Pain Medicine: History, Emergence as a Medical Specialty, and Evolution of the Multidisciplinary Approach

Rollin M. Gallagher

Scott M. Fishman

History of Pain Treatment

The treatment of pain reaches back into prehistory. As an alarm system that prompts withdrawal from harm and pursuit of circumstances conducive to healing, pain has an adaptive function. It is ironic that, despite its intrinsic aversive quality, pain commands our attention and is a vital part of life. Although pain is universally avoided, individuals born with a rare condition in which they are unable to perceive pain have a poor quality of life and shortened life expectancy.

The word “pain” can be traced to Poine, the Greek goddess of revenge, which reflects historical appreciation for the emotional complexity of the experience of pain. In ancient times, pain was associated with evil spirits or magic, and its management took place in corresponding domains. Priests or sorcerers might seek relief through sacrificial offerings or dramatic rituals to dispel evil spirits. Ancient cultures employed heat, cold, pressure, trauma, and even primitive operations to relieve pain. Some primitive cultures performed deliberate bleeding or trephination (cutting of holes in the body or skull) to release pain. The ancient Egyptians even employed early neuromodulation by applying electric eels to the body of a person in pain. In the Greek and Roman civilizations, pain was framed as an organized perceptual phenomenon that functioned through discrete organ systems.

During the Renaissance, DaVinci advanced the notion of organ-based physiology and, within this model, posited that the spinal cord and brain subserve transmission and perception of pain. The 17th through 19th centuries saw major advances in the understanding of pain, heralded by Descartes’ specificity theory of pain. The 19th century saw the harnessing of the analgesic properties of morphine, aspirin, and cocaine, as well as the discovery of general anesthesia. The rich history of regional anesthesia has in large measure been surveyed by David Brown in Chapter 1.

During the 20th and 21st centuries, enormous advances in understanding and treating pain have revealed a level of complexity that Hippocrates, DaVinci, or Descartes could never have imagined. Much of this information is covered in other chapters of this volume, as synthesized by Allan Basbaum in Chapter 51. Table 28-1 briefly lists selected landmarks in pain control, along with the scientific understanding of nociception and pain, that underpin today’s pain medicine practice and the translation of this understanding into clinical practice (1). Yet, despite these gains in the science and art of pain management, translation of this knowledge remains inconsistent. Society at large, while giving greater attention to pain and suffering, even in many respects reaching the threshold of regarding pain relief as a fundamental human right, has struggled with how to value and support pain relief and how best to integrate pain care into modern Westernized biomedicine (2).

Sociobiology of Altruism and the Healing Role

Communication of pain and suffering, and the responses of others who comfort and heal—be it as parent, relative, friend, or even stranger—is closely connected with the human trait of altruism. Altruism reflects our species’ instinctual response to the perceived suffering of others, a response considered to be a sociobiologically based genetic trait with survival value to our species, one that is shaped and perpetuated by kinship bonds (3). The role of professional healers in social systems can be considered as a behaviorally refined and culturally focused expression of altruism extended to expanded kinship systems. This altruistic motive may be very strong even when it results in no short-term survival benefit for the social group, such as in palliative care of the terminally ill (see Chapter 49). The gradual organization of humans into groups such as tribes, communities, community networks, states, or nations, has promoted the evolution of the healers into defined, intergenerational cultural roles. In Western society, these roles are codified by laws and standards into distinct health professions such as medicine, nursing, and psychology. In many instances, the rules and principles of governance for these professions transcend community and cultural affiliations, as when clinicians are duty-bound to treat sick or injured enemy combatants in times of war. When professional standards of science and ethical practice are engulfed by ideological, political, or economic agendas, the professions suffer—as in the Nazi medical experiments on concentration camp inmates during World War II.

The power of the healing role is evident in the complementary and alternative traditions of healing and caregiving, including the relief of pain. These ubiquitous and ingrained traditions persist despite the ascendance of scientific medicine as the dominant healing profession. Their persistence demands explanations beyond arguments of socioeconomic disparity; that is, that such practices would disappear if every society could afford Western medicine. For example, although Western

scientific medical practice is developing in China alongside, and sometimes blended with, traditional Chinese medical practices, traditional Chinese medical practices have thrived in North America and Europe. Nowhere is the interpenetration of complementary and conventional (“allopathic”) therapies better demonstrated than in pain medicine, which combines the most contemporary advances in medical and behavioral neuroscience with ancient Eastern traditions such as acupuncture and meditation. The movement to incorporate complementary and alternative practices into a holistic approach that also offers Western treatments has come not from the medical establishment but to a large extent from consumers seeking relief from pain and suffering. The value of some of these practices no longer mystifies medical science, which has come to recognize efficacy for both acupuncture and meditation and to offer explanatory mechanisms for their beneficial effects. Mechanisms to account for the benefits of needle insertion and stimulation are described by Michael Butler in Chapter 34.

Table 28-1 A sampling of milestones in the intellectual history of pain medicine

195 A.D.	Cannabis use first documented.
1646	Suarino describes snow and ice for pain relief.
1799	Davy describes the anesthetic properties of nitrous oxide.
1805	Serturner isolates the alkaloid morphine (Morphium) and demonstrates its use for sedation and pain control.
1842	Muller postulates the doctrine of specific nerve energies (i.e., afferent sensory neurons are specialized for different sensations), spurring research into pain sensation.
1842	Braid develops hypnosis as an evolution of Mesmer’s ideas.
1846	Morton uses ether to allow painless excision of neck tumor at Massachusetts General Hospital.
1861–65	Morphine syringe invented and morphine used extensively in Civil War.
1883	Weir Mitchell describes causalgia in Civil War soldiers and the use of morphine.
1885	Halstead advocates for induction ether anesthesia.
1894	Von Frey initiates research into specific nociceptors in skin and pain pathways in spinal cord and brain.
1894	Goldscheider formulates Pattern Theory B (stimulus intensity and central summation determine levels of pain).
1899	Salicylic acid first commercially developed into acetylsalicylic acid (aspirin).
1900	Sherrington postulates physiologic specialization of receptors B.
1901	Frazier performs trigeminal neurectomy for facial pain.
1911	Spillar and Frazier initiate anterolateral cordotomy.
1945	Beecher differentiates intensity of pain from intensity of nociception in describing wounded soldiers in WW II; attributes the disparity to the meaning of the pain (i.e., I will survive and go home versus I have to go back and face battle).
1943	Livingston postulates reverberating spinal cord circuits to account for persistent pain of causalgia.
1953	Bonica introduces the term “pain clinic” to describe the multidisciplinary team that specializes in treating pain, and publishes his seminal textbook, The Management of Pain.
1955	White and Sweet describe cingulectomy.
1959	Noordenbos proposes sensory interaction theory: Destruction of the balance of slow small unmyelinated fibres and fast large myelinated fibres leads to pathologic pain.
1961	Gerard proposes loss of spinal pain fiber inhibition.
1965	Melzack and Wall propose the gate theory of pain perception and modulation.
1960s	Carbamazepine first described as effective for trigeminal neuralgia.
1967	Cicely Saunders founds the Saint Christopher’s Hospice in Great Britain.
1973	Pert and Snyder (Johns Hopkins), Simon (New York University), and Terenius (Uppsala University) prove the existence of the opiate receptor, demonstrating the existence of the endogenous pain control system.
1973	Bonica (University of Washington) organizes the first scientific meeting devoted solely to pain with support from National Institutes of Health and Industry. This conference (at Issaquah, near Seattle) gives rise to the International Association for the Study of Pain.
1973	Melzack proposes a new conceptual model of pain, with three parallel systems: the gate control system, the motivational-affectivity system, and the sensory-discriminative system.
1973	Fordyce proposes pain as learned behavior and the operant conditioning model of pain.
1973	Sternback proposes pain behavior as an interpersonal identity in the physician–patient relationship.
1974	The International Association for the Study of Pain (IASP) is formed.
1974	The IASP begins its journal, Pain, with Patrick Wall as editor-in-chief.
1975	Endogenous opioid peptides—enkephalins—are discovered by Hughes and Kosterlitz (University of Aberdeen).
1978	Biopsychosocial model of medicine articulated by Engel (Rochester) in Science.
1982	Blumer describes the reduction of pain in depressed patients taking tricyclic antidepressants.
1986	IASP publishes Classification of chronic pain: Description of chronic pain syndromes and definition of chronic pain terms, edited by Mersky and Bogduk. Pain syndromes classified by a multiaxial system: anatomic region, bodily system (e.g., central nervous system), temporal characteristics, subjective intensity, etiology.
1992	Devor, Wall, and Catalan first describe effects of systemic lidocaine (sodium channel blockade) on ectopic firing of injured pain neurons.
1992	U.S. federal government publishes first clinical practice guideline: Topic is acute pain control after surgery or trauma. Multidisciplinary guideline panel, co-chaired by Carr (Boston), establishes a collaborative methodology for developing evidence-based pain guidelines including evidence ratings.
1992	First randomized clinical trial (RCT) demonstrating efficacy of tricyclics over selective serotonin reuptake inhibitors for neuropathic pain, by Max and colleagues (U.S. NIH).
1994	Gabapentin, due to demonstrated safety, begins to be widely used by pain specialists as first-line treatment for neuropathic pain, despite absence of RCTs (which eventually are completed demonstrating efficacy).
1997	Rainville and Bushnell, in Science, describe neuroimaging studies demonstrating mediation of affective component of experimental pain by activation of anterior cingulate gyrus and its attenuation with hypnosis.
Dates were obtained from various historical accounts of pain science and pain medicine. The authors are particularly indebted to Isabelle Baszanger’s comprehensive treatise, Inventing Pain Medicine: From the Laboratory to the Clinic. New Brunswick, NJ: Rutgers University Press, 1998.

Emergence of Pain Medicine: A Medical Specialty

It is said that to understand pain is to understand medicine. Pain is a complex phenomenon that encompasses both a neurophysiologic event, explained by a rational biomedical science, and an experience of suffering that mobilizes our human instinct to care. In considering when in the course of our evolution the event of pain became particularly human, one must consider its profoundly personal qualities that reverberate throughout an individuals’ consciousness. Suffering is at once profoundly personal and private, but also the most poignant of interpersonal states. The language used to define those interpersonal links is intrinsically human and humane. For example, “empathy” implies a capacity beyond just understanding, that extends to the ability to vicariously experience suffering in others. Altruism and empathy are the instincts that draw us most powerfully to enter medicine and assume the role of healer. Nowhere in medicine is empathy more needed, but more difficult to sustain, than in the care of patients with persistent unrelenting pain (4,5). Although behavioral neuroscientists have made important gains in helping us to understand this encounter and to leverage this understanding to help patients recover from debilitating pain, management of this encounter itself is generally left to instinct, not training, in the traditional medical curriculum.

The problem of understanding the neurophysiology of pain and the pain experience has challenged some of the best minds of medicine. The many new discoveries described in this volume document an explosion of basic and clinical science in this area just in the past few decades. The final chapter of this volume points out that, not only do we possess detailed knowledge of the physiology, molecular biology, and pharmacology of acute pain at the levels of soma, spinal cord, and brain, but we are beginning to glimpse the molecular neurobiology and genetics of chronic pain. As this knowledge becomes more sophisticated, separation of mind and body (e.g., in the concept of “psychogenic pain”) no longer is tenable. Brain imaging now enables us to visualize the workings of the mind interacting with the environment through various afferent sensory systems and their modulation, including nociception and analgesia. This knowledge has generated new drug and non-drug treatments at an ever-accelerating pace. When one of the authors (RMG) began his practice of medicine as a family physician in rural Colorado in 1971, outpatient pharmacologic treatment of chronic pain was limited to aspirin, acetaminophen (Tylenol), and occasional brief use of opioid analgesics for acute pain—their use was strongly discouraged for persistent pain, except when due to terminal cancer. The anxiety of acute pain was treated with a new miracle drug called diazepam (Valium). Routine orthopedic treatment for acute low back pain was propoxyphene (Darvon), Valium, and 2 to 3 weeks of bed rest for patients who avoided back surgery—these interventions have since been discredited for most cases of acute low back pain. Today’s physician is armed with a myriad of effective pharmacologic, behavioral, and physical therapies; invasive procedures; and cross-cultural complementary and alternative treatments such as acupuncture and meditation. Learning how, when, and in what combination to apply these tools in patients with chronic pain requires physicians to be competently trained in three core clinical skills: to evaluate and formulate the salient biopsychosocial dimensions of chronic pain in each patient; to generate a prioritized, goal-oriented management plan; and to implement that treatment plan effectively within a health care system (6,7). The new specialty of pain medicine comprises this core group of cognitive and behavioral skills (8). Although each traditional medical specialty contributes to this knowledge base and skill set, their respective specialists are not trained to manage the entirety of the spectrum of chronic pain. Table 28-2 outlines the special skills contributed by traditional specialties in pain medicine.

A Climate of Change

Pain medicine is presently practiced as a subspecialty, but has no single most appropriate parent specialty. Its specialized knowledge, education, training, and multidisciplinary nature suggest that pain medicine’s evolution as a specialty parallels that of other disciplines, such as emergency medicine or physical medicine and rehabilitation. Knowledge and skills of the latter disciplines, initially fragmented, later coalesced into primary medical specialties because of the inability of multiple specialties to offer an integrated approach that would best serve patients and medical science. Integration of diverse specialties into the formally recognized, differentiated medical specialty of pain medicine benefits the public at a time when society demands improved medical attention to pain (2). This benefit is particularly salient as regulations and standards for pain-related assessment and treatment in all health care facilities proliferate, undergraduate medical and continuing education in pain management are increasingly mandated, and administrative and legal complaints are lodged with increasing frequency against physicians who either overmedicate or undertreat pain.

The knowledge base and skill set of the specialty of pain medicine, as delineated by the American Board of Pain Medicine (9) and more recently by the U.S. Accreditation Council for Graduate Medical Education’s Committee on Fellowships (10) comprise the anatomy, physiology, molecular biology, and psychology of the pain experience; the pathophysiology, clinical phenomenology, and epidemiology of conditions leading to chronic pain; the delineation of individual pain problems in a single patient; the appropriate application of relevant treatments (Table 28-2); the administrative aspects of pain treatment within a health system; and goal-oriented treatment planning and chronic disease management. A similar list has been developed by the Faculty of Pain Medicine of the Australia and New Zealand College of Anaesthetists (11).
This constellation of qualifications is not currently contained in any one traditional American Board of Medical Specialties (ABMS) specialty training program. Skillful application of the treatments listed in Table 28-2, often in combination, is required to effectively manage and remediate chronic pain but has not been a goal of previous specialty training. Specialists in pain medicine must be trained to use these tools at a level of evidence-based care that can be standardized and replicated in training programs across the country (12).

Table 28-2 Examples of disease and treatment contributions to pain medicine from traditional specialties

Specialty	Illness/disease knowledge contribution	Medical skill/treatment contribution
Anesthesiology	Acute pain Chronic pain Cancer pain	Regional anesthesia (including neurolytic) Spinal anesthesia Operative anesthesia
Neurology	Peripheral neuropathy Neuropathic pain Central pain Headache	Assessment of neuropathic pain Neuropathic pain analgesia Headache medication
Neurosurgery	Spine disease Central pain	Implantable medication pumps Neurostimulation Spine evaluation and surgery
Orthopedic Surgery	Low back pain Physical disability	Spine evaluation and surgery Joint surgery
Palliative Care	Cancer pain	End-of-life symptom management Bioethics
Primary Care	Chronic diseases	Chronic disease management Biopsychosocial medicine
Psychiatry, Behavioral Medicine	Psychiatric comorbidity Somatoform disorders Stress, behavior and emotions Fibromyalgia Personality and coping	Antidepressant analgesia Behavioral rehabilitation Biofeedback and relaxation Biopsychosocial formulation Psychotherapies (Cognitive-behavioral, group, family, hypnosis) Psychiatric diagnosis; psychological and psychometric evaluation Psychopharmacology
Radiological Medicine		Diagnostic imaging Procedure imaging Radiotherapy
Rehabilitation Medicine, Physical Therapy	Musculoskeletal medicine Myofascial pain Physical disability	Physical therapy Physical rehabilitation Transcutaneous electrical nerve stimulation Trigger-point therapy
Rheumatology	Joint diseases Fibromyalgia	Joint injections Peripheral nociceptive analgesia (nonsteroidal anti-inflammatory drugs)
Complementary and Alternative Medicine		Acupuncture Massage Meditation Tai Chi

The State of Pain Treatment in Medicine

Access to pain treatment is uneven in our society, depending on the race, gender, and socioeconomic status of the patient, as well as on the education and training of the physician (13,14,15,16,17,18,19). These socioeconomic factors, which extend into areas such as litigation and reimbursement, are discussed in detail by Professor Loeser in Chapter 29. Despite medicine’s
traditional mandate “… to relieve often, to comfort always,” physicians often harbor mistaken or negative attitudes about treating pain (20). Reimbursement for pain-relieving treatments is often refused by insurance payors, and access to comprehensive pain rehabilitation is almost nonexistent in many areas of the United States. Inadequate access to care takes place despite compelling data to support the effectiveness of comprehensive pain care (in comparison with conventional medical care) in reducing pain, restoring function, and returning injured persons to work (21,22,23,24,25,26). Access to reimbursement for individualized care related to pain and pain-related drug abuse is also inadequate (27,29). Unnecessary barriers to treatment impose needless suffering on patients and their loved ones, and shift the financial burden of disability from the health insurance sector to businesses and taxpayers (30,31).

Recent actions by regulators, major health care organizations, courts, and legislatures suggest that society is increasingly intolerant of medicine’s inattention to pain and suffering (2). The Veteran’s Affairs medical system was the first large-scale system to respond to this trend by designating pain as the “fifth vital sign” in all its hospitals (32). The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) followed suit by likewise designating pain as the “fifth vital sign” and by requiring health care institutions to provide organized pain assessment and treatment in order to be accredited (33). Both the American Medical Association (AMA) and the Association of American Medical Colleges (AAMC) recently recommended inclusion of pain and palliative care in every medical school curriculum (34,35,36).

A recent civil lawsuit finding a physician guilty of elder abuse for undertreating pain led the California State Legislature to require physicians to complete specific pain-related continuing medical education (37). The California State Legislature has also mandated a curriculum in pain and palliative care for all medical schools (38). Nationally, an act of Congress declared 2001–2010 as “The Decade of Pain Control and Research,” and The National Institutes of Health has launched a focused initiative in pain research (39,40,41).

Historically, chronic pain has been treated, at least initially, by primary care physicians. The role of the primary care physician to ease suffering may be eclipsed as the patient with chronic pain is referred to a sequence of specialty physicians, each evaluating the condition from a narrow perspective. Fragmented, costly, and ineffective care often follows, allowing pain to evolve from a symptom to a disease (42). This transformation is characterized by neuropathologic changes such as sensitization, plasticity, and kindling of sensory and affective systems (43). It also shifts the costs of disease burden from insurer to society (30,44,45). The Institute of Medicine recognized the fragmentation of pain care two decades ago, stating: “Such evaluations require expertise in a number of disciplines and in skills such as functional and psychosocial assessment and neurological and musculoskeletal examinations. Currently, few individual clinicians are competent to conduct such multidisciplinary evaluations of pain patients or to recommend and coordinate appropriate therapy. The patient is typically referred to a series of experts, each of whom does part of the assessment and/or part of the treatment. Of course the very problem with this practice is that care is expensive, fragmented, and ineffective” (46).

Treating pain will be—and should always be—part of the clinical responsibility of every physician. Up to 65% of primary care patients report having pain (47,48). The generalist model suffers from diminishing returns when medical and social needs exceed the capacity of the medical care that can be provided by a single generalist. Yet, the number of generalist physicians and allied health practitioners who serve as gatekeepers has grown tremendously (49,50). Although generalist care offers important advantages for the patient in pain, well-designed specialty models are also necessary and feasible within managed care models of health care delivery (51). Evidence suggests that the current focus on having generalists meet the needs of patients must be balanced by maintaining an adequate workforce of pain medicine specialists (52,53) in a collaborative care model in which pain medicine provides workable clinical algorithms that help primary care systems manage pain more effectively but also provides timely clinical back-up (45,54,55,56,57,58).

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