Chronic pain is a very common problem, certainly a problem we encounter very frequently in our clinics.
Pain is not as simple as it might seem
Pain is initially a simple and straightforward mechanism: the purpose of pain is to serve as a warning to damage or potential damage to tissue in the body. As Chinese medicine practitioners, we often treat pain according to this logic, we address the location and the nature of the pain directly: either by treating the anatomic area, or by treating the related meridian or organ; treating joint pain with the liver organ, treating lower back pain with the kidney organ, treating the meridian whose course runs along the pain location, etc.
However, clinical experience and research, has proven pain to be more complex. If it was just a simple warning mechanism, then there should be correlation between pain location and degree, and between tissue damage. Surprisingly, the clinical reality is that this correlation does not exist, especially in the case of chronic pain.
This is due to the fact that pain is a sensation that is transmitted from the brain. The brain receives extensive amounts of signals and information through the nervous system, and responds to this information. The response is not based solely on the information coming directly through the nervous system, but is also largely affected by a combination of learning processes based on memories of previous experiences, behavioral patterns and emotional state. The result is that pain does not demonstrate an objective factual reality, but rather a complicated subjective interpretation.
“Pain is an opinion on the organism’s state of health rather than a mere reflective response to injury”
[Phantoms in the brain, by VS Ramachandran and Sandra Blakeslee]
This terrific phrase “pain is an opinion” is a phrase I have adopted to repeatedly remind myself of the complexity of the journey to heal pain.
There are many interesting talks on this issue of pain, one I can recommend is this one >>
Understanding pain through the Shang Han Lun
The physiological model of the Shang Han Lun in general, and specifically the formula Xin Jia Tang, presented in the text, provide us with amazing insights on understanding pain.
The Tai Yang conformation is responsible for the motoric functions of the body. Functions of this conformation include warming of muscles and joints, regulating movement of Wei Qi in the channels, and invigorating blood flow.
When there is a pathological situation in this conformation, in can often manifest as pain. Line 1 in the text, outlines the basic symptoms of a Tai Yang pathology, which include pain and stiffness in the nape of the neck. The scope of painful obstruction in this conformation, is much larger than this, and can include headaches, general body pain, back pain and joint pain.
Line 35 of the text lists this wide range of pain manifestations in a Tai Yang pathology:
太阳病，头痛发热，身疼腰痛，骨节疼痛，恶风，无汗而喘者，麻黄汤主之。
When in greater yang disease (there is) headache, heat effusion, generalized pain, lumbar pain, joint pain, aversion to wind, absence of sweating, and panting, ma huang tang governs.
Clinically, the Tai Yang conformation can be linked to muscular related pain (both skeletal muscles, as well as internal organs), joint pain and neural pain. There are several pathologies of the Tai Yang conformation, but the most interesting one in relation to chronic pain is the disharmony between Ying Qi and Wei Qi – Ying Wei Bu He.
This is a situation in which the Wei Qi (protective qi) and the Ying Qi (nutritive qi) are not cooperating to regulate the body’s reaction to external stimuli. The Wei Qi tends to become over-defensive, making it aggressive, constantly alert and ready to pounce, while neglecting the functions of warming and nourishing the muscles and joints, and regulating movement in the channels. The symptomatic expression of this syndrome can widely vary, but includes a dynamics of excessive tension in the body, and hyper-sensitivity, both physical and emotional. Pain is often a result of this dynamics. This syndrome is addressed through the use of the formula Gui Zhi Tang.
In Line 387, there is specific mention of the connection between the formula Gui Zhi Tang and pain:
吐利止而身痛不休者，当消息和解其外，宜桂枝汤小和之。
When vomiting and diarrhea cease and there is persistent generalized pain, after considering (the patient’s condition), resolve the exterior (accordingly). Gui zhi tang is appropriate for mildly resolving.
The Shang Han Lun discusses numerous modifications of this formula, among them the formula Xin Jia Tang, which offers important insights to the understanding of the chronic pain mechanism.
Xin Jia Tang treats pain due to blood deficiency with lack of nourishment to muscles and joints. Clinically, this can manifest in various forms of pain:
- Chronic stiffness in the muscles, which can ultimately lead also to joint pain, increased tendency to orthopedic injury, as well as fibromyalgic pain.
- Tendency to muscle spasm, with sharp intense and sudden pain. Most often occurs in the Gastrocnemius muscle of the leg, or in the foot, but can also manifest as sudden stomach ache, period pains or chest pains.
The Line that mentions Xin Jia Tang is Line 62:
发汗后，身疼痛，脉沉迟者，桂枝加芍药生姜各一两人参三两新加汤主之。
When after the promotion of sweating (there is) generalized pain, and a pulse that is sunken and slow, gui zhi jia shao yao sheng jiang each one liang ren shen three liang xin jia tang governs.
Xin Jia Tang is actually short for the formula with the longest name in the text. The full name is:
Gui Zhi jia Shao Yao Sheng Jiang ge yi liang Ren Shen san liang Xin Jia Tang.
Many formulas names in the text are basically a list of their ingredients. This is the case here – the name of the formula is actually:
Gui Zhi Tang with the increase of dose of Shao Yao and Sheng Jiang by 1 liang each, and with the addition of 3 liang of Ren Shen.
[* Liang – 两- is a measure word equal to about 15 grams.]
The unusual thing about the name of this particular formula, is the addition of the last 3 words – Xin Jia Tang- 新加汤 – which means “the formula with new addition”. These words are of significance to understanding the context of the formula. The formulas mentioned in the text, were not written by Zhang Zhong Jing himself, but taken from other sources, mainly from the ancient text Tang Ye Jing. The fact that Zhang Zhong Jing added to the name of this formula “the formula with new addition”, points out to many commentators that this is one of the few formulas, if not the only one, that Zhang Zhong Jing modified himself. This leads to the assumption that he felt that the existing formulas for pain were not accurate enough to address an aspect of pain he often encountered in the clinic.
The mechanism of action of Xin Jia Tang
Understanding the conformations that are treated by a formula, are significant to understanding the mechanism of action. Many lines in the Shang Han Lun, begin with mentioning the conformation which is pathological, however, the one that refers to Xin Jia Tang, does not specify any particular conformation. As mentioned above, bodily pain is associated with a Tai Yang pathology, but it doesn’t necessarily mean that this conformation is the source of the pathology. In this case, in addition to pain, there are 2 more symptoms that lead us to the understanding of the underlying source:
- The pulse is deep and slow.
- The pain started following sweating.
A deep pulse is usually related to an internal pathology. The combination of a slow pulse with bodily pain is explained in line 50 of the text:
脉浮紧者，法当身疼痛，宜以汗解之。假令尺中迟者，不可发汗。何以知然？以荣气不足，血少故也。
When the pulse is floating and tight, as a rule there should be generalized pain and (therefore) it is appropriate to resolve (the illness) by sweating. (However) if the pulse at the cubit is slow, one cannot promote sweating. How does one know this? Because the construction qi is insufficient and the blood is scant.
This line begins with a description of a common case of pain due to Tai Yang pathology. In this case, the pulse should demonstrate the Tai Yang dynamics, and be floating and tight. The treatment strategy, should be a basic Tai Yang pathology treatment strategy, which is sweating.
The second part of the line, describes a different clinical situation, which is represented by a pulse which is slow. This, according to the text, is an indication of ying and blood deficiency. This line illustrates, that although pain is related to an obstruction of the Tai Yang, the source of the pain can be deficiency, and therefore cannot be treated with sweating.
The pulse described in line 62 in relation to the formula Xin Jia Tang is a deep and slow pulse, indicating an internal deficiency of ying and blood. In addition to this, we have also been told that the pain started following a sweating episode. Unnecessary sweating results in loss of Ying Qi and Yang, another indication that this is a deficiency syndrome. Based on all of the above, sweating is not appropriate in this case.
So if sweating is not the right treatment strategy, why are we instructed to use a modification of Gui Zhi Tang?
- While Gui Zhi Tang can be used as a formula to induce sweating, it is not a sweating formula, it is a harmonizing formula. Line 12 of the text explains, that in order for this formula to effectively induce sweating, it must be accompanied by eating hot rice porridge and covering up with a blanket.
- Gui Zhi Tang originally is composed of equal doses of Gui Zhi and Shao Yao. In Xin Jia Tang the dose of Shao Yao, which has an astringent effect, is doubled. This modification moderates the sweating effect of Gui Zhi, and enhances Gui Zhi’s ability to warm and invigorate movement inside the channels.
- The modification of Gui Zhi Tang where Shao Yao is doubled in dose, is called Gui Zhi Jia Shao Yao Tang, appearing in line 279 of the text. This line describes a pain syndrome, due to a pathology which originated in the Tai Yang, but is currently linked to Tai Yin. While this line states abdominal pain, line 274 links Tai Yin to pain in the limbs, so clinically the pain treated by this formula could be anywhere in the body.
The conclusion of all this is that we are discussing a combined Tai Yang-Tai Yin syndrome. The pain is a manifestation of obstruction to the movement of the vital forces of the Tai Yang conformation.
How is the Tai Yin conformation involved in pain syndromes?
The Tai Yin conformation replenishes and supplies the vital substances necessary for bodily functions. If this conformation cannot provide the Tai Yang conformation with the necessary forces for its function, there will be a clinical manifestation of Tai Yang pathology, but treatment will require not only Tai Yang regulation, but also Tai Yin reinforcement.
Once we have realized the conformations involved, we can apply the dynamics characterizing these conformations for the differential diagnosis in cases of chronic pain.
Pain originating in a Tai Yin pathology, needs to be diagnosed according to the characteristic dynamics of this conformation. Since the Tai Yin is responsible for supplying the body with the qualities necessary for maintaining or restoring health, pain linked to this conformation will be characterized with:
- Physical and emotional difficulties in overcoming the challenges of healing and rehabilitation.
- Behavior patterns of systematically avoiding participation in activities in constant fear of pain.
- Muscle and body weakness, contributing to maintaining a state of pain.
This will be combined with the Tai Yang pathology dynamics of over-protecting the body, manifesting as:
- Physical and mental tension, causing among other things increased muscle tension, complicating the pain.
- Sensitization of the nervous system, resulting in pain sensation from stimulation that is not ordinarily painful.
These 2 conformations are also characterized with sensitivity to cold. This sensitivity could manifest as general feeling of cold, but could also manifest as an increase in pain when exposed to cold, as cold to touch in area of the pain itself, or as slower motion related to painful area. If the symptoms indicate heat, there might be need for either another formula, or a modification in this formula. In any event, this is not the formula for pain due to acute inflammation with signs of redness, heat sensation and swelling.
To summarize, the existing formulas used to treat pain had already demonstrated that the pain mechanism could result from a Tai Yang pathology, obstructing the movement of Wei Qi in the muscles and channels, or from a combined Tai Yang-Tai Yin pathology, with difficulty recovering from a harmful incident. Why did Zhang Zhong Jing feel there was a need for yet another modification?
Ingredients of Xin Jia Tang
Gui Zhi 45g
Shao Yao 60g
Sheng Jiang 60g
Da Zao 45g
Zhi Gan Cao 30g
Ren Shen 45g
There are 2 additional modifications:
- The dose of Sheng Jiang has been doubled and is equal to the dose of Shao Yao.
- Ren Shen has been added to the formula.
Both modifications indicate that the author of this formula felt there is need for an increase of herbs which support the Tai Yin conformation, one for harmonizing and one for strengthening. This, in my opinion, is an indication of an amazing observation, which links us to the modern understanding of pain: “pain is an opinion”, pain is not only about restoring the health of the damaged tissue, but also about restoring the confidence of the body in its healing abilities.
How can this formula treat pain?
Pain causes the body to contract. This harms the blood flow to the damaged area, causing obstruction both to the flow of nutrients into the damaged area, as well as removal of waste from the damaged area. The formula Gui Zhi Tang harmonizes Ying Qi (nourishing qi) and Wei Qi (defense qi). Restoring the balance between nourishment and defense enables the healing process.
More specifically for pain, is the added dose of Shao Yao, which increases the effect of the combination Shao Yao+Zhi Gan Cao. This combination, known as Shao Yao Gan Cao Tang, is mentioned in line 29 as a treatment for muscle contraction, and is commonly used to treat a large variety of pain disorders.
The increase in dose of Sheng Jiang, brings harmony to the Middle Jiao and enhances fluid circulation to the muscles, relieving the body of the sense of distress.
The addition of Ren Shen, strengthens the body and restores a sense of stability and security, allowing the body to relax and “let go” of the protecting forces in favor of the healing forces.
* English translations taken from: Shang Han Lun: On Cold Damage, Translation & Commentaries . Feng Ye , Nigel Wiseman , Craig Mitchell
Shang Han Lun 