In ancient China, there were nine styles of needles respectively named as 镵针 Chanzhen (sagittate needle), 圆针 Yuanzhen (round-pointed needle), 鍉针 Dizhen (arrow-shaped needle), 锋针Fengzhen (Sharp needle), 铍针 Pizhen (sword-shaped needle), 圆利针 Yuanlizhen (round-sharp needle), 毫针 Haozhen (filiform needle), 长针 Changzhen (long needle) and 大针 Dazhen (large needle), which were used to treat different types diseases. Chapter Seven of Ling Shu (Miraculous Pivot) in Nei Jing (Yellow Emperor’s Classic of Internal Medicine) records that, "Nine styles of needles are suitable for different purposes. Each has its own functions in terms of length and size." The most commonly used is the filiform needle nowadays and the rest are almost abandoned. Can filiform needles replace the other ancient needles to treat various kinds of diseases? The answer is definitely no, because the shape and size of the needle may be closely related to the curative effects.

In 1968, four gold and five silver needles were unearthed in an ancient tomb of the Western Han Dynasty (202 BC-8 AD) found in Mancheng City, Hebei Province, China. Experts have confirmed that these gold and silver needles are the earliest needles specifically used for acupuncture and the earliest metal needles ever discovered. Due to the long history and poor corrosion resistance, some needles have become rusty and broken, but the remaining parts of needle bodies showed the sizes of ancient needles roughly. These needles are all short in the body and long in the handle. The full length of the needles is 6.5-6.9 cm; the length of the needle body is 1.5-4.3 cm and the diameter is more than 1.5 mm. I have seen Huatuo (a brand of acupuncture needles) duplicates of ancient gold and silver needles with the scale of 1 to 1. They are roughly the same in thickness as modern mercury thermometer.

At that time, due to the limitation of technology, acupuncture needles had large diameters to achieve a balance between hardness and flexibility. Due to gradual progress of materials and technology, and the patients' fear of pain, the diameters of the needles have become thinner and the material has also changed from gold and silver to stainless steel. The diameters of modern needles are mostly about 0.25-0.3 mm, or even 0.12 mm, which means an ancient needle is 3-5 times thicker than a modern one.

The curative effect of acupuncture is closely related to the selection of points and the tools used. 

Hua Tuo, a famous practitioner in Eastern Han Dynasty (25-220 AD), was very good at treating pain. In San Guo Zhi: Fang Ji Zhuan (The Records and Biography of Three Kingdoms: Medicine) written by a famous historian, Chen Shou, in Western Jin Dynasty (266-366 AD),  Hua Tuo's exquisite acupuncture techniques are described, "If the patient needed acupuncture, Hua Tuo needled only one or two places. Before the insertion, he would ask the patient to tell him once qi arrived. Once the patient said 'yeah, it has arrived', he would remove the needle and the patient would recover."

The question is where to insert the needle and what kind of needles should be used for such immediate effects? Only one or two acupoints are needled and the needle is removed immediately after qi arrives, when the disease shall be cured. The needle production technology level at that time meant that thick needles must have been used. The Jiaji acupoints on the back are covered by strong and compact muscles. Thick needles are applied to separate muscles to release the adhesion of muscle tissues so as to achieve the effects of unblocking the channels and collaterals and relieving pain. It is said that Jiaji acupoints found by Hua Tuo are mostly used to treat back pain (without verification here). Modern acupuncturists also use Hua Tuo Jiaji acupoints in the treatment of backache, but rarely can they achieve the effect of curing the disease immediately after the arrival of qi and removal of the needle. Therefore, the change of needle thickness may be an important reason for the decrease of the curative effect of regular acupuncture with filiform needles.

Chapter One of Lingshu (Miraculous Pivot) in Neijing (Yellow Emperor’s Classic of Internal Medicine) states, "When there is no qi arrival after insertion, manipulating the needle is needed. Once qi arrives, the needle can be withdrawn. The arrival of Qi indicates curative effect which is like wind blowing clouds and the clear blue sky showing up. That's the principle of needling."

I think this is memorized by every TCM practitioner who shall apply it in clinical practice. However, the fact is that every acupuncturist is trying to find and get the feeling of qi arrival, the effect “like wind blowing clouds and the clear blue sky showing up” does not occur often. Therefore, many an acupuncturist uses a large number of acupoints and needles (from dozens to even more than a hundred), lengthens the duration of needle retention, and adds electric needle stimulation and other ways, in the hope of improving curative effects. Let’s think carefully if ancient acupuncturists used so many thick needles for the treatment, could the patients tolerate the pain?

To be continued......