Similarities and differences between the trigger point of myofascial pain and the traditional meridian points

Ding-Jiong Sun

Hainan Provincial Hospital of traditional Chinese Medicine，Haikou，Hainan Province，China，570000

Keywords:Trigger point of myofascial Meridians Points Acupuncture

ABSTRACT In recent years, the treatment of myofascial pain trigger point is a relatively popular technology，many people regard it as "Ashi point" in meridian theory, but compared with the traditional meridian theory, the description of myofascial pain trigger point is more intuitive and easier to master. This paper expounds the similarities and differences between myofascial pain trigger point and traditional meridian theory from the aspects of theory, basic research and clinical application, in order to provide a specific idea for the scientific interpretation of meridian phenomenon in traditional Chinese medicine.

Meridian theory is the core content and theoretical basis of acupuncture and moxibustion in traditional Chinese medicine. Its formation has been perfected and supplemented for a long time.The appearance of Huangdi Neijing basically marks the formation of classic meridian theory, which is the theoretical basis of acupuncture treatment of diseases.Ashi acupoint is a special method of acupoint selection in meridian theory. Its concept was first seen in Lingshu Jingjin:The treatment is to use fire needle to insert and output the needle at a very fast speed. The intensity of acupuncture is based on the patient's feeling of acupuncture, and the pain points are used as acupuncture points.Records in the Qianjin Yaofang written by Sun Simiao of Tang Dynasty:If a person is ill, he will squeeze at a certain part of his body. If there is pain and acupuncture can treat his disease, that is the acupoint.Ashi point has no fixed position and name, but takes local pain point or special feeling as the standard of location[1].

"Myofascial pain trigger point" was first proposed by American clinician Janet Travell in 1942. It is believed that it is a position that can cause pain on skeletal muscle. Pressing at this position with certain force can cause local and remote pain. At the same time, a tension band and a strip like nodule can be usually felt at this place[2].There are two kinds of trigger points for myofascial pain: activation trigger point and recessive trigger point.The trigger point of activation is spontaneous local or distant pain. The recessive trigger point is that there is no spontaneous pain in general, and only under specific conditions can it be transformed into the activated trigger point and produce pain symptoms[3].At present, the commonly used treatment methods of myofascial pain trigger point are acupuncture (including dry acupuncture, wet acupuncture, hot coagulation acupuncture, etc.), cold compress and stretch therapy, manipulation and massage, deep physical therapy (including laser, ultrasonic, infrared, shock wave, microwave, etc.), oral antipyretic analgesic or muscle relaxant, etc[4].Among them, dry acupuncture is similar to acupuncture in traditional Chinese medicine, but its theoretical basis is the functional disorder of muscle mechanics. The key point of its operation is to use acupuncture needle to insert muscle after determining the pain point, and to induce local or remote muscle to produce convulsive reaction through repeated lifting and inserting in muscle, so as to achieve the analgesic effect[5].This acupuncture method is very similar to the "Ashi point" and "meridian conduction" phenomenon in the traditional meridian theory, but the trigger point of myofascial pain is different from the traditional meridian theory from the theoretical basis to clinical application.

1.Similarities and differences

1.1differences in positioning methods

The location of Shu Points in traditional meridians follows the direction of meridians, which is generally located by the method of bone size measurement. Even the extra meridians have a relatively fixed location.The Ashi point of "pain as Shu" takes the tenderness point or sensitive point on the patient's body surface as the location of acupoint selection. Ashi point has no specific location and meridian tropism. Generally speaking, it is considered as the reaction point on the body surface or on the meridian circulation route due to stagnation of meridians and collaterals after visceral lesions.

There is no specific location of myofascial pain trigger points, most of which are located in the muscle abdomen. It is based on the anatomical location of muscles and the physiological state of the onset of the disease as its positioning method, which is characterized by "pain".Generally speaking, the location of myofascial pain trigger points should conform to the following characteristics[6]-[7]:① The nodule with clear tenderness can be touched subcutaneously. ② Local touch causes distant involvement pain. ③ Local acupuncture or pressing can cause the beating of local and distant muscles.Research shows that [8], the trigger point of myofascial pain is actually because the muscle is in a long-term state of tension and contraction, which leads to the accumulation of local metabolites, and the local acid environment stimulates the muscle, which will produce the recessive trigger point of myofascial pain,when the body is in trauma, fatigue or immunity decline, the invisible pain points will be transformed into activated pain points, which will cause local and involved pain of trigger points.

1.2 Differences in subcutaneous structure

Traditional meridians and acupoints can be arranged or positioned according to the direction of meridians and collaterals. They can be in any position of the body without specific organizational structure.The generation of myofascial pain trigger point is due to the longterm low volume, static and continuous contraction of muscle, which changes the tension of skeletal muscle and the imbalance of local biomechanics, resulting in local hypoxia and high metabolism state, accumulation of metabolites, and local high H + ion concentration stimulating muscle to produce pain point[9].This structure is the aggregation of myofibrillar pathological cells and beaded myofibrillar contracture nodule. On its cross section, large and deep stained round cells can be seen. The trigger points of tendon and muscle start stop point have inflammatory thickening phenomenon. Under the electron microscope, muscle ischemia phenomenon can be seen, and the contracture nodule accompanied by spontaneous discharge phenomenon[10].

1.3 Difference of acupuncture methods

Traditional Chinese medicine acupuncture emphasizes "Qi to be effective". After acupuncture at specific acupoints, the feeling of "acid, numbness, heaviness and distention" should be produced. This feeling may be transmitted locally or along the meridians. The nature and intensity of Qi obtained under acupuncture are closely related to the effect obtained[11].The commonly used techniques include lifting and inserting, twisting and rotating, and passing Qi through the meridian, etc. The purpose of which is to "get Qi", mainly emphasizing the feeling of the patient after the injection.

The treatment of the trigger point of myofascial pain emphasizes the "inactivation" of the trigger point, releasing the contracture muscle bundle in the muscle, and keeping the biomechanics of the body or joints in a normal balance[12].Acupuncture is a common treatment. The main point of acupuncture is to destroy the tissue structure of the pain trigger point through acupuncture, so as to relax the contracture muscle bundle, so as to activate the pain trigger point and relieve the pain.The needling method is divided into dry needling and wet needling. The diameter of dry needling is about 0.2-0.7mm.Wet acupuncture is similar to drug injection, that is, to inject a certain amount of anesthetics at the pain trigger point to inactivate the pain trigger point.The commonly used acupuncture technique is similar to the "canggui probe point" in acupuncture. The stimulation amount is determined according to the patient's condition and age. The specific acupuncture depth, direct or oblique needling are determined through the anatomical mechanism of the pain site.Generally speaking, the successful mark of acupuncture at the trigger point of myofascial pain is "prick jump", that is to say, after acupuncture, it can cause the twitch reaction of local muscles -- beating, the more times of beating, the better the effect[13].Xia Yanzhi et al[14],were satisfied with the therapeutic effect of acupuncture on pronator teres syndrome. The acupuncture method was to determine the stimulating point on pronator teres muscle, and then to carry out local acupuncture and take local muscle beat as the therapeutic standard.

1.4 The difference of analgesic mechanism

At present, a variety of studies have shown that[15], the content of nitric oxide and serotonin, which play an analgesic role in the body, has increased significantly, while the content of prostaglandin, which is the pain causing substance, has decreased significantly, so as to achieve the purpose of analgesia, or the release of β - endorphin and the inhibition of substance P after acupoint acupuncture, so as to achieve the analgesic effect.

However, the pathogenesis of myofascial pain trigger point is related to the high concentration of acetylcholine at the end plate joint. When acupuncture reaches the muscle fibers and structures around the trigger point, the concentration of acetylcholine in local tissues does not change much, while when acupuncture accurately at the trigger point, the concentration of acetylcholine at the trigger point is significantly reduced, especially the concentration of acetylcholine reactive substances, that is to say, the key to the success of treatment is to make sure that acupuncture reaches the trigger point[16].Du Chaoqun et al[17] treated 59 cases of lumbar myofascial pain syndrome by injection of medical ozone pain trigger point. It was found that local ozone injection at the pain trigger point could effectively inhibit the inflammatory reaction, edema, exudation, etc. around the muscle, so as to achieve the purpose of analgesia.

1.5 Differences in the scope of treatment

The treatment scope of myofascial pain trigger point is mainly chronic pain of skeletal muscle and limited function of bone and joint. In addition to acupuncture, there are also local manipulation, hot compress of traditional Chinese medicine, physical therapy and other treatment methods to destroy the tissue structure of trigger point and eliminate the pain trigger point so as to achieve the purpose of pain relief and improvement of function.Chen Bo et al[18]used ultrasound-guided extracorporeal shock wave to Treat 60 cases of neck shoulder myofascial pain syndrome and got good effect.Yang Yiling et al[19]can effectively treat the patients with lumbodorsal myofascial pain syndrome by using the hot compress and the position of the pain stimulating point after the alcohol immersion of traditional Chinese medicine.

The traditional treatment of meridians and acupoints is similar to that of myofascial pain trigger points, which can be treated locally by acupuncture, traditional Chinese medicine application, massage and modern physical therapy instruments.But the treatment range of meridians and acupoints is much larger. Meridians and collaterals are the direct response of the viscera on the body surface. Stimulation of acupoints can not only treat pain, but also effectively treat viscera diseases. Even Ashi acupoints can treat not only pain, but also viscera diseases

2. Thinking and Prospect

There are many coincidences between the theory of myofascial pain trigger point and the theory of meridians and collaterals. The treatment methods of dry acupuncture, wet acupuncture and flash acupuncture are very similar to the traditional acupuncture methods.Myofascial pain can also be treated by modern physical therapy instruments such as electronic biofeedback and low-frequency electrical stimulation[20][21]. The theoretical basis of its treatment is the "inactivation" of trigger points. Similarly, these methods can be used in the treatment of meridians and collaterals.The way to find the trigger point of myofascial pain is the same as the way to select acupoints along meridians.For example, its tenderness has obvious far-reaching involvement pain, which is the same as the sense of meridian circulation in the meridian theory, that is, the abnormal sense generated by pressing a certain acupoint can spread to the distance along the route of meridian circulation.After acupuncture at the trigger point of myofascial pain, the patient is required to have local muscle swelling and beating, or radiation pain at the distal end of the muscle.The traditional acupuncture method requires acupuncture after acupuncture, through a variety of lifting and inserting, twisting and a variety of double manipulations to make patients have the feeling of acid and numbness swelling, which is called "get Qi". If this feeling of acid and numbness swelling can radiate to the far end, the effect is better. From this point of view, the two treatments are very similar.Limited by natural science and technology, the ancient Chinese couldn't make a concrete explanation of the meridian phenomenon, thus forming a more abstract meridian theory.With the development of modern science and technology, people have been able to make scientific explanations for many physical phenomena, and the trigger point of myofascial pain can be regarded as a part of the explanation of meridian phenomenon.The meridian theory of traditional Chinese medicine has evolved for thousands of years, and its content is extensive and profound. It is also an important step in the modernization of traditional Chinese medicine to integrate the trigger point of myofascial pain into the meridian theory.