancer Pain Basics for the Primary Care Physician
Author: J. David Sinclair, MD, FRCP(C), East Side Pain Management, Mercer Island, Wash.
Editor’s Note—With the formation of the American Pain Society (APS) Managed Care Task Force in 1997, the problem of pain management immediately identified was the lack of pain education received by primary care providers (PCPs) and medical directors.1 Chronic pain management will be reviewed and discussed as a medical problem—the rational treatment of which always falls within the domains of more than one therapeutic discipline.
The History of Pain
As the records of every race are examined, there will be found testimonials to the omnipresence of pain. Prayer, exorcisms, and incantations speaking to the prevalence and scourge of pain are found on Babylonian clay tablets, in papyri associated with the days of pyramid builders, in Persian leathern documents, and in inscriptions from Mycenae on parchment scrolls from Troy. Such records continue down through the ages in every civilization and culture.2 There is reason to believe that pain is inherent in any life linked with consciousness.
Primitive concepts linked pain with the intrusion of magic fluids, evil spirits, or pain demons. The Egyptians believed painful afflictions (other than wounds) were caused by the gods or spirits of the dead entering through nostril or ear in the night. Routes of departure would be vomit, urine, sneeze, or sweat. Concepts of pain in India attributed the universality of pain in life to the frustration of desires. Buddhist and Hindu thought attached much more significance to the emotional level of experience. In the Chinese canon of medicine, the 2 opposing unifying forces—the Yin and the Yang—are in balance to assist the flow of the vital energy Chi. Deficiency or excess of the Chi causes imbalance of the 2 forces and results in disease and pain. Ancient Greeks were intensely interested in the nature of sensory data. Hippocrates contended that the deficiency or excess of one of the 4 humors answered the question of the source of pain. Plato believed that sensation resulted from movement of circulating atoms, and Aristotle distinguished the 5 senses. After Aristotle’s death, Straton of Greece and later Herophilus and Erasistratus of Alexandria provided anatomic evidence that the brain was part of the nervous system and that nerves were of 2 kinds for movement and for feeling.
Then for nearly 4 centuries, this work was lost to the Roman world until rescued and developed to a high level of anatomic sophistication by Galen in the first century. Despite Galen’s great contributions, Aristotelian concepts of the 5 senses and pain as a passion of the soul persisted for 23 centuries.
In the Middle Ages, the center of medicine shifted to Arabia, where Avicenna distinguished external senses and internal senses locating the latter in cerebral ventricles. He treated pain with exercise, heat, and massage in addition to opium and other natural drugs.
The Renaissance fostered the scientific spirit but there was no advance in pain therapy. It was in the seventeenth century when Descartes, William Harvey’s contemporary, described the results of his extensive anatomical studies and established the precursor of the specificity theory that was introduced 2 centuries later.3
The eighteenth century saw the beginning of the new era of analgesia with Joseph Priestly’s discovery of nitrous oxide and the subsequent observation made by Sir Humphrey Davy of the analgesic properties of this gas.
In the nineteenth century, physiology emerged as an experimental science leading to significant advances in pain theory and leading to twentieth century theories of pain, which in 1965 culminated in Melzack and Wall propounding the gate-control theory of pain. Since its publication, this theoretical construct has been the twentieth century’s springboard into the millennium for prodigious volumes of fruitful new research into pain.4,5
Pain Medicine
The specialty of pain medicine is concerned with the prevention, evaluation, diagnosis, treatment, and rehabilitative needs associated with painful disorders. Pain medicine has a defined body of knowledge and scope of practice and is recognized as a discreet specialty by the American Medical Association (AMA).
Pain as a subject for intellectual endeavor independent of the pathology that was its underpinning began with the invention of pain medicine. This invention was the brainchild of John Bonica, whose work in this area began to take root in the early 1960s. His efforts were infused with the momentum in pain research, which was stimulated by Melzack and Wall’s gate-control theory of pain.6
Central to the development of pain medicine as an independent area for clinical and research activity was the awareness that acute pain and chronic pain were in many important ways neurobiologically distinct phenomena. This phenomenological difference imposed a responsibility on clinicians to learn to think outside the box. The management of chronic pain, which had had to fit into an acute pain model, was now liberated into a new world of pain.
Clinicians and basic science researchers in medicine and nursing, neurobiology, pharmacology, physiology, psychiatry, psychology, and social science populate the new world of chronic pain evaluation and management (E&M). In addition to its obvious significance to patients, chronic pain E&M, because of its enormous monetary implications, is of major significance to industry, government, lawyers, pharmaceutical manufacturers, insurance companies, and hospital administrators.7
Chronic pain patient advocacy groups have developed strong social and political voices. Departments of Health, State Boards of Medical Examiners, State Medical Associations, and Labor and Industry collaborate on establishing guidelines for the education about and the use of opioids in noncancer chronic pain. The Agency for Health Care Policy and Research (AHCPR) has established low back, acute, and cancer pain guidelines for treatment. Complementary/Alternative Medicine (CAM) advocates speak to chronic pain concerns from their perspective. The Commission for Accreditation of Rehabilitation Facilities (CARF) reviewed its pain standards and renamed them the CARF Interdisciplinary Pain Rehabilitation Program Standards. They were implemented in 1999. In recent months, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) has established Pain Assessment and Management Guidelines.8 The Americans with Disabilities Act (ADA) has implications in regard to the notion of pain as disability.9 Last, but easily not least, the fifth edition (2001) of the AMA Guides to the Evaluation of Permanent Impairment has completely revised the chapter on pain. It now includes a method for evaluating impairment due to chronic pain and a description of how the method can be integrated with the impairment rating methods used in other chapters.10
This report will address and attempt to provide a roadmap through the changing and sometimes bewildering landscape of chronic noncancer pain management.
The International Association for the Study of Pain (IASP) has defined pain as: an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage. Recently, that definition has been expanded to accommodate the notion that the paining person may not be able to verbalize his or her pain.
Important in the reading and full understanding of this definition are several phrases.
1) ". . .sensory and emotional. . ." The experience of pain is always both sensory and emotional. In the mind of the individual, the perception is assigned a meaning that represents a threat that soon becomes assigned significance in disease terms;11 2) ". . .associated with actual. . .tissue damage. . ." This is clearly understood in the case of an acute injury or painful organ system illness, but note: 3) ". . .or potential tissue damage. . ." In this phrase, "potential" has the meaning of with the capacity to be as in the pain experienced before a tibia, fixed at one end and rotating at the other actually breaks. Of special significance is the connotation of stored in the meaning of "potential." The physics sense of potential energy is stored energy. The phrase "potential tissue damage" reflects the notion that our tissue damaging experiences have been stored in our minds at a level below awareness and are available for conscious re-experience under circumstances of threat; 4) ". . .or described in terms of such damage" points to the influence of language in the experience of pain. Consider the words we commonly use to describe the experience of pain: burning, stabbing, ripping, tearing, searing, exploding, twisting grinding pounding, crushing. From the moment in our lives when we become verbal, we are trained by language to know with robust, albeit benighted, assurance that we do not experience pain unless we are in some way physically damaged. This verbal association carries significant implications for the treatment of chronic noncancer pain in a person who either has no damage or the damage has been successfully addressed at an anatomical level or has spontaneously healed. As Ogden Nash so insightfully quipped, "Sticks and stones may break my bones but words will damn near kill me."
Donald D. Price, in Psychological Mechanisms of Pain and Analgesia, contends that the IASP definition is confusing and not experiential enough.12 He proposes pain is "a somatic perception containing: 1) a bodily sensation with qualities like those reported during tissue damaging stimulation; 2) an experienced threat associated with this sensation; and 3) a feeling of unpleasantness or other negative emotion based on this experience of threat.
Our cultural assumptions about pain being an indicator for damage drives many chronic pain patients on fruitless, expensive, counter-therapeutic, 9-year expeditions in search of the cure.6 These expeditions are usually outfitted by physicians.
Failing to accept a management approach to a chronic pain problem dooms the patient to treatment failure as surely as failing to observe diet, tobacco, alcohol, and physical fitness recommendations dooms patients with hypertension, cardiac failure, and diabetes to failed or inadequate recovery.
There seems to be no doubt that, in the past, cancer pain has suffered less than optimal management. Chronic noncancer pain may indeed be badly managed in our society, and there is a need for funding and support of chronic pain treatment facilities and education. Our current societal outcry that doctors are failing to adequately treat, nay, are withholding known good treatment from sufferers of noncancer chronic pain is a disturbing reflection of the cultural bias that we can take a pill to fix a complex biopsychosocial problem. At best, such an outcry is supported by individuals who demand the quick fix and fail to accept that the only truly successful therapies for this problem rest on a foundation of self-management. At worst, it is driven by interests devoted to a movement toward liberalization of opioids and marijuana that would ride on the coattails of successful and appropriate cancer pain-control initiatives. While good chronic pain strategies may indeed include the use of analgesics including opioids, analgesics will never be the foundation of treatment. Analgesics remain an adjunctive element to the basic requirements of pain rehabilitation.
Introductory Neurophysiology of Pain
No particular stimulus is painful. Whether a stimulus will be perceived as painful depends on all of: the nature of the stimulus, the situation in which it is experienced, memories, present emotions, and assigned meaning (which predict the future).13 There are no pain fibers and no pain pathways in the brain. Pain is a complex perception that has profound emotional meaning and cognitive significance.
In cross-section, a mixed peripheral nerve can be imagined to be like a coaxial cable. The cross-section reveals axons in several diameter—some myelinated and some not. The axons can be grouped into distinct populations in descending diameter: A-alpha, A-delta, and C. Each group has its characteristic conduction velocity; the slowest being the narrowest and unmyelinated C fiber.
The weight of evidence suggests that nociceptive (potentially ultimately painful) input travels on the small unmyelinated C, and small myelinated A-delta fibers. Unmyelinated primary afferents (going to the spinal cord) contain a variety of neuroactive substances, especially glutamate, in vesicles. These substances are released by high-intensity peripheral stimulation. Nociception responsive receptors in the dorsal horn of the spinal cord respond to these neuroactive substances. C-fiber terminals also contain neuroactive peptides capable of enhancing glutamate activity and thereby contributing to long-term changes in dorsal horn neurons.
Morphological and biochemical changes occur in the central nervous system (CNS) following peripheral nerve injury. Non-pain fibers send sprouts into receptive areas where ordinarily only pain fibers would send their stimuli. Pain producing chemicals of the neurokinin class accumulate in spinal cord dorsal horn locations where ordinary stimuli can now release them. Nitric oxide (NO) produced by injury-related changes may excite or disinhibit central neurons. Second messenger systems activated by the chemicals glutamate and aspartate already residing in the neurons may change membrane excitability. Massive release of glutamate triggered by trauma may result in the death of inhibitory interneurons producing a hyperalgesic state. Endogenous opioid precursor increase may reduce hyperalgesia, as does the alpha-adrenergic agonist clonidine.
Cell systems in the dorsal horn respond variably to mechanical, heat, and nociceptive inputs. In addition, their response is plastic; ie, variable under dynamic influences that alter input-output relationships (the traffic through that neurobiochemical corridor). (See Figure 1.)
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This plasticity is manifest in virtually all-measurable evidence of spinal cord function. The phenomena of spontaneous pain, hyperalgesia, and allodynia are known to be due to injury-induced hyperactivity of these cell systems in the dorsal horn.14
Attributes of consciousness contribute ultimately to the expression of the state of paining. Depression, anxiety, euphoria, expectation, and other components of consciousness are known to influence how we experience any stimulus including those that can result in pain.
The complexities of the systems subtending consciousness are currently beyond human comprehension.15 The actions of the opiates, long known to change the affective component of nociception may have a part to play in elucidation of consciousness’ underlying pathways. Clearly one of the frontiers for advances in the understanding of pain and therefore pain pharmacology is the elucidation of the mechanisms underlying the role of the higher order (cerebral/conscious) processing of pain.
In the past 15 years, several new pathways and brain regions have been discovered. Their understanding holds promise of being important to various aspects of pain processing. They include spine to thalamus, spine to pontine, and amygdala pathways as well as the amygdala, cingulate cortex, retrosplenial granular cortex, and caudate putamen complex.
Spinothalamic activation of arcuate nucleus and spino ponto amygdaloid activation of amygdala may modulate pain, stress, and emotional reactions related to pain. Activation of amygdala, cingulate cortex, and retrosplenial granular cortex may be related to the immediate unpleasantness stage and/or the suffering associated with prolonged pain states. The caudate putamen complex may be related to pain modulation and/or abnormal motor activity seen in patients with neuropathic pain disorders.16
Neurophysiologic changes occur in chronic pain states, ie, chronic pain is not just acute pain that persists. These changes result in: 1) "wind up" or increasing responsiveness to repeated identical stimuli; 2) after-discharge or prolonged impulse discharges that long outlast the initial response to the nociceptive stimulus; and 3) expanded receptive field, ie, a response-altered group of neurons may respond to neuronal activity in nearby neurons that are stimulated from a body area unrelated to or remote from the body area causing the original pain.
The observations described above have significant implications insofar as they affect our understanding of the fact that acute and chronic pain are 2 different animals. The cartoons of Melzack and Wall’s gate-control theory of pain are a helpful summary of how some of these phenomena can begin to be conceptualized. (See Figures 2 and 3.)
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Psychological Considerations
The most universal form of stress is pain. No other physical symptom is more pervasive. Traditional views of pain as either directly associated with physical pathology or psychologically based have proven to be inadequate. Some observations that are illustrative of the either/or fallacy are:
• Patients with objectively determined equivalent degrees and types of tissue pathology vary widely in their reports of pain severity;
• Asymptomatic individuals often reveal radiographic evidence of structural abnormalities;
• Patients with minimal objective physical pathology often complain of intense pain;
• Surgical procedures designed to inhibit symptoms by severing neurological pathways believed to subserve the reported pain may fail to alleviate the complaint;
• Patients with objectively equivalent degrees of tissue pathology treated with identical interventions respond in widely disparate ways;
• Prospective studies have linked job satisfaction to future pain reports;
• You don’t need a body to experience a body;
• A chronic pain study at Wright State University Medical School in a family practice setting has found that nearly two thirds of participants have borderline personality disorder (BPD) according to a highly structured (DSM-IV validated) interview;
• An assessment using the Million Clinical Multaxial Inventory of patients awaiting admission to an outpatient chronic pain treatment program revealed that 66% of subjects were diagnosed with a personality disorder;
• 30-50% of people who seek treatment in primary care do not have specific diagnosable disorders and for up to 80% of people complaining of back pain, no anatomical basis for pain can be found;
• Physicians treating these patients should be aware of the maladaptive personality types they will frequently encounter.
A 1993 study assessed 200 patients with chronic low back pain (pain disability present for longer than 1 year) for both current and lifetime psychiatric syndromes.17 Results revealed that even when the somewhat controversial category of somatoform pain disorder is excluded, 77% of patients met lifetime diagnostic criteria and 59% demonstrated current symptoms of at least 1 psychiatric diagnosis. In addition, 51% met criteria for at least 1 personality disorder.
More important was the finding that those patients with a positive lifetime history for psychiatric syndromes (54% of those with major depression and 94% of those with anxiety disorders) had experienced these syndromes before the onset of their back pain. Clearly some psychiatric syndromes appear to precede chronic low back pain (substance abuse and anxiety disorders) whereas others, specifically major depression, develop before or after the onset of the back pain.
Richard Sternbach outlines the interpersonal description of pain.18 He describes pain transactions following the work of Berne19 in clinically illuminating fashion with no assumptions that the patient is aware of the game aspect of what he or she is doing or that the motives are conscious. In his case illustrations of 1) The Basic Pain Game; 2) The Home Tyrant; 3) The Professional; 4) The Addict; 5) The Somatizer; and 6) The Confounder, Sternbach offers a serious and helpful perspective on patient that PCPs meet when they treat chronic noncancer pain.
When people have pain and they have been asked to see a psychologist they may disdain the idea on the basis of feeling that their pain is being trivialized or that their doctor thinks them to be a "head case." The truth is that pain management without psychological management is impoverished pain management. A doctor’s referral to a psychologist is evidence that the physician understands that pain can interfere with all parts of a person’s life. As noted above, pain creates stress. It is important to work in pain management with the whole person, not just the part that has pain. After all, it is the person (not the elbow, back, or shoulder, etc) that is suffering.
Because the psychological parts of chronic pain are always of some degree of importance and because many patients may resist that notion, the physician may have to "sell" the idea. It is important for patients to know that neither is the physician abandoning them to the psychologist nor is he or she asking them to believe that psychological treatments are going to make them all better. They also need to know that the physician does not think that they are mentally ill and that the psychologist will not be probing for descriptions of their growing up years. They need help to understand how the new information, skills, and problem solving assistance they will receive will speed their recovery. When the physician is supportive of the importance of involving a psychologist, it paves the way for successful psychological and subsequent medical and rehabilitation interventions. Patients need to be advised that their work with the psychologist will result in improved coping with negative feelings like frustration and depression improved ability to relate with people who don’t understand their problem. They will have the opportunity to learn relaxation techniques to control muscle spasms and pain and be better able to adjust to lifestyle changes that resulted from the pain problem.
Office Evaluation of the Chronic Noncancer Pain Patient
Pain is a ubiquitous symptom that is essential for survival.20 It will come as no surprise to a PCP that pain has been identified, second to respiratory infections, as the most common reason for seeking medical care. Chronic and acute recurrent pain is the presenting symptom in more than 80 million office visits to physicians each year.6 And the costs of chronic pain have been estimated to exceed $125 billion.
Office evaluation of this complex experience can be a daunting task in the sociomedical context that expects physicians to make complete and accurate assessments, then opine and prescribe definitively (with patient expectation of a quick cure) in a matter of minutes.21
The ballooning literature on chronic pain and the social pressures for better pain management might mislead the conscientious PCP into a belief that assessment and management of chronic pain is becoming an arcane practice accessible only to the pain cognoscente. This is not the case. Various national and international surveys indicate that between 11% and 30% of the population deems itself to be suffering from some form of chronic pain.22 Primary care management provides good results for all but 2-3% of that group, who will need to be referred for special pain care. Assessment and management of chronic pain is not rocket science. It is an ineluctable primary care endeavor that adheres to the time-tested format of 1) history taking; 2) physical examination; 3) laboratory investigation; and 4) treatment that has sustained medicine through many epochs of clinical practice.
As the late Janet G. Travell, co-author of the Myofascial Trigger Point Manual23 was fond of saying, "The mystery’s in the history."24 History taking in the context of chronic noncancer pain is the most elegant of diagnostic tools. History taking with a chronic pain patient usually requires a shift in historical emphasis away from anatomical events toward social and environmental circumstances in which the anatomical aspects have become embedded.25,26 An understanding of the patient’s belief system about body function and medications will often uncover erroneous information and maladaptive ideation and behaviors surrounding activity and medication use.
Physical examination of the chronic pain patient can be frustrated by pain behaviors that interfere with some or all aspects of the evaluation. Regardless, a good evaluation can be accomplished within those limitations. In fact, pain behavior can inform the examiner when special tests during a physical examination that take that behavior and run with it are incorporated into the evaluation.27
Particularly useful in these examinations are the methods described in the Stanley Hoppenfeld book, Physical Examination of the Spine and Extremities, Appleton-Century Crofts, 1976.
Laboratory investigation is more often than not fruitless. That observation notwithstanding, good practice, to say nothing of our anxious medico-legal atmosphere, imposes on physicians the need to establish baseline data from a variety of investigations. These investigations may ordinarily include panels of blood work, urinalysis and x-ray, MRI, bone scan and EMG and nerve conduction tests. Other investigation as deemed appropriate to the specific patient may round out ones understanding of the problem and will provide the basis for a well worked-up referral to a pain specialist or clinic should that become necessary.
The major difficulty many PCPs will encounter in evaluating the chronic pain patient will be the difficulty of getting beyond the bias [of viewing] persistent pain exclusively as a symptom of an objectively verifiable somatic injury or disease.
The tendency to focus exclusively on the 2 possibilities 1) that the patient has an undiagnosed somatic disease; or 2) that she or he has a severe form of a correctly diagnosed disease that has not responded to conventional therapy leads to extensive diagnostic studies aimed at finding a somatic source of pain. The [medical model] therapeutic approaches we develop to such patients reflect a desperation and somatic pre-occupation that is communicated to the patient who in turn is already somatic cause avid.25 This communication too often propels the patient to yet another treating physician "[usually] a specialist who is challenged to do further testing and usually obliges."28
Therapeutic Approaches to Chronic Noncancer Pain
Analgesics and Adjuvants
Three types of analgesic medications are available: 1) non-opioids including aspirin, other nonsteroidal and anti-inflammatory drugs (NSAIDs), and acetaminophen; 2) opioids; and 3) some drugs not usually thought of as analgesics, which act as adjuvants when given with NSAIDs or opioids or have analgesic activity of their own in some types of pain.29
With increasing doses, acetaminophen, aspirin, and the other NSAIDs all reach a ceiling for their maximum analgesic effect. Acetaminophen is as effective as aspirin but does not have the adverse effects characteristic of aspirin. Some patients (namely, alcoholics, patients who are fasting and those taking cytochrome P-450 enzyme-inducing drugs) concurrently may develop hepatic injury after moderate overdose or even high therapeutic doses of acetaminophen.30
In single full doses, most NSAIDs are more effective than full doses of aspirin or acetaminophen and some can equal or exceed the analgesic effect of usual doses of oral narcotics combination products, or even injected opioids. Whether this is also true in repeated doses, in chronic pain it is not well established and chronic administration of NSAIDs can cause major adverse effects. Some patients may respond better to one NSAID than another and NSAIDs have an additive effect that permits use of lower doses of opioids in some situations.
The adverse effects of all NSAIDs are qualitatively similar to those of aspirin. The inhibition of platelet aggregation, unlike aspirin, wears off when most of the drug has been eliminated. The NSAID decrease in renal vasodilator prostaglandins and the decrease in renal blood flow cause fluid retention and may cause renal failure in some patients.
Cyclooxygenase 2 (COX 2) selective inhibitors are said not to disrupt the homeostatic or regulatory organ and tissue actions of prostaglandins and thromboxane on blood vessels, platelets, stomach, and kidney.31 They appear to cause less GI toxicity than nonselective NSAIDs. They do not inhibit platelet aggregation or increase bleeding time and they may have a prothrombotic effect. Other adverse effects are similar to those of nonselective NSAIDs.29 The ghost of the parent molecule roams within these improved agents. Prudence would indicate the value of routine baseline and subsequent organ system function evaluation with kidney and liver function tests as well as routine hematological and urine testing. Regularly monitored, the use of these new agents can be a boon to the arthritic chronic pain segment of a PCP’s patient population.
Opioid use in chronic noncancer pain is an acceptable gambit under carefully evaluated and monitored circumstances. The literature is replete with clinical trials reflecting the value and safety of opioid use beyond its traditional and acknowledged essential role in the management of severe acute pain and cancer pain. These studies need to be challenged from the points of view that they reflect a certain selection bias in terms of participants, and that although the studies may be prospective in design, they are not longitudinal studies that would reflect the reality of a PCP’s practice.
Opioid dose requirements vary widely from one patient to another. The usual dose may be inadequate for a given pain problem. Full agonist opioids unlike NSAIDs generally have no ceiling for their analgesic effectiveness.
The selection of appropriate analgesic medication can be difficult, and pain may not be adequately reduced with strong opioids alone. Adjuvant analgesics’ use resides in the fact of there being many different neurotransmitters and receptors involved in pain.32 Many potential targets for medication therapy exist. Adjuvants, while not typically thought of as having analgesic properties are helpful in maximizing pain control and lowering the required dosage of opioids; moreover they can be used in combination with acetaminophen and non-steroidal therapies.
Antidepressants and anticonvulsants are the mainstay of therapy in a variety of neuropathic pain syndromes that, compared with somatic pain, may be less responsive to opioids. These medications can reduce the burning quality of neuropathic pain. Tricyclic antidepressants when tolerated in doses between 75 and 200 mgm per day relieve pain in 55-67% of patients.
The use of the selective serotonin reuptake inhibitors (SSRIs) can reduce neuropathic pain by 70-80%.
Anticonvulsant medications are useful in the treatment of neuropathic pain. Tegretol has well-established efficacy in trigeminal neuralgia. Gabapentin (Neurontin) has demonstrated efficacy in patients with postherpetic neuralgia. Doses beyond 1800 mgm are not generally effective but doses up to 3600 mgm divided throughout the day or taken as a single bedtime dose may be necessary. Neurontin has become an important addition to the migraine prophylaxis armamentarium.
N-methyl-D-aspartate (NMDA) receptors in the spinal cord dorsal horn neurons reduce their "wind-up" firing under the influence of NMDA receptor antagonists. Dextromethorphan and ketamine are examples of these agents. Dextromethorphan is available as a cough suppressant capsule and may be useful in doses of 120 to 960 mgm per day. Drowsiness and other adverse effects have limited the clinical application of NMDA antagonists.
Tramadol (Ultram) is a weak agonist for all opioid receptors but it also inhibits norepinephrine reuptake and stimulates release of serotonin. In clinical trials involving patients suffering from chronic pain, tramadol was found to be no more effective than acetaminophen and codeine combinations. Tramadol is free of acetaminophen and NSAID adverse effects on organ systems and may have a place in the treatment of patients with osteoarthritis, neuropathic pain, low back pain, or postsurgical joint replacement.
The use of nontraditional nonprescription preparations has increased to the extent that in 1997, 42% of Americans reported using alternative medications in the previous year. One of the most publicized products is glucosamine. A dose of 500 mgm of glucosamine 3 times daily was better than placebo in reducing pain, morning stiffness improving mobility, and general activity. As an adjunct therapy for osteoarthritis it is worth considering when traditional therapy fails.
Because the Federal Drug Administration (FDA) has no regulatory authority over the manufacturing processes used in the natural or "phytoceutical" industry, the use of herbal remedies is not without hazard. Moreover reports of drug interactions reflects a growing list of potential serious problems within the natural groups and between over-the-counter (OTC) and prescribed medications in combination with "natural" products.33
Nerve Blocks and Neurolysis
Diagnostic nerve blocks may be useful in delineating the pain problem.34 Whether this use can be validated is moot.35 (See Figure 4.) Intra-articular steroid injections of lumbar and cervical zygopophyseal (facet) joints lack evidence of effective sustained outcome. The more precise medial branch (of posterior division of dorsal ramus of nerve root) block followed by radiofrequency lesioning (electrocoagulation) appears to have strong evidence of long-term efficacy.
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Epidural corticosteroid injections are frequently used with the aim of reducing inflammation and edema around the nerve root. The indications for and the efficacy of this treatment continue to be debated.
Neural blockade can be useful for facilitating rehabilitation; however, the evidence is weak for other than short-term benefit. In behaviorally based rehabilitation programs nerve blocks may be counter therapeutic if they are not integrated into a comprehensive multimodal program that actively discourages dependency on passive treatments and the equally undesirable notion of "something in there that hasn’t been fixed yet."
Sympathetic plexus blocks have potential diagnostic and therapeutic value for patients with chronic pain by 1) blocking visceral fibers; 2) interrupting interaction between sympathetic nervous system and ordinary "pain" fibers; 3) producing vasodilation for relief of ischemia and facilitation of healing; and 4) relief of ischemic pain.
Neurolytic blocks are nerve blocks that destroy tissue and are not the initial treatment for noncancer chronic pain.
There are technologically elegant approaches that are relatively new. They include 1) intrathecal catheter insertion for attachment to a programmable pump for continuous infusion of opioid or other medication; 2) spinal cord stimulators (SCSs); and 3) intradiscal electrothermal coagulation (IDET). Each of these has its indications and champions, the latter far outnumbering the former. However, the jury is still out insofar as knowing to what extent these therapies, on balance, promote the well-being of the complicated chronic noncancer pain patient.
Nonpharmacological Therapies
Pain management includes general health management with specific attention to abnormal weight, sleep disturbance, cardio-pulmonary risk reduction, and avoidance of harmful habits such as tobacco, alcohol, and street drug use. Nicotine is associated with increased pain and it decreases the effectiveness of antidepressants by reducing their plasma concentration.
The goal of pain management is to reduce pain while improving function, sleep, mood, and reconditioning. Pain levels do not significantly improve until the patient has begun reconditioning and has increased his or her level of daily activity.
Physical Therapy (PT). Acute pain modalities and hands-on approaches to PT must be shunned. Reconditioning activities from a deactivated state require active range of motion (AROM) and flexibility and strength training. Ideally, these are begun at a level in keeping with a patient’s pre-test performance and progress gradually on the basis of weekly goals based on the pre-test and made clear to the patient at the outset.
Occupational Therapy (OT). Job tasks and household chores are less likely to provoke pain with the use of proper postures and body mechanics. Many chronic pain patients have some deficiencies in their awareness of where their bodies are in space.36 Tracking of patient performance through videotaped records of body mechanics and pain behaviors can be informing and therapeutically useful to patients. They can "see" their improvement. Reproduction of work tasks within a pain program setting is sometimes a key ingredient to successful re-entry to the work place. In addition, OT can perform on site work place analyses in support of the patient’s need for job site modification.
Multidisciplinary Pain Clinics (MPCs). For a PCP to orchestrate appropriate therapies for the complex chronic pain patient, although feasible, would be an onerous responsibility. More importantly, the endeavor would likely result in the perpetuation of "a little bit here; a little bit there" or stacked therapy. When not integrated with each other, good therapies for complex problems lose therapeutic power and are not likely to be beneficial.
In the situation in which a patient’s complex chronic pain experiences and circumstances have not shown signs of yielding to motivation (persuasion), medication, and self-directed rehabilitation efforts, it is probably because the patient has not yet been able to make the attitudinal adjustment that is required to be a successful manager of his or her pain. In this case, the patient may need to be involved in a clinic setting. Not only will the full array of therapies and personnel be available for achieving physical rehabilitative goals, the setting will provide a venue for patient and family education. Learning about the nature of chronic pain, its reasons for being when "there’s nothing wrong" are critical. Learning how to manage to live a full life in a situation where there is no cure requires a big psychological effort for most people. The clinic setting can provide the patient with the intense therapeutic exposure that is needed to make the essential adjustment from an "acute pain" belief system to a new understanding of what is required for independence from endless, unhelpful, passive strategies.
Chronic pain patients need to know that the pain won’t change usefully until they improve their function. This idea is counter-intuitive to most chronic pain patients; consequently they need to be motivated to work ahead with treatment despite residual pain. They need to come to grips with the understanding that chronic pain may not entirely resolve and that medication may not be a long-term strategy. In some circumstances, significant others need to learn about ways that their relationship with the patient can be delaying evidence of improvement. The relationship may be enabling or codependent. Significant others can benefit from becoming aware of the extent to which their involvement in the problem may be counter-productive to achieving a positive result.
Psychology. Promoting psychological adjustment is an essential ingredient of the nonpharmacological management of chronic pain. Insofar as the persuasive abilities of a PCP can be imbued with a psychological spin, those abilities may effectively be used with patients who know and trust their PCP.21 As noted above, psychological treatment of the complex chronic pain patient may need to be referred and may need to take place within the context of a MPC.
Complementary Medicine (CM). The role of CM encompasses a broad domain of healing resources. CM has been defined to include all health systems, modalities, and practices with their accompanying theories and beliefs other than those intrinsic to the politically dominant health system of a particular society or culture in a given historical period. One recent national survey found that the users of CM tended to be mostly middle aged and white. Chiropractic treatment, therapeutic massage, relaxation techniques, and acupuncture—in that order—were the 4 most frequently used CM therapies. Other surveys have found that individuals with chronic musculoskeletal and rheumatological disorders are high users of CM treatment. Few CM users completely reject conventional medicine. They seek out conventional medicine first and if they are not completely satisfied they migrate to CM practitioners to supplement their conventional treatment.
A number of small, controlled clinical trials support the efficacy of CM therapies such as acupuncture and mind-body techniques for treating various chronic pain syndromes. Four out of 8 high-quality studies of acupuncture reported statistically significant positive results. All studies with positive results focused on musculoskeletal conditions. An AHCPR review of the literature on treatments for low back pain found that chiropractic was effective for acute low back pain but data were insufficient to judge efficacy in chronic low back pain. A National Institutes of Health (NIH) technology assessment conference found "strong evidence" to support the use of relaxation techniques and hypnosis in reducing chronic pain. If reviewers who analysed available literature are to be believed one might conclude that the evidence for efficacy of many standard (biomedical) therapies is no better or worse than for the major CAM approaches.37,38
PCPs should be willing to discuss all plausible treatment approaches both conventionally and complementary. Acupuncture and mind-body approaches in the treatment of chronic noncancer pain warrant being categorized as plausible.39,40 PCPs willing to initiate a dialogue with their patients regarding CAM will most likely enrich their relationship with their patients and increase the likelihood of a positive response to therapy.
Psychological Approaches
Current understanding of pain mechanisms is informed by voluminous literature about the effect of attention, expectation, and emotion on the experience of pain. The postulate that the experience of pain is a consequence of the perception of a threat—real or imaginary—to the integrity of the body suggests that the complaint of chronic pain regardless of its original cause is a means of communicating the distress associated with that threat. Regardless of the particular psychological constructs a physician brings to his or her treatment of the chronic pain patient, chronic pain management without attention to its psychological aspects is poor pain management indeed.
Psychotropic medication. Patients with chronic pain usually have taken a wide variety of analgesic medications, which have "eased" or "taken the edge off" the pain but have never completely relieved it. Some patients with chronic noncancer pain have become habituated to opioid analgesics. Successful treatment usually requires using psychotropic medication while gradually reducing the amount of the opioid analgesic medications and substituting less potent analgesics before attempting a total weaning.
Psychotropics are frequently used as co-analgesics for insomnia and depressive symptoms; however, there is evidence that they have an analgesic effect, which is independent of effects on mood and sleep.
All classes of psychotropic medications have been used in the treatment of chronic pain. In clinical practice, the most useful group (when tolerated) are the tricyclics, SSRIs, the NSRIs, and the atypical antipsychotics such as olanzapine.
The effects of psychotropic medication are partly central, but current knowledge of the neuropharmacology of pain suggests that neurotransmitters at the level of the spinal dorsal horn neuron can be manipulated by a variety of psychotropic drugs, and thereby reduce the nociceptive input.
Phenothiazines have been used as co-analgesics, but their usefulness in the management of chronic pain has been questioned and some avoid their use on the basis of the risk of tardive dyskinesia not to mention sedation and depression.
Anti-seizure medication. This class of medication has a long history of efficacy in the treatment of trigeminal neuralgia. Recent studies clearly indicate efficacy in other forms of chronic pain especially of neuropathic origin. Neurontin (gabapentin) referred to briefly in the "analgesics and adjuvants" section has been demonstrated to have good clinical utility and safety. In clinical practice, its psychotropic quality of mood stabilization is particularly useful.
Psychological Treatment Techniques. Chronic pain patients are usually sensitive to the implication that there may be no physical basis for their pain. The rationale for introducing psychological therapies must, therefore, be presented in ways that patients come to know that their PCP knows that their pain is real, and that the psychological interventions are aimed at correcting any circumstances in their lives that may be exacerbating their experience of pain worse than it needs to be.
Muscle relaxation reduces both anxiety and muscle tension, thus reducing the input of nociceptive impulses. Benson has commented on the cognitive aspect of the relaxation process, and has emphasized "the relaxation process is an innate physiological response shared by many different techniques. It should not be identified or confused with any one procedure." Of particular interest to the PCP may be the work of Jon Kabat-Zinn who has made useful to our culture many elements of time honored relaxation techniques.41
Biofeedback refers to the presentation of information about a biological function to the patient as an aid to relaxation or as a means of helping to control a physiological function. Biofeedback as an aid in the management of chronic pain is supported by many reports; however, its use in chronic pain can contribute to a gross oversimplification of the nature of chronic pain problems, which are implicit in this therapy.
Assertive training may be useful to increase the individual’s sense of control and mastery, both over the pain and in a variety of personal situations.
Cognitive behavior therapy aims at modifying pain related cognitions (attitudes, beliefs, and expectations) so as to alter the pain experience. Cognitive behavioral therapy is generally effective in reducing the reported severity of pain and achieving improved levels of functioning among patients who accept this type of approach for pain management. However, many studies of psychological treatments of chronic pain fail to use standardized methods of evaluation or validated outcome measures, which makes the reported treatment results difficult to compare.
Education with accurate and relevant information about a patient’s condition can reassure patients about the reality and the cause of their medical condition. Patients can be educated to modify their expectations of themselves, initially to accept pacing and function within limitations, then to gradually increase the level of activity under supervision.
Family therapy aims at clarifying the possible relationship between the patterns of interaction of family members and the pain complaint. It is often the case that pain is reinforced by family tensions, and that it is a communication when other more appropriate expressions of distress or emotional needs are blocked. Family-focused assessment views the pain complaint, in part, as a family problem.
Hypnosis is clearly useful for some patients. Its overall role within a pain management plan is limited.
Psychotherapy’s role is usually to explore and clarify the role of anger, hostility, and guilt in the development and perpetuation of chronic pain. In a comparison of "psychodynamic psychotherapy" and "cognitively oriented supportive psychotherapy" there were no differences between the two groups after the completion of therapy. One year later, the "dynamic psychotherapy" group showed significant improvement in regard to activity level but not in any of the other outcome measures; illness behavior, anxiety, depression, and pain.
Stress management aims to help the patient identify stressful situations that exacerbate pain and to modify the individual’s response to these situations.42 Stress management, when taught in a group, allows patients to benefit from suggestions made by other members of the group as opposed to the therapist’s suggestions. The peer-driven improvement is often successful.
Community support groups that are formed for self-engrossed misery massaging are to be shunned. Self-help groups are successful to the extent that they act as behavior normalizing organizations helpful to patients who are experiencing a strong sense of isolation and can provide a means of reintegration into the community.
Statutory benefits advice can in some cases be appropriate when significant improvement is unlikely.
Vocational retraining will be required for the patient who is unable to continue in, or return to their ordinary job. Advice concerning what is appropriate in job choices will generally require vocational counseling.
Chronic noncancer pain is ubiquitous. The PCP has the ideal relationship with the paining patient to prevent, diagnose, educate, treat, and provide direction for rehabilitation of these often-complex pain problems.
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