INTRODUCTION

To incorporate acupuncture as an effective medical procedure for pain management and trauma rehabilitation, health care practitioners need a basic understanding of needling mechanisms.

GENERAL PRINCIPLES OF HEALING PROCESS INDUCED BY ACUPUNCTURE NEEDLING

Researchers have accumulated an impressive amount of evidence of the cellular and molecular events underlying tissue response to needling. Clinical observation shows that acupuncture needling achieves at least four therapeutic goals:

Needling reduces bodily stress by stimulating the secretion of endorphins, relaxing the cardiovascular and muscular systems, and restoring the physiologic and autonomic balance (homeostasis), which includes normalizing visceral functions that are impaired during stressful assault via neurohormonal pathways.

Our clinical evidence shows that acupuncture is an effective modality in controlling inflammation. Needling and needle-induced lesions are foreign invaders to our body. Needling and its lesions stimulate and increase the number and the activity of immune cells and control the inflammatory process (see Chapter 4), which reduces both acute and chronic inflammation.

Needling promotes and accelerates soft tissue healing. Soft tissue includes nerves, muscles, connective tissues (tendons, ligaments, joint capsules, fascial coating of muscles), and some functional structures like blood and lymphatic vessels. Soft tissue damage may be caused by physical activities, injuries from accidents, or inflammation from repetitively overusing the muscles. In addition, almost all internal diseases, for example, asthma, gastritis, nephritis, and especially arthritis, cause discomfort, pain, or inflammation in superficial soft tissues. After acupuncture treatments, soft tissue inflammation and pain subside. Often internal diseases are alleviated or cured along with peripheral tissue healing.

Finally pain relief is achieved by homeostatic balancing and soft tissue healing in most cases, whereas immediate pain relief frequently happens even before tissue healing is complete.

NEEDLING AND DE QI SENSATION

Modern sterile stainless steel acupuncture needles with plastic guide tubes make needling safe, technically easy, and less painful. Needling, however, always produces a certain sensation. The nonpainful sensations produced by needling are traditionally called de qi (deh chee) in traditional Chinese medicine (TCM).

The needling process includes the following procedures:

During procedure no. 3, a needle can be manipulated by unidirectional or bidirectional (i.e., clockwise or counterclockwise) rotation or “pistoning” (up and down motion). This manipulation creates winding of connective tissue around the needle, which makes the practitioner feel the needle being grasped by body tissue.³

Once the needle has punctured the deeper tissues, especially the muscles, the patient will feel nonpainful sensations termed de qi (deh chee) in traditional Chinese acupuncture, which means that qi (i.e., the vital energy flow) has obtained or arrived. About 90% of needling will produce some sort of de qi sensation, depending on the nerve fibers encountered by needling and surrounding tissue milieu, such as tissue perfusion and inflammatory mediators.⁴ Needling the points on limbs may produce a de qi sensation of brief electric shock running up or down along the entire length of the limb. When needling the points on the back, a de qi sensation could be experienced more as localized sensations, like deep aching, soreness, and heaviness.

The phenomenon of de qi sensations can be explained by the types of nerve fibers stimulated by the needling (Table 3-1). Types II, III, and IV muscular afferent fibers not only generate de qi, but they also produce pain sensation if they are injured or pathophysiologically excited; so they represent de qi and pain-transmission nerves. Patients should be warned that some needling sensations such as aching or soreness may last 1 or 2 days.

Table 3-1 De Qi Sensation and Its Related Nerve Fibers in the Muscles

A needling-induced lesion stimulates the epidermis, dermis, underlying connective tissues (elastic fibers, collagen, basal lamina, deeper fascia), muscular tissues (skeletal muscles and smooth muscles of blood vessels), and nervous tissues (nerve fibers of sensory neurons and postganglionic neurons). The cells lesioned by the needling will be replaced with the same type of fresh cells without scar formation, since the lesions are very fine and tiny.

A needling activates chain reactions in both local tissues and the CNS (the spinal cord and brain). Thus we categorize needling mechanisms as peripheral and central. Both peripheral and central mechanisms, however, are physiologically inseparable. This chapter describes some of the major peripheral tissue reactions and the next chapter discusses the central mechanisms.

The following local chain reactions are started right after needling:

LOCAL SKIN REACTION AND CUTANEOUS MICROCURRENT MECHANISM

The neurovasculoimmune function of the skin is the first line of the body’s defense system. Needling stimulates the following skin tissues:

When an acupoint transits from latent phase (normal tissue) to passive phase, it becomes tender (Chapter 2). Around a tender acupoint the skin electrical conductance increases and the resistance decreases as discussed in Chapter 2. Inserting a needle into this acupoint will provoke an acute local inflammatory defensive response from all the previously mentioned tissues. The first visible response is the flare response, resulting in the appearance of redness around the needle. This vasodilatation function of the autonomic nervous system (ANS) is mediated by substance P secreted by cutaneous nociceptive sensory nerves. Then the immune reaction is triggered by mast cells, which produce histamine, platelet activating factor (PAF), and leukotrienes. The needle-induced lesion simultaneously activates interaction between the blood coagulation system and the immune complement system.

The body surface wears a layer of electric charges because the human body bathes in the electromagnetic field of the earth. Normally, dry skin has a DC resistance in the order of 200,000 to two million ohms. At acupuncture points this resistance is down to 50,000 ohms.⁵ Melzack and Katz⁶ found no difference in conductance between acupuncture points and nearby control points in patients with chronic pain.

This phenomenon can be explained by the dynamic nature of the acupoints. In a healthy person, DC resistance of the acupoints is the same as that of nonacupoints. In a chronically sick person, the acupoints transit from the latent phase (healthy tissue) to the passive phase (tender or sensitized tissue) in a predictable sequence and location (see Chapter 2). The sensitive area of acupoints is getting larger in chronic conditions, which contributes to high electrical conductance and low resistance.

In acute injury, acupoints appear around injured tissue. There is 20 to 90 mV of resting potential across the intact human skin, outside negative and inside positive.⁷ Most acupoints are measured at 5 mV higher than in nonacupoint areas.⁵ This higher voltage at acupoint loci can be explained histologically and pathologically. The configuration of most acupoints is rich in nerve fibers and/or vasculolymphatic structures, and once sensitized, inflammation may accumulate more fluids in the tissues of an acupoint. All these conditions may increase conductance and compensate the loss of resistance at acupoint loci according to Ohm’s formula: V = IR.

Insertion of a metal needle makes a short circuit from the skin battery and thus creates a microcurrent, called a current of injury, moving from inside to outside. The tiny lesion created by an acupuncture needle causes negativity at the needling site and produces 10 mA of current of injury, which benefits tissue growth and regeneration.⁸

These microcurrents induced by the needling are not sufficient to initiate nerve pulses to the spinal cord; thus the microcurrents will not generate effects of “needling tolerance” like “morphine tolerance,” meaning that repetitive needling will not reduce its therapeutic effect. In case of electroacupuncture stimulation of more than 3 hours’ duration, the analgesic effect will gradually decline. Professor J.S. Han of the Beijing Medical University explained that possibly long-lasting electrical stimulation, especially with high frequencies such as 100 Hz, increases the release of cholecystokinin octapeptide (CCK-8), which is an endogenous antiopioid substance.⁹

NEEDLE MANIPULATION: MECHANICAL SIGNAL TRANSDUCTION THROUGH CONNECTIVE TISSUE

During acupuncture treatments, more than 90% of the needling elicits de qi sensation. De qi elicited by manipulation of the needles increases the effectiveness of muscle relaxation and helps relieve pain. (Warning: Caution should be taken in treating weak or older patients because they may not be able to tolerate even weak manipulation and may suffer from flare-up pain after treatment. For these patients, simple insertion of the needle to the proper depth is sufficient. Flare-up pain can be alleviated easily by inserting one or two needles at the painful site. No manipulation is suggested for some facial points because of the dense capillary bed in such areas, which could cause bleeding or bruising on the face.)

The research team of the University of Vermont College of Medicine demonstrated that manipulation promotes tissue healing by producing biomechanical, vasomotor, and neuromodulatory effects on interstitial connective tissue.³

When a needle is inserted into the body tissue, there is an initial coupling between the metal needle shaft and elastic/collagen fibers. This initial affinity is caused by both surface tension and electrical attraction between the metal needle and connective tissue charges. Once this wrapping has occurred, frictional force takes over. Then rotation of the needle increases the tension of the fibers by winding them around the needle, which pulls and realigns the connective fiber network

The experienced practitioner detects the needle resistance to rotation (needle grasp) while the patient feels de qi sensation. This needle grasp process deforms the extracellular matrix, fibroblasts attached to collagen fibers, and possibly capillary endothelial cells.

In response to this mechanistic deformation, cells generate cascades of cellular and molecular events, including intracellular cytoskeletal reorganization, cell contraction and migration, autocrine release of growth factors, and activation of intracellular signaling pathways and of nuclear binding proteins that promote the transcription of specific genes. These effects lead to the synthesis and local release of growth factors, cytokines, vasoactive substances, degradative enzymes, and structural matrix elements. Release of these substances changes the extracellular milieu surrounding needled tissues and finally promotes local healing. These effects may expand to distant connective tissues to spread the healing process with long-term effects. Thus mechanical signals produced by simple needle manipulations generate cascades of downstream physiologic healing effects.¹⁰

Clinical evidence shows that this mechanical signal transduction resulting from proper needle manipulation (rotation or “pistoning”) may help desensitize sensory receptors and restore normal pain threshold. It is common, especially in treating acute injuries, for pain, tenderness, and swelling to subside during or shortly after needling.

LOCAL RELIEF OF CONCURRENT MUSCLE SHORTENING AND CONTRACTURE

Acupuncture effectively provides local relief of concurrent muscle shortening and contracture. All the local muscle pain stimulates the muscle to generate tender points, persistent involuntary contracture, and shortening of the muscles fibers, resulting in tense and stiff muscles. Four types of local muscle pain are most common: (1) mechanical, chemical, or physical (such as burning) injuries; (2) repetitive strain, overstretching, or a long time of shortening beyond the muscle’s tolerance when maintaining the same posture for a long time; (3) diseased viscera projecting pain to the body surface partially via mechanism of segmental neuronal reflex; and (4) referred pain associated with a diseased joint and its accessory structures.

Local muscle pain involves afferent sensory fibers (nociceptors), muscle fibers, and blood vessels. The nerve endings of sensory fibers contain neuropeptides substance P (SP), calcitonin gene-related peptide (CGRP), and somatostatin (SOM). Under pathologic conditions the neuropeptides can be released from the sensory nerve endings and influence basic tissue functions such as neuronal excitability, local microcirculation, and metabolism. When tissue-threatening (noxious) stimuli (mechanical, physical, or chemical) occur, the neuropeptides are released from the sensory nerve endings, which triggers a cascade of events leading to neurogenic inflammation. SP and CGRP cause vasodilatation and increase the permeability of the microvasculature. Histamine is liberated from mast cells when exposed to SP. All these substances diffuse to neighboring tissue, resulting in an expansion of the inflammation.

Once this neurogenic inflammation diffuses, fluids and proteins shift from the blood vessels into surrounding interstitial spaces. This process releases vasoneuroactive substances: bradykinin from protein (kalidin) in the blood plasma, and serotonin (5-hydroxytryptamine, 5-HT) from platelets. Leukotrienes and prostaglandins are released from the surrounding tissue cells at the injured site. All these substances increase the sensitivity of affected nerve endings. Thus the noxious stimuli result in tenderness (sensitized nociceptors) and then spontaneous pain (nociceptor excitation) in the localized region of muscle.

When nociceptors are sensitized, their firing threshold decreases. Under such physiologic alteration, any slight stimulus such as light pressure may cause the nerve ending to fire impulses to the CNS. This light pressure does not elicit any response from the normal unsensitized nerve ending. If the sensitization continues, it may further decrease the firing threshold of the nociceptors and the excited nociceptors may spontaneously discharge impulses to the CNS, which causes sensation of pain.

Repetitive strain or overuse injuries are common muscle activities that result in local muscle pain. If muscles are used for repetitive movement without adequate recovery time between movements or are held under a load in a relatively fixed position for prolonged periods, discomfort, soreness, or pain will develop following those activities, with peak discomfort during the first day or two. Pain makes muscles tender to palpation, restricted in range of motion, and sometimes slightly swollen. With this type of injury, some disorganization of striation of muscle fibers can occur, and a lack of myofibrillar regeneration could persist for up to 10 days.¹¹ Changes in blood chemistry have been noticed, including increases in plasma interleukin-1, acid-reactive substances, lactic dehydrogenase, serum creatine, phosphokinase, aspartate aminotransferase, and serum glutamic-oxaloacetic transaminase. Most of these enzymes are involved in muscle metabolism.

The literature on Chinese traditional acupuncture indicates that the diseased viscera project pain to predictable points or areas of the body surface. In general this is the manifestation of the segmental mechanism of viscerosomatic neuronal reflex. For example, inflammation of a kidney may cause tender points or painful spasm in the lumbar area, resulting in lower back pain with tender points palpable at the T10 to L2 level on the back muscle (erector spinae). For some patients additional tender points also appear in the neck region. This segmental mechanism plays an important role in treatment of the pain symptoms and is discussed in detail later. Needling these tender points associated with diseased organs relieves pain and other symptoms, such as cramping, inflammation, and ulcer.

Joint diseases and dysfunction can cause muscle pain. Because of the segmental reflex, the activity of sensory nerves influences the activity of efferent nerves from motor neurons of the same muscle; however, the sensory nerves of neighboring muscles and joints also affect this muscle. Stimulation of knee joint nociceptors excites afferent motor neurons of both flexor and extensor muscles.¹² It is possible that sensory input from a joint will lead to a contraction in neighboring muscles. Then the contracted muscles may put physical stress on the joint and its accessory structures, such as capsules, ligaments, and disks. All these structures will produce pain because they are richly innervated by sensory nerves.

All types of muscle pain of different pathophysiologies converge to produce similar phenomena: they produce tense, stiff, and shortened muscles and provoke the formation of tender points and enlarged contraction knots within the muscle. Some of the contraction knots, if not released immediately, become persistent muscle contracture, resulting in a chronic condition.

Those sensitized spots are also found in other soft tissues that are richly innervated by sensory nerves, such as tendons, ligaments, possibly periosteum, and superficial and deep fascia. Modern clinicians call these tender spots and contracture trigger points, dermopoints, motopoints (neuromuscular attachment points), nodes, and other terms, all of which represent some of the different aspects of the acupoints in traditional Chinese acupuncture.

Acupoints have different histologic composition and pathophysiologic phases (Chapters 1 and 2). Some acupoints consist mostly of sensitized nerve fibers; others, in addition to the sensitized nerve receptors, contain muscle contraction knots. Internal factors, such as diseased organs and arthritis, will sensitize acupoints all over the body. Remarkably their locations are highly predictable, partly because of a segmental mechanism or special tissue features associated with sensory nerve fibers. During acute injuries sensitized spots are provocatively formed according to the type of injury and body anatomy involved. For example, the mild ankle sprain (inversion injury) causes only elongation of ligaments on the lateral ankle, whereas a severe ankle injury may tear the ligaments between the fibula and tibia in addition to the lateral ligaments. Knowing anatomy helps in locating the most effective tender points for treatment. (To help locate the effective acupoints, the clinical chapters of this book describe some of the neuromusculoskeletal anatomy in relation to body mechanics.)

The muscle, tendon, or fascia that harbors tender or painful points may resist stretch and become tense, stiff, shortened, and painful. Most acupoints used for pain treatments are of muscular nature as discussed in Chapter 1.

Before we examine pathologic contracture, we review the membrane depolarization and five steps involved in healthy muscle contraction.

Depolarization can be described as follows. When a cell is not agitated, the outside of the cell membrane is electrically positive, the inside negative. When electric impulses or bioactive molecules stimulate the cell, positive Na⁺ ions flow into the cell through the membrane so that the outside becomes less positive; this means the electricity flows into the cell. Then positive K⁺ ions flow out from inside to restore positive polarity of the outside, which means that positive electricity flows out from the inside. Finally Na⁺ ions are pumped out and K⁺ ions are pumped in by molecular channels; so the concentration of Na⁺ ions outside and K⁺ inside is restored. This represents one cycle, and the process is called depolarization (Figure 3-1). The depolarization consumes metabolic energy.

Figure 3-1 Diagram of depolarization of a nerve cell.

All five steps of muscle contraction are related to depolarization and consumption of energy:

Now we compare the same steps of pathologic contraction with physiologic contraction. This process was discussed in Chapter 2, but is briefly reviewed here because it is an important mechanism in clinical acupuncture practice. Dr. D.G. Simons explained this process and called it the energy crisis hypothesis.”¹³ We modify his hypothesis as follows (also see Figure 2-2, p. 22).

Thus the ischemia, hypoxia, low energy supply, and muscle shortening will continue and become a vicious circle (see Figure 2-2, p. 22) until appropriate treatment interrupts the vicious circle of energy crisis. The muscle contracture during such an energy crisis has a higher temperature than normal muscle tissue does. This pathologic contraction is an endogenous, not voluntary, impulse initiated and may persist indefinitely. Clinical experience shows that any method that interrupts the energy crisis will help relax the muscle and reduce muscle pain. Needling, electrical stimulation, physical stretch, proper exercise, and drug injection are effective procedures used to break the energy-consuming vicious circle and to separate actin from myosin to relax the shortened muscle.

Manipulation of the needle has been suggested to deform connective fibers, and this mechanical signaling induces tissue healing. Clinical evidence shows that manipulation also helps to stretch muscles and breaks the energy crisis of some acupoints. Needling can precisely target and release endogenous contracture deep inside the muscles. These findings demonstrate the effectiveness of acupuncture procedures for muscle relaxation, restoration of local blood circulation, and promotion of tissue healing without any side effects. If local sensitization or endogenous contracture is acute and localized, muscle relaxation can be achieved immediately. Otherwise more treatments are needed to first destroy the endogenous contracture histologically and then promote tissue regeneration to replace the destroyed muscle fibers.

NEUROCHEMICAL MECHANISMS OF ACUPUNCTURE ANALGESIA

Neurochemical mechanisms of acupuncture analgesia (AA) have been intensively investigated in many Chinese, Japanese, South Korean, and North American universities. Professor Ji-shen Han’s laboratory at Beijing Medical University, Professor Cao Xiao-ding’s laboratory at the Shanghai Medical College of Fudan University, and Professor Bruce Pomeranz’s laboratory at the University of Toronto have contributed solid scientific data explaining the neurochemical process of AA.

Recently Professor Zang Hee Cho and his research team at the University of California, Irvine, cooperated with Tian Tan Hospital in Beijing and have obtained new evidence by using functional magnetic resonance imaging (fMRI) techniques (Chapter 4). Our explanation of AA mechanisms is oversimplified for the purpose of this textbook. For example, after pain impulses reach the spinal cord, at least six neural pathways transmit those impulses from the spinal cord to the cerebral cortex, and numerous neurochemicals are released at different sites to modulate pain signals, such as three different endorphins (enkephalin, beta-endorphin, and dynorphin), cholecystokinin (CCK), serotonin, adrenocorticotrophic hormone (ACTH), SOM, substance P, vasoactive intestinal peptide (VIP), neurotensin, CGRP, gamma-aminobutyric acid (GABA), and more. Detailed description of these interactions among the neurochemicals is beyond the scope of this clinical textbook. More detailed discussions are provided in Chapter 4.

The neurochemical mechanisms not only provide analgesia (pain relief) but also promote homeostasis and tissue healing and improve the immune system, the endocrine system, the cardiovascular system, other systems like the digestive system, and psychologic adjustment. These mechanisms explain why different problems, such as asthma, tinnitus, irritable bowel, gastric ulcers, and others, improve in the same course of pain treatment by acupuncture needling. Acupuncture restores the control system of the body and promotes self-healing, which are suppressed during the process of the disease or injury.

Mechanisms of pain perception and therefore its treatment involve the following parts of the nervous system:

The quantitative nature of acupoint physiology discussed in previous chapters is the basis for our evaluation method and treatment protocol. Clinically we first select two types of acupoints (Chapter 5), local and distant, or symptomatic and homeostatic points. Local points are located in painful tissues and are more sensitive or are painful. In chronic cases these sensitized local points may stimulate neurons inside the spinal cord; they synapse with and finally sensitize those spinal neurons.¹⁴

Thus, when we stimulate the symptomatic acupoints, we also stimulate the sensitized neurons in the same segment of the spinal cord. This means we stimulate segmental circuits when we select local points. Distant points are located far from those local points, and their tenderness represents a homeostatic imbalance (Chapter 2).

Close attention should be directed to the phenomenon that homeostatic acupoints (HAs) become tender in a predictable sequence all over the body when homeostasis declines.² Everyone, including healthy persons, has a certain number of tender HAs all over the body. The difference between the healthy and the less healthy bodies is that the healthy ones have fewer tender HAs and the less healthy ones have more tender HAs. Those points, representing homeostatic changes, appear in predictable locations. In chronic cases more tender points are distributed all over the body. In a healthy person with an acute injury, tender points appear locally around the injured area. Clinically segmental (local) treatment may suffice for acute injuries, but both segmental (local or symptomatic) and nonsegmental (distal or homeostatic) points should be used for chronic symptoms to achieve optimal self-healing. Now it is clear that when we place needles into local painful points, AA is produced through segmental mechanism. If we use distal points, AA works through a nonsegmental mechanism. These mechanisms enhance one another.

Neural mechanisms in AA can be explained step by step as shown in Figure 3-2. Pain (cell 1) sends messages to the spinal cord, where they are relayed up through pathways (cell 2) to the brain centers, thalamus, and cortex; these messages are perceived as pain (see Chapter 4). When we use acupuncture to treat this pain, we select both local (segmental circuit) and distal (nonsegmental circuit) acupoints. Wherever we insert a needle into a patient’s body, the needling stimulates afferent sensory receptors of small-diameter nerves in the skin and muscles, as discussed previously (cutaneous A-delta and C fibers, muscular type III and IV fibers, sometimes type II fibers).

Figure 3-2 Neural mechanism of acupuncture analgesia. E, Endorphins; M, monoamines; ALT, anterolateral tract; DLT, dorsolateral tract; STT, spinothalamic tract.

(Redrawn from Stux G, Hammerschlag R, editors: Clinical acupuncture scientific basis, Berlin, 2001, Springer.)

Let us start with the examination of segmental mechanism. During the needling of a local point in the painful area, the impulses travel from the acupoint (cell 5) to the spinal cord (cell 6) to activate spinal neurons (cell 7) and secrete enkephalin and dynorphin to inhibit the pain messages. Next the needle impulses are relayed through cell 6 to the midbrain (cells 8 and 9) and the pituitary. The midbrain uses enkephalin to activate the raphe descending pain-inhibition system (cell 11).

The pain-inhibition system (cell 11) secretes monoamines, serotonin, and norepinephrine to inhibit pain transmission through dual functions:

Finally the needling signals generate neuronal activities in the highest brain level, the neocortical area. Professor Zang-Hee Cho and his research team provided the first scientific evidence for this central processing.¹⁵ This cortical processing is responsible for the modulation of pain perception.

It is clear that when distal points (nonsegmental circuit) are selected, the needle impulses bypass spinal cord neuron 7 and travel directly to the supraspinal level: the midbrain and pituitary/hypothalamus. Segmental circuits (local points) activate the spinal cord, in addition to the midbrain and pituitary/hypothalamus. To achieve maximal results, both segmental (symptomatic acupoints) and nonsegmental (homeostatic acupoints) circuits should be used.

To summarize, local points (also called Ashi, segmental, or symptomatic acupoints) directly inhibit pain messages, and distal (homeostatic) points promote systemic homeostasis. They synergistically enhance pain relief and healing.

Using this scientific rationale, the physiology of the acupoint system, and our clinical evidence, we designed an Integrative Neuromuscular Acupoint System (INMAS) protocol using both segmental and nonsegmental mechanisms for practically every kind of peripheral pain symptom. In general, symptomatic acupoints (SAs) are selected for specific symptoms, and HAs are selected for nonspecific effect to restore systemic homeostasis. Thus our INMAS protocol, which combines SAs, HAs, and paravertebral acupoints (PAs), can be applied to a variety of symptoms recorded in the classic acupuncture literature. Please note that PAs and SAs are on the peripheral nerves of the same segments.

BLOOD COAGULATION SYSTEM AND IMMUNE COMPLEMENT SYSTEM

A needle-induced lesion is a minute trauma to the tissue cells and mostly causes invisible tiny internal bleeding. This lesion activates the restorative control mechanisms involving the neuroendocrine-cardiovascular–mediated immune response, and thus promotes tissue healing and homeostatic restoration, resulting in systemic healing of the whole body in addition to local healing of the pathological symptoms.

Needling-induced chemicals from lesioned connective tissue such as collagen fibers and mast cells activate blood coagulation factor XII (the Hageman factor). In addition to causing blood coagulation, factor XII activates other factors to attract immune cells to the site of needling. The lesioned tissue cells stimulate mast cells and produce peptides such as bradykinin and histamine, whose peripheral function includes vasodilatation and increased vascular permeability and immune-related cytokines.

The enhanced vasodilatation of capillaries improves blood flow to the site and enables immune cells to move from the blood circulation to trigger the defensive immune reaction around the needling lesion. Chemicals are released to activate immune cells and excite nociceptive sensory fibers.

When the needle is removed, tissue repair processes are stimulated, lesioned cells are digested, and protein synthesis is mobilized. The lesion-induced healing is directed by systemic neurohormonal mechanisms. The pituitary starts to increase the blood volume of ACTH, which triggers synthesis and the secretion of physiologic corticosteroids and other hormones. This process protects the body from stress, including reduction of the inflammatory reaction (see Chapter 4). Descending neural control systems from the brain inhibit and desensitize the nociceptive neurons in the spinal cord and peripheral nerve endings, and balance the ANS, which normalizes blood flow and energy metabolism. Finally the body’s homeostasis is improved or restored and local tissue healing and pain relief are accelerated.

SUMMARY

Acupuncture needling therapy is a drugless inoculation of minute “traumas” or lesions into the body to restore the mechanisms of self-healing, including autonomic homeostasis, tissue healing, and pain relief. At the needling site, a cutaneous microcurrent circuit is built to produce a current of injury (about 10 mA), which stimulates tissue growth. Mechanical stimulation from the needle, especially from needle manipulation, deforms the connective collagen and elastic fibers, which transduces signals for tissue healing and gene transcriptions.

The needling and its lesion also induce a local antiinflammatory reaction against the intrusive lesion. Endogenous muscle contracture (nonvoluntary muscle contraction), which creates an energy crisis in shortened muscles, can be relaxed by needling the corresponding acupoints to restore normal muscle physiology. Neurophysiologically there are segmental and nonsegmental neural mechanisms. Needling signals from symptomatic (segmental) points are processed at both the spinal cord and supraspinal cord centers (midbrain, thalamus, pituitary, and cortex); stimulation signals from distant homeostatic (nonsegmental) points may be directly relayed to supraspinal cord centers. Both mechanisms enhance one another to activate descending control systems, which includes the secretion of chemicals and hormones into the blood and cerebrospinal fluid to restore homeostasis and neural modulation of pain relief.

Patients respond differently to acupuncture treatments because of their physiological differences. About 28% of the clinic population are excellent responders, 64% good and average responders, and 8% weak or nonresponders.²

Differentiation of patients and prediction of prognosis are important parts of the treatment procedure in acupuncture therapy. Understanding the needling mechanisms facilitates development of a practical protocol for all pain symptoms. Our INMAS protocol (see Chapter 5) simplifies the process of point selection. INMAS provides a standardized protocol required by Western medicine and ensures the personalized treatment practiced in TCM. Our 16-point quantitative evaluation method provides a generally predictable prognosis of pain management.

This chapter discusses the peripheral effects of acupuncture stimulation. Chapter 4 presents a discussion of the central effects of acupuncture stimulation. To help understand both peripheral and central mechanisms, a brief outline of both mechanisms is provided here.

It is clear that acupuncture stimulation, with both peripheral and central effects, activates the physiologic processes of built-in complex survival mechanisms to restore and maintain homeostasis. The peripheral effects involve the creation of needle-induced lesions, cutaneous microcurrent, mechanical signal transduction through connective tissues, local relief of muscle shortening and contracture, and other local neuroendocrine-immune reactions. The central effects are a form of CNS response resulting from peripheral sensory stimulation. This response includes the neural immune interaction, the humoral and ANS, especially vagus nerve pathways, and the neural efferents based on other hypothalamic neural circuits. It should be emphasized that the peripheral and central effects of acupuncture stimulation are physiologically inseparable.

Newly available molecular imaging tools such as high-resolution and high-sensitivity molecular-imaging positron emission tomography (PET) and high-field fMRI enable us to investigate the mechanisms of the human brain, especially the higher brain (the cortex), such as neurochemical and hemodynamic responses in vivo to acupuncture stimulation. The information gained from these tools will promote better understanding of the mechanisms of acupuncture and help to select more effective clinical procedures.

The central effects of acupuncture stimulation activate the four front lines of homeostasis: (1) the nervous system, (2) the immune system, (3) the endocrine system, and (4) the cardiovascular system controlled by neural pathways such as the ANS, especially the vagus nerve pathway. These built-in homeostatic survival mechanisms are discussed briefly in Chapter 4.

All the available scientific data definitely support and justify the INMAS (see Chapter 5) and its clinical application. Both laboratory and clinical data match and agree with each other. The following points explain how the fMRI data support clinical procedures.