Discussion on pain
Traditional Chinese Medicine (TCM) is probably one of the oldest complementary therapies and continuously practised systems of medicine in the world. Developed through empirical observation by the Chinese over thousands of years, this unique medical system is used to treat a wide range of diseases, and is of especial use in treating various kinds of pain.
Everyone will, at some time or another, suffer from pain or disability. Pain is an unpleasant experience associated with actual or potential tissue damage. It may arise from accident or injury, cancer, arthritis, a multitude of physical ailments or even emotional distress. It may affect the head, neck, torso or any of the extremities as well as internal organs, causing different kinds of pain, such as headache, neck pain, throat pain, shoulder pain, joint pain, abdominal pain and lower back pain.
No matter what the cause, pain, especially chronic pain, transcends simply physical hurt. It limits the activities of everyday living and can erode the sufferer’s ability to function. However, pain is, in reality, nature’s way of protecting the body from potential tissue damage, because it serves as a warning signal, alerting the person that something is wrong. In this sense we can say that to avoid pain is to avoid severe injury.
How do modem medicine and TCM explain the occurrence of pain? Modern medical research has discovered that pain signals are transmitted by specialised nervous system cells (receptors), which are found throughout the skin and other body tissues. These cells respond to injury, inflammation or tissue damage. Immediately after receiving these messages, the signals travel by electrical and chemical means, from receptors through sensory neurons to the spinal cord and then through interneurons in the spinal cord to the brain, where they are finally interpreted as pain. TCM takes a different view: that the body maintains a balance between the principles of Ym and Yang, and between Qi and Blood. Qi and Blood travel through the body along well-defined pathways called channels. When there is not enough Qi and Blood (Emptiness or Deficiency), or when they are stuck in one area (Fullness or Excess), there is an imbalance between Yin and Yang, the Internal organs are not functioning optimally, and illness and pain develop.
Pain, whether acute or chronic, could have a variety of causes. Acute pain is usually characterised by acute onset, a short duration, normal functioning of both the peripheral and central nervous systems, a predictable course and, in most cases, a good outcome. In terms of modern medicine, acute pain usually is the result of an injury, surgery, inflammation or medical illness. Acute pain often goes away with the healing process.
Chronic pain, however, is different; it is the kind of pain that most people worry about as it lasts beyond the expected time for healing; that is, it does not go away when it is supposed to.
Chronic pain is often difficult to relieve or cure completely, and may occur even if there is no tissue damage or physical cause. The exact causes of chronic pain are not fully understood, or, in other words, one could say that there is no adequate medical explanation for many chronic pain cases.
Pain can be extremely debilitating and frequently requires unique treatment approaches. In some cases it can be seen that the damaged tissues have been repaired, but nevertheless the pain continues. Besides tissue damage, there are some other clinical symptoms associated with pain, such as muscle tension, spasm, stiffness, or weakness. There could also be some degree of immobilisation of an injured part by the patient in order to avoid pain from movement. It has also been observed that, whatever the cause of chronic pain, feelings of frustration, anger and fear make the pain more intense and more difficult to treat.
In short, pain, especially chronic pain, interferes with normal life and physical activities. We could even say that such pain can often diminish the quality of people’s life in terms of their psychology, sociology and physiology. It is, finally, one of the most frequent causes of suffering and disability in the world today.
Pain control by TCM
In Western medicine it is quite common to find or be told that doctors are unable to find the real cause of pain in patients even after extensive examination. Patients are often told: There is nothing wrong with you’, or ‘Sorry, we can do nothing about it, and you’ll have to learn to live with it7 or even ‘It is all in your head’. It is poor practice, however, for a doctor to make such comments to patients; they don’t have to live in pain. Fortunately, since acupuncture has acquired a very good reputation as a treatment for relieving pain, many physicians are now referring their patients for an acupuncture or herbal evaluation, or patients are starting to investigate the potential of acupuncture and herbal treatment for themselves.
In terms of pain control, the effects of Chinese herbal and acupuncture treatment include:
• to relieve pain completely, or give as much relief as possible
• to reduce pain levels
• to improve the ability to deal with pain
• to regulate the emotions
• to increase the energy
• to increase the ability to perform everyday functions
• to enhance the quality of life
• to reduce reliance on inappropriate medications.
Points from different channels are, according to TCM theory, energetically connected to specific organs and body structures. The purpose of acupuncture treatment for pain is to use selected points on these channels to activate Qi and Blood circulation, and balance Yin and Yang. During the treatment, moxibustion and point massage are also often applied simultaneously.
Acupuncture treatment for pain is varied and based largely on what is causing the patient’s suffering; the treatments for acute and chronic pain are often quite different. In chronic pain patients, treatment that had proved useful for acute pain management may lose its effectiveness, be inappropriate or even be counterproductive.
The Chinese do not limit the use of Chinese herbs and acupuncture to alleviating pain; they use combinations of herbs and acupuncture to treat the whole range of diseases that are encountered in association with the pain. These include TCM therapies for hypertension, hypotension, allergy, asthma, diabetes, stomach ulcers, depression, infections, etc. It is clear that many diseases respond better to modem medicine, whereas some may respond better to Chinese herbal medicines and acupuncture. However, in the majority of cases Chinese herbal medicine and acupuncture may either be a reasonable alternative for, or be used in conjunction with modem medicine. For this reason all TCM schools and universities in China continue to offer courses and training in both TCM and modem medicine at present. During Chinese herbal and acupuncture treatment, it should be kept in mind that essential contact and communication with other specialists must be maintained, for instance with neurologists, neurosurgeons, orthopaedists, internists, radiologists, and physical and occupational therapists, so that patients receive the necessary support at their time of greatest need.
In China, increasingly acupuncturists are applying acupuncture to diminish pain directly or decrease the amount of drugs needed for the control of pain, even during surgery. This well-known practice indicates that acupuncture potentially has anaesthetic effects. After conducting thousands of experiments on both animals and people, researchers become firmly convinced that acupuncture was indeed effective in its own right for anaesthesia. In consequence, acupuncture has been used quite successfully in place of chemical anaesthesia for many types of surgery in the last 30 years in China. It has been shown to be effective in gastric (Ye Qiang et al 1984), dental (Lin Guochu et al 1984) and thyroid surgery (Zhuang Xinliang 1984). It is also potentially indicated for those patients unable to tolerate regular anaesthesia. Because of its efficiency in acupuncture anaesthesia, doctors in many hospitals, especially the affiliated hospitals of TCM universities, use acupuncture routinely in cases of thyroidectomy.
The advantages of acupuncture anaesthesia include:
• fewer side-effects than with chemical anaesthesia
• more cooperation from the patient during the operation
• a lack of disturbance of the brain and memory following anaesthesia
• the patient remaining alert during the procedure
• rapid recovery of functional activities after the operation, etc.
The disadvantages of acupuncture anaesthesia include:
• a feeling of pulling and tugging during the operation
• inadequacy with children and some senile patients
• inability to replace all kinds of chemical anaesthesia
• sometimes a need for local chemical anaesthesia, etc.
Modern research on pain control by acupuncture
Over the past thirty years, both patients and professionals have been asking questions about how acupuncture works in a modern, scientific sense? What are the mechanisms? Is there any scientific evidence that supports the effectiveness of acupuncture?
In order to reply to these questions, since the 1970s scientists and practitioners both in China and in other countries have been conducting a number of scientific studies and clinical trials, which are described in this section. This research has tended to substantiate the ancient theories of traditional Chinese medicine. Other recent research has revealed that human beings are complex bioelectric systems (Becker 1985), and on this basis the mechanics of acupuncture can now be better understood.
To date, a few theories have been suggested concerning these questions.
Transmission of pain impulses along acupuncture channels
The first theory is that most pain impulses travel along the same pathways as those of the traditional Qi circulation (i.e. the channels). It is an objective fact that pain is always transmitted along certain pathways. These pathways are closely related with channel theory in TCM. An interesting observation is that when acupuncture needling is used in the treatment of pain, and when the needle sensation (Deqi) is reported along a particular channel, the greatest reduction in sensitivity to pain is be found in a line along the middle of the channel (Fujian Provincial Research Institute for Traditional Chinese Medicine 1979). This reduction in sensitivity decreases gradually as one moves from the centre of the channel to its outer boundary—that is to say, the more the needle is moved towards the central line of the channel, the less the patient feels the pain. Observation has also shown that pain transmission along the course of the channels is greatly diminished when certain methods are used to promote the circulation of the channel (Li Baojiao 1981). Pain transmission along the channels is, conversely, greatly increased when certain methods are used to block the channel circulation.
Pain-gate theory
Another theory suggests that pain impulses are blocked from reaching the spinal cord or brain at various ‘gates’ within the nervous system. Research studies have shown that both peripheral and central nerves are very important in pain relief by acupuncture (Lu Guowei et al 1979, Shanghai no. I People’s Hospital 1977, Wu Jianping et al 1979).
In the peripheral nervous system acupuncture when used to treat pain can, firstly, block the conduction of sensory fibres in the algetic nerves (Lu Guowei et al 1979, Qiu Maoliang et al 1989); secondly, it can cause downward inhibition of the dorsal horn cell conduction in the spinal cord resulting from the noxious stimulation (Qiu Maoliang et al 1989). It is the peripheral nerves that receive and conduct the acupuncture ‘message’; the II, III and IV fibres could all participate in the pain-relief process.
In the central nervous system the structures at various levels, including the spinal cord, brain stem, thalamus, caudate nucleus and cortex, participate in the process of pain relief by acupuncture.
SPINAL CORD
Scientific research has found that acupuncture can cause postsynaptic inhibition in the posterior horn of the spinal cord (Qiu MaoIiang et al 1989). It has also been found that the acupuncture ‘message’ is conducted to the medulla oblongata from the anterior funiculus of the spinal cord, and then to the medial reticular structure (Qiu Maoliang et al 1989). Afterwards, it is conducted downwards to the posterior funiculus of the spinal cord, where it causes postsynaptic inhibition by depolarising the fine afferent nerve endings. This has the effect of partially blocking the afferent impulse from the fine fibres.
BRAIN STEM AND PARAFASCICULAR NUCLEUS
In the brain stem, electroacupuncture has been found to control the activity of hyperalgetic neurons in the reticular structure of the midbrain (Qiu Maoliang et al 1989). In animal experiments, it was found that electroacupuncture stimulation of the median raphe nuclei could raise the pain threshold in the animals, improving their ability to resist the pain (Qiu Maoliang et al 1989). Impairment of the locus ceruleus increased the capacity for pain relief by electroacupuncture, whereas activation and stimulation of this structure decreased its pain-relief capacity. Researches also showed that acupuncture treatment led to the release of neural impulses from the grey matter around the aqueduct of the midbrain, the giant nucleus in the medial reticular structure of the brain stem and the median raphe nuclei (Qiu Maoliang et al 1989). From here, ascending impulses inhibit electrical activity of the hyperalgetic cells in the parafascicular nucleus of the thalamus, and descending impulses inhibit the activity of neurons transmitting pain impulses in the posterior horn of the spinal cord, so relieving the pain. The parafascicular nucleus has been found to be one of the important key locations in the transmission of pain impulses.
CAUDATE NUCLEUS
Research has established that when the caudate nucleus is stimulated, the pain threshold is increased, which could increase the pain-relieving effect of electroacupuncture, whereas inhibition of the caudate nucleus decreases the pain-relieving effect (Qiu Maoliang et al 1989).
Generally speaking, when the pain impulse enters the central nervous system, it can take a circuitous route to the cerebrum. The posterior horn of the spinal cord and the parafascicular nucleus are two key locations in the reception and transmission of pain impulses. The caudate nucleus, the grey matter around the aqueduct of the midbrain, the giant nucleus in the medial reticular structure of the brain stem and the median raphe nuclei are also very important.
Stimulation of endorphins
A third theory suggests that acupuncture stimulates the brain’s production of polypeptides that reduce pain sensitivity. Scientists have discovered that one of its possible mechanisms is that it increases the release of natural pain-relieving molecules known as endorphins by the brain (Qiu Maoliang et al 1989). These are very similar to opiates (such as morphine), which are potent anaesthetic agents. In China this work was performed and directed in the 1970s by Professor Han Jisheng, an internationally known researcher of acupuncture, when a research programme to study acupuncture-induced anaesthesia was initiated during the Cultural Revolution. His studies showed that electrical stimulation of inserted acupuncture needles caused release of different amounts of endorphin compounds into the central nervous system (Han Jisheng et al 1979). This is the key mechanism that is most widely used as explanation for the effect of acupuncture treatment in relieving pain. This is not a complete explanation, however, of all of acupuncture’s pain-alleviating mechanisms, because acupuncture has other physiological effects besides decreasing pain sensitivity. For instance, it often increases local blood circulation in areas of muscle spasm, and can decrease the muscular contraction that often causes or contributes to painful conditions. Thus, local actions such as decreasing tissue swelling (due to better blood circulation) and lessening muscle spasm may, in turn, release pressure on nerves or interior organs, contributing to the pain relief.
Effects on neurotransmitters
Another theory suggests a central nervous system connection that induces the production or secretion of other chemicals in the body such as neurotransmitters, hormones and lymphokines, etc. Though most of these chemicals are used up fairly quickly, clinical experience indicates that acupuncture generally has cumulative effects. Thus, acupuncture must provide some training effect in the body’s autonomic mechanisms that control and regulate the physiological reactions to pain.
Acupuncture treatments have been found to affect several neurotransmitters, resulting in changes in their blood serum levels. In particular, acupuncture may bring about the following biochemical changes.
SEROTONIN CHANGES
It has been found that levels of serotonin (5-HT), one of the neurotransmitters with the greatest potential influence on sensitivity to pain, change in correspondence with the degree of pain relief reported during acupuncture treatment (Chinese Academy of Traditional Chinese Medicine 1977, Han Jisheng 1978, Jin Guozhang et al 1979). That is to say, the higher the level of 5-HT that is recorded, the greater is the level of pain relief. Acupuncture, and especially electroacupuncture, can increase the level of 5-HT, which helps to increase the pain threshold. For instance, Yi Qingchen et al (1978) has reported that when the pain threshold is increased by acupuncture on ST-36 Zusanli in rabbits, a higher serotonin level is recorded by perfusion streaming in the ventricles of brain. Similarly, Zhu Dinger (1980) has reported that high serotonin levels can be detected in the thalamus, medulla oblongata and midbrain when electroacupuncture is used for sedating pain.
ACETYLCHOLINE CHANGES
Other studies have shown that, when the pain threshold is raised by the use of acupuncture, a high level of acetylcholinesterase is recorded in the cerebral cortex, caudate nucleus and hypothalamus, and when the threshold is artificially decreased, a low level of acetylcholinesterase is recorded (Chinese Academy of Traditional Chinese Medicine 1976, 1978, Ge Zi et al 1983). It appears, therefore, that the level of acetylcholine (Ach) could play an important role in acupuncture pain relief.
CATECHOLAMINE (CA) CHANGES
The results of some studies indicate that noradrenaline (NA) has the opposite effect in pain relief (Han Jisheng et al 1979). That is, when the pain threshold is raised and pain relief is obtained, there is a low level of NA recorded in the cortex, hypothalamus, brain stem, spinal cord and striate body. It is also very interesting to observe that dopamine (DA) levels increase in the caudate nucleus when the pain threshold is raised by electroacupuncture, and in addition the level of homovanillic acid (HVA), one of the products of the metabolism of DA, is high in the midbrain and hindbrain.
In short, acupuncture achieves its effects by working with a the body’s own chemicals, rather than the addition of synthetic chemicals. This approach has several advantages over drug-based medicine.
Psychological and cultural factors
Psychological and cultural factors are also important in pain. It is believed that many psychological modalities, including formal relaxation and distraction training as well as clear explanations before giving acupuncture treatment, may directly ameliorate pain and increase the person’s positive attitude to the treatment. People who are very anxious about the acupuncture treatment and feel very nervous during it would have a lot of muscular tension generally in their body, which may directly diminish the effectiveness of acupuncture in relieving pain.
Conversely, because of cultural differences, Chinese people find it easier to undergo acupuncture treatment for pain syndrome than do Westerners, and during the treatment they also tend to cooperate more with the acupuncturist, which in turn results in less muscular tension, cramp and nervousness. AU these are very important for achieving the therapeutic result.
Another contributing factor could be external suggestion. Until recently, it has been commonly believed, particularly by medical practitioners, that the effect of acupuncture on pain is a form of hypnosis, or can be explained by the ‘placebo effect’, but there is lack of evidence for this belief. Studies have shown, conversely, that there is no correlation between capacity to be hypnotised or belief in the treatment and the subsequent results (Qiu Maoliang et al 1989). People who receive acupuncture and do not believe that it will help are just as likely to respond to it as people with full faith in the treatment. The successful use of acupuncture to treat many animal diseases is one of the best arguments that the effect of acupuncture on pain is not a form of hypnosis.
