The proportion of each Sasang typology is 1% of TaiYang, 54% of TaiYin, 17% of ShaoYang and 27% of ShaoYin. 《Dong-Yi-Shou-Shi-Bao-Yuan》 said “At this time, we can see 10,000 people in a county. In a nutshell, there are 5,000 people is TaiYin, 3,000 is ShaoYang, 2,000 is ShaoYin, and only three or four people is TaiYang.” Myung Jin Oh, et al. (2013) used QSCCII method to diagnose 40 healthy people, with result of that TaiYin and ShaoYin accounted for 39.0% and ShaoYang for 19.5% respectively. The Sasang typology proportion of 265 healthy volunteers reported by Kim is 41.9% in TaiYin, 37.6% in ShaoYin and 20.5% in ShaoYang (Sun Ho Kim, 1996). The above results are basically consistent with this study. The results showed that the weight and height of TaiYin were higher than those of ShaoYang and ShaoYin. The traditional medical books recorded that "TaiYin is well-developed and obese (Zhe-nan XUAN, 2005)". Chun-yu JIN, et al. (2012) reported that the body mass and height of TaiYin were higher than those of ShaoYang and ShaoYin. The above results are basically consistent with this study. This time, there were more men are ShaoYin and more women are TaiYin, but the difference was not statistically significant. Sun Ho Kim, et al. (1996) reported that in men, the number of ShaoYin is more than that of TaiYin, while in women, the number of TaiYin is more than that of ShaoYin, which is very similar to this result. Within ShaoYin group, There is a significant difference between men and women in type O, A, B and AB, which is statistically significant. The characteristics of ShaoYin’s viscera are "large kidney and small spleen", the function of lower energizer (Kidney, baldder, large intestine, small intestine) tends to strong. Its reproductive capacity is stronger than other Sasang typologies. Bi-yun Zhang, et al. (2017) found that the highest proportion of premature ovarian failure (POF) patients was type A, and the lowest was type O. It just shows that the function of kidney is more powerful with type O.
There are few specimens of TaiYang, so we should study them later. The right side of DL and MCV of the median nerve in the TaiYin is extended or declined. The right side of ulnar, peroneal and tibial nerves are conductive advantage. 96% of the volunteers were right-handed, and they used their right hands to write more in their study and life, besides TaiYin has the characteristics of large liver, small lung, astringent Qi and turbid blood, which leads to more microcirculatory diseases than other Sasang typologies. In the same right hand, the ulnar nerve is conductive to the right side, suggesting that there may be a potential conduction disorder in the carpal tunnel. Ying LIU, et al. (2017) examined 180 CTS patients, found that 78 of the left hand and 102 of the right hand had CTS, which indicated that the incidence rate of right hand was higher than that of left hand. Compared with asymptomatic or healthy people, the SCV of median nerve declined and DL extended in patients with symptomatic CTS, but there was no significant difference in DA reduction (Yao YAO, 2017). It is speculated that the right hand is the most flexible and commonly used limb, and the risk of injury is higher than that of the left hand. 《Huang-Di-Nei-Jing》said ”the sprit is well managed when Yin-Yang is balanced”. As Yang has the function of warming and promoting Yin, TaiYin who has more Yin characteristic would cause slow metabolism and endogenesis of phlegm dampness. This would lead to Physiological and pathological environment of terminal nerve. This may be the reason why the conduction function of the right side of the median nerve is lower than that of the left side.
DA and MCV of ulnar nerve and MCV and FL of tibial nerve in TaiYin, ShaoYang and ShaoYin were extended or declined on the right side. That says, the right side of ulnar and tibial nerve’s conduction is superior. In the initial state of study of 100 healthy subjects, the right side of ulnar and tibial nerve’s MCV was increased than the left (Chun-yu JIN, et al., 2011). The PA of the median nerve of TaiYin is higher on the left side; The PA of the ulnar nerve of ShaoYin is higher on the right side; The MCV of the ulnar and tibial nerves of ShaoYang is increased on the right side. In patients with diabetic peripheral neuropathy (DPN), DL of median, ulnar, posterior tibial and right side of common peroneal nerve extended, DA and MCV is declined (Guo-ping XING, 2009). Through acupuncture and moxibustion, MCV of the left median, ulnar and right peroneal and tibial nerves increased significantly (Dong-cai WANG,2017). It is speculated that the right handedness is one of the possible factors for the conduction advantage of the right limb.
DL of peroneal nerve of TaiYin, ShaoYang and ShaoYin was extended on the right side, and MCV was increased on the right side. Zhen-he HAN, et al. (2010) reported that the DA of peroneal nerve of healthy Korean was lower and DL was longer than that of Chinese Korean.Cai-hong Cai-hong Ma and Xiao-yun HUANG (2017) compared the Hui nationality group with the mixed group and the Han nationality group, the Hui nationality group’s DL of common peroneal nerve extended, MCV and DA declined. Anatomically, the position of the peroneal nerve is shallow so it is vulnerable to external influences such as physical squeeze. It is speculated that living habits (such as kneeling, sitting, etc.) are the important reasons for the potential injury of the anterior peroneal nerve of ankle joint.
In this study, DL, FL (R), DA, MCV of median nerve and DA,FL (L) of ulnar nerve and DA, MCV, FL (L) of peroneal nerve are extended or declined in TaiYin than that of ShaoYang. Chun-yu JIN, et al. (2012) showed that DL and FL of median, ulnar, tibial and peroneal nerves in TaiYin were extended than those in ShaoYang, which was consistent with the results of this study. It is said in《Dong-Yi-Shou-Shi-Bao-Yuan》that “Tai-Shao-Yin-Yang has different Visceral pattern, which depends on variation of Yin-Yang balance (Zhe-nan XUAN, 2015).” 《Ling-Shu·Ni-Shun-Fei-Shou》said “Fat people, whose blood is black and turbid, whose Qi is unsmooth and slow. Thin people, whose blood is clear and Qi is smooth.” Above shows that different amount of Yin-Yang in viscera produces four different constitutional typology, namely Sasang. The internal environmental factors of different constitutional typology directly affect the physiological and pathological changes of nerve, and make them change accordingly.
DL (R), DA of median nerve, DA, MCV, FL of tibial nerve, FL of peroneal nerve extended or declined in the TaiYin than that of ShaoYin. DL (L), DA (L) of ulnar nerve extended or declined in ShaoYin than that of TaiYin. FL (R) of median nerve is extended in TaiYin than that of ShaoYin. According to traditional Chinese Medicine (TCM) that Yang is functional for warming and motivating. Meanwhile, Yin is functional for moist and mourishing. Since TaiYin has larger Yin/Yang balance than ShaoYin has, so the nerve conduction function of TaiYin tends to weak. Li-yan JIN (2018) examined the conduction function of the median nerve, and found that FL (L) is extended in TaiYin than that of ShaoYang and ShaoYin, and FL (R) in TaiYin was extended than that of ShaoYin ( P < 0.05). Sheng-ai PIAO (2019) tested the conduction function of peroneal nerve. The results showed that DL and FL in TaiYin were extended than that of ShaoYang and ShaoYin. DL, MCV in TaiYin and ShaoYin were all right side extended than that of left side.
DA of median nerve in ShaoYin was extended than that of ShaoYang, MCV and FL of median nerve in, and DA of ulnar nerve in ShaoYin was extended or declined than that of ShaoYang (P < 0.05). ShaoYang has the constitutional characteristic of ”a bit more amount of Yang than Yin; Upper excess and lower deficiency”. ShaoYin has the constitutional characteristic of “a bit more amount of Yin than Yang; Lower excess and upper deficiency”. The median and ulnar nerves of the upper limbs of ShaoYang has nerve conduction advantage than ShaoYin, but there is no significant difference in nerve conduction between the lower limbs. It is speculated that the Qi of ShaoYang is rather stronger, and ShaoYin is rather easier to lose the QiXue, and the spleen tends to weak and cold so the significant difference of PNAP could be observed. According to Gang-hua YAN, et al. (2010) TCM Constitution can be divided into three types: “Qi and Yin deficiency”, “phlegm and blood stasis”, “Yang deficiency and blood stasis”. Their median, ulnar and peroneal nerve conduction parameters are MCV is gradually slowed down, DA is gradually declined, DL is gradually extended. Qi LI (2010) reported that among the various types of Type 2 diabetic peripheral neuropathy, Toronto's clinical scoring system was used to evaluate the degree of nerve injury that “Deficiency of yin and hyperactivity of heat” group has the mildest nerve injury. The significant difference of MCV is between “Yin deficiency and heat excess” group and “blood stasis and venation” group, the former is lighter than the latter. Yuan-bo Xin, et al. (2015) investigated and analyzed the Sasang typology and TCM constitution by questionnaire, found that the TaiYang is closely related to the hygrothermal constitution, the TaiYin is closely related to the phlegm and dampness constitution, the ShaoYang is closely related to the Yin deficiency constitution, and the ShaoYin is closely related to the Yang deficiency constitution. Go Jung-hyun, et al. (2010) observed that phlegm dampness constitution is similar to the TaiYin; Qi deficiency, Yang deficiency and Qi depression are similar to ShaoYin; Yin deficiency constitution is similar to ShaoYang; Damp heat constitution is similar to TaiYang and ShaoYang; Blood stasis constitution is similar to ShaoYin and TaiYin.
For median nerve, ShaoYin is greater than ShaoYang and TaiYin (L) (P < 0.05); For ulnar nerve, TaiYin is greater than ShaoYin (L) (P < 0.01); For peroneal and tibial nerve, TaiYin is greater than ShaoYang and ShaoYin (P < 0.01). In addition, the ratio of nerves with low conduction function in tibial nerve, that TaiYin was higher than ShaoYin (R) and ShaoYang (L). It is said in 《Dong-Yi-Shou-Shi-Bao-Yuan》 that “The Qi of grief and anger rises, the Qi of like and happy drops. If you have too much rising Qi, the lower energizer will be damaged. If you have too much descending Qi, the upper energizer will be damaged. The temperament characteristics of ShaoYin is freely like and deeply happy. The Qi of descent is too much to damage the upper energizer. Their internal organs are characterized by small spleen and large kidney and their body shape is that upper body is thin, while the lower body is thick. ShaoYin have small spleen which functions to transport and disperse essence, so they are easily to lose Qi-Xue and the spleen tends to be weak and cold. Therefore, the proportion of injured nerves in upper limbs is significantly higher than that in lower limbs. The temperament characteristics of ShaoYang is suddenly grief and deeply angry, so the Qi of rising is too much to damage the lower energizer. Their internal organs are characterized by small kidney and large spleen and their body shape is that lower body is thin, while the upper body is thick. ShaoYin have more amount of Yang with less amount of Yin that they have weak kidney function so the kidney is easy to be overheated. Therefore, their nerve conduction function is rather stronger and the ratio of FL ≥ 2SD is the smallest. The temperament characteristics of TaiYin is freely happy and deeply like. Their internal organs are characterized by small lung and large liver and their body shape is characterized by waist hypertrophy. Because of they have small lung and the weakness of promoting blood, TaiYin are prone to be in the state of "blood turbid and Qi astringent. The proportion of injured nerves in lower limbs was significantly higher than that in ShaoYin and ShaoYang.
Tibial nerve hypofunction rate is TaiYin (R) greater than ShaoYin ( P < 0.01); TaiYin (L) greater than ShaoYang ( P < 0.05). It can be seen that constitutional specificity leads to the susceptibility of the body to certain diseases. Compared with ShaoYang and ShaoYin, TaiYin are more likely to suffer from potential nerve damage because of their constitution characteristics of "big liver, small lung, turbid blood and astringent Qi"
There is a significant correlation between AMP. and DUR. It is a stable electrical characteristic of skeletal muscle motor unit, when it exceeds a certain time limit, the variability of amplitude becomes larger (Yang QIN, et al., 2011). The ratio of the median nerve is ShaoYin > ShaoYang > TaiYin, i.e. DL is ShaoYang/ShaoYin < TaiYin; Proximal latency is ShaoYang < ShaoYin/TaiYin; Proximal duration is ShaoYang/ShaoYin < TaiYin; DA/PA is ShaoYin > ShaoYang > TaiYin. The integrity of CMAP wave-forms in the median nerve of ShaoYin was verified, suggesting that it can be used to distinguish the Sasang typology. The change of tibial nerve ratio suggests that the conduction function of TaiYin is lower than that of ShaoYin and ShaoYang. It was found in previous studies that among the different TCM Syndromes of CTS patients, the median nerve conduction function of healthy volunteers is better than that of “cold dampness blocking collaterals” group, then the “cold dampness blocking collaterals” group is better than “Qi and Yin deficiency group” (Shuo ZHANG, 2011). Among the different TCM Syndromes of DPN patients, the most significant difference of MCV and DA had been observed between “Yang deficiency, cold coagulation” group and “phlegm and blood stasis” “Qi and yin deficiency” groups, especially in the median nerve (Guo-xin GAO, 2013). In addition, DPN nerve conduction test is characterized by high abnormal rate of MCV in tibial and median nerve (Zhu LIU, et al., 2014). In aerobic exercise group, DL and MCV of common peroneal and posterior tibial nerves were significantly improved (Yan WANG, 2015).
The above median, ulnar, peroneal and tibial nerve conduction parameters show that the nerve conduction function of ShaoYang with overheated constitution is superior to that of TaiYin with astringent Qi constitution and ShaoYin people with supercooled constitution. The ratio of AMP. / DUR. of median nerve can sensitively reflect the difference of constitutions, and can be used in the differential diagnosis of Sasang typology.