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How does acupuncture work? The role of S1 remapping

Acupuncture is a medical therapy that originated in China several thousand years ago and is rooted in a complex practice ritual based on a philosophy that predates our current understanding of physiology. Despite its long history, though, the intervention itself, particularly when coupled with electrical stimulation, significantly overlaps with many conventional peripherally-focused neuromodulatory therapies. A large body of clinical research has explored acupuncture for chronic pain disorders, demonstrating that acupuncture may be marginally better than sham acupuncture (e.g., non-inserted needles) in reducing pain ratings, but with small effect size. Still, several questions remain: how exactly does acupuncture work? Is acupuncture any better at improving physiological (i.e., objective) outcomes for chronic pain?

Even after so much clinical research, controversy persists as to whether or not acupuncture differs from placebo. Sham (non-inserted needle) acupuncture, which certainly sends inputs to the brain via skin receptors, is a sham device coupled with specific ritual and may thus produce a stronger placebo effect than, for example, a placebo pill. However, such symptom improvements may occur due to completely different physiological mechanisms compared to real acupuncture, whose mechanisms may more specifically target pathophysiology.

Most chronic pain disorders lack established biomarkers or objective outcomes. However, for carpal tunnel syndrome (CTS), a neuropathic pain disorder, local peripheral nerve-based outcomes are well established. These outcomes reflect physiology of the median nerve, which suffers from ischemia and fibrosis due to CTS, an entrapment neuropathy. Moreover, it’s not just the nerve in the wrist that’s affected in CTS. Research has clearly demonstrated that the brain, and particularly the primary somatosensory cortex (S1), is re-mapped by CTS. Following up on our pilot acupuncture neuroimaging study, our recent study is the first sham-controlled neuroimaging acupuncture study for CTS. Our results demonstrated that both real and sham acupuncture improved CTS symptoms. However, objective/physiological outcomes (both at the wrist and in the brain) showed specific improvement for acupuncture, compared to sham acupuncture, and were linked to long-term improvement in CTS symptoms.

Basic Acupuncture by Kyle Hunter. Public domain via Wikimedia Commons.

Our results are analogous to a recent sham-controlled study of albuterol inhaler for asthma, which demonstrated that, while sham acupuncture and placebo inhaler was as effective as an albuterol inhaler in terms of symptom reduction, objective physiological outcomes (i.e., spirometry to assess forced expiratory volume) demonstrated significant improvement only for albuterol. Hence, sham acupuncture may “work” by modulating known placebo circuitry in the brain. In contrast, real acupuncture may improve symptoms by re-wiring the primary somatosensory cortex, in addition to modulating local blood flow to the peripheral nerve in the wrist. In other words, both peripheral and central neurophysiological changes in CTS may be halted or even reversed by electro-acupuncture interventions that provide more prolonged (compared to sham acupuncture) and regulated input to the brain – something that future longer-term neuroimaging studies should explore.

Interestingly, in S1, different body areas are represented in spatially distinct cortical regions. In fact, this body-specific map may serve as the basis for a crude form of “acupoint specificity” for acupuncture – a controversial topic, for sure. In the current study, we evaluated this speculative hypothesis by also comparing acupuncture local to the most-affected wrist with acupuncture targeting the opposite ankle. Our results suggested that both local and distal acupuncture improve median nerve function, and that neuroplasticity in S1 subregions specifically targeted by these local and distal acupuncture interventions (i.e. wrist and leg S1 cortical representations, respectively) were linked to improvements in median nerve function at the wrist following therapy.

While our research is an important step toward understanding how acupuncture works, more research linking objective/physiological and subjective/psychological outcomes for acupuncture analgesia needs to be performed. Once we better understand how acupuncture works to relieve pain, we can better optimize this therapy to provide effective, non-pharmacological care for chronic pain patients.

Featured image: 20100928 AlphaCityAcupunks-8 by Marnie Joyce. CC BY 2.0 via Flickr.

Recent Comments

  1. John Marlon

    If interested in this subject I suggest reading some of the works by Dr. Ji-Sheng Han. In particular The Neurochemical Basis of Pain Relief by Acupuncture, volumes 1 and 2.

  2. Anna Kelly, MD, L.Ac.

    Intriguing research! I think of the Tan balance method of acupuncture, which I often utilize in the clinic with great results, and its treatment of right wrist pain (for example) with points on the opposite ankle, and no local (wrist) points. Obviously there is a connection via the somatosensory cortex of these 2 limb regions. What, precisely, is the “known placebo circuitry in the brain”?

  3. Stephen Rodrigues, MD

    Acupuncture is and acupuncture is not what you think it is supposed to be.
    Acupuncture, the stainless steel metallic tools are the most perfect for a particular universal invisible paradigm for pain and dysfunctions.

    It’s a term that describes in the entire encyclopedia of logic, reasoning, mythology, science and evidence.
    If one throws out everything except the science you’ll end up with a tool.
    The most important instrument ever invented by humankind.
    Actually it’s a derivation of the nail.
    The nail is the most important tools ever discovered by humankind.
    Match that with a hammer and then you can build monuments. I.e. The hammer and chisel build the pyramids.

    C. Chan Gunn, Janet G Travell, and Edward Rachlin all solve this problem a half a century ago.
    Here’s the equation: Intramuscular micro scars + intramuscular stimulation = resolution of the intramuscular micro scars.

    That’s it – plain and simple.
    The needle is a stimulating device for reinjury which will ignite the innate healing cascade of wound repair which is the only force which can heal.

    One of the beautiful things about the human body is that it is automatic, self-contained, auto healing, and perfection.
    It’s pretty much idiot proof. Thank goodness because if my head was not attached to get it.
    The only thing you have to do in favor of their body, mind, and soul is to be loyal to our daily chores.
    Well-balanced diet
    Mindfulness, brain training for pain exercise, and junk data deletion.
    Physical exercise, physical training, and physical therapy.
    Sleep hygiene making certain that we have a steady-state regimen.

    Believe it or not that’s all we have to to do to maintain wellness.
    BUT – There the teeny-weeny little bitty data point very in the above and that is muscles can only contract and we are required to pull them out every day.
    Stretch is an absolute daily requirement.
    The lack of stretch is the number one reason why people kill themselves.
    Hard to believe yet true.

    There was a time when everyone believe the earth was flat – although it’s literally impossible people believe that.
    Everyone agreed until we really needed to know the earth was round and then everyone accepted this fact.
    There was a time when everyone believe there were group of people who were only worth 3/5 of a human being – although it’s not true and literally impossible.
    Everyone agreed until we really needed to know.
    That event took the Civil War to settle.
    Were still fighting that battle right now.

    As a family practice Doctor who now understands that there only 3 categories of problems or pain: injury, invasion and malfunction.
    Injury is what football players get when they crash into each other thousands of times.
    Our skin, subcutaneous, connective tissue, and muscle tissues act like a shock absorbing flack vest protecting us from breaking.
    It’s a perfect design. It does require daily maintenance. The treatment for injury is lots and lots and lots of TLC in the form of elbow grease, hands-on manipulative physical therapy.
    Muscles of the first and natural location where chronic pain and dysfunction resides.
    The skeleton and nervous system cannot store and project out pain signals because it’s impossible.
    Invasion must receive medication and or surgery.
    Malfunction must receive surgery and or medication.
    Critial point of humaity
    Injury will not respond to medications or surgery.

    Injury come from life and living.

    Our muscles take a licking with stresses strains wounds and scars and require – one of the most important daily requirements everyone absolutely has to do in that is – stretch.

    If we don’t stretch everyday our muscles will do what they are supposed to do and began to fill up with stresses, strains, wounds, and scars contract lockup and then squeeze the life out of us.

    If we don’t take care of ourselves particularly with sleep retreat restoration our muscles will not have a chance to heal thoroughly and completely.

    Our muscles will just store those noisy wounds and scars until we all get a chance to get back to our muscles.

    Love your muscles and they will love you back.

    These microscopic wounds and scars will increase in density over decades – without stretching – and they will began to falter, atrophy, dystrophy, and fail to support a quality of life.

    Muscle failure is chronic pain. Muscles will fail through 5 stages. Stage 5 Muscle Failure is complex chronic miserable pain in the treatment of choice most people will take into their own hands to suicide.

    Muscles will only respond to stretch.

    Stretch breaks up all of those wounds and scars so that mother nature can go in and healed them by natural processes.

    Muscles full of stresses and strains wounds and scars will fulfill their DNA programmming which is to constrict squeeze and like a boa constrictor will crush nerves bones in the life out of you.

    Many people will escape this torment by killing themselves.

    There only 3 ways to help your muscles heal from the inside; 1. Stretch. 2. Stretch plus thin needling to reboot and reset the contractile engines. 3. Stretch plus reboot plus micro mincing the muscles with a hypodermic needle.

    This is what you think, believe, and know to be true yet incorrect which is a travesty of humankind:
    back pain plus spinal fusion equals resolution. No this is impossible and illogical.
    Back pain plus opium and cocaine derivatives equals logical management. No this is impossible and illogical.

    The idea of removing skeletal components was invented to circumvent physical therapy and to think you can quick fix the human body by using radiologic evidence.

    60-40 years ago my predecessors decided to only use surgery and drugs to treat a normal process when neglected will become deadly.

    Every American has been trapped in this for-profit, for-prestige, for-ego, for- market share, travesty against humanity.

    With my knew awareness I call this situation an Epic American Health Services Holocaust.

    My medical predecessors lost their minds, blinded themselves and decided to use surgery and drugs and the place of injury. Although there is a little benefit from those it’s impossible for them to fully and thoroughly benefit injury embedded in the muscle tissues.

    Physical therapy costs you about 50 bucks and then you will be back to normal.

    The close minded, criminal minded, deceitful and deceptive deception idea of using surgery on YOU will generate the doctors, anesthesiologists, hospital, hospital CEOs in Wall Street $100,000 per event – leaving you with nothing which will benefit your pain. Basically they’re using millions of Americans as cash for all units.

    The only downside to this is the downstream abject misery, carnage, and human waste.


    If you would like some information which would help you help yourself follow my links.

  4. Anna Kelly, MD, L.Ac.

    Intriguing research! I think of the Tan balance method of acupuncture, which I often utilize in the clinic with great results, and its treatment of right wrist pain (for example) with points on the opposite ankle, and no local (wrist) points. Obviously there is a connection via the somatosensory cortex of these 2 limb regions. What, precisely, is the “known placebo circuitry in the brain”?

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