How Does Acupuncture Work?

By: Dr. Steven Scappaticci, B.Sc. (Hons.), CSCS, DC, FRCms

Acupuncture is a treatment modality that has been around for centuries. With origins dating back to China in 100 BC, acupuncture now comes in many forms. The most popular form is that of Traditional Chinese Medicine (TCM). Having said that other types of acupuncture do exist, namely Contemporary Medical Acupuncture, Japanese Superficial Acupuncture, and the lesser known Cosmetic Acupuncture, just to name a few. Needles can be stimulated manually or electrically with or without the use of co-interventions such as moxibustion, herbs, and physical therapy.
 
            This blog will not compare or make claims as to the efficacy of each one; rather it will focus on the scientific rationale that exists for Contemporary Medical Acupuncture – the method I practice, in an attempt to explain to the reader how acupuncture works.
 
            Regardless of the type of acupuncture practiced, all acupuncture ideologies use very fine needles. The quickest summation of the action of acupuncture, particularly Contemporary Medical Acupuncture is, “peripheral nerve stimulation with fine solid needles (with or without electricity) to induce physiological changes on the activity of the nervous system & its effectors, for therapeutic purposes” (McMaster Contemporary Medical Acupuncture, 2016).
 
            But what does that even mean? Before we answer that, we must understand that any pain we experience, whether it be emotional or physical, is experienced in the brain. Pain is in the brain! If we could control our brains, we could control our pain – obviously a feat much easier said than done. However, this is a good segway into the concept of Neuromodulation, which is the ability of the nervous system to regulate some of its own activities in response to external (exogenous) or internal (endogenous) stimuli.
 
            The body is the master compensator, meaning if it has trouble with a particular function, it will find the path of least resistance to perform that action in a different way. An example is when walking, if an individual cannot send their leg forward far enough while keeping their leg straight, the body may compensate by rotating the trunk to help move that leg even further. Why and how these things happen are not always fully understood at the neurological level, as we only know a small fraction of how the nervous system works and its capabilities.
 
            But back to the brain! In order to understand pain, we must first understand how the brain interprets pain (Note: I tried to explain things simply, with some extra information in parentheses). All pain that is sent to the brain (via afferent signaling) starts via pain receptors (nociceptors) that are found all over the body. Within our bodies, we have two main nerve types that carry pain information to the brain – C Fibers (diffuse & dull pain) as well as A-Delta Fibers (sharp pain) (Audette & Ryan, 2004).
 
            When there is a site of injury there is inflammation and a release of chemical substances in the tissues that can activate these pain receptors (nociceptors). Specifically, substances such as: Histamine, Protons, Bradykinin, & Substance P all act as pain receptor irritants. When the threshold for peripheral pain receptors becomes lowered, individuals become hypersensitive to pain (Hyperalgesia) (Audette & Ryan, 2004).
 
            When those peripheral fibres (i.e. in the arms, legs…etc.) relay the information to the back of the spinal cord (i.e. dorsal roots at multiple surrounding segmental levels) the signal actually crosses to the other side of the spinal cord before the signal is sent to the brain on the other side of the body (via lateral spinothalamic tract to the sensory cortex on the opposite side of the body) (Audette & Ryan, 2004). So for example, if your left elbow hurts, that sensation is actually interpreted by the right side of the brain! Isn’t that cool?
 
            Now when someone sprains their ankle, there’s often swelling and bruising present and the signs of injury and inflammation are obvious. But what happens when a patient complains of that left elbow pain but when you look at their elbow you do not see those classic signs of inflammation? Well this brings us to the topic of Neurogenic Inflammation, which essentially means that there are substances (listed above) that are lingering due to the trauma that are causing that pain, despite to overt signs of swelling & bruising. This along with some cellular (histological) changes in the tissue cause pain such as this to exist.          
 
            So how do we neuromodulate to decrease pain signaling? It is important to target neuro-reactive sites. These sites generate signals to the brain (neural sensory afferent input) that elicits neurological responses with therapeutic value. These sites can be found everywhere throughout the body in sites such as: neuro-vascular bundles, motor points (this is a big one!), muscle-tendon junctions, joint capsules & ligaments, and more.
 
            As per my education and training, a three level approach is often best when treating pain. First, treating the Local peripheral tissues (i.e. the affected shoulder, elbow, knee…etc.) is essential. Next the Spinal Segmental (spinal cord) levels that supply the affected area are targeted. So if someone were having shoulder pain, it would be beneficial to not only insert needles in their shoulder but also insert needles in the muscles of the neck (at the levels of C4, C5, & C6) as these spinal levels supply the joint, muscles, & skin. Lastly, it is important to target what are called Supra-Spinal level. These are points used in the distal limbs (i.e. hands, feet) to attempt and affect the areas of the brain that deal with chronic pain and emotion.
 
            Skipping over the biochemical nature of the resultant physiology involving acupuncture for simplicity sake, some of the goals of an acupuncture treatment include: increasing blood flow to the tissues (perfusion), increasing strength of the muscles (strength), improved joing awareness (proprioception), and decrease pain signaling (nociception) (McMaster Contemporary Medical Acupuncture, 2016). All of these contribute to decreased pain and improved function.  
 
            For some who are reading this blog, it was all brand new information. It is a very large topic, as there were some aspects I didn’t touch upon. For others it may be a refresher of pre-existing knowledge. Regardless, I hope you can take a few things from it. If you have any questions or comments, I would love to hear from you!
 
References
—  Joseph F. Audette, Angela H. Ryan. The role of acupuncture in pain management. Physical Medicine and Rehabilitation of North America 2004;15:749-772
—  McMaster University: Contemporary Medical Acupuncture Program. (2016).