Application of Yin–Yang in Traditional Chinese Medicine (TCM)(2)

4.Assisting Diagnosis

All clinical signs and symptoms are ultimately attributed to Yin–Yang imbalance. Yin–Yang is the foundation for the pattern identification by Eight Principles. Diseases may be classified as Yin or Yang according to their nature. Because disease is Yin–Yang imbalance, the key is to correctly differentiate the disease’s Yin–Yang nature and Yin–Yang imbalance. Complicated clinical conditions are then simplified, and a correct diagnosis will be made.

Yin–Yang attributes and relationships are helpful for diagnosis in both Yin/Yang syndrome differentiation and in the Yin/Yang nature of clinical manifestations. High fever, red eyes/tongue/face, restlessness, hyperactivity, a loud voice, coarse breath, and a rapid–strong pulse generally indicate a Yang syndrome. Chills, a pale face/tongue, listlessness, sleepiness, a quiet voice, weak breath, and a slow–weak pulse generally indicate a Yin syndrome.

Common manifestations and their corresponding Yin–Yangimbalances are summarized in Table 1.2 . These manifestations are helpful in assisting the diagnosis of the Yin or Yang attribute of clinical manifestations and the Yin or Yang nature of a syndrome.

The determination of Yin or Yang attributes of clinical manifestations is also important. A yellow/red and bright color (face/skin, coating or body of the tongue, urination) is of Yang manifestations, while a pale or ashen color is of Yin manifestations. A hot body is of Yang, while a cold body is of Yin. A thirsty and dry mouth is of Yang, while an unthirsty and wet tongue is of Yin. Yang pulse “Cun ” (front position) is superficial, big, rolling, and rapid. Yin pulse “Chi ” (rear position) is deep, fine, choppy, and slow.

5.Guiding the Treatment

Treatment adjusts Yin–Yang and establishes the relative equilibrium between them. The choice of treatment principle is based on disease nature and on Yin–Yang’s four relationships (opposition, interdependence, mutual consumption, and inter-transformation). In TCM, treatment always aims at restoring Yin–Yang balance. The following therapeutic principles derived from Yin–Yang are the most significant:

Table 1.2.Clinical manifestations of Yin–Yang syndrome.

• “Replenish what is in deficiency” and “Reduce what is in excess.”
• “Treat cold with warming methods” and “Treat heat with cooling methods.” Exogenous pathogens which cause acute disease in normally healthy patients are usually of an excessive pattern. The treatment principle is to eliminate or reduce the pathogens. Yin pathogens (e.g. cold) are counteracted by Yang factors (e.g. warming therapy); Yang pathogens (e.g. heat) are counteracted by Yin factors (e.g. cooling therapy).
• Yin or Yang excess should be “consumed” or “reduced.” If Yang dominates, heat should be reduced. If Yin dominates, coldness should be reduced. For instance, fever might be reduced by using a reducing method to puncture acupuncture points LI4, LI11, and GV14, or Shixuan.
• Yin or Yang deficiency should be “replenished” and “enhanced.” If Yang is weaker, it should be tonified and warmed; if Yin is weaker, it should be nourished. In practice, Yang is tonified and warmed with warming needling and moxa.
• Prick the left (Yang) to treat the right (Yin). Prick the top (Yang) to treat lower limb diseases (Yin), etc.
• Prick the Back-Shu points (from Yang meridians) to treat Zang organ (Yin) diseases. Prick the Front-Mu points (from Yin meridians) to treat diseases of Fu (Yang) organs.
• Complicated cases may require complex treatment; for example, one may “treat the Yang aspect for the Yin type of diseases” or “treat the Yin aspect for the Yang type of diseases.” Or one may reduce Yang to relieve hypertensive dizziness and headaches with Yin deficiency and Yang rising to the head. Or one may replenish Yin fluid when high fever (Yang heat) consumes body fluids. In acupuncture, Yang meridian points may be needled for Yin meridian disorders, and vice versa.

Note that support and warmth of Yang must be emphasized in treatment because changes in Yang will lead to changes in Yin — Yang is the commander! Yin can be nourished by warm Yang. It is important to avoid injury to Yang through carelessly using the cooling nature of food and herbs.

6.Describing Properties and Functions of Herbs and Selecting for Treatment

• The herbal property refers to a herb’s cold  hot  warm  or cool  nature. Properties are classified according to the herbs’ different actions and therapeutic effects. For example, herbs used for heat (Yang) syndromes have a cold/cool property. They clear heat, purge fire, remove toxins, and nourish Yin. Cape jasmine fruit (Zhizi) and Scutellaria root (Huangqing) are examples of cold/cool herbs. Herbs used for cold (Yin) syndromes have a hot/warm property. They disperse cold, warm the interior, support Yang, and treat collapse. Dry ginger and red ginseng are examples of hot/warm herbs.
• The five flavors of herbs are the pungent  sweet  sour  bitter  and salty  tastes. “Tasteless” or “bland”  is usually grouped with “sweet”; and “astringent”  is usually grouped with “sour.” “Pungent,” “sweet,” and “tasteless” are of Yang, whereas “sour,” “bitter,” and “salty” are of Yin.
• Herbs tend to act on the body by moving upward (ascending, ) moving downward (descending, ), moving outward (floating, ), and moving inward (sinking, ). Herbs with upward and outward actions are of Yang; herbs with downward and inward actions are of Yin.

Use of these properties and functions in selecting Chinese herbs in treatment will be discussed in detail in other sections.