Etiology in TCM
Author: Dr. Lee
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Time: 2010/11/26 16:50:32
Etiology in TCM is comparatively simple, including three aspects, internal causes, external causes, and non-external and non-internal causes.
External causes include abnormal changes of weather, such as excessive cold, summer-heat dampness, dryness and fire. When these abnormal changes of weather attack human body, exogenous diseases will be caused. For instance, common cold occurring in summer is believed to be caused by pathogenic cold that has invaded the body during winter and high fever running in winter is due to the attack of pathogenic heat that may has invaded the body in summer. That is why such pathogenic factors manifested in opposite seasons are called latent pathogenic factors.
In TCM, exogenous diseases are called cold attack (or exogenous febrile disease), often taken as a separate branch of study in TCM and listed as the first disease in many large medical books. Such a phenomenon has something to do with the simple classification of etiological factors and determination of the causes of many different diseases in TCM.
For example, TCM believes that beriberi (flaccidity of feet due to deficiency of vitamin B1) is caused by water and dampness because they come from the earth. So TCM understands myocarditis due to deficiency of vitamin B1 as invasion of beriberi into the heart. According to TCM, patients with beriberi should avoid rice and just take food made of flour because paddy grows in water and beriberi is caused by invasion of water and dampness into the body.Fortunately, such an analogy quite accords with modern science. According to modern science, refined rice lacks vitamin B1, but flour is rich in vitamin B1.
The analysis made above shows that the names of many diseases in ancient times had something to do with etiological diagnosis. However such diagnosis in many cases was just symptom diagnosis. That was to decide the cause and name of a disease according to the symptoms. Due to the difference between the ancient and modern understandings of etiology, it is difficult to decide whether a disease named in ancient times is similar to a diseases named in modern times.
There was a breakthrough made during the Ming and Qing Dynasties. Wu Youke, a doctor living in the 60s of 17th century, made careful observation about epidemic diseases and found that these exogenous diseases were not necessarily caused by invasion of abnormal changes of weather, but by a sort of virulent factors that invaded the body through mouth and nose. Such as a sort of virulent factors were different from any other factors. They may attack human beings but did not affect domestic animals. If the nature of such virulent factors was revealed, there would be certainly possible to develop a drug to control such factors.
With the development of history, the population in the south of China increased fast and infectious diseases increased. Then the school of warm diseases appeared. YeTianshi (1667-1746 AD) was one of the important figures in this school. In dealing with infectious diseases, doctors of this school replaced the practice of syndrome differentiation according to the six Channels with the ideas of wei (defensive-phase), qi (qi-phase), ying (nutrient-phase) and xue (blood-phase) as well as the upper, middle and lower san jiao (Triple Energizer). They used herbs acrid in taste and cold in nature, such as sang ye (Folium Mori), ju hua (Flos Chrysanthemi) and lian qiao (Fructus Forsythiae),to replace herbs acrid in taste and heat in nature, such as ma huang (Herba Ephedrae) and gui zhi (Ramulus Cinnamomi), further developing the theory of Shang Han Lun (Treatise on Cold Diseases).
The internal causes include emotional changes, improper diet, physical exhaustion and excessive sexual activity. Though TCM emphasizes the importance of physical movement and restriction of sexual activity, it never advocates asceticism. It points out that lonely life is an important factor responsible for many physical and mental diseases. Guided by the theory of wu xing (five elements), TCM has established a close relationship between mental state and the five zang-organs. It is just due to such a physical-mental relationship that TCM takes mental problems as part of the physical diseases and regards physical diseases as part of the mental problems. For example, excess of heart-q/leads to excessive laughter and deficiency of heart-q/causes grief and sorrow. However in the West, people with mental problems were regarded as criminals and evils even in the 18th century and were punished physically.
Li Gao, one of the four great doctors in the Jin and Yuan Dynasties, was one who first made theoretical study on improper food and overstrain in causing diseases. He wrote a book entitled Nei Wai Shang Bian Huo Lun (Differentiating Internal and External Source of Sickness) to discuss diseases that appeared to be caused by external factors but actually caused by internal factors. Such diseases should be treated by regulating the spleen and the stomach. He wrote another book entitled Pi Wei Lun (Treatise on Spleen and Stomach) to discuss spleen and stomach, suggesting that stomach-qi was yuan qi (primordial-qi) and developed a series of important prescriptions, still popular now.
The so called non-internal and non-external causes refer to wound, injury due to insect bite and animal attack, poisoning and hereditary factors.
