In the decade since the publication of the National Institutes of Health (NIH) white paper on acupuncture in 1997, peer-reviewed, responsible research into the mechanism and efficacy of acupuncture has been prolific. As this research has identified acupuncture as a safe, efficacious, and cost effective modality to treat a variety of pain problems, it is in the process of being gradually integrated into the field of conventional pain medicine.
Brief History
Acupuncture is a complex therapeutic process that has its roots in prehistory and is undergoing constant evolution as its use in the conventional modern healthcare setting expands and understanding of its mechanism grows. Now, having existed for almost forty years in the public consciousness of the general population of the United States and scientific community, there is considerable familiarity with the basics of acupuncture as a therapeutic modality. Most are aware that acupuncture is the use of thin, solid needles in various patterns on the body. Although this is taken for granted in 21st century America, prior to July 26, 1971, outside of Asian communities, acupuncture was a wholly unknown entity in the United States. On that date, James Reston’s landmark article describing his experience with acupuncture in China was published in The New York Times . Mr. Reston was a reporter for the “Times ” who had traveled to China in 1971 in preparation for Richard Nixon’s historic diplomatic visit. Mr. Reston required an emergency appendectomy in Peking and had his postappendectomy pain successfully treated with acupuncture. This experience was recounted to the American people in The New York Times publication and served as the first major exposure of the English speaking U.S. population to acupuncture. Shortly after Nixon’s trip, physicians began formal and informal trips to China where they witnessed surgical anesthesia using only acupuncture needles. Whereas Reston’s article ignited popular interest in acupuncture, these reports began to fuel curiosity in the medical and scientific communities and served to spark scientific exploration of the bizarre “new” technique. As the specifics of the endorphin theory of acupuncture analgesia were discovered in the late 1970s, respect within the scientific community grew proportionately.
While likely practiced for several thousands of years BCE, the first known text that formally describes acupuncture theory is Huang Di Nei Jing ( Yellow Emperor’s Classic of Medicine ), which dates to the 2nd century bc . A more comprehensive text with greater unification of acupuncture theories was written in the first and second centuries ad and was called the Nan Jing ( Classic of Difficult Issues) . By this time, most of the concepts that underlie classical acupuncture theory such as acupuncture point location, channels, and disease classification had been defined. Transmission of knowledge occurred largely along familial lines in China leading to a multitude of diverse ways of practicing acupuncture.
From the 2nd century ad to the 16th century ad , these theoretical concepts and the practical application of acupuncture underwent an extensive and continual refinement that typifies the empirical evolution of this system of treatment. These refinements and the current state of acupuncture theory and practice were captured in the Zhen Jiu Da Cheng ( Great Compendium of Acupuncture and Moxibustion) which is attributed to Yang Ji-Zhou and was published in 1601. This text, referred to as the Da Cheng , became the preeminent source for medical information for subsequent generations in Asia and Europe. In fact, it was this text that was translated into various languages and transmitted to Europe and Japan by traveling physicians and missionaries from the 1600s through the 1900s and served as the basis for the development of classical acupuncture in these regions.
The practice of acupuncture and herbal medicine experienced a dramatic decline in China in the first half of the twentieth century. This process was driven by the larger cultural process of modernization patterned after Western science during this same period. Prior to the 19th century, China was the undisputed power that dominated the Eastern Hemisphere. A series of events in the 19th century including the Opium Wars, the Taiping Rebellion, and famine claimed tens of millions of lives and left China politically weakened and at the mercy of Western powers such as the French and the British for the first time in history. Accustomed to military and scientific superiority, the defeat of China by the British in the Opium Wars initiated a cultural drive to quickly adopt the principles of Western science that allowed their military adversaries to prevail. This infatuation with Western military science spilled over into all areas of science including medicine. This devotion to modernization according to Western principles was epitomized in the early 1900s by the repudiation of classical acupuncture and Chinese medicine and a commitment to license only Western-trained physicians.
Economic necessity and political expediency led to the simplification and systemization of the variegated forms of classical acupuncture under Mao in the second half of the 20th century in China. After Mao came to power, it became clear that the cadre of newly trained Western physicians, numbering roughly 40,000, was grossly inadequate to care for the more than 500 million Chinese citizens. Mao’s declaration that “Chinese medicine is a great treasure-house” came in 1958 and served as the theoretical basis for the barefoot doctor movement that was initiated in 1969. During this period, Mao called on previously marginalized practitioners of acupuncture and classical Chinese medicine to create a simplified system of Chinese medicine that could be easily taught and disseminated among his corps of barefoot doctors whose aim would be to care for rural villages. This new system eventually became known as Traditional Chinese Medicine (TCM). Ironically, this system is a 20th century creation and omits many of the complexities and nuances of pre-Mao classical Chinese medicine. Interestingly, the pre-Mao classical forms of acupuncture find their most authentic preservation outside of China, in Europe, Japan, and America.
The Japanese began practicing acupuncture in the 6th century ad and developed unique forms of acupuncture. From its earliest forms in Japan, acupuncture took on distinct qualities. Whereas in China acupuncture was closely combined with herbal medicine, in Japan physical medicine techniques and massage evolved in parallel with acupuncture. Consequently, the acupuncture of Japan requires the careful palpation of subcutaneous and muscular restrictions and nodules. Because of this, Japanese acupuncture has found an easy marriage with physical medicine techniques in modern America such as osteopathic manipulation and Janet Travell’s trigger point therapy. The greater freedom enjoyed by modern Japanese society when compared to modern China afforded an environment more amenable to continued evolution and integration with other modern medical practices.
Primitive experimentation with acupuncture began in Europe during the early 19th century as translations of the Da Cheng reached England, France, and Germany via military and missionary physicians returning from China. More serious integration with modern Western medicine did not occur until the middle of the 20th century in Europe and later in the United States.
Acupuncture is not Monolithic
It is important to realize that acupuncture is a general term that subsumes many specific techniques. Rather than thinking of acupuncture as a monolithic therapy, it may be helpful to think of acupuncture as one would think of the term injection. Injections using lidocaine and placed into an infraspinatus trigger point clearly represent a very different intervention as compared to a transforaminal epidural steroid injection or the intramuscular administration of ketorolac. Acupuncture techniques can be as distinct.
A Brief Primer of Acupuncture Techniques
Classical Chinese acupuncture typically involves the insertion of needles into locations on the body that have been empirically defined over thousands of years. Depth of needles insertion is often determined by achieving a characteristic aching or tingling sensation referred to as De Qi. When reference is made to classical or traditional acupuncture points, this generally implies the group of some 360 “principal” points described in ancient times. It is important to realize that classical acupuncturists have also described several thousand additional “extra” acupuncture points. Classical conceptions of acupuncture channels or meridians refer to linear pathways that connect individual acupuncture points.
Japanese acupuncture also evolved throughout ancient times and recognizes acupuncture points and channels similar to those of classical Chinese acupuncture. Japanese acupuncture involves a more refined system of palpation of subcutaneous and muscular tissue and insertion of needles into areas of myofascial restriction determined by this palpation. Depth of needle insertion is characteristically intracuticular and therefore much more superficial than in classical Chinese acupuncture. A branch of Japanese acupuncture, Ryodoraku, describes acupuncture points and channels as shifting anatomic location according to patterns of pathology manifested by individual patients. Interestingly, many of the sham acupuncture protocols in randomized controlled trials (RCTs) use needling techniques identical to Japanese acupuncture.
Neuroanatomic acupuncture is a modern acupuncture technique that is characterized by the insertion of needles into points on the body that have a neuroanatomic significance. Points are generally chosen with the aim of stimulating peripheral nerves, neurovascular bundles, fascia, tendons, muscles, ligaments, joints, and richly innervated structures such as the periosteum and interosseus membranes; electrical stimulation of these points is common. Neuroanatomic acupuncture uses classical acupuncture needle techniques according to modern biomedical knowledge.
Percutaneous neuromodulation therapy (PNT), also referred to as percutaneous electrical nerve stimulation (PENS), is a specific form of neuroanatomic acupuncture that positions acupuncture needles in soft tissue or muscles to stimulate spinal nerves and peripheral nerves. After a specific neuromusculoskeletal (NMS) diagnosis is made, the spinal nerves that correspond to the dermatome, sclerotome, myotome, and autonomic innervation of the pathologic region are stimulated at a variety of different electrical frequencies in a variety of different patterns. Acupuncture needles are also placed locally and regionally around the pathologic area according to neuroanatomic principles and stimulated with a variety of electrical frequencies.
Auricular acupuncture is a microsystem technique that involves the insertion of various types of needles into predetermined points and points with altered bioelectrical conductance on the external ear. As a microsystem, all aspects of the body are postulated to have representation on the external ear in a holographic fashion. Chinese scalp acupuncture (see Chapter 19 ) is also a microsystem technique and is characterized by the threading of needles along the scalp according to the underlying functional characteristics of the brain.
Medical Acupuncture is the Unification of Classical Acupuncture and Modern Medicine
The optimal acupuncture treatment of pain problems requires familiarity with classical acupuncture teachings as well as modern neuromuscular anatomy and neurophysiology. This unique integration of classical and modern knowledge is the exception rather than the rule among acupuncture practitioners. Many nonphysician acupuncturists lack the requisite familiarity and experience with the modern neuroanatomic understanding of pain to optimally treat many pain problems. While classical acupuncture techniques can be quite effective in treating pain, an approach that does not include the intentional integration of modern neuroanatomic concepts is suboptimal. Among physicians who practice acupuncture, this integrated approach is the ideal, but also not the rule. Some physicians obtain training only in modern neuroanatomic techniques, and this is also a suboptimal approach to pain problems.
Medical acupuncture is the practice of acupuncture by physicians; as a discipline it represents the integration of classical acupuncture with modern medicine. Medical acupuncture has evolved since the middle of the 19th century initially in Western Europe, then in Japan, and most recently in the United States. It has found its most refined expression in the work of Joseph Helms, MD. Helms has developed a robust and elegant integration of classical acupuncture with diverse modern acupuncture techniques such as neuroanatomic acupuncture, PNT, auricular acupuncture, and scalp acupuncture. It is this integrated system of acupuncture that is referred to by the term medical acupuncture in this chapter.
Medical Acupuncture Education
Medical acupuncture is taught to physicians in the United States through continuing medical education courses. The World Health Organization has promulgated acupuncture education standards for physicians and recommends that licensed physicians obtain at least 200 hours of formal training in acupuncture to acquire this specialty medical skill.
The American Board of Medical Acupuncture (ABMA) was established in 2000 to promote the safe and efficacious practice of acupuncture by physicians through a standardized examination and certification process. The ABMA is not a member of the American Board of Medical Specialties. The ABMA stipulates requirements for training, experience, and examination. In general, board certification by the ABMA requires 300 hours of formal training in acupuncture, a minimum of 2 years of clinical practice, and passing a standardized written examination. The ABMA currently recognizes 10 training programs in the United States and Canada. The majority of board certified physician acupuncturists have been trained by the Helms Medical Institute, founded by Joseph Helms.
What are the Effects of Medical Acupuncture?
As a comprehensive therapeutic system with a variety of techniques, medical acupuncture has wide-ranging effects including pain reduction, improvement in sleep, improvement in anxiety and depression, a reduction in pain medication, improvement in function, and an improvement in energy and vitality. Conversely, most therapies in conventional medicine have narrowly defined effects such as pain reduction from an epidural steroid injection or improved sleep from a sedative-hypnotic drug. Acupuncture that is used to treat a pain problem can be expected to have multiple effects simultaneously. This is particularly important because many pain problems represent a vicious cycle of pain, dysfunction, psychoemotional disturbances, fatigue, and sleep problems. Part of the robust nature of medical acupuncture is the ability to affect all of these seemingly disparate problems.
Medical Acupuncture is More than Needling
The practice of medical acupuncture involves therapeutic lifestyle recommendations in addition to needling. Specific dietary suggestions are often combined with prescriptions for exercise or activity modification. Further, classical acupuncture teachings describe an implicit relationship between physical dysfunction and imbalances in the cognitive and emotional spheres. This relationship and the specific areas of psychoemotional imbalances are discussed with the patient. Having a coherent way to understand the relationship between physical and mental imbalances can be enormously helpful for patients. By providing a means for understanding and exploring self-defeating thoughts and behaviors, this system often helps define a path for improving overall self-efficacy.
Medical Acupuncture View of the Human Organism
The accumulation of knowledge about human physiology, biochemistry, and pathophysiology within the sphere of modern medicine has been prodigious in the last 50 years. Much of this progress has relied on the ever improving ability to focus on the ever more exact building blocks of the human body. Much of medical therapeutics derives from this scientific process, but also remains incompletely understood. For example, tricyclic antidepressants are effective in treating many chronic pain states and are widely used for this purpose. We know that these medications have many mechanisms of action including the inhibition of presynaptic reuptake of serotonin and norepinephrine as well as blockade of sodium and voltage-dependent calcium channels. We do not know, however, the mechanism of action responsible for analgesia, nor do we know why some patients respond and others do not. Powerful reductionistic science has identified the mechanisms of these medications and part of the pathophysiology of chronic pain, but will unlikely reveal the unanswered questions of in vivo analgesic mechanisms and individual variability of response. Modern scientific paradigms from modern physics such as systems theory and quantum mechanics will likely be required to propel modern medicine into the next stages of advancement. Scientific approaches to reality require both reductionistic and synthetic processes of investigation. Systems theory is an excellent example of a synthetic scientific approach.
Systems theory teaches us that complex systems as primitive as unicellular organisms behave in ways that defy reductionistic, linear laws. Whereas reductionistic models of scientific investigation have proved invaluable for determining many of the components of living systems, this approach to science is suboptimal in providing information about how these components interact in the living organism. Systems theory instructs that complex systems, of which the human body is a quintessential example, have emergent properties. Emergent properties are unique properties of complex systems that are not present in any of the more simple parts of the whole, but arise only when all parts interact to form the complex whole. A laudable yet nascent drive in modern medicine is the administration of individualized care. The doctrine of conventional modern medicine is that the specific disease entity must be identified and the pharmaceutical or intervention that is most appropriate to the disease entity must be delivered. That is, all patients with knee osteoarthritis ought to receive the same treatment, all patients with insomnia ought to receive the same treatment, all patients with depression ought to receive the same treatment, and any patient with all three diseases ought to receive all three treatments.
Systems theory teaches us that this is a rudimentary approach to the complex system of the human body. First, not all humans with the same disease process will respond the same way to the same treatment. We know that there are individual differences in the pharmacokinetics of medication metabolism and individual differences in the healing process after surgery. Thus, the best principles of modern science tell us what Dr. Osler told us more than 100 years ago—“It is much more important to know what sort of a patient has a disease than what sort of a disease a patient has.” The goal, then, is individualized approaches that take the complexity of the person’s constitution as well as the disease process into account. The specific science and ability to do this in clinical practice is developing, but still poorly defined.
Interestingly, medical acupuncture presents clinicians with an approach that follows these ideals. Part of the nonspecific effects that are attributed to acupuncture’s effectiveness in RCTs may in fact be due to the systematic approach of acupuncture that seeks to identify constitutional factors for a patient and individual treatment for a presenting complaint based on that person’s identity and constitution. The classical framework of acupuncture has developed an empirical system that, in essence, looks for emergent properties. Through the thousands of years of empirical observations and subsequent pattern definition, acupuncture has sought to answer the following types of questions: What unique characteristics arise when a person complaining of knee pain also is a competitive, hard driving, leader without other medical problems, versus an overweight, jovial man who also suffers from chronic, debilitating allergic rhinitis? While the conventional approach to treating knee pain in these two patients would be identical, with likely variable results, the acupuncture approach for each would be unique, likely with good results based on large RCTs.
Most of these aspects of acupuncture have not been explored from the perspective of conventional science such as RCTs and are largely speculative. However, such factors, which have been derived from millennia of careful observation and inductive reasoning, may provide insight into the efficacy of acupuncture observed in clinical trials and may lead to new theories that will further reveal the myriad of unknown mechanisms in the functioning of the human body in health and disease.
Medical Acupuncture and the Treatment of Complex Chronic Pain
Medical acupuncture is a versatile modality that interacts with psychological, neurologic, endocrine, immunologic, and musculoskeletal aspects of the human organism. With these multiple points of input, medical acupuncture is ideally suited for the treatment of pain, which by nature manifests in the psychoneuromusculoskeletal sphere of humans.
The human organism is viewed as a complex multidimensional and integrated whole by physician acupuncturists. This view contrasts with that typically held by conventional pain medicine physicians. Conventional medicine is generally satisfied with dissecting an organism or molecule down to its smallest part and assuming that it understands the functioning of the organism when it has understood the functioning of all of its parts. In conventional clinical pain medicine, we are generally looking for one of a relatively few pain generators, such as a herniated nucleus pulposus or degenerated cartilaginous surface. As such, the biomedical model of pain seeks to identify and treat the physical pain generator that is assumed to be the sole cause of the patient’s pain. Recognition that this approach is inadequate has fostered the development of the biopsychosocial model used to understand and treat pain states.
Similarly, medical acupuncture recognizes that many pain problems are a complex manifestation of dysfunction in multiple spheres: myofascial, neurologic, psychological, emotional, endocrine, and genetic. Further, it is recognized that the experience of the organism is greater than the sum of all of these individual spheres.
Ronald Melzack recently described a new theory of pain that proposes a similarly complex and multidimensional view of pain problems. It is intriguing that medical acupuncture is capable of influencing virtually all of the components described by Melzack’s new theory of pain.
The Neuromatrix Theory of Pain
Consciousness in general and the awareness and experience of pain in particular are phenomena that remain more in the realm of mystery than in clear understanding. The medical acupuncture view of these phenomena closely parallels many aspects of the most instructive modern theories. The gate control theory holds that peripheral noxious signals are transmitted to the brain for conscious sensation via the spinal cord. These signals are modulated by other afferent inputs from the periphery and also by descending control from subcortical brain centers.
In 2004, Melzack promulgated a revision to his original gate control theory which he terms the neuromatrix theory of pain . A revision of the original theory was prompted by clinical experience with amputees with phantom limb pain. These patients continue to experience identical patterns of arm pain, fatigue, itch, and movement in the absence of the affected limb. Out of these observations, a new theory is derived that focuses primarily on the brain. Melzack describes his neuromatrix theory subsequently.
“The neuromatrix theory of pain proposes that pain is a multidimensional experience produced by characteristic “neurosignature” patterns of nerve impulses generated by a widely distributed neural network—the “body-self neuromatrix”—in the brain. These neurosignature patterns may be triggered by sensory inputs, but they may also be generated independently of them. Acute pains evoked by brief noxious inputs have been meticulously investigated by neuroscientists, and their sensory transmission mechanisms are generally well understood. In contrast, chronic pain syndromes, which are often characterized by severe pain associated with little or no discernible injury or pathology, remain a mystery. Furthermore, chronic psychological or physical stress is often associated with chronic pain, but the relationship is poorly understood. The neuromatrix theory of pain provides a new conceptual framework to examine these problems. It proposes that the output patterns of the body-self neuromatrix activate perceptual, homeostatic, and behavioral programs after injury, pathology, or chronic stress. Pain, then, is produced by the output of a widely distributed neural network in the brain rather than directly by sensory input evoked by injury, inflammation, or other pathology. The neuromatrix, which is genetically determined and modified by sensory experience, is the primary mechanism that generates the neural pattern that produces pain. Its output pattern is determined by multiple influences, of which the somatic sensory input is only a part, that converge on the neuromatrix.”
Melzack’s neuromatrix theory of pain shifts the focus away from the Cartesian concept of a one-to-one relationship between specific sensory experiences such as tissue damage or inflammation and the sensation of pain. This particularly applies to chronic pain states in which multiple factors such as psychological stress, physical injury, and cognitive states affect a genetically influenced and widely distributed neural network to produce multidimensional outputs such as the awareness and perception of pain as well as dysfunctional thoughts and action patterns.
This theory, then, proposes a richly complex understanding of chronic pain that emphasizes the role of genetics, thoughts, emotions, physical sensations, stress pathophysiology, and the emerging field of psychoneuroimmunology. The medical acupuncture view of chronic pain has many parallels to Melzack’s neuromatrix theory, both in its understanding of the sources of chronic pain and in its treatment.
Figure 17-1 illustrates the sensory inputs that influence the genetically determined neuromatrix: cognitive, sensory, and emotional. Medical acupuncture targets all of these inputs, the neuromatrix itself, and also the output programs that are often dysfunctional. Classical acupuncture often focuses on psychoemotional disturbances, whereas modern neuroanatomic acupuncture aims at treating musculoskeletal sources of dysfunctional inputs to the neuromatrix as well as spinal cord regions involved in spinal modulation. Scalp and auricular acupuncture are directed at affecting the neuromatrix itself. Acupuncture has also been shown to influence the stress regulation output program of the neuromatrix. While Melzack emphasizes the genetic contribution to the neuromatrix, classical acupuncture always strives to understand and treat the constitution of an individual, which can be understood as the genetically determined phenotype of an individual.
The conventional biomedical approach to pain focuses evaluation and management strategies solely on the musculoskeletal sensory inputs to the neuromatrix, much in line with the Cartesian understanding of pain processing. And, within this subset of sensory inputs, the focus is even more narrowly put on joint, nerve, and tendon generators of afferent activity.
The medical acupuncture approach to pain not only recognizes the value of treating all three groups of inputs to the neuromatrix (see Fig 17-1 ), but also focuses on an expanded set of tissues in the periphery capable of stimulating the neuromatrix. As such, medical acupuncture not only evaluates and treats dysfunctional joints, nerves, and tendons, but also muscle, ligaments, and fascia. Furthermore, medical acupuncture directs therapy at the neuromatrix itself and the stress response output program of the neuromatrix.
This ability to comprehensively intervene at all points in Melzack’s neuromatrix theory for pain experience (sensory inputs, neuromatrix itself, and subsequent outputs) defines medical acupuncture as a uniquely robust therapeutic tool for the treatment of pain problems.
Mechanisms
Twentieth Century Mechanisms
Since its introduction to the American scientific community in the 1970s, acupuncture has often been perceived as a therapeutic modality whose mechanism is mysterious and unknown at best, and inert in terms of modern physiology at worst. Researchers who sought to prove the latter hypothesis as well as those who were curious about discovering possible physiologic mechanisms produced a prolific body of basic science data in the 1970s and 1980s. This research led to the endorphin and monoamine hypothesis of acupuncture analgesia which has since been supported by an enormous collection of animal and human studies. Bruce Pomeranz, PhD, was one of the most prominent researchers in this area. He, indeed, set out to prove that acupuncture had no measurable physiologic effects. After publishing 66 papers investigating the mechanism of acupuncture analgesia, his conclusion was that the evidence supporting the endorphin hypothesis for acupuncture analgesia was stronger than that for almost any other therapeutic agent used in conventional medicine ( Fig. 17-2 ).
An acupuncture needle entering the skin and muscle in the arms or legs will activate unmyelinated C-fibers and small diameter myelinated A-delta fibers in the periphery that synapse onto cells of the anterolateral tract in the dorsal horn of the spinal cord. These cells give rise to two sets of projections. One set travels rostrally to eventually synapse on the midbrain, pituitary, and hypothalamus. The other set synapses on inhibitory interneurons in the spinal cord where dynorphin and enkephalin are released presynaptically to block ascending neurotransmission of painful signals along the spinothalamic tract. Meanwhile, the rostrally projecting cells of the anterolateral tract will stimulate cells in the periaqueductal gray causing the release of enkephalin, which will disinhibit cells of the raphe nucleus. The raphe nucleus is part of an endogenous descending analgesic pathway. Disinhibition of these cells activates this descending analgesic pathway, which causes the release of monoamines such as serotonin onto cells of the spinothalamic tract in the spinal cord that carry painful stimuli to the brain. Serotonin postsynaptically inhibits these cells, thereby dampening down the neurotransmission of painful signals from the periphery to the brain along the spinothalamic tract. Thus, the original acupuncture stimulus activates multiple neurochemical pathways in the brain and spinal cord and decreases the neuronal transmission of painful stimuli from the periphery to the brain. The ascending anterolateral tract neurons also stimulate the pituitary to release ACTH and β-endorphin into the bloodstream.
Twenty-First Century Mechanisms
Whereas 20th century research of the mechanism of acupuncture paralleled the discovery of the endorphin receptors and the gate control theory of pain, 21st century research is focusing on the brain, neuroimmunology, and connective tissue.
The research of Helene Langevin, MD focuses on the role of connective tissue as a dynamic whole body communication matrix and offers a fascinating model for the mechanism of acupuncture’s affect on the body. Loose connective tissue forms an anatomic network throughout the entire body. Most medical doctors spend little time thinking about fascia and connective tissue, and when they do, they think of it as purely structural in nature. In reality, fascia and connective tissue are intimately involved in complex regulatory mechanisms in the body such as ligand-receptor binding and gene transcription. Mechanotransduction is the biophysical process that is at the center of this research and forms the link between structure and function. Mechanotransduction is the process by which cells sense mechanical forces and transduce them into changes in intracellular biochemistry and gene expression.
What is Fascia?
Fascia is loose connective tissue that surrounds and interpenetrates all components of the human body including muscles, nerves, blood vessels, and organs. It provides structural integrity, serves as a matrix for intercellular communication, and is involved in biochemical and bioelectric signaling. The structural integrity of the soft tissue of the body is composed of a complex network of fascia and loose connective tissue on the macroscopic level and an equally complex microscopic network. The microscopic network is composed of an extracellular matrix of collagen and fibroblasts and an intracellular cytoskeleton of microfilaments, intermediate filaments, and microtubules.
How Does Acupuncture Interact with Fascia and Loose Connective Tissue?
The research of Langevin and colleagues has demonstrated that the twirling of the acupuncture needle that is typical in clinical practice creates mechanical changes in the collagen and fibroblast network of the extracellular matrix. In fact, her work using histologic sections and specialized ultrasonography has shown that the manipulation of the acupuncture needle produces characteristic changes in the surrounding loose connective tissue such as the wrapping of collagen fibers. She has demonstrated that these mechanical changes in the connective tissue are accompanied by active cellular changes such as lamellapodia formation and fibroblast spreading. Although not yet conclusive, this research supports the hypothesis that acupuncture needling activates diverse biological processes such as gene transcription, protein synthesis, and neuromodulation through the mechanism of mechanotransduction ( Fig. 17-3 ). These biochemical phenomena may underlie many of the unknown mechanisms of the therapeutic effects of acupuncture.
Biochemical Milieu of Trigger Points
Although the subject is not as novel as the work of Langevin and colleagues, the research of Jay Shah, MD is equally fascinating and instructive. Clinicians have long relied on the pioneering work of Janet Travell, MD in treating myofascial pain. Trigger point needling with and without local anesthetic is used by medical acupuncturists to treat many types of myofascial pain. However, until recently, convincing basic science research characterizing the qualities of trigger points has been lacking. In the January 2008 publication of The Archives of Physical Medicine and Rehabilitation, Dr. Shah describes an innovative technology that allows the real time biochemical assay of the trigger point milieu. A 30-gauge microdialysis needle is used to noninvasively sample 11 histochemicals in clinically identified trigger points. This study confirms that biochemicals associated with pain and inflammation (protons, substance P, TNF-α, bradykinin, and many others) are present in higher concentration in active trigger points than in latent trigger points and control muscle points. Furthermore, after needling the trigger points, concentrations of substance P, and CGRP are shown to decline. Though requiring additional study, this work offers a convincing basic science explication for the mechanisms underlying the dry needling of trigger points that is an integral part of medical acupuncture.
Brain Imaging
Extensive animal and human data indicate that many of the beneficial effects of acupuncture are mediated through the central nervous system. However, whereas mechanisms such as central modulation of endorphins and monoamines and the recruitment of the midbrain descending analgesia system are well characterized, much is not known about how acupuncture interacts with the CNS. In the last decade, interest has accelerated in the use of functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) imaging to further understand the effects of acupuncture on the brain.
Acupuncture Effects on the Brain
Nonpainful stimulation of peripheral nerves using transcutaneous electrical stimulation causes an increase in activation of the somatosensory, motor, premotor, posterior parietal, and cingulate cortices, as well as the thalamus and cerebellum as measured by fMRI. Painful stimuli produce activation in multiple regions of the brain including the primary and secondary somatosensory cortices, the insular cortex, the anterior cingulate cortex, the thalamus, and the prefrontal cortex.
Reproducible data show that acupuncture modulates an extensive network of cortical, subcortical, and brainstem regions in the brain. Numerous fMRI studies have demonstrated that acupuncture elicits a response in multiple cortical regions including the primary and secondary somatosensory cortices, the insular cortex, and the prefrontal cortex when compared to a variety of needle and nonneedle controls. A robust limbic network, including the hippocampus, amygdala, hypothalamus, and anterior cingulate cortex is also modulated. Brainstem structures involved in endogenous descending analgesia such as the periaqueductal gray are recruited by acupuncture therapy. Whereas nonacupuncture transcutaneous stimulation of peripheral nerves and painful peripheral stimuli generally produce an increase in signaling in the brain’s pain matrix, acupuncture therapy produces a modulation or a decrease in signaling intensity in the same regions of the brain.
Interestingly, acupuncture stimulates widespread deactivation of brain regions involved in the affective and cognitive aspects of pain, and also is able to influence the brain structures that control the physiologic stress response. The amygdala translates somatosensory stimuli into affective states. The amygdala exhibits patterns of sensitization and hyperactivation in response to chronic pain states. Acupuncture therapy elicits deactivation of the amygdala in healthy controls and in patients with chronic pain. Additional limbic structures involved in consolidation of somatosensory memory and the interface of cognitive and emotional mentation are also affected by acupuncture. The hypothalamus receives and integrates diverse information about the internal and external environment and produces a coordinated output program. A major aspect of hypothalamic output is orchestration of the body’s response to physiologic and psychological stress through the hypothalamic-pituitary-adrenal axis. The classical descriptions of acupuncture encouraging a return to homeostasis in the body are interesting in light of recent fMRI research demonstrating modulation of the hypothalamus in pain states.
Napadow and colleagues have also explored the effects of acupuncture on the dysfunctional neuroplasticity that develops in chronic pain patients. This dysfunctional central neuroplasticity may be part of the basis for their persistent pain, and its correction may underlie some of the therapeutic effects of acupuncture in chronic pain states.
A fascinating set of studies by this group has evaluated the brain effects of acupuncture on carpal tunnel syndrome (CTS) patients versus healthy controls. For the patients with CTS, the region of the sensorimotor cortex subserving the first three digits of the affected hand demonstrated hyperexcitability to nonnoxious stimuli when compared to healthy controls. After 13 acupuncture treatments performed over 5 weeks, the dysfunctional cortical hyperexcitability seen in the carpal tunnel patients diminished significantly. Healthy controls did not exhibit a similar rearrangement in cortical activity. These studies are an excellent example of the beneficial neuroplasticity that can be induced by acupuncture therapy.
Figure 17-4 illustrates group-averaged difference mapping of the contralateral sensorimotor cortex for CTS patients before and after acupuncture. Hyperactivity to nonnoxious stimuli in the contralateral sensorimotor cortex was exhibited in the median nerve innervated third digit at baseline. This hyperactivity in the third digit diminished after acupuncture treatment.
