There has been growing interest in the West about the application of acupuncture to control pain since President Nixon's well-publicized trip to China in 1971. The fascination with this ancient medical modality was heightened when a member of the press corps, James Reston, received acupuncture during an appendectomy. The subsequent publication in 1998 of the National Institutes of Health (NIH) consensus statement on the clinical applications of acupuncture based on over 2000 scientific articles brought a degree of optimism that acupuncture would become a mainstay in the war against pain.1
There has been some dampening of the initial enthusiasm, however, with continued skepticism regarding the efficacy of acupuncture. This skepticism arose from the lack of high-quality randomized controlled clinical trials (RCTs); but the results of a number of recent large RCTs using sham acupuncture controls have nevertheless left many believing that acupuncture is just an elaborate placebo ritual.2 As we shall discuss in more detail, the introduction of sham acupuncture has serious flaws but was based on the desire of researchers to filter the clinical practice of acupuncture through the mesh of standard placebo controlled methodology used in pharmacological research. Although clearly not a universal panacea for all pain syndromes, a more careful reading of the literature in fact does support that acupuncture is a cost-effective method for the treatment of pain.
The goal of this chapter is to lay the basic theoretical and physiological groundwork for understanding the clinical applications of acupuncture for pain. Then the current clinical data regarding the efficacy of acupuncture in various pain syndromes will be discussed. Attention will be given to understanding the pitfalls in devising a true placebo control for acupuncture trials, and our discussion of the literature will focus on the effect this has had on the outcomes of a number of large clinical trials for common pain conditions. Finally, a brief representation of some of the different treatment styles for common pain syndromes is outlined, and the chapter concludes by identifying further educational resources in this field.
BRIEF HISTORY OF ACUPUNCTURE
The term acupuncture is from the Greek acus, “needle,” and punctura, “puncture”; it is the English translation of chan in Mandarin and hari in Japanese.
The clinical practice of inserting needles into the body (initially stone or flint needles) occurred in China by the 5th centuries BC and was followed some time later, between the 2nd and 3rd centuries BC, by the first written medical text on Chinese medicine, the Huang Di Nei Jing, or the Yellow Emperor's Classic of Internal Medicine. In this text, acupuncture was the most cited treatment method, with Chinese herbal therapies endorsed more cautiously because they were considered dangerous and potentially lethal if used incorrectly. In China, there was a slow evolution of practice, and by the 19th century, acupuncture had lost most of its support in the Imperial Court and herbal therapies were preferred. In the early 20th century, acupuncture had been eliminated from medical training colleges and was practiced mainly by itinerant healers with education provided through family traditions. In the 1930s Cheng Dan'an, a Western-trained Chinese physician, undertook to bring acupuncture out of its superstitious and metaphysical past and ground it on a more secure foundation based on Western concepts of anatomy and thereby bring it into the mainstream. His decision to pursue this effort was based on a personal experience that he had when his father had treated him with acupuncture for back pain. Cheng developed the seminal acupuncture text that is still used in China and is the basis for the acupuncture approach called Traditional Chinese Medicine (TCM) now practiced in the West.3 With this modernized form of acupuncture, point combinations were often written for specific clinical presentations, in direct parallel to how herbal combinations were taught. This led to a proliferation of books giving point combinations that were thought of as canonical in the West but are actually the result of Western scientific and political influences on the evolution of acupuncture in China. In Japan, acupuncture has been practiced for over 500 years and has developed with an emphasis on using classical Chinese texts to guide practice, with less influence by the historical factors that led to the development of TCM in China. The use of TCM formulas has been readily adopted by Western researchers both because of the mistaken viewpoint that these formulas had an uninterrupted and ancient pedigree in China and because of the ease of maintaining scientific reproducibility. As discussed later in the chapter, this has had a significant adverse impact on study design and has led to some of the difficulties interpreting the results of recent large clinical trials in pain.
BASIC ACUPUNCTURE THEORIES
Chinese Taoist theories of yin and yang, or the balance of opposing influences in nature, underlie the theoretical framework used in acupuncture to understand human health. Human beings are seen as an integral part of a larger macrocosm that includes all the elements of the surrounding world. These elements are seen to have varying degrees of influence on the human organism, and factors such as weather, diet, and social environment are all taken to have significant effects on an individual's health. The dynamic balance of these external factors, together with the internal physical and emotional state of the organism, interacts in a complex way to influence health and disease. As a correlate to this holistic view of human health, Chinese medicine makes no distinction between mental and physical illness and largely bypasses the mind-body dualism that plagues Western medical traditions.
In this integrated framework, the workings and function of the internal organs are believed to have specific, observable effects on the external appearance of the individual. Subtle changes seen on the surface of the body are all seen to reflect accurately on the homeostasis of the internal organ system. For example, alterations in the skin color and skin texture, variations in the suppleness and compliance of underlying muscles, the quality of arterial pulses, and the appearance of the tongue and eyes are important factors that go into making a diagnosis and treatment plan.2
As an outgrowth of Taoist theories of health, forces were postulated to explain how the internal and external systems interrelated. This metaphysical construct led to the concept of qi, or vital energy. As a means of developing organized treatment strategies that could explain empirical observations of human health and disease, qi was postulated to flow in various channels or meridians in the body. There are 12 principal meridians, 8 extra meridians, and a total of 361 classic acupuncture points that are located on these proposed energy channels. Although an anatomical correlation to the meridians has not been located, the concept is useful to understand and treat symptoms seen in various disease and pain states and may provide clues about the deep organization of the nervous system (Fig. 98-1).
Diagrams of the 12 regular meridians and their organ correlates and two of the governing extraordinary meridians. (From Omura, Y. Acupuncture Medicine: Its Historical and Clinical Background. Tokyo, Japan: Japan Publications Inc; 1982. Used with permission by Dover Publications.)
The sine qua non of acupuncture treatment is for the practitioner to elicit the de qi response when inserting and manipulating the needle with a twisting and thrusting motion. This needle technique has been misinterpreted as a sensation that is as felt by the patient, indicating that the qi has been moved. This misinterpretation has been tacitly accepted in Western clinical research as a key component of ensuring the authenticity of the acupuncture treatment. Current clinical evidence strongly suggests that this phenomenon is not an adequate method of validating the treatment protocol.
Over the last 30 years, a great deal of scientific evidence has accumulated to verify that both acupuncture point (AP) stimulation and electroacupuncture (EA) stimulation have reproducible physiologic effects. Three main lines of evidence are presented in the following discussion. All go to the heart of the neurologic mechanisms that are currently understood to modulate and influence pain.
The evidence for the release of endogenous opioids with AP and EA derives from the seminal work done by Pomeranz and Chiu4 in animals and Mayer et al.5 in humans in the 1970s. Since that time, a large body of evidence has developed to show that both AP and EA lead to the release of endorphins and enkephalins into the cerebrospinal fluid (CSF). Furthermore, the release of these neuropeptides has been demonstrated to play a role in the analgesic effect of acupuncture as evidenced by opioid-receptor antagonists that can abolish the analgesia obtained with acupuncture in both human and animal models of acute pain.
Since the initial studies, both the met-enkephalin-responding neurons in the dorsal column of the spinal cord and the endorphin and enkephalin active sites in the periaquaductal gray zone of the brain have been shown to be involved in acupuncture analgesia. Both the parameters of stimulation and the site of stimulation have significant effects on the type of chemical releases. In particular, antiserum to met-enkephalin abolished acupuncture analgesia but antiserum to dynorphin did not when a true acupuncture point was stimulated, whereas the reverse was true when a nonacupuncture or sham point was stimulated.5 Manual acupuncture (MA) involves the insertion of an acupuncture needle into an acupuncture point followed by application of a stimulation technique, the most classic of which is a Chinese method of twisting the needle while thrusting up and down to elicit the de qi response. This method has been found to activate a broad range of afferent fibers, including Aβ, Aδ, and C.6 In EA, a stimulating, alternating current via the inserted needle is delivered and has been found to activate Aβ and Aδ-fibers.7 Centrally, the sensory information from acupuncture stimulation ascends through the spinal ventrolateral pathway to the brain with multiple effects that involve a network of brain regions, including the nucleus raphe magnus (NRM), periaqueductal gray (PAG), locus coeruleus, arcuate nucleus (Arc) of the hypothalamus, and the accumbens, caudate nuclei, and amygdale. There is a growing list of chemical releases that are felt to mediate acupuncture analgesia, including the opioid peptides (μ-, δ- and κ-receptors), glutamate (NMDA and AMPA/KA receptors), 5-hydroxytryptamine, and cholecystokinin octapeptide (CCK-8). Among these, the opioid peptides and their receptors in the descending pain modulatory pathway play an important role in mediating acupuncture analgesia.
One factor that may influence the response of a particular individual to acupuncture appears to involve CCK-8 receptor density.8 Interestingly the blockade of CCK receptors also potentiates the placebo analgesic response.9 Recently published evidence suggests that a patient's analgesic response to acupuncture may be related to the patient's genetic profile. In a Korean study using cDNA microarrays, investigators found that “high responders” had 375 genes that showed significant up- or downregulation compared to “low responders.” Many of the genes that showed upregulation were related to signal related biomolecules and stress and immune function, suggesting that genetics may play a role in the patient's response to acupuncture.10
Electro-acupuncture stimulation has also been found to elevate levels of 5-hydroxytryptamine (5-HT) in the raphe nucleus, which enhances acupuncture analgesia presumably through descending inhibitory control mechanisms. Destruction of these neurons in the raphe nucleus of the midbrain or injection of paracholorophenylalanine, which lowers cerebral levels of 5-HT, will attenuate acupuncture analgesia, and injection of pargyline, which slows enzymatic degradation of 5-HT, enhances acupuncture analgesia.11 There has been further elucidation of the specific subtypes of 5-HT receptors influenced by EA. In particular, intrathecal injection of antagonists of 5-HT1A and 5-HT3 receptors, but not 5-HT2A antagonists, significantly blocked EA-induced depression of cold allodynia in the neuropathic rat and reduced spontaneous pain behaviors.12
The hypothalamic-pituitary-axis and catecholamines are also influenced by EA and AP and may further influence the analgesic response to pain through both immune modulation and modulation of the sympathetic responses. It has showed that spinal α2-adrenoceptors play a crucial role in inhibitory descending pain control by noradrenergic projections from supraspinal nuclei to the dorsal horn, particularly in modulating neuropathic pain.13,14 Intrathecal injection of α2 receptor antagonist yohimbine, but not α1 receptor antagonist prazosin, significantly blocked EA analgesia in neuropathic rats.12
There is evidence to suggest that acupuncture analgesia may also work through blockade of NMDA and AMPA/KA receptors. In the rat spinal nerve ligation model, EA decreased nerve injury-induced mechanical allodynia.15 Immunochemical studies revealed that nerve ligation increased the expression of NMDA receptor subtype NR1 immunoreactivity, which could be reduced by low-frequency EA.16
Spinal cord glia (microglia and astrocytes) make important contributions to the development and maintenance of inflammatory and neuropathic pain.17 It appears that EA can also act to inhibit microglial activation in mice and rat models of chronic pain.18,19
Recent technological advances in mapping brain activity using functional magnetic resonance scanning (fMRI) have begun to be applied to acupuncture. Comparison has been made between tactile sensation (tapping the skin with a wire at 2 Hz) and AP using a manual stimulation technique. The acupuncture stimulation used in this study involved twisting the needle at 2 Hz in L I4 (a point in the first dorsal interosseous muscle of the hand). Stimulation of an acupuncture point in this manner produces a deqi sensation, which is a full, aching feeling at the point of the needle and is believed to be important in obtaining the clinical effect with AP. The results of unilateral AP showed bilateral neural modulation of cortical and subcortical structures. The primary action was to decrease signal intensity in the limbic region and other subcortical areas. Tactile stimulation did not produce these changes in fMRI. In addition, if the needle was placed in the point and left at rest or placed subcutaneously and not in the muscle, fMRI signal decrease in these deep subcortical structures was not seen. This suggests that the response of the organism to AP depends on activation of the muscle sensory afferents and not the superficial afferents in the skin.20
Although most of the focus on the physiology of acupuncture has been on the release of endogenous opioids, the use of positron emission tomography (PET) has allowed the study of acupuncture effects on the opioid receptors themselves. In a study using 11C-carfentanil (an analog of the μ-opioid receptor) as the tracer, both short- and long-term increases in μ-opioid receptor binding potential in the cingulate, caudate, and amygdala were observed in patients receiving acupuncture therapy. In the comparison group that received sham acupuncture, the effects on μ-opioid receptor binding potential were not present, suggesting that acupuncture and sham acupuncture function by different mechanisms.21
PET has also allowed us to study the effects of acupuncture on brain metabolism. In a recent study by Park et al. using fluorodeoxyglucose (an analog of glucose) as the tracer, acupuncture stimulation was shown to increase glucose brain metabolism in the left insula, bilateral thalami, the superior frontal region of the right frontal lobe, and the inferior frontal region of left frontal lobe. At the same time, glucose metabolism was decreased in the cingulate and parahippocampal regions of the left limbic lobe. This study suggests that acupuncture changes regional brain glucose metabolism patterns in a very specific and specialized way based on the acupoints stimulated.22
These studies suggest that the grid of acupuncture points may be focused regions in the peripheral nervous system that represent a network of nodes that have profound and specific effects on modulating and regulating the activity of the central nervous system.
It is still an open question whether acupuncture has an influence on pain and other disease states that goes beyond the direct effect of the chemical releases previously mentioned. The early data using fMRI suggest that the sensory stimulation provided by acupuncture may have direct and selective effects on CNS function. Although the demonstration that endogenous opioids can be consistently released in both animal and human experimental models has been an important step in verifying that acupuncture analgesia has a physiologic basis, there continues to be debate about whether this effect is sufficient to explain the observed clinical benefits. Humoral effects are nonspecific and short-lived and cannot explain why a certain treatment method for a particular condition would have a sustained or permanent disease-modifying result. The chemical releases observed with EA and AP may just be an epiphenomenon, indicating that there is an influence on the CNS without yet comprehending what the actual changes are. Table 98-1 lists the problems with our current understanding of acupuncture analgesia.
Humoral Theories and Problems Associated with Acupuncture Analgesia
||Download (.pdf) TABLE 98-1
Humoral Theories and Problems Associated with Acupuncture Analgesia
Humoral Theory of Acupuncture Analgesia
Endogenous opioid effect
Humoral effect short-lived.
Fails to explain importance of point selection and meridians.
Fails to explain disease modification and sustained analgesia obtained with acupuncture.
Difficult to implement theory to explain effects of nonpain-related conditions such as stroke.
Fails to capture neuromodulating effects of acupuncture.
An example of how the neurohumoral model fails to comprehend the clinical effect of AP is a recently published study using heat stimulation (moxabustion) of an acupuncture point on the fifth toe (B67) to turn breech babies after the 33rd week of pregnancy. The results of the study were profound, showing a significantly improved turning of the infants to the cephalic position at delivery compared with the control group. Of 130 fetuses in the intervention group, 98 (75.4%) were cephalic, compared with 62 (47.7%) of 130 fetuses in the control group (P < .001; relative risk = 1.58; 95% CI, 1.29–1.94).23
One theory that may help better explain the long-term effect of EA and AP is that by stimulating peripheral sensory afferents of the skin and muscle, sustained changes occur in the CNS through central neuromodulation. We are now just beginning to understand the basic mechanisms of pathologic neuromodulation that can lead to chronic pain. A fundamental concept that has emerged is that sustained nociceptive input can have profound effects on the CNS that cause adverse neuroplastic changes.24 Interestingly, continuing along this line of argument, unlike transcutaneous electrical nerve stimulation (TENS), AP and EA do rely on a more “painful stimulation” of the peripheral nervous system.25 In effect, through controlled stimulation of peripheral nociceptors, acupuncture may be causing a reverse neuroplasticity in the CNS.
A clue to the neuroplastic changes that may be occurring in the CNS with EP and AP is found in the literature looking at c-fos expression. The production of the fos protein in spinal cord and cerebral neurons is known to occur with painful peripheral nerve stimulation and is a guide to the location of neurons that have been activated by this noxious input. It is believed that the observed c-fos release in the CNS couples transient intracellular signals to long-term changes in the central processing of peripheral sensory input and heralds the initiation of adverse neuroplastic changes in response to nociceptive input.26
We now know that EP causes the expression of c-fos in certain cells of the CNS, but in cells that are different from those which express c-fos with noxious input.27 In addition, EA has been shown to suppress fos expression in the spinal cord dorsal horn in response to mechanical noxious stimulation.28 There is also evidence to suggest that point specificity is important. In a study of inflammatory pain in the hind foot of a rat, Gallbladder 30 produced significant anti-hyperalgesia, although Triple Warmer 5 (Waiguan) and sham points, an abdominal point and a point off meridian near GB30, did not.29 These early data with animal models suggest that some form of reverse neuroplasticity is taking place with acupuncture stimulation.
There is a growing literature on maladaptive cortical changes in chronic pain leading both to regions of brain atrophy and to cortical sensitization.30,31 In studies that used carpal tunnel syndrome as a model of peripheral nerve dysfunction, structural remodeling and neuroplasticity in cortical and subcortical regions of the brain were found. Acupuncture was found to have a conditioning effect on cortical sensitization.32
CORRESPONDENCE TO MYOFASCIAL TRIGGER POINTS
The previous section shows how basic research in acupuncture intersects with the current thrust of the work being done in understanding the physiology of pain. In addition, there is some evidence to suggest that EA and AP depend on stimulation of muscle sensory afferents. On the clinical side, the techniques developed for trigger-point injections and our understanding of their mechanisms of action are relevant to acupuncture techniques. Early on, Melzack demonstrated the high degree of point correlation between myofascial trigger points and acupuncture points.33 The connection between myofascial pain and acupuncture is explained in terms more relevant to practitioners of acupuncture (Table 98-2 and Fig. 98-2).34
Acupuncture and Myofascial Trigger Point Correlations
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Acupuncture and Myofascial Trigger Point Correlations
Region of Body
Dorsal zone: Frontal region of forehead to occiput. Down back to lateral ankles.
B 11–25, 41–45
B 53, 54
B 31, 34
Thoracic and lumbar
Lateral zone: Temporalis region of head to lateral arm to wrist extensors. Down flank to lateral aspect of leg.
GB 3–6, 8
GB 20, 21
Sternocleidomastoid and scalenes
Tensor fasciae latae
Zone: Mouth to anterior neck, anterior chest wall.
Down abdomen to medial aspect of leg and foot.
The Yang cutaneous zones are composed of the tendinomuscular, divergent, luo, and regular meridians of the regions diagramed. The zones act much like myofascial maps of muscular dysfunction and help organize both diagnosis and treatment of pain syndromes. (From Seem M. A New American Acupuncture: Acupuncture Osteopathy, the Myofascial Release of the Bodymind Holding Patterns. Boulder, CO: Blue Poppy Press; 1993. Used with permission.)
Andersson has proposed that the key element underlying the physiologic effect of AP and EA is the sensory stimulation of the low- and high-threshold mechanoreceptors in muscle tissue, which occurs with trigger-point injection methods as well.35 One can theorize that needle stimulation of the skin afferents tends to elicit a protective pain reflex that has as its main evolutionary goal to withdraw from danger. In contrast, needle stimulation of deeper afferents in muscle and tendons, which are not normally involved in these protective reflexes, elicits a pain inhibitory rather than a pain-withdrawal reflex. Andersson makes the point that sustained, physical activity such as running also stimulates these muscle afferents, and many of the physiologic benefits of exercise might be related to the activation of the same mechanoreceptors that are stimulated with EA and AP.
Stimulation of the muscle mechanoreceptors also has distant effects on muscle tone that is not seen with cutaneous sensory stimulation. To illustrate this, EA of Large Intestine 4 and 11 (points in the first dorsal interosseous and extensor digitorum communis [EDC] muscles, respectively) has been shown to suppress the contralateral stretch reflex in the EDC, whereas painful subcutaneous stimulation in the same location had no effect.36
In a recent review, there have been a number of clinical trials showing that trigger-point injections and dry needling have similar efficacy and that the type of solution injected into the trigger point is irrelevant to clinical outcome. This suggests that the most important factor in relieving the pain associated with a trigger point is the needle stimulation of the muscle sensory afferents.37 This is supported by many of the physiologic studies of EA and AP, in which the effect was achieved only when the needle stimulation occurred in the muscle underlying the acupuncture point, again showing the convergence of clinical experience with the work on myofascial trigger-point needling.
Recently, a group from the National Institute of Health has developed an acupuncture dialysis needle that allows in vivo sampling of the chemical milieu of an acupuncture point. A point in the neck, gall bladder 21 which corresponds to a common trigger point in the upper trapezius muscle was studied. In comparison of three groups, those with pain at rest in the region of gall bladder 21 with findings consistent with an active myofascial trigger point, those with no pain at rest but with evidence of a latent trigger point issue in the upper trapezius characterized by a taught band sensitivity to deep palpation, and healthy normal controls, the group with pain at rest had markedly elevated levels of substance P (SP), calcitonin gene-related peptide (CGRP), a lower pH, as well as other chemicals known to be involved with neurogenic inflammation and peripheral sensitization, including bradykinin, and tumor necrosis factor alpha (TNF-α).38 This suggests that the physiology of an acupuncture point is not static and can change in response to various pathological states. When active, the effect of this process of peripheral sensitization can then make an acupuncture point more responsive to minimal needling techniques. The converse is suggested as well, in that in a healthy normal state, the acupuncture point gallbladder-21 may be minimally responsive to needling and requires more aggressive stimulation to produce any central physiological effect.
An exhaustive review of the acupuncture literature was performed by a panel of experts convened by NIH, and their findings were published in the November 1998 edition of JAMA.1 The conclusions of the review reveal that for many of the common pain conditions such as back pain, tendinitis, arthritis, headaches, and neuropathic pain, better-designed studies are needed to determine scientific efficacy. A series of meta-analyses have been published by Ernst on the effect of acupuncture for the treatment of back pain, osteoarthritis, and neck pain. Conclusions were similar in all cases: that in the studies that were deemed to be well-designed randomized controlled trials, acupuncture was often better than control treatments but inconsistently better than sham acupuncture treatments.39-41 All of the studies reviewed suffered in general from small patient numbers, inconsistent use of outcome measures, and widely variable treatment strategies. Each of these methodologic problems makes it difficult to draw strong generalizations from these meta-analyses.
Sham needling is a means of introducing a placebo control into acupuncture research. Types of sham needling protocols used include inserting the needle a standard needling depth off meridian or on what are considered ineffective points without needling to obtain the de qi sensation. Other methods to make the technique more inert include minimal acupuncture where the needle is inserted into the subcutaneous fascia again without adding any additional needle stimulation. Streitberger and Kleinhenz and later Park developed placebo needle techniques in which the needle touches the patient's skin over a verum acupuncture point or a point off meridian but does not penetrate. In both of these research devices, the needle telescopes into the needle handle as it comes into contact with the skin, making it look to the patient as though the needle has penetrated through the skin.42,43
To correct these methodological deficits, a series of strongly powered RCTs have been published over the last 10 years, many from Germany, where acupuncture has been a covered service in the national health care system. This has led to a better understanding of the efficacy of acupuncture for common pain conditions as well as the effectiveness when this modality is delivered broadly by physician practitioners. However, important methodological issues continue to present difficulties. For example, a study by Leibina et al. in 2005 enrolled 150 subjects with chronic low back pain and randomized them to usual care versus usual care with verum acupuncture or usual care with sham acupuncture. The verum acupuncture formula was developed by an expert, and treatment in both the verum and sham group was performed by the expert 5 times per week for 2 weeks, then once a week for 10 weeks, Although both the sham and verum acupuncture groups did significantly better than usual care, there was no statistical difference between the expert formula and sham groups. Patients in the verum group were needled at the same points and the practitioner used a needle technique to elicit the de qi response, yet the results were no better than putting the needles superficially into the subcutaneous fascia in locations 10 to 20 mm away from the official acupuncture points used in the study.44 Contrast the result of this study with one performed by Molsberger's group in 2002 where he randomized 186 subjects with chronic low back pain into conventional orthopedic care (COT: physical therapy, diclofenac) versus COT with verum and COT with sham acupuncture. Subjects received three sessions per week for 12 weeks, and at the conclusion of treatment and at 3-month follow-up, the verum acupuncture group was significantly better than both COT and the sham with COT. A key difference in the acupuncture protocol used in the Molsberger study was that in addition to eliciting the de qi response at the points fixed by the protocol or formula, the acupuncturist was allowed the addition of 3 extra points that were individualized to the patient presentation.45
As a result of these trials, subsequent large trials sponsored by the German National Health Care system (GERAC initiative) devised a set of protocols to study patients with chronic low back pain, osteoarthritis of the knee, and headache.46-48 The acupuncture protocol for each condition was designed by expert consensus and involved fixed points with the addition of a set of possible variable points that a practitioner could select based on the individual presentation. The trial design was multicenter with hundreds of physician acupuncturists enrolling patients in their practices across Germany. After patients were enrolled, they had the option to either be part of a randomized study comparing verum acupuncture to superficial sham points or be part of a large observational study comparing verum acupuncture to usual care. As in the Leibing study, the outcomes could not statistically distinguish between verum and sham, although both groups did significantly better than usual care. In a comprehensive meta-analysis that includes the above pain trials and groups the data from a number of large, well-designed trials from the United Kingdom, United States, Spain, and Sweden, a total of 14,597 patients were analyzed who were involved in trials with nonacupuncture controls and 5230 patients who were involved in studies in which the control was sham acupuncture.
Acupuncture was statistically superior to control for all analyses (P < .001), but the effect sizes were larger when the control group did not involve a sham acupuncture technique. The effect sizes in the analysis of nonacupuncture controlled studies were 0.55, 0.57, and 0.42 for spine-related pain, osteoarthritis, and chronic headache, respectively. The effect size when the control was sham acupuncture was by comparison 0.37, 0.26, and 0.15.49 After review of data from controlled studies in which sham acupuncture was the control (superficially inserted needles into nonclassic locations), Lewith has argued that these sham locations for needle insertions are clearly not inert. It is likely that sham points that are not traditionally considered true acupuncture points have some efficacy, and he estimated that there is an analgesic effect from sham point stimulation in 40% to 50% of patients in comparison to an effectiveness in 60% of patients for true acupuncture point stimulation.50
Lundeberg argues that both sham needling and even use of a nonpenetrating placebo needle have physiological effects via such mechanisms as diffuse noxious inhibitory control (DNIC) that occurs any time tissue is traumatized (needle insertion) or if even the threat of trauma has occurred (needle in contact with skin).51 There are styles of acupuncture, specifically Japanese techniques that utilize minimally invasive methods and even skin scratching techniques to effect a successful treatment.52,53
Part of the confusion about the consideration of minimal acupuncture methods as an inert placebo in acupuncture studies may come from the myriad of basic science studies on acupuncture analgesia using normal healthy animals and humans in contrast to clinical trials that are conducted on subjects with various chronic pain conditions. It is well known that in pathological pain states, the skin and deeper somatic tissues become sensitized as a result of both peripheral and central mechanisms.54 Central sensitization leads to expanded receptive fields, resulting in a larger topographic distribution of responsiveness to small sensory inputs from the periphery. Even in visceral disease, there is evidence that by means of a process called dorsal root reflexes, a strong afferent drive to the dorsal horn can lead to retrograde release of neuropeptides such as substance P (SP) and calcitonin gene-related peptide (CGRP) into peripheral somatic and cutaneous tissue, leading to neurogenic inflammation. With tissue level peptide release, discrete areas of skin and muscle will become sensitized, leading to lower sensory thresholds and a greater responsiveness to minimal input.55 In the early 1800s, Sir Henry Head characterized this phenomenon in humans in his seminal papers, in which he discusses patients who develop cutaneous allodynia and hyperalgesia in distinct multisegmental patterns in response to visceral disease.56
This leads to the concept of state dependent effects of acupuncture points, which has been clearly demonstrated with recent fMRI studies comparing healthy normal controls to individuals with pathological states. For example, in patients with carpal tunnel syndrome (CTS), the cortical brain response to needle stimulation at acupoint LI-4 in CTS patients compared with healthy controls (HC) was markedly different. CTS patients responded to verum acupuncture with greater activation in the hypothalamus and deactivation in the amygdala compared to HC. A similar difference was found between CTS patients at baseline and after 5 weeks of acupuncture therapy, suggesting that the brain response after a series of acupuncture treatments to needle stimulation at LI-4 became similar to that seen in HC.57 In the same group of CTS patients, a nonnoxious stimulation to the affected hand led to a hyperactive response of the somatosensory cortex when compared to HC. Again after 5 weeks of acupuncture, this hyperactive response diminished and became similar to that seen in the HC. This supports the concept that in a pathological state like CTS, the system becomes sensitized and minimal peripheral input leads to an exaggerated cortical response that could be reversed with a course of acupuncture.32 This supports Lundeberg's argument that in individuals with various pain conditions minimal or nonnoxious input with a sham acupuncture protocol can still have strong central effects on the central nervous system and is not an inert intervention.
A study at NIH strongly suggests that degree of responsiveness to needle stimulation may change dramatically based on the pathological state of an individual and that points not commonly thought to be classical acupuncture points may become active in response to disease by a process of neurogenic inflammation.58
A number of treatment styles of acupuncture have influenced the practice of acupuncture in the United States. Many of these styles date back to prerevolution medical traditions prevalent in China prior to Mao and were exported to other Far East countries. One method commonly practiced in US is called acupuncture energetics. This technique evolved in Europe based on interpretations of the classic Chinese texts and was influenced by the Vietnamese in France. With this approach, point selection for pain is governed by the pattern of pain and symptoms presented by the patient and involves palpation of the areas of pain, much as one would do for assessing the location of trigger points. Japanese techniques rely heavily on palpation of soft tissue as well, with the exception of the needling technique, which is not as deep, and often there is no attempt to elicit the de qi response.
Postrevolutions styles of traditional Chinese medicine are strongly influenced by herbal treatment strategies. During the Communist revolution in China, an attempt was made to make acupuncture more systematic and uniform in technique and point location. This led to the use of diagnostic techniques developed by herbalists because it was felt by Mao to be more scientific.3 An attempt is made to diagnose the state of balance of the internal organs by asking general questions and using pulse and tongue diagnosis. Palpation of the soft tissues is less common, and point selection is often directed at bringing the general state of health back to homeostasis rather than focusing on the specific local complaints of pain.
Other treatment techniques include Korean four-needle technique, where only four needles are placed regardless of the presenting condition, and Korean hand acupuncture that represents the whole body with extra points found in the hand. Auricular acupuncture is a more widely spread treatment technique that also takes a small part of the body—the ear—and represents the whole body in that region. A special aspect of this treatment method involves the use of a point localizer that is essentially an impedance meter.59
Unfortunately, there is no clinical research currently to guide treatment type or style for specific clinical conditions. From personal clinical experience, however, failure of one technique for a particular condition does not always imply total acupuncture failure, and there is some value in trying a few treatment techniques before labeling the acupuncture ineffective for the condition. In addition, although compared to many medical interventions, acupuncture is relatively safe; however, serious adverse effects have been reported, including serious infections, vascular injury, and pneumothorax, that require proper precautions.60
The accreditation of acupuncture educational programs is directed by the Accreditation Commission of Acupuncture and Oriental Medicine (ACAOM), formerly called the National Accreditation Commission for Schools and Colleges of Acupuncture and Oriental Medicine. The organization that credentials nonphysicians to practice acupuncture in the United States is the National Certification Commission of Acupuncture and Oriental Medicine (NCCAOM). The NCCAOM requires candidates to complete 1725 hours of formal didactics and 500 hours of clinical training in acupuncture. Candidates who meet these requirements are then eligible to sit for a national written and practical examination administered biannually. Despite these national standards, the practice of acupuncture is still further regulated by each state. Currently, 43 states and the District of Columbia license acupuncturists, and most follow the NCCAOM guidelines for nonphysicians.
The regulation of the practice of acupuncture by physicians and dentists also varies from state to state. As of 1999, 35 states permit physicians to practice acupuncture within the current scope of their license without requiring additional training. There are eight states that do require some additional training and certification (from 100 to 300 hours, depending on the state). Four states (Hawaii, Montana, Rhode Island, and Vermont) do not permit physicians to practice acupuncture within the scope of their license without the full training that nonphysicians are required to take.61
For full membership in the American Academy of Medical Acupuncturists (AAMA), individuals must have an active MD or DO license (or equivalent) to practice medicine under U.S. or Canadian jurisdiction, have completed a minimum of 220 hours of formal training in medical acupuncture (120 hours didactic, 100 hours clinical), and have 2 years of experience practicing medical acupuncture. Currently, most physicians are able to satisfy the educational and clinical requirements demanded by any state except the four previously mentioned by completing the training offered by the Helms Institute and through the Department of Medicine at the Brigham and Women's Hospital, both of which offer a 300-hour course in medical acupuncture that would satisfy both the AAMA requirements and most state requirements to practice acupuncture.
The federal Health Care Financing Administration (HCFA), which is responsible with administering the Medicare program, currently denies coverage for acupuncture pending establishment of the scientific efficacy of this modality. With a showing of such efficacy, HCFA may consider acupuncture as a “reasonable and necessary” service, at which time coverage would be authorized under the Federal Social Security Act 37.
As we move into the 21st century, the future of acupuncture for the treatment of pain is secure but still in need of better scientific validation. Acupuncture in many ways is out in front in the race to gain general scientific approval in comparison with other complementary and alternative treatment modalities. This is demonstrated by literature reviews and acceptance in many traditional Western medical hospital settings. But as the older sister in a family of holistic treatments, great responsibility still lies on those who are involved in this field and on those who will become involved in the future to help tear away the shroud of mystery that still clouds our view of this 2000-year-old treatment modality.
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