Acupuncture in the Western Medical Context
BY PROFESSOR PHYLLIS BERGER
‘Acupuncture’ refers to the insertion of a solid needle into any part of the human body for disease prevention, therapy or maintenance of health 1. The most studied mechanism of stimulation of acupuncture points employs penetration of the skin by these thin, solid, metallic needles, which are manipulated manually or by electrical stimulation 2.
Acupuncture is a component of the health care system of China that can be traced back for at least 2,500 years. The general theory of acupuncture is based on the premise that there are patterns of energy flow (Qi) through the body that are essential for health. Disruptions of this flow are believed to be responsible for disease. Acupuncture may correct imbalances of flow at identifiable points close to the skin. The practice of acupuncture to treat identifiable pathophysiological conditions in American medicine was rare until the visit of President Nixon to China in 1972. Since that time, there has been an explosion of interest in the United States and Europe in the application of the technique of acupuncture to Western medicine 2.
Western medical acupuncture, the approach used by many of the conventional healthcare professionals who practice acupuncture, is based on contemporary neurophysiology and the recognised mechanisms of sensory neuromodulation. Acupuncture points are thought to correlate to sites where external stimuli result in a greater sensory stimulus, such as motor points of muscles and peripheral nerve bundles. Diagnosis is carried out conventionally and therapy is based on selection of points, such as ‘trigger points’ found on physical examination in musculoskeletal pain complaints, or other points based on the nerve supply of the tissues at that site 1.
Melzack theorizes that classic acupuncture and trigger point stimulation techniques are generally painful and that they produce analgesia based on overstimulation of the peripheral nociceptive system, inducing a self-regulating pain modulating effect. He went on to speculate that the close correlations between trigger points and acupuncture points for pain is remarkable since the distribution of both types of points are historically derived from such different concepts of medicine. Trigger points are firmly anchored in the anatomy of the neural and muscular systems, while acupuncture points are associated with an ancient conceptual but anatomically non-existent system of meridians which carry Yin (spirits) and Yang (blood). Despite the different origins, however, it is reasonable to assume that acupuncture points for pain relief, like trigger points are derived from the same type of empirical observation: that pressure at certain points is associated with particular pain patterns, and brief, intense stimulation of the points by needling sometimes produces prolonged relief of pain. These considerations suggest a hypothesis; that trigger points and acupuncture points for pain, though discovered independently, represent the same phenomenon 3.
Dry needling is a technique of inserting acupuncture needles into trigger points and is a very effective treatment used by medical practitioners, physiotherapists and chiropractitioners. Trigger point acupuncture has been found in clinical studies to be as effective as lidocaine injection in inactivating a myofascial trigger point and providing symptomatic relief 4.
Many investigators including Travell & Simons (1983) and Bonica (1984) advocated the injecting of procaine into the trigger points. It was stated by Travell that this was necessary to relieve pain as the procedure itself produced unendurable pain for certain patients. However this is not the general experience with dry needling, although when inserting the needle it does cause some transitory pain that quickly passes especially if the needle is left in position without being touched for a brief period. Subsequent rotary movement of the needle then gives no more than a prickling sensation to be followed quickly by one of a variety of sensory changes, often that of a diffuse numbness, known in Traditional Chinese acupuncture as the ‘de Qi’ sensation. The main objection to inserting procaine into trigger points is that the effficacy is not dependent on its local anaesthetic properties and it may produce potentially undesirable local and general side effects. According to Baldry the most important factor in alleviating myofascial pain is the mechanically irritating effect of inserting the needle 5.
Shah et al. 6 developed a clinical protocol (9 subjects, 3 in each group) designed to assess the local biochemical milieu of myofascial trigger points (MTrPs) in subjects with normal, latent and active trigger points in the upper trapezius, analysing neck pain and the presence or not of trigger points. A 32-gauge microdialysis needle was used capable of collecting small volumes (0.5 microlitres) and sub-nanogram (<75kDa) levels of solutes from muscle tissue. The main outcome measures were levels of pH, substance P (SP), calcitonin gene-related peptide (CGRP), bradykinin, serotonin, norepinephrine, tumour necrosis factor-alpha (TNF-a) and Interleukin–1 beta (IL-1 beta) determined by analysis of samples. It was discovered that the overall amounts of SP, CGRP, bradykinin, serotonin, norepinephrine, TNF-a and IL-1beta were significantly higher in the active group than either of the normal and the latent groups (P<0.01), pH was significantly lower in the active group than the other two groups (p<0.03) and that the amounts of SP and CGRP were significantly lower at the end of sampling after the twitch response was elicited in the MTrPs than at baseline (p<0.02) indicating that the local biochemical milieu does appear to change with a local twitch response. Additional studies by Shah indicated that active MTrPs are known to be associated with chronic pain states.
Peripheral effects of Acupuncture
In: Biomedical acupuncture for pain management: an integrative approach 7, it was stated that a needling-induced lesion stimulates the epidermis, dermis, underlying connective tissues (elastic fibres, collagen, basal lamina, deeper fascia) muscular tissues (skeletal muscles and smooth muscles of blood vessels) and nervous tissues (nerve fibres of sensory neurons and post-ganglionic neurons). The cells lesioned by the needling will be replaced by the same type of fresh cells without scar formation, since the lesions are fine and small. Needling activates a chain reaction in both local tissues and the CNS (spinal cord and brain). These peripheral and central mechanisms are inseparable.
The peripheral mechanisms are:
- Local skin reaction and cutaneous microcurrent mechanisms
- Local interaction between needle shaft and connective tissue
- Local relaxation of concurrent muscle shortening and contracture which improves local blood circulation through a muscular reaction and an autonomic reflex
- Neural mechanism: nociceptive and moto/neural activation, CNS-mediated neuroendocrine activity, segmental and non-segmental pathways via the afferent somatic neurons (A delta and C fibres) and sympathetic neurons
- Local immune responses (lymphatic tissue and mast cells)
- DNA synthesis to replace injured tissues and repair the acupuncture lesions
The first visible response after needle insertion is the flare reaction. This vasodilatory function of the autonomic circulation is mediated by SP secreted by cutaneous nociceptive neurons as indicated by Shah et al. with its concomitant mast cell triggered immune reaction producing histamine, platelet activating factor and leukotrienes 8.
It has been recorded that the normal direct current (DC) resistance of the body surface of dry skin (200,000 to two million ohms) is reduced at acupuncture points (50,000 ohms) 9with most acupoints measuring 5mV higher than the non-acupoint areas, with the outside registering a predominance of negative ions and the inside a predominance of positive ions. Melzack and Katz found no difference in conductance between acupuncture points and control points in patients with chronic pain 10. The higher voltage at acupoints which are rich in nerve fibres and/or vasculolymphatic structures is due to the dynamic nature of acupoints as they become sensitised and more extensive in area, when they are activated by disease or injury. This phenomenon is due to the increased inflammatory substances that may accumulate producing more fluid in these tissues and or acupoints. These conditions may increase conductance and insertion of a metal needle creates a short circuit across the skin battery and elicits a microcurrent, known as the ‘current of injury’. The small lesion created by an acupuncture needle creates a 10 mA negative current at the needling site which benefits tissue growth and regeneration 11.
Baldry (1989) and Macdonald et al. (1983) discovered that it is possible to alleviate chronic low back pain by inserting needles to an approximate depth of 4 mm of skin and subcutaneous tissues overlying a trigger point embedded in a muscle. The twitch response or de Qi is usually achieved and according to Baldry is left in situ, for no longer than 10 minutes. This is contrary to the belief that the most effective response is produced with a deeper needle insertion into a muscle and a stronger elicited stimulus 12. Although 90% of acupuncture treatments elicit the de Qi sensation (increases the effectiveness of muscle relaxation and relief of pain), a flare-up pain may occur in the elderly or weaker individual, and it is therefore recommended that simple insertion of a needle to the proper depth is sufficient in these patients to achieve the desired pain relief 7.
Central effects of Acupuncture
The central effects of acupuncture affect spinal cord (SC) neurons and those in the brain particularly the brainstem, midbrain, thalamus, hypothalamus, pituitary gland and cortex. Symptomatic acupoints in the periphery affect the sensitised neurons in the same segment of the spinal cord with the release of enkephalin and dynorphin to produce inhibition of pain. These SC neurons are activated and stimuli are then relayed through ascending pathways to the midbrain, thalamus, hypothalamus and cortex. The midbrain (periaqueductal gray) releases enkephalin to activate the descending pain inhibitory system. The descending pain modulatory system secretes monoamines, serotonin and norepinephrine.
- Inhibition of ascending pain messages
- Releases beta-endorphin by the hypothalamus/pituitary axis into the blood and cerebral-spinal fluid promoting physiological analgesia and homeostasis including activation of the immune, cardiovascular and respiratory systems which also impacts on tissue healing.
- Secretion of ACTH by the hypothalamus activates the adrenal gland to modify the pain sensation and the immune reaction – the HPA axis being part of the central mechanism of acupuncture 7, 13.
- Alteration in the secretion of neurotransmitters and neurohormones and changes in the regulation of blood flow, both centrally and peripherally, have been documented. There is also evidence of alterations in immune functions produced by acupuncture 2
- Finally, the needling sensation generates neuronal activities in the neocortical area 13, 14.
Many studies in animals and humans have demonstrated that acupuncture can create multiple biological responses. A focus of attention has been the role of endogenous opioids in acupuncture analgesia. Considerable evidence supports the claim that opioid peptides are released during acupuncture and that the analgesic effects of acupuncture are at least partially explained by their actions 15. That opioid antagonists such as naloxone reverse the analgesic effects of acupuncture further strengthens this hypothesis 2.
Table 1: The mechanisms of Acupuncture 16
Works via A delta stimulation and ascending and descending neuronal relays
Local anaesthetic pre-acupuncture can prevent the pain response
Endogenous opioids increase: beta endorphin, metenkephalin, dynorphin
Some effects can be blocked by naloxone but not at kappa opioid sites
Analgesic and mood enhancing
Analgesic and sedative
Widespread autonomic effects
Normalises blood flow, BP, gastric motility, etc, pain relief
Local release of C-GRP
Nerve growth factor (NGF) increase
Has a tophic effect on sensory and autonomic nerves
Cholecystokinin (CCK) increase
Antiepileptic, endogenous opioid antagonist, can contribute to acupuncture tolerance
The most recent research indicates that acupuncture modulates gene expression of endorphins (preprometenkephalin, preprodynorphin) 17, which may explain the sustained effects of treatment beyond any temporary increase in neuro-transmitter action.
Whilst diagnostic methods differ considerably, there is no clear distinction in a practical sense between the traditional and Western approaches ie in terms of the insertion of needles. There can be, however, considerable variation between the styles of practice adopted by individual practitioners of acupuncture. The method of treating a particular condition in a patient may therefore vary considerably in terms of the points chosen, depth and duration of needling, whether needles are stimulated manually or electrically, and whether additional therapies are also incorporated into the treatment session 1.
Uses of Acupuncture
Acupuncture is most commonly used to treat painful complaints, especially musculoskeletal pain 5 such as that associated with osteoarthrosis of the knee, headaches, chronic neck and low back pain. It is also gaining ground in palliative care for: pain, shortness of breath and anxiety, nausea and vomiting, xerostomia, natural and treatment-induced hot flushes, ulcers, post-operative pain or acute pain, improving immunity, hiccup, radiation rectitis, urinary frequency, pruritis and depression 16.
Evidence in Science of Acupuncture
Evidence for the benefits of acupuncture is increasingly sound 18,19 although trial methodology remains problematic because previously it was difficult to devise an acceptable placebo. Recently the Streitberger needle, a non-skin piercing needle was developed to eliminate all non-specific effects of the puncture 20. Needling non-acupuncture points undoubtedly has some neuro-physiological effect and is thus not truly inactive. That ‘placebo control’ acupuncture may have a physiological effect is supported by recent studies showing that stimulation of skin mechanoreceptors coupled to C unmyelinated afferents result in activity in the insular region. Activity in these C- tactile afferents have been implicated in a limbic reward response. It is likely that control procedures used in many acupuncture studies (superficial or minimal needling) aimed at being inert are in fact activating these C tactile afferents and consequently are not inert. These ‘control procedures’ probably activate the reward system and induce feelings of wellbeing 21. Conversely non-needling placebos may not be deemed sufficiently credible as evidence. Campbell noted that C tactile fibres in humans respond to light touch, project to the limbic system and are thought to be responsible for feelings of calm and wellbeing. These findings are thought to be relevant to acupuncture as regards both clinical practice and research 22.
Acupuncture is used increasingly in veterinary practice 16 which has no placebo involvement and data from animal research provide strong support for the hypothesis that therapeutic acupuncture is mediated at least partially by opioidergic and/or monoaminergic neurotransmission involving the brainstem, thalamus, and/or hypothalamic as well as pituitary action 14, 23.
Neuroimaging studies in humans have validated that acupuncture modulates a widely distributed network of brain regions including the limbic areas, sensorimotor and prefrontal cortices, brainstem nuclei and the cerebellum. Although these networks demonstrate overlap with those supporting placebo analgesia, differences in modulation of dorsolateral prefrontal cortex and rostral anterior cingulate cortex may support non-specific pain expectancy while amygdala, insula and hypothalamus modulation may demonstrate some acupuncture specificity 24,25.
Recently it was demonstrated that both superficial and deep needling (with de qi) resulted in amelioration of patellofemoral pain and an increased feeling of well being 26. This clearly implicates the limbic system which consists of a group of brain structures including the hippocampus, amygdala and their interconnections and connections with the hypothalamus, septal area and portions of the tegmentum. This area contains many of the centres related to emotion and reward. The pleasurable aspect of the acupuncture experience has largely been ignored as it has been considered to be part of the antinociceptive effects. It has previously been reported that physical exercise and electroacupuncture in animals result in modulation of the peptidergic 27 content of the limbic structures. These results are supported by recent animal studies in Japan that have clearly demonstrated that acupuncture results in activation of the reward system 28. These findings are supported by positron emission tomography studies in patients which showed that the insula ipsilateral to the site of needling was activated as well as the dorsolateral prefrontal cortex, the anterior cingulate and the midbrain 24.
It is suggested by Napadow et al. that brain processing of acupuncture stimuli in chronic neuropathic pain may underlie its beneficial effects. Functional MRI (fMRI) was used to evaluate verum and sham acupuncture stimulation in Carpal Tunnel Syndrome (CTS) and healthy controls (HC). CTS patients were retested after 5 weeks of acupuncture therapy. CTS patients responded to verum acupuncture with greater activation in the hypothalamus and deactivation in the amygdala as compared to HC, controlling for the nonspecific effects of sham acupuncture. For baseline CTS patients responding to verum acupuncture, functional connectivity was found between the hypothalamus and the amygdala – the less deactivation in the amygdala, the greater the activation in the hypothalamus and and vice versa. This is regarded as the first evidence suggesting that chronic pain patients respond to acupuncture differently to HC, through a coordinated limbic network including the hypothalamus and the amygdala 25.
Recent Studies on Acupuncture
Investigation of the effectiveness of acupuncture in addition to routine care in patients with chronic neck pain compared to routine care alone (drugs, massage, physiotherapy, exercise and patient education). A randomised controlled multicentre trial plus non-randomised cohort in general practices was performed in Germany that included 14,161 patients with the duration of pain existing longer than six months. Patients were randomly allocated to an acupuncture group or a control group receiving no acupuncture. Patients in the acupuncture group received up to 15 acupuncture sessions over three months. Patients who did not consent to randomization received acupuncture treatment. All patients were allowed to receive usual medical care in addition to study treatment. Treatment success was essentially maintained through 6 months and it was concluded that treatment with acupuncture added to routine care in patients with chronic neck pain was associated with improvements in neck pain and disability compared to treatment with routine care alone 29.
Tukmachi et al. in an open randomised, controlled trial found that both manual and electroacupuncture causes a significant improvement in the symptoms of osteoarthritis of the knee either on its own or as an adjunct therapy with no loss of benefit after one month 30.
A large case series was evaluated in Spain between 1997 and 2000 in which 563 patients received up to a maximum of 15 acupuncture treatments. It was found that a course of acupuncture treatment in these patients was associated with a significant reduction in the mean pain score and 75% of patients reported an improvement of more than 45% 31. In another study (randomised, single blind and controlled with the Streitberger needle) by the same authors (Vas et al.) to determine the effectiveness of acupuncture as a therapy complementary to the pharmacological treatment of osteoarthritis of the knee it was demonstrated that acupuncture showed significantly better effects, both clinically and statistically in the reduction of pain intensity as measured by pain VAS, the WOMAC index and in decreased consumption of diclofenac 32.
A Programme for the Evaluation of Patient Care with Acupuncture (PEP-Ac) was initiated in Germany in 2006 which included five randomised trials and a large observational study in a total of 4048 patients, a survey of physicians providing acupuncture and three systematic reviews. The aim of this study was to investigate the efficacy, effectiveness and safety of acupuncture with the following three indications: chronic headache, chronic low back pain and chronic osteoarthritic knee pain. The results show that for all three indications acupuncture when compared to no treatment produces a clear benefit that lasts for several months. There was however a lack of evidence supporting its superiority over sham acupuncture (minimal acupuncture with superficial needling at non-acupuncture points) for all indications except osteoarthritis of the knee 33 – however this is not surprising since even minimal needling have been shown to produce peripheral and central effects.
A systematic review of randomised controlled trials, including a met-analysis, to determine the effectiveness of acupuncture treatment for pain and function of patients with osteoarthritis of the knee was performed. WOMAC scores were used to assess the effect with internal validity and heterogeneity of studies being taken into account. Thirteen studies were available, of which eight, involving 2362 patients, could be combined. For both reduction of pain and improvement of function, acupuncture was significantly superior to sham acupuncture (p<0.05 for all comparisons) in both the short term and the long term. Compared with no additional intervention (usual care), acupuncture was again superior for pain and function. It was therefore concluded that acupuncture is an effective treatment for osteoarthritis of the knee and can be considered instead of non-steroidal anti-inflammatory drugs for patients whose symptoms are not controlled by education, exercise, weight loss if appropriate and simple analgesics 34.
It is appropriate to mention at this point that previous evaluation of studies from the European Guidelines for the management of chronic back pain (European Spine Journal 2006) 35 did not conclusively recommend acupuncture for the treatment of CLBP. This conclusion was derived from large and prestigious trials (PEP-Ac) comparing acupuncture with ‘sham’ showing a non-significant trend 30.
A recent review article published in The Spine Journal (2008) on ‘Evidence-informed management of chronic low back pain with needle acupuncture’ 36 systematically reviewed the literature to determine the effects of acupuncture for CLBP by updating a previous Cochrane review on this topic from 2003 until 2006. The same strategy as the previous review (2003) 36 was used evaluating electronic databases MEDLINE, EMBASE and CENTRAL.
In this review there appeared to be some evidence for the use of acupuncture for the treatment of CLBP. When compared with no treatment, there is evidence that acupuncture is effective in pain relief and functional improvement immediately after a series of treatment and in the short-term follow-up. Compared with other treatments evidence suggests that acupuncture is not more effective for pain relief and functional improvement. The most consistent evidence appears to be for the addition of acupuncture to other therapies, which demonstrated more effective benefit in pain relief and functional improvement than the same therapies without acupuncture. However given the inconclusive evidence for the effectiveness of acupuncture when compared with sham acupuncture, more studies are needed to determine whether the positive demonstrated benefits extend beyond placebo.
However as previously mentioned, it is possible that placebo control acupuncture may have physiological effects due to stimulation of C fibre afferents activating the insular region and a limbic reward response and this may nullify the comparison between placebo and active treatment 21.
Pain relief is the expectation of every patient in pain and it would seem appropriate to offer best treatment practice that included the addition of acupuncture while advancing our knowledge of the exact science of this subject.
Acupuncture is becoming recognised as an integral part of modern medicine and is used alongside drug treatment in general practice, pain clinics, rheumatology clinics, physiotherapy departments and some maternity units 37.
There is a risk when treating patients with acupuncture, as it is in all other forms of medical treatment, of the occurrence of adverse effects. The more serious complications are pneumothorax, septicaemia and spinal lesions. Other less serious complications include dizziness, discomfort or sweating (transient hypotension), ecchymosis without pain, post treatment malaise, minor local haemorrhage/bruising, aggravation of symptoms, itching or redness around the needling site (a rare possibility of allergy to the metal needle) and pain in the puncture region. However one of the major advantages of acupuncture is that the incidence of adverse effects is substantially lower than that of many drugs or accepted medical procedures used for the same conditions 38.
It therefore seems appropriate to use acupuncture to assist in many medical conditions especially in pain management, symptom control in palliative medicine and inflammatory disease. Acupuncture can be used as a stand alone treatment or in conjunction with ‘usual’ medical care with the added benefit of few, if any, side effects.
- http://www.library.nhs.uk » link to the article
- NIH Consensus Statement Online 1997 Nov 3-5; month, day]; 15(5):1-34
- Melzack R. trigger points and acupuncture points for pain: correlations and implications. Pain 1977;3(1):3-23. Review.
- Carlson CR, Okeson JP et al. Reduction of pain and EMG activity in the masseter region by trapezius trigger point injection. Pain 1993;55:397-400.
- Baldry PE. Some basic observations leading to its development In: Acupuncture, Trigger Points and Musculoskeletal Pain. Churchill Livingston Longman Group UK Limited 1989;4:36.
- Shah JP et al. An in vivo micro analytical technique for measuring the local biochemical milieu of human skeletal muscle. Journal of Applied Physiology 2005; 99(5):1977-84.
- Ma Y-T, Ma M, Cho ZH. Peripheral mechanisms of acupuncture In: Biomedical acupuncture for pain management: an integrative approach. Elsevier Churchill Livingston USA 2005;3:26-34.
- Baldry PE. Activation and deactivation of trigger points In: Acupuncture, Trigger Points and Musculoskeletal Pain. Churchill Livingston Longman Group UK Limited 1989;5:51.
- Becker O, et al. Electrophysiological correlates of acupuncture points and meridians. Psychoenergetic Systems. 1976;1:195-212.
- Melzack R, Katz J. Auriculotherapy fails to relieve chronic pain. JAMA 1984;251:1041-1043.
- Pomeranz B. Effects of applied DC fields on sensory nerve sprouting and motor nerve regeneration in adult rats. In: Nuccitelli R, editor: Ionic currents in development. New York, 1986, Alan R Liss.
- Macdonald AJR, Macrae KD, Master BR, Rubin AP. Superficial acupuncture in the relief of chronic low back pain. Annals of the Royal College of Surgeons of England. 1983;65:44-46.
- Cho Z-H, Wong EK, Fallon JH. Neuro-Acupuncture Volume 1 Neuroscience Basics Q-puncture, Inc. Los Angeles CA. 2001.
- Cho Z-H, et al. Functional magnetic resonance imaging of the brain in the investigation of acupuncture. In: Stux G, Hammerschlag R, editors: Clinical Acupuncture. Berlin: Springer-Verlag. 2001.227pp.
- Thompson JW, Filshie J. Transcutaneous electrical nerve stimulation (TENS) and acupuncture. In: Doyle D, Hanks G, MacDonald N (eds). Oxford textbook of palliative medicne. 2nd ed. Oxford: Oxford Medical Publications, 1997.
- Filshie J. Acupuncture in palliative care. European Journal of Palliative Care 2000;7(2):41-44.
- Lee JH, Beitz AJ. The distribution of brainstem and spinal cord nuclei associated with different frequencies of analgesia. Pain 1993;52:11-28.
- Filshie J, White A (eds). Medical Acupuncture: a western scientific approach. Edinburgh: Churchill Livingstone, 1998.
- Ernst E, White A (eds). Acupuncture: a scientific appraisal. Oxford: Butterworth- Heinemann, 1999.
- White P, Lewith G, Hopwood V, Prescott P. The placebo needle, is it a valid and convincing placebo for use in acupuncture trials? A randomized single-blind, cross-over pilot trial. Pain 2003;106(3):401-9.
- Lund I, Lundeberg T. Are minimal superficial acupuncture or sham acupuncture procedures acceptable as inert placebo controls? Acupunct Med 2006;24(1):13-5.2.
- Campbell A. Role of C tactile fibres in touch and emotion – a clinical and research relevance to acupuncture. Acupuncture in Medicine. 2006;24(4):169-171.
- Zhou WT, Du MY, Wu WY, Jiang Y, Han JS. Effect of intracerebral microinjection of naloxone on acupuncture and morphine analgesia in the rabbit. Sci Sin 1981;24:1166-78.
- Pariente J, White P, Frankowiak RS, Lewith G. Expectancy and belief modulate the neuronal substrates of pain treated by acupuncture. Neuroimage 2005; 25:1161-7.
- Napadow V, Kettner N, Liu J, Li M, Kwong KK, Vangel M, et al. hypothalamus and amygdala response to acupuncture stimuli in carpal tunnel syndrome. Pain 2007a:doi:10.1016/i.pain.2006.12.003.
- Lundeberg T. Some of the effects of acupuncture in knee pain may be due to activation of the reward system. Acupuncture in Medicine 2006; 24 (Suppl): S67-70.
- Bucinskaite V, Theodorsson E, Crumpton K, Stenfors C, Ekblom A, Lundeberg T. effects of repeated sensory stimulation (electroacupuncture) and physical exercise (running) on open-field behaviour and concentrations of neuropeptides in the hippocampus in WKY and SHR rats. Euro J Neuroscience 1996;8(2):382-7.
- Yoshimoto K, Fukuda F, Hori M, Kato B, Kato H, Hattori H, et al. Acupuncture stimulates the release of serotonin, but not dopamine, in the rat nucleus accumbens. Tohoku J Exp Med. 2006;208(4):321-67.
- Witt CM, Jena S, Brinkhaus, B, Lieker B, Wegscheider, Willich SN. Acupuncture for patients with chronic neck pain. Pain 2006;125:98-106.
- Tukmachi E, Jubb R, Dempsey E, Jones P. The effect of acupuncture on the symptoms of knee osteoarthritis – an open randomized controlled study. Acupuncture in Medicine 2004;22(1):14-22.
- Vas J, Perea-Milla E. Mendez C. Acupuncture and moxibustion as an adjunctive treatment for osteoarthritis of the knee – a large case series. Acupuncture in Medicine. 2004;22(1):23-28.
- Vas J, Mendez C, Perea-Milla E. Acupuncture vs Stretberger needle in knee osteoarthritis – an RCT. Acupuncture in Medicine 2006;24(Suppl):S15-24.
- Linde K, Streng A, Hoppe A, Jurgens S, Weidenhammer W, Melchart D. The Programme for the Evaluation of Patient Care with Acupuncture (PEP-Ac) – a project sponsored by ten German social health insurance funds. Acupuncture in Medicine. 2006;24(Suppl):S25-32.
- White A, Foster N, Cummings M, Barlas P. Acupuncture treatment for chronic knee pain: a systematic review. Rheumatology 2007;doi:10/1093/rheumatology
- Airaksinen O, Brox JL, Cedraschi C, Hildebrandt J, Klaber-Moffett J, Kovacs F, et al. European guidelines for the management of chronic nonspecific low back pain. (Chapter 4). Eur Spine J 2006;15:S192-300.
- Ammendolia C, Furlan AD, Imamura M, Irvan E, van Tulder M. Evidence-informed management of chronic low back pain with needle acupuncture. The Spine Journal 2008;8:160-172.
- Marcus P. Acupuncture in modern medicine. Acupuncture in Medicine 1992;10(S):101-108.
- Liggins CA. Guidelines for safe acupuncture practice. Meridian Special Revised Edition from the Acupuncture Association of the South African Society of Physiotherapy. 2006:1-26.