Chapter 78. Acupuncture

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 one of the members of the press corps, James Reston, received acupuncture during an appendectomy.

Despite the initial enthusiasm, there continues to be skepticism regarding the efficacy of acupuncture. Given the lack of definitive clinical data, some of the skepticism is warranted. Acupuncture, however, is not alone in this regard when it comes to pain treatments, and much of the standard clinical care provided by pain physicians stands on less secure ground. The publication of the National Institutes of Health (NIH) consensus statement in 1998 on the clinical applications of acupuncture was based on over 2000 scientific articles and has put acupuncture on more solid ground in the medical community (the citations are available at the web site of the National Library of Medicine).1 Although clearly not a universal panacea for all pain syndromes, acupuncture has held up well under the last 20 years of scientific scrutiny and seems destined to continue as a viable method for the treatment of pain.

The goal of this chapter is to lay the basic theoretic and physiologic groundwork for understanding the clinical applications of acupuncture for pain. Then the current clinical data regarding the efficacy of acupuncture in various pain syndromes is discussed. 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.

The term acupuncture comes from the Greek words acus (needle) and punctura (puncture) and 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 fifth century bc and was followed some time later, between the 2nd and 3rd century bc, by the first written medical text on acupuncture, the Huang Di Nei Jing or the Yellow Emperor’s Classic of Internal Medicine.

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, interact 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 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 flexibility 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 lead to the concept of qi, or vital energy. As a means of developing treatment strategies, 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 correlate to the meridians has not been found, the concept has still proved useful to help understand and treat certain patterns of symptoms seen in various disease and pain states (Fig. 78-1).

Neurohumoral Data

Over the last 30 years, a great deal of scientific evidence has accumulated to verify that both acupuncture stimulation (AP) and electro-acupuncture stimulation (EA) has reproducible physiologic effects. There are three main lines of evidence that 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 Pomeranz3 in animals and Mayer4 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 have been demonstrated to play a role in the analgesic effect of acupuncture as evidenced by opioid-receptor antagonism 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 (i.e., the intensity and frequency of EA) 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 non-acupuncture or sham point was stimulated.5

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 mid-brain 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.6

The hypothalamic–pituitary–axis and catecholamines are also influenced by EA and AP and may further influence the analgesic response to pain both through immune modulation and modulation of the sympathetic responses.

Neuroimaging Data

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 2Hz) versus AP using a manual stimulation technique. The acupuncture stimulation used in this study involved twisting the needle at 2Hz in LI4 (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 just 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.7

Evidence for point specificity has also been obtained in a recent study by Cho et al.8 An acupuncture point on the lateral aspect of the small toe, Bladder 67 (B67), which is known as an influential point for vision, was stimulated and observed to cause increased fMRI activity in the occipital lobes in 12 subjects. Stimulation of the eyes directly with light caused a similar activation, whereas stimulation of a sham acupuncture point 2 to 5 cm away from B67 failed to cause occipital lobe activation.

Both of these studies are preliminary, however; they suggest that the grid of acupuncture points that has evolved over the last 2000 years may indeed represent a network of nodes in the peripheral nervous system that have profound and specific effects on modulating and regulating the activity of the central nervous system.

Neuromodulation Data

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. One of the problems is that such humoral effects are nonspecific and short-lived and cannot explain why certain treatment methods for particular conditions 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 78-1 lists the problems with our current understanding of acupuncture analgesia.

To give just one example of how the neurohumoral model fails to fully comprehend the clinical effect of AP, there 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).9

One theory that may help to 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.10 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.11 In effect then, 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 can be 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 can act as 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.12

We now know that EP causes the expression of c-fos in certain cells of the CNS, but in cells that are different than those that express c-fos with noxious input.13 In addition, EA has been shown to suppress fos expression in the spinal cord dorsal horn in response to mechanical noxious stimulation.14 This early data with animal models suggest that some form of reverse neuroplasticity is taking place with acupuncture stimulation.

Another approach to studying the neuromodulatory effect of peripheral nerve stimulation with acupuncture on the CNS utilizes somatosensory-evoked potentials (SEP). The most fruitful of this method is the pain SEP, which is the evoked potential generated when recording over the skull with painful stimulation in the periphery. Dental pulp stimulation is the most reliable model for this technique. In a recent review, Xu presents strong arguments to suggest that AP and EA have a suppressive effect on pain SEPs and that this effect is point-specific, in that stimulation of points on unrelated meridians fail to provide a suppressive effect on the pain SEP. This argues against a purely neurohumoral acupuncture effect since one would expect that if suppression of the pain SEP depended only on the release of endogenous neuropeptides then any point would do, and that meridian-specific points would not be superior in efficacy.15

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. Recently, a connection between myofascial pain and acupuncture has been laid out in terms more relevant to practitioners of acupuncture16,17 (Table 78-2 and Fig. 78-2).

Andersson has also recently 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.18 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.19

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.20 This is supported by many of the physiologic studies of EA and AP, in which the effect was only achieved 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.

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, osteoarthitis and neck pain. The 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.21–23 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.

After reviewing data from controlled studies in which sham acupuncture was used as the control (deeply inserted needles into nonclassic locations), Lewith has proposed that these sham locations for needle insertions are not altogether 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. To sort out the relative benefits of deep-needle stimulation in classic points versus sham points, large numbers would be needed to avoid a type II statistical error (i.e., failure to reject the null hypothesis). In comparison, trials of acupuncture in which either minimal acupuncture (i.e., superficially placed needles in nonclassical locations) or mock TENS was used as a control treatment, the relative success of true acupuncture is much greater.24 With new funding sources from the National Center for Complementary and Alternative Medicine at NIH, acupuncture research over the next decade should provide more answers to both the methodologic and clinical questions that are still largely unanswered.

There have been a number of recent clinical studies of improved methodologic quality that are suggestive of clinical efficacy. For example, in a recent review of a technique of EP called percutaneous electrical nerve stimulation (PENS), the authors summarize significant findings in the treatment of acute herpetic neuralgia, pain from bony metastases, migraine headaches after electroconvulsive therapy, chronic low back pain, and lumbar radiculopathy. These findings suggest that this technique can have lasting profound effects on difficult pain syndromes that allowed improved function and a reduction in the use of analgesic medications.25

There are a number of different treatment styles of acupuncture that have influenced the practice of acupuncture in the United States. Many of these styles herald back to pre-revolution medical traditions that were prevalent in China prior to Mao and had been exported to other Far East countries. One method commonly practiced in this country 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 involve 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 that the needling technique is not as deep, and often there is no attempt to elicit the deqi response.

Post-revolutions styles of traditional Chinese medicine are heavily 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 herbalist because it was felt by Mao at the time to be more scientific.26 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 into homeostasis rather than focusing on the specific local complaints of pain.

Percutaneous electrical nerve stimulation was developed in the United States and Canada. The treatment strategies are based on a neuroanatomic assessment of the pain generator rather than on traditional acupuncture theories. The pattern of pain is viewed and interpreted on the basis of which spinal segments are involved, and then EA is done along those segments (Figure 78-3).

There are numerous other treatment techniques including 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.27

Unfortunately, there is no clinical research at this time to help guide treatment type or style for particular clinical conditions. From personal clinical experience, however, failure of one techniques 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, there are still some serious adverse affects that have been reported, including serious infections, vascular injury, and pneumothorax that require proper precautions to prevent.28

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 (NCCA). The NCCA requires that candidates 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 actual practice of acupuncture is still further regulated by each individual state. Currently, 33 states and the District of Columbia license acupuncturist and most of these follow the NCCA 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 (anywhere from 100 to 300 hours depending on the state). Four states do not permit physicians to practice acupuncture within the scope of their license without the full training that nonphysicians are required to take (Hawaii, Montana, Rhode Island, and Vermont).29

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 US 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 Office of Continuing Medical Education at the University of California–Los Angeles (UCLA). Harvard Medical School, through the Department of Anesthesiology at Beth Israel Deaconess Medical Center, is now also offering 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 into many traditional western medical hospital settings. But as the older sister of a much greater 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.