REGIONAL ACTION OF ACUPUNCTURE STIMULATION
There are many findings that acupuncture act at a spinal (segmental or regional) level. Noxious stimuli from the periphery lead to release peptides in the spinal cord level. These peptides (tachykinins substance P, neurokinin A, calcitonine gene-related peptide, somatostatin etc) modulate the transmition of nociceptive information to the CNS. Using treatment modalities like TENS, Acupuncture and electroacupuncture, we can block the nonociceptive signals, activating descending pain inhibitory systems which act at the level of the specific myelotome. Acupuncture and electroacupuncture have an inhibitory effect on interneurons of the spinal cord (lamina V) and this inhibition is mediated by opiate pain-relieving system.[17] Also, many laboratories have shown changes in dorsal horn cell activity (gating) during mechanical, chemical and electrical stimulation of somatic and visceral fields. Transcutaneous electrical nerve stimulation (TENS) of somatic areas dicreases the spontaneous and noxiously evoked activity of a majority of dorsal horn neurons (wide-dynamic-range (WDR) cells, High threshold (HT) cells, and high threshold inhibitory (HTi) cells), reducing the perception of pain. [18]
This mechanism can be the spinal (regional) action of many analgesic physical methods which we use in daily practice in physiotherapy. Another regional reaction concerns the activation of an area through reflex arches. Those are produced after the stimulation of a peripheral sensory receptor. The stimulus is directed with afferent neural fibers to a sensory or motor nucleus of the spinal cord and a response reaction is produced there.
Analytically:
Viscero-cutaneous reflex or splanchno-fascial reflex. According to that, a functional or organic disease of a viscera causes pain, hypalgesia, tension or irritation to a particular area of the skin. As a general rule, the skin area where pain is projected has, in relation to the painful viscera, common somotomic origin as to the embryo and consequently it is innervated sensorially from the same neurotome of the spinal cord. The skin and the related viscera have the same segmental innervation usually by dorsal roots, spinal nerves and nuclei (referred pain resulting from reflex phenomena). The nociceptive impulses from the affected viscera pass to the dorsal horn and then to anterior horn of spinal cord across interneurons. Visceral afferent nociceptors converge on the same pain projection neurons as the afferents from the skin.[19,20,21,22]
For example, stimulation of the descending colon with barium chloride is going to create paleness (shrinking of the melanin cells-melanocytes) in an area or 2-3 neurotomes of the specific myelotomes (T9-T12). Moreover, injection of adrenaline 10% to the stomach gastric mucosa, in the gall bladder or in the fascia of the spleen, is going to create skin «shining» at a specific small area of the dermotomes of those organs. [23]
Pain in the gall bladder is projected on the skin of the right hypochondrium and on the top part of the right shoulder, a pain related to stomach ulcers corresponding to the 11th thoracic vertebra. The viscero cutaneous reflex we have just described is transmitted via the sympathetic chain. Dissection of the spinal cord does not affect this reflex. It is abolished by the dissection of the sympathetic chain. This reflex is a diagnostic reflex.
Cutaneous visceral reflex . The irritation of a skin point influences functionally the organ by which the cutaneous area is connected according to the neurotomes. Experimentally, to patients with acute angina pectoris the injection of procaine in cutaneous tender points of the anterior thoracic wall brings about fast recession of the precordial pain. Electrical stimulation of the point Futu (L.I. 18) on both sides, provokes analgesia capable of achieving thyroidectomy. This point is found in an area of innervation from the third dorsal cervical spinal nerve. The fascial of the thyroid gland and the above lying skin area where the specific acupuncture point is found are sensorially innervated from the same cervical myelotome. This reflex does not depend on superior brain centres. It follows a clearly neurotomic distribution. Dissection of the visceral nerves abolishes the reflex. Dissection of the vagus nerve does not influence the healing effect. It looks like the myotatic, monosynaptic reflexes. This is a therapeutic reflex.
Viscero-muscular and viscero-visceral or somato-autonomic reflexes are internal reflexes. It is they who interpret muscular contraction and vasocontraction observed in diseases of the internal organs. Sensory fibres from the muscles, the vessels and the affected organ originate from the same myelotome on neighbouring nuclei which are functionally interconnected.[24] This reflex produses reflex spasm of the skeletal muscle (trigger points of m. pectoralis) during myocardial ischemia. Also, through this reflex we interpret muscular pain during the function of the muscle under conditions of limited blood supply.[25] The sensation of needle insertion into somatic nerve endings in the muscle, ascends with afferent impulses to the anterior hypothalamus. Efferent impulses originate from the same reflex centre of hypothalamus, descend to the cholinergic vasodilator nerve and dilate the blood vessels of the muscle. Dissection of the dorsal spinal roots and that of the visceral nerves abolishes this reflex. A kind of viscero-visceral reflex is activated during the direct excitation of a ganglion by placing a needle deeply in the ganglion or all around the ganglion. As an example I would like to mention point SI 18, which is a meeting point of the head of the arm 3 Yang meridians. This point is being acupunctured during acute pain of the muscular - skeletal system. Why this point is so important in treatment of myoskeletal diseases. It is mentioned [26] that application of local anaesthetics to the mucosa overlying the sphenopalatine ganglion can block pain and is extremely effective on myoskeletal pain especially of the neck and back.
The acupuncture point LE 18 and the sphenopalatine ganglion coincide. In this area, there exists the largest collection of neurons in the head outside the brain itself. It is intimately connected to the trigeminal nerve and nucleus, and the superior cervical sympathetic ganglion. It seems to be the final switch between the body and the brain.
Somatomotors or cutaneo-muscular segmental reflexes. A harmful stimulus to the skin stimulates the axons of sensory fibres of groups III and IV of peripheral nerves. The information of stimulation enters the posterior horns of the spinal cord and is transmitted with the help of intermediate neurons to the motor neurons of the anterior horns. This pathway is polysynaptic and permits on one hand control and on the other deviation of sensory stimulation. Thus, the stimulation of a group of sensory receptors on the muscles, tendons or the skin will cause contraction or relaxation of muscles in the stimulated area (segmental distribution of the reflex). In this manner, by a sensory stimulus (puncture) it is possible to enlist neurons on the same or on the opposite side of the initial stimulation. The usual response to the sensory stimulus is the ipsilateral stimulation of flexors and the inhibition (relaxation) of extensors and the contralateral inhibition of flexors and stimulation of extensors (flexor and cross-extensor reflex).[27,28] Most rehabilitation treatments by electrophysical agens and, of course, acupuncture, use cutaneo-muscular reflexes to achieve muscle relaxation and to ameliorate the intramuscular blood supply to individual muscles or muscular groups. The selection of the area to be stimulated depends on the target muscle.
Vegetative reflexes are reflexes through the vegetative nervous system (sympathetic and parasympathetic). There is a large number of short and long vegetative reflexes which "close" the nervous circuit in the brain, the spinal cord, in the big nervous ganglia or in smaller peripheral ganglia. There are not only segmental reflexes. Many vegetative reflexes have been describe in medicine. As an example I will mention the segmental and suprasegmental reflexes that are prodused due to local biochemical changes and tissue damage in patiens with acute myocardial ischemia (AMI). This reflex is known as Bezold-Jarich reflex (abnormal vagovagal reflex) and produce severe bradycardia, peripheral vasodilation, severe hypotension and atrioventricular block. These reflexes involves afferents and efferents of both cardiac vagi and cardiac sympathetic nerves which produse sympathosympathetic reflexes. In the AMI patiens exist also suprasegmental reflex responses result from nociceptively induced stimulation of the medullary centers, hypothalamic centers, limbic structures and neuroendocrine function.[29]
According to Gunn, some other common condition of autonomic dysfunction that responce well to acupuncture treatment are the vasomotor, sudomotor, glandular hyperactivity and smooth muscle spasm observing in spondylotic radiculopathy. When pain dissapeare, this autonimic phenomena dissapeare.
Vegetative reflexes can be activated by a) local stimuli, b) general stimuli and c) regional stimuli. From the university of Goteborg [30] we have the information that acupuncture may affect the sympathetic system via mechanism at the hypothalamic and brainstem levels and the post-stimulatory sympathetic inhibition that creates, persist for more that 12 hours after acupuncture.
Vegetative reflexes are the clearest evidence of the organisms reaction as an open thermodynamic system. We know very little about these reflexes. The major problem is in describing the connections between the human cortex and the peripheral outflow to smooth muscles, cardiac muscles, secreting glands, sensory organs and vessels. Some organs (heart, gut, spleen, kidney) receive both sympathetic and parasympathetic innervation, while other organs (adrenal, medulla, vascular tissue, skin and muscles) gain only a sympathetic supply. Vegetative nervous system, clinically speaking, is not so autonomus as we believe and seems to be "synergic rather than antagonistic".[31,32,33]
SEGMENTAL DISTRIBUTION OF ACU-POINTS
Three big main meridians cross the frontal thoracic and the frontal abdominal wall. The M of the Spleen, Stomach, Kidney and the Conception Vessel Meridian. During their course via abdominal and thoracic wall, this meridians develop 66 ipsilateral points (110 bilateral) Independently of the name of the meridian, if we apply acupuncture to the points found on the thoracic area, we influence the thoracic viscera or their functions, while when we apply acupuncture, using the points developing into meridians of the frontal abdominal wall, we influence the abdominal viscera or their functions. Moreover, all the meridians follow a course towards the middle frontal and the middle dorsal line similar to the segmental distribution of the deep pain that Keelgren [34] has put on a chart after injection of NaCl in the interspinal ligaments of the vertebrae. The dermotomal distribution of the sympathetic fibres coincides with the distribution of the points of acupuncture of the second branch of the Meridian of the urinary bladder.
The same accurate neurotomic distribution of the acupuncture points seems to be preserved by the Urinary Bladder Meridian with the Governing Vessel Meridian. The acupuncture points Lung 1 and 2, Urinary Bladder 13, 14, 15, 41 and Governing Vessel 14, have been used for centuries by acupuncturers for the treatment of lung diseases . All these points concern T2 T4 dermotome of the lungs and they correspond dermotomically to the outlets of the sympathetic chain of the dorsal lung plexus (2nd 4th thoracic sympathetic ganglion). The big bronchial tubes are autonomously innervated by this sympathetic plexus, and also the division of the trachea and all the vessels which transport blood to the bronchial tree. From the same anatomical region start the preganglionic branches of the lower cervical and of the first and the second thoracic ganglion of the sympathetic chain, which are going to form in the depths of the dorsal cervical triangle, the stellar ganglion. The shu-mu technique (synchronus stimulation of abdominal-mu and thoracic, back-shu, points) is a special ancient method that uses the segmental distribution of acu-points to treat deseases of internal abdominal organs.
GENERAL ACTION OF ACUPUNCTURE STIMULATION
Teams of neurophysiologists and research workers on the effect of acupuncture, of electroacupuncture, of electrotherapy and other methods of physical agens have studied the possible mechanisms and the ways of analysing of the peripheral stimulation from the CNS and also the way of answering of the CNS to these stimuli. The integrity of the peripheral nervous system and the spinal cord is considered necessary for the application of acupuncture. It is well known that acupuncture points are «silent» in paraplegic limps (individuals with complete sensory-motor paraplegia) or in experimental animals in which surgical resection of the spinal cord has been effected.[35]
A peripheral stimulus, depending on its quality, may stimulate specific nuclei of the CNS and provoke secretion or qualitative modification of neurotransmitting substances in the blood and the CSF. Besides, each combination of acupuncture points may activates different nerve circuits. This view was based on two experimental results from the University of Peking.[36]
Experiments on rabbits have shown that following arterial anastomosis of two rabbits (cross circulation technique), analgesia is achieved not only for the rabbit on which acupuncture is applied but also for the rabbit in which the blood of the former circulated through the anastomosis. Furthermore, a CSF transfusion from a cat-donor to which acupuncture analgesia had been applied to another cat-receptor causes analgesia to the donor cat after 10 minutes. Since then, the existence (following acupuncture) of analgesic neurotransmitting substances to the CSF and peripheral blood has been repeatedly confirmed and this clearly shows the activation of central pain control systems (and others) through ancient acu points. Reference to these points is related on one hand to the topographical paradox of the points and on the other to their important therapeutic action. Their particularity has been established both by studies (on experimental animals) and clinically (on patients) and it is well known that randomly selected sham acu-points have an analgesic effect on 28-35% of patients when compared to acu points that have an analgesic effect on 55%-85% of the patients. Papers published from time to time relate to acu points Lung (L) 7, Stomach (S) 36, Large intestine (LI) 4, Spleen (Sp) 6, Large Intestine (LI) 10, Triple Heater (TH) 5, Liver (Liv) 3 and Pericardium (P) 6. The systems activated through these points may be a) opiate endogenous analgesic systems, b) non-opiate systems and c) central sympathetic pain inhibition systems through the reticular formation of the brain.
In recent years, the analgesic action of acupuncture is used for the treatment of cases with acute or chronic pain and less for the surgical analgesia it can offer influencing the chemistry of the descending pain control system. This system consists of four parts: a)spinal system (dorsal horn), b) cortical and diencephalic system, c) mesencephalic (PAG & PVG) system and d) pontine (nucleus raphe magnus) system. Each system uses differente types of endogenous opioid peptides.[37,38] There is clear evidence of the analgesic action of acupuncture in this field. I mention that of 1500 articles in Medline, 1100 concern the pain-killing and the analgesic action of acupuncture. The most important among these articles concern laboratory studies on experimental animals and clinical studies in veterinarian clinics.
This fact excludes suggestion (animals cannot be subject to suggestion), hypnosis, placebo effect (in part) but not stress-induced analgesia.
Pomeranz,[6] mention the following results in support of the analgesic (endorphinergic) action of acupuncture: Four different opiate antagonists abolish the analgesic action of acupuncture. Naloxone abolishes the analgesic effect. A microinfusion of naloxone or the infusion of endorphin antibodies (to the CNS) abolish the analgesic effect. Mice with a genetically reduced concentration of opiate receptors in the CNS have a poor response to acupuncture. Rabbits with endorphin deficiency do not respond to the acupuncture stimulus. Endorphin levels increase considerably in peripheral blood and in the cerebrospinal fluid during electro-acupuncture while on the contrary their levels in the CNS are reduced. The analgesic effect of acupuncture lasts much more when one impedes the enzymatic degradation of endorphin. The analgesic effect of acupuncture is transmitted through the blood (cross circulation) and the cerebrospinal fluid. The inhibition of pituitary endorphin abolishes the acupuncture effect. An increase of messenger RNA for pro-enkephalin in the brain (pituitary) is observed for 24-48 hours following acupuncture.
About 60% of patients suffering from myofascial pain of the lumbar portion of the spinal cord are considerably relieved after the application of warm compresses (43-51°C) or ultrasound and the improvement of symptoms lasts from 90 minutes to 7 days. On the contrary, the application of electroacupuncture to general acu points relieves the patients for weeks, months or up to 3 years. This was noted (from Price at al.) on 58% of the patients with chronic myofascial pain of the lumbar portion of the spinal cord to which acupuncture was applied . Han suggests that the specific, long-term analgesic effect of acupuncture is due to two factors: a) the activation of a neurogenous serotonin and methencephalin circuit in the upper part of the descending pain inhibition system (in the mid diencephalon). This results in the continuous inhibition (at the level of the spinal cord) and the non-conduction of harmful stimuli from the spinal cord to the CNS, and therefore the non-perception of pain and b) the (peripheral) activation of low-threshold muscular mechanic receptors. In this manner there is an increase of the activity of thick-diameter nerve fibres (pain modulating system) and a long-lasting inhibition of muscular pain. The long-term pain-killing effect of acupuncture is the most difficult point of contemporary theories. Han's theory (1987 - mesolimbic analgesia system) may be the explanation for one of the acupuncture analgesic mechanisms[39]. At least, activation of "Diffuse Noxious Inhibitory Controls" (DNIC) triggered by nociceptive peripheral stimuli that activates Aä and C fibers (some formes of acupuncture and moxa) can be an other mechanism of central action of acupuncture and involves complex loops from spinal and supraspinal structures[40,41]. From these studies came as a result that neurotransmitting substances, opioid and non-opioid substances of spinal cord and CNS are the main co-ordinators of the "stimulation - analysis - response" phenomenon and they are responsible for the generalised internal chemical reactions of the organism that follows an acupuncture treatment.