The Physiology of Acupuncture

Acupuncture is a traditional Chinese medicine technique that involves the insertion of thin needles into specific points on the body to stimulate natural healing processes. The practice has gained popularity as a complementary therapy for a variety of conditions, including chronic pain, digestive disorders, and depression. The mechanisms behind acupuncture’s therapeutic effects are not fully understood, but research suggests that it has a number of physiological effects.

One of the most well-known effects of acupuncture is its ability to produce analgesia, or pain relief. Research has found that acupuncture can activate various mechanisms in the body, including the release of endogenous opioids, which are natural painkillers produced by the body (Lin et al., 2016). Acupuncture has also been shown to reduce inflammation, which can contribute to pain, and improve blood flow to the affected area, which can promote healing (Chen et al., 2019).

Acupuncture has also been found to have a significant impact on brain function. Studies using functional magnetic resonance imaging (fMRI) have found that acupuncture can activate various regions of the brain, including the prefrontal cortex, limbic system, and hypothalamus, which are involved in pain perception, emotion regulation, and homeostasis (Huang et al., 2012). Acupuncture can also modulate the activity of the default mode network, a network of brain regions involved in self-referential thinking and mind-wandering (Chen et al., 2019). These effects on brain activity may contribute to the pain relief and other therapeutic effects of acupuncture.

Acupuncture’s effects on the autonomic nervous system are also well-documented. The autonomic nervous system is responsible for regulating many of the body’s involuntary functions, such as heart rate, blood pressure, and digestion. Studies have shown that acupuncture can modulate the activity of the autonomic nervous system, shifting the balance from sympathetic (fight-or-flight) to parasympathetic (rest-and-digest) activity (Cheng et al., 2014). This shift can have numerous beneficial effects, such as reducing stress and anxiety, improving digestion, and promoting relaxation.

Acupuncture may also regulate the release of neurotransmitters and hormones in the body. Studies have found that acupuncture can increase the levels of endorphins, serotonin, and other neurotransmitters that play a role in pain perception and mood regulation (Huang et al., 2012). Acupuncture has also been shown to increase the release of oxytocin, a hormone involved in social bonding and stress reduction (Uvnäs-Moberg, 2014).

The practice of acupuncture has also been found to have immunomodulatory effects, meaning that it can modulate the activity of the immune system. Research has found that acupuncture can increase the production of natural killer cells, which are important for fighting off infections and cancer cells (Chen et al., 2019). Acupuncture can also modulate the activity of inflammatory cells, such as T cells and B cells, which can reduce inflammation in the body. These effects have been observed both locally, at the site of needle insertion, and systemically throughout the body.

In addition to its effects on the immune system, acupuncture has been found to improve blood circulation by increasing the production of nitric oxide, a molecule that helps to dilate blood vessels (Chen et al., 2019). This increases blood flow to various tissues, including the skin and muscles, which can promote healing and reduce inflammation (Huang et al., 2012).

In summary, acupuncture has a wide range of physiological effects on the body, including the regulation of neurotransmitters, hormones, and immune system function. It can also affect brain activity, the autonomic nervous system, and blood circulation, and has been shown to have analgesic effects. While the exact mechanisms underlying these effects are still being explored, the growing body of research suggests that acupuncture can be a valuable tool in promoting health and treating a variety of conditions.

References:

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Acupuncture Reduces High Blood Pressure

A few months ago Terenteva et al. published their research findings on the effect of acupuncture in a group of middle-aged individuals with hypertension. Forty five adults with hypertension were randomly assigned to either an acupuncture group or a control group. The acupuncture group received 3 sessions of acupuncture per week for 8 weeks. The following points were needled bilaterally for 20 mins: St36, St37, Pc5, Pc6, Liv3, Sp4, and LI11.

The researchers found that acupuncture “resulted in beneficial reductions of aortic hemodynamics and arterial stiffness”. “Acupuncture decreased brachial systolic blood pressure (SBP) and diastolic blood pressure (DBP) by approximately 10 and 6 mmHg, respectively.” It also reduced aortic SBP by 10 mmHg. Although these effects seem small, they can decrease cardiovascular risk by over 30%.

The mechanisms behind the effects are thought to come from an increase in secretion of vasodilators (nitric oxide) and a decrease in secretion of vasoconstrictors (endothelin-1, angiotensin II). Modulation of the autonomic nervous system by decreasing sympathetic activity may also play a part.

Acupuncture Benefits Patients With Tennis Elbow

Earlier this year Ural et al, from Yildirim Beyazit University Medical School in Ankara, studied the effects of acupuncture on patients with lateral epicondylitis/epicondylopathy (LE). Lateral epicondylitis or tennis elbow, as it’s more commonly known, is an overuse injury that leads to pain on the lateral aspect of the elbow and/or forearm. It usually affects people aged 40 or over. Treatment can include rest, NSAIDS, bracing, physiotherapy, shockwave therapy, steroid injections, platelet-rich plasma injections, Botox injections or surgery.

Diagnostic ultrasound of the common extensor tendon (CET) in people with LE can reveal oedema, bone irregularities and increased CET thickness. Common extensor tendon thickness provides information on the severity and progress of LE.

The authors randomly split 41 patients with LE into 2 groups. The control group was advised to rest and prescribed NSAIDS, exercise and bracing. The acupuncture group received the same intervention as the control group but with acupuncture in addition. The patients were offered 10 sessions (25 min each) of acupuncture over a period of 4 weeks. Six acupoints (LI4, LI10, LI11, Lu5, SJ5 and one Ah Shi point) were used and the needles were inserted into muscle and stimulated manually to achieve deqi (needling sensation). The assessments prior to and following the course of treatment consisted of a subjective pain evaluation, pressure pain threshold testing, a function questionnaire (Duruoz Hand Index) and an ultrasound evaluation of CET thickness.

Results showed that pain and function scores improved in both groups. Whereas pain pressure thresholds and CET thickness decreased in the acupuncture group only. Improvements in pain, function, pain pressure threshold and CET thickness were significantly higher in the acupuncture group.

The authors conclude that “acupuncture treatment not only reduces pain but improves the tendon morphology in LE patients.”

Acupuncture Benefits Patients With Carpal Tunnel Syndrome

A few months ago Ural et al, from Yildirim Beyazit University Medical School in Ankara, published an interesting paper looking into the effects of acupuncture on carpal tunnel syndrome (CTS). Their work was published in Evidence-Based Complementary and Alternative Medicine.

CTS affects more women than men and has a prevalence of 1-5%. Causes include overuse of the hand, diabetes, rheumatoid arthritis, hypothyroidism and pregnancy. Symptoms can include pain numbness and tingling of the first 3-4 fingers, as well as weakness and wasting of the hand muscles supplied by the median nerve. Some of the commonly used treatments are rest, non-steroidal anti-inflammatory drugs, splinting, steroid inject injections, vitamin B6 supplementation, physiotherapy and eventually surgery. The cross-sectional area (CSA) of the median nerve has been found to increase in association with the severity of CTS. In fact, this increase in CSA is so reliable that it can be used to diagnose CTS or predict the need for surgery.

Ural et al recruited 27 female patients with mild to moderate CTS. On average, their symptoms had lasted about 1.5 years. They were randomised into an acupuncture group and a control group. Both groups wore a night wrist splint for 4 weeks. In addition to the night splint, the acupuncture group received 10 sessions of acupuncture over 4 weeks. Nine acupuncture points were used and the needles were retained for 25 minutes. Evaluations of hand function (DHI and DASH) and pain (VAS), electrophysiological tests and ultrasound measurements of CSA were taken before and after treatment.

The results showed that symptom severity, hand function and electromyographic measurements improved in both groups but improvements were significantly greater in the acupuncture group. In the acupuncture group, pain decreased by just under 50% (from 9/10 to less than 5/10), and hand function measurements improved by 15-22%. These are impressive results when we consider that they took place over a month and that patients had been symptomatic for 1.5 years prior to that. CSA of the median nerve was unchanged in the control group but significantly reduced in the acupuncture group (8% reduction). The authors believe that this is the first time the effect of acupuncture on median nerve CSA in patients with CTS has been demonstrated.

Ural et al conclude that “acupuncture improves not only clinical and electrophysiological findings but also morphological features in patients with CTS”, however “the relationship between change of CSA and electrophysiological changes was not correlated. The small sample size of our study may cause this result”. They suggest confirming the results in future studies with larger sample and long-term monitoring.

Acupuncture Decreases High Blood Pressure

A recent study published in Medical Acupuncture has shown that electroacupuncture can significantly reduce systolic and diastolic blood pressure in hypertensive subjects. After the treatment, plasma levels of norepinephrine, renin and aldosterone were all significantly decreased and this is thought to be related to the beneficial effects of the electroacupuncture.

Acupunture Mechanisms Revealed

Research on mice by da Silva et al has revealed new mechanisms underpinning the workings of acupuncture. They injected carrageenan into the calf muscles of mice. This created an inflammatory response with associated pain and swelling. Manual acupuncture of Spleen 6 (an acupuncture point in the lower leg) reduced pain, heat and swelling of the muscle. Repeated acupuncture of Spleen 6 produced a phenotypic change from pro-inflammatory cells (M1 macrophages) to anti-inflammatory cells (M2 macrophages) with an associated increase in interleukin-10 concentrations in muscle which led to reduced pain and inflammation.

Acupressure Wristband Relieves Nausea

A few days ago Medical News Today reported on how wearing a wristband could affect nausea. Nausea is one of the most debilitating symptoms experienced by people who get migraine. Dr. Zoltan Medgyessy of the Berolina Clinic in Lohne, Germany studied 41 patients who experienced an average of 33.1 migraine days during the previous three months. Their average nausea intensity was 6.2 out of 10. Within less than 30 mins of wearing the wristbands, over 80% of patients experienced a decrease in nausea symptoms and the average estimated nausea intensity dropped to 2.9 out of 10.

The wristband stimulates the acupuncture point Pc6 (Neiguan) which has been used for centuries in Traditional Chinese Medicine to help relieve nausea. Dr. Medgyessy commented “acupressure wristbands are drug-free and that is an important advantage in using this therapy for migraine nausea as they have no risks for interaction with migraine drugs or the side effects commonly experienced with antiemetics, such as dizziness or tiredness”. The wristbands can also be used for nausea from morning sickness, motion sickness, chemotherapy and post-operative nausea.

Acupuncture NICE For Headaches

The National Institute for Health and Clinical Excellence (NICE) has released its first clinical guideline on how to diagnose and manage headaches. It differentiates 4 types of headache: tension-type headaches, migraines, cluster headaches and medication overuse headaches. NICE recommends acupuncture as a treatment option for tension-type headaches and it says we should “consider a course of up to 10 sessions of acupuncture over 5–8 weeks for the prophylactic treatment of chronic tension-type headache”.

Acupuncture Helps Nerves Regenerate

Several experiments have been conducted on animals to study the effects of acupuncture or electroacupuncture on nerve injuries. Here are some of the results and conclusions:

• acupuncture increases the survival of damaged neurons
• electroacupuncture increases the number of nerve fibres
• electroacupuncture increases axon density and blood vessel area
• electroacupuncture improves nerve conduction speed
• electroacupuncture improves the function of de-innervated muscle tissue

So those are the effects on rats, rabbits and frogs…but what about humans? Well, a study conducted in Germany at the Heildelberg School of Chinese Medicine and published in the European Journal of Neurology showed some promising results. Forty seven patients with peripheral neuropathies of unknown cause were assigned to either an acupuncture group or a control group (the control group received the best medical care but no specific treatment for peripheral neuropathy). The patients were evaluated over a year by nerve conduction studies.

Over three-quarters of the acupuncture group improved. These results are even more impressive when we realise that the natural progression of the neuropathies, as shown by the control group, was one of gradual deterioration.

The overwhelming data suggests that acupuncture can help promote nerve regeneration and this remains true whether the nerve problem results from injury or some undefined cause.

Pain And Perception

I read an interesting article in BBC News Health a couple of weeks ago. It reviewed 2 recent studies on pain. The first was published in The Journal of Pain by Atsuo Yoshino et al. Subjects were shocked with an electric current whilst they were shown pictures of sad, happy or neutral faces. Photos of an emotional face usually provoke the same emotional response in the person viewing the picture. Although the electrical stimulation was the same in all cases, subjects felt more pain when looking at sad faces.

The second study was conducted by Marion Hofle et al. in Pain. The researchers asked the subjects to place one of their hands under a screen. On the screen, they played a video of a hand being pricked by a needle, poked by a cotton bud or just left alone. The subjects perceived the hand on the screen as their own.  A painful or non-painful stimuli was applied simultaneously to the video. Viewing the needle prick increased the unpleasantness ratings of the stimulus.

As these studies have shown, negative emotional states and negative expectation seem to increase pain and so the mind plays an important role in the experience of pain. As a physiotherapist, dealing with pain is a daily occurrence and I can remember qualifying as an acupuncturist over 10 years ago…I was desperately keen to use my new skill on anyone that was willing to try and worked hard at convincing anyone that was hesitant to try! With those that were initially hesistant…possibly due to a slight needle aversion, I quickly noticed their exaggerated responses to acupuncture. I can remember several occasions when I would gently touch them with a finger or with the plastic guide tube that surrounds the needle and they would jump and shout “ouch”…to which I would reply “relax, we haven’t started yet!” I’ve now learnt from those experiences and no longer feel the need to convince everyone to have acupuncture…no matter how great I think it is!

John Milton was right in Paradise Lost…“The mind is its own place, and in itself can make a heaven of hell, a hell of heaven.”