Acupuncture: Review of the evidence

A demonstration of electro-acupuncture for a lower body injury

A demonstration of electro-acupuncture for a lower body injury

Most people associate acupuncture with Traditional Chinese Medicine (TCM), but it is important to be aware that Acupuncture and TCM are not tethered at the hip. Regardless of its theoretical basis, based on the traditional and official definition, the term acupuncture refers to the actual insertion of a needle (usually a solid needle) into the body (Fan et al. 2016). 

A Very Brief Overview of Western Medical Acupuncture 

The word acupuncture meaning ‘to prick with a needle’ was coined by Willem ten Rhyne. 

The earliest detailed report on Chinese and Japanese medicine to be written by a European was by Willem ten Rhyne, a Dutch physician who published Dissertatio de arthritide in 1683. 

Following this lineage, the concept of medical acupuncture was pioneered by Felix Mann who began to view acupuncture as a form of peripheral nerve stimulation technique. In this approach needles are inserted into anatomically defined sites, and stimulated manually or with electricity.

Preferential sites for acupuncture stimulation are associated with areas rich in specialized sensory receptors such as muscle spindles, Golgi tendon organs, ligament receptors, Paciniform and Ruffini’s receptors (joint capsules), deep pressure endings (within muscle belly), and free nerve endings (muscle and fascia). All of these areas are highly innervated and as a result there are a number of physiological responses that help modulate the experience of pain.

Acupuncture Research Has Matured

For certain condition (particularly musculoskeletal pain) there is evidence from The Cochrane Collaborative and other high quality systematic reviews:
• Chronic pain (MacPherson et al. 2017, Vickers et al. 2012)
• Acute pain (Murakami et al. 2017)
• Low back pain (Andronis et al. 2017, Chou et al. 2017, Qaseem et al. 2017)
• Tension-type headaches (Linde et al. 2016)
• Migraines (Linde et al. 2016, Yang et al. 2016)
• Osteoarthritis (Lin et al. 2016, Woods et al. 2017)

Mechanism of Action

The responses to acupuncture are multifactorial - physiological and psychological factors interplay in a complex manner. Exactly how acupuncture works is still up for discussion. Researchers have been studying potential biological pathways by which needling might relieve pain. Most of the research in the past have focused on endogenous opioids.

Another plausible mechanism of action is a localized adenosine response, as it has been demonstrated that acupuncture needles trigger a release of adenosine from the surrounding cells into the extracellular fluid. This chemical release works to ease pain by stimulating neuroimmune responses at both the peripheral and central levels.

It is important to acknowledge the placebo response, but also to be aware that the placebo response is likely just one of the reasons why patients respond to acupuncture. It is also a within the realm of reasons that patients have a complex biopsychosocial response to acupuncture that INCLUDES but is not LIMITED to placebo. Several plausible theories attempt to explain how acupuncture works but none are proved beyond doubt, this includes but is not limited to:
• The meaning response (Moerman et al. 2002)
• The gate control theory of pain (Zhang et al. 2012)
• Stimulate of the release of endogenous opioids (Han 2004)
• Stimulate of the release of endogenous cannabinoids (McPartland et al. 2014, Hu et al. 2017)
• Purinergic Signaling (Tang et al. 2016Sawynok et al. 2016)
• Interactions between non-neuronal cells and neurons (Ji et al. 2016, Pavlov et al. 2017)
• Neuroplasticity (Maeda et al. 2017)
• C tactile Afferents (Chae et al. 2017)
• Mesenchymal Stem Cells (Salazar et al. 2017
• Local changes in microcirculation (Kaneko et al. 2016, Tsuchiya et al. 2007)

Summary Points: Many clinicians explain the mechanism of action in neurophysiological terms.

If you use Occam's razor, the insertion of an acupuncture needle is a form of novel stimuli, that functions by sending anti-nociceptive input to the neuroimmune system. This contributes to a number of physiological changes across different areas of the peripheral and central nervous systems, including peripheral receptors, dorsal horn of the spinal cord, brainstem, sensorimotor cortical areas, and the mesolimbic and prefrontal areas.

More to Explore

Related Links
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• What role can acupuncture play in concussion rehab 
• Acupuncture for knee pain
• Acupuncture for neck pain

Research Links
Bivins, R. (2001). The needle and the lancet: Acupuncture in Britain, 1683-2000. Acupuncture in Medicine.

Fan, A.Y., He, H. (2016). Dry needling is acupuncture. Acupunct Med. 

White, A. & Ernst, E. (2004). A brief history of acupuncture. Rheumatology.

Low back pain
Andronis L, Kinghorn P, Qiao S, Whitehurst DG, Durrell S, McLeod H. (2017). Cost-Effectiveness of Non-Invasive and Non-Pharmacological Interventions for Low Back Pain: a Systematic Literature Review. Appl Health Econ Health Policy.

Chou, R., Deyo, R., Friedly, J., Skelly, A., Hashimoto, R., ... Brodt, E.D. (2017). Nonpharmacologic Therapies for Low Back Pain: A Systematic Review for an American College of Physicians Clinical Practice Guideline. Ann Intern Med.

Qaseem, A., Wilt, T.J., McLean, R.M., Forciea, M.A. (2017). Clinical Guidelines Committee of the American College of Physicians.. Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain: A Clinical Practice Guideline From the American College of Physicians. Ann Intern Med.

Chronic Pain
MacPherson, H., Vickers, A., Bland, M., Torgerson, D., Corbett, M., Spackman, E., ..., Watt, I. (2017). Acupuncture for chronic pain and depression in primary care: a programme of research. Southampton (UK): NIHR Journals Library.

Vickers, A. J., Cronin, A. M., Maschino, A. C., Lewith, G., Macpherson, H., Foster, N. E., . . . Collaboration, F. T. (2012). Acupuncture for Chronic Pain. Archives of Internal Medicine.

Acute Pain
Murakami, M., Fox, L., Dijkers, M.P. (2017). Ear Acupuncture for Immediate Pain Relief-A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Pain Med.

Linde, K., Allais, G., Brinkhaus, B., Fei, Y., Mehring, M., Vertosick, E. A., . . . White, A. R. (2016). Acupuncture for the prevention of episodic migraine. Cochrane Database of Systematic Reviews.

Yang, Y., Que, Q., Ye, X., Zheng, G.h. (2016). Verum versus sham manual acupuncture for migraine: a systematic review of randomised controlled trials. Acupunct Med.

Tension Headaches
Linde, K., Allais, G., Brinkhaus, B., Fei, Y., Mehring, M., Shin, B., . . . White, A. R. (2016). Acupuncture for the prevention of tension-type headache. Cochrane Database of Systematic Reviews.

Knee OA
Lin, X., Huang, K., Zhu, G., Huang, Z., Qin, A., & Fan, S. (2016). The Effects of Acupuncture on Chronic Knee Pain Due to Osteoarthritis: A Meta-Analysis. The Journal of Bone & Joint Surgery.

Woods, B., Manca, A., ... Sculpher, M. (2017). Cost-effectiveness of adjunct non-pharmacological interventions for osteoarthritis of the knee. PLoS One.

Mechanism of Action
Chae, Y., Olausson, H. (2017). The role of touch in acupuncture treatment. Acupunct Med.

Chavan, S. S., & Tracey, K. J. (2014). Regulating innate immunity with dopamine and electroacupuncture. Nature Medicine.

Gerber, L.H., Sikdar, S., Aredo, J.V., Armstrong, K., Rosenberger, W.F., Shao, H., Shah, J.P. (2017). Beneficial Effects of Dry Needling for Treatment of Chronic Myofascial Pain Persist for 6 Weeks After Treatment Completion. PM R.

Han, J.S. (2004). Acupuncture and endorphins. Neurosci Lett.

Hu, B., Bai, F., Xiong, L., Wang, Q. (2017). The endocannabinoid system, a novel and key participant in acupuncture's multiple beneficial effects. Neurosci Biobehav Rev.

Ji, R.R., Chamessian, A., Zhang, Y.Q. (2016). Pain regulation by non-neuronal cells and inflammation. Science.

Kaneko, Y., Kime, R., Furuya, E., Sakamoto, A., & Katsumura, T. (2016). Effects of Acupuncture Stimulation on Muscle Tissue Oxygenation at Different Points. Advances in Experimental Medicine and Biology.

Langevin, H. M. (2014). Acupuncture, Connective Tissue, and Peripheral Sensory Modulation. Critical Reviews in Eukaryotic Gene Expression.

Lund, I., & Lundeberg, T. (2016). Mechanisms of acupuncture. Acupuncture and Related Therapies.

Maeda, Y., Kim, H., Kettner, N., Kim, J., Cina, S., .... Napadow, V. (2017). Rewiring the primary somatosensory cortex in carpal tunnel syndrome with acupuncture. Brain.

Mcpartland, J. M., Guy, G. W., & Marzo, V. D. (2014). Care and Feeding of the Endocannabinoid System: A Systematic Review of Potential Clinical Interventions that Upregulate the Endocannabinoid System. PLoS ONE.

Moerman, D. E. (2002). Deconstructing the Placebo Effect and Finding the Meaning Response. Annals of Internal Medicine.

Nardini, C., Devescovi, V., Liu, Y., Zhou, X., Lu, Y., Dent, J.E. (2016). Systemic Wound Healing Associated with local sub-Cutaneous Mechanical Stimulation. Sci Rep.

Pavlov, V.A., Tracey, K.J. (2017). Neural regulation of immunity: molecular mechanisms and clinical translation. Nat Neurosci.

Salazar, T.E., Richardson, M.R., Beli, E., ... Grant, M.B. (2017). Electroacupuncture Promotes CNS-Dependent Release of Mesenchymal Stem Cells. Stem Cells.

Sawynok, J. (2016). Adenosine receptor targets for pain. Neuroscience.

Tang, Y., Yin, H., Rubini, P., & Illes, P. (2016). Acupuncture-Induced Analgesia: A Neurobiological Basis in Purinergic Signaling. The Neuroscientist.

Torres-Rosas, R., Yehia, G., . . . Ulloa, L. (2014). Dopamine mediates vagal modulation of the immune system by electroacupuncture. Nature Medicine.

Tsuchiya, M., Sato, E.F., Inoue, M., Asada, A. (2007). Acupuncture enhances generation of nitric oxide and increases local circulation. Anesth Analg.

Zhang, F., Wu, L., ... Liu, H. (2017). Neurobiological Mechanism of Acupuncture for Relieving Visceral Pain of Gastrointestinal Origin. Gastroenterol Res Pract. (OPEN ACCESS)

Zhang, R., Lao, L., Ren, K., & Berman, B. M. (2014). Mechanisms of Acupuncture–Electroacupuncture on Persistent Pain. Anesthesiology. (OPEN ACCESS)

Zhang, Z.J., Wang, X.M., McAlonan, G.M. (2012). Neural acupuncture unit: a new concept for interpreting effects and mechanisms of acupuncture. Evid Based Complement Alternat Med.