October 29th 2004 - INTRODUCTION
Pain in its myriad forms is one of the most common symptoms for which patients seek relief. Acute pain is an unpleasant experience primarily associated with tissue injury, and the protective response patients have to pain provides the clinician with valuable diagnostic information.
The reaction to pain is highly subjective and, as a function of higher centers, is extremely variable. It is influenced by many factors depending on the individual patient and his or her situation. When pain becomes chronic, the multi-factorial influences (e.g. anxiety; depression; social, cultural, and economic factors; and secondary gain) play an even larger role.
When treating a patient for pain, it is essential first to determine the primary cause, the pathogenesis, and secondary or contributing factors. The relief of pain may then be achieved by removal of the primary cause (e.g. cure of an infection), neutralization of the effect of the stimulus (e.g. emollients for an ulcer), relief of discomfort (e.g. biofeedback), suppression of the disease process (e.g. anti-inflammatory agents), and dulling or obliterating the sense of pain (e.g. analgesics or acupuncture).1
Although the medical profession has chosen to emphasize the pharmacological methods of pain control, many non-pharmacological options are available. Their applicability and efficacy are documented below. (Although this chapter liberally utilizes childbirth pain control, the examples and concepts can be generalized to any situation involving acute and/or chronic pain.)
THE EXPERIENCE OF PAIN
A psychological model
Pain is generally acknowledged to be a complex physiological/psychological phenomenon. It involves motivational and emotional components and conceptual interpretation, which may or may not have their basis in actual nociception. Verbal reports of pain and associated behavioral responses are controlled, at least in part, by psychological, cultural, and situational factors.
For acute pain, such as that of childbirth, in which the painful experience can be directly related to nociceptive input, a multiprocess feedback model can be considered. However, one must keep in mind the complexity of the psychological processes intervening between sensory event and observable response, ranging from the physiological to the social aspects of personality. These include elements of:
• information processing
• performance ability
• attitudes and beliefs
• secondary gain
• designated sick roles.
In the psychological model, the brain infers information from bodily signs and integrates this with existing personal and situational variables to direct behavior. When consideration must also be given to the interactions with interested observers, such as physicians, family members and birth attendants, who influence the interpretation with their own experiences and attitudes about pain, the complexity becomes even greater.
According to this model, which does not differ in essence from a general model of stress, a primary appraisal of the personal danger or threat posed by the painful stressor is followed by a secondary appraisal of one’s ability to cope, based on emotional feedback, and contributions of situational and socio-cultural response factors. On this basis, a woman in labor could choose to consider pain as “positive”, “functional”, or “creative”; “pain with a purpose”; or, alternatively, “part of a process involving injury”2 In the course of a pain management program carried out with 84 patients with low back pain, those who more strongly endorsed “organic” concepts about the nature and treatment of pain reported higher levels of disability, while reductions in reported “organic” pain beliefs improved reported disability and endorsement of “psychological” concepts about the nature and treatment of pain was not associated with disability.3 Several studies indicate that “catastrophizing” predicts pain or is associated with lower pain tolerance.4, 5
This conceptualization of painful stress suggests that intervention could be successful at several levels: cognitive patterning, physiological arousal associated with emotional stress, and control of environmental stimuli. Examples of appropriate strategies could be: cognitive coping skills such as restructuring and utilization of preparatory information and attention shifts; muscular relaxation, physical or electrical stimulation, and biofeedback techniques; and structuring of the environment in a way conducive to effective coping (such as by making it non-threatening and comfortable).6
Neuropsychological mechanisms of pain
According to research on the mechanisms of pain, pain can be treated not only by anesthetic blocks, surgical intervention and the like, but also by influencing the motivational-affective and cognitive factors as well.7 The traditional specificity theory of pain, first enunciated by Descartes in the 17th century, holds that pain messages are conducted from specific pain receptors at the periphery through discrete pathways to pain centers in the brain. However, there are individual differences in pain responses, pain is not consistently stopped by cutting or blocking the “pain pathway”, and it is now known that non-painful types of stimulation will activate the A-delta and C fibers that are associated with pain. Therefore, later modifications of pain theory took into account patterning of nerve impulses over time to reflect differences in degree and intensity of stimuli and summation of signals from an extended area.8
The currently accepted view of pain is the gate control theory which Melzack & Wall9 formulated in 1965. Based on neurological data and a categorization of the words used to describe pain, this theory conceptualizes the pain experience as having sensory-discriminative, motivational-affective, and cognitive-evaluative components or modalities, corresponding to different patterns of nervous impulses. Neurologically, a specialized cluster of nerve cells in the substantia gelatinosa of the spinal column is thought to operate like a valve or gate, controlling nerve signals before they evoke the perception of, and response to, pain. Besides this monitoring of sensory data in the central nervous system, gating is also influenced by the relative amount of activity in large-diameter (A-beta) and small-diameter (A-delta and C) nerve fibers. The large fibers tend to inhibit transmission, or close the gate, preventing pain, and the small fibers tend to facilitate transmission, or open the gate, resulting in pain. The fact that large fibers are activated by pressure, touch, massage, and vibration suggests a mechanism for such pain control techniques as acupressure, acupuncture, and transcutaneous electrical nerve stimulation (TENS). Such stimulation apparently closes the spinal gate via the large-fiber system. Melzack & Casey7 expanded this theory by proposing the possibility of a higher level gate, in the reticular or limbic structures of the brain, that probably mediates the drive to escape from unpleasant stimuli. At central nervous system levels, the biochemical mechanisms of gate control may involve the endorphins, natural morphine-like substances that have been implicated in the pain-controlling effects produced by acupuncture.10
Pain in childbirth
A psychological/social learning approach to pain emphasizes control of motivation, expectation, focus of attention, stress, and feelings of anxiety, depression and helplessness. Factors specifically operative in labor pain include these as well as social support and the physiological factors of hunger, rest, and muscular tension.11 All of these can contribute to the interpretation of pain being placed on the nociceptive message provided by uterine contractions. The influence of motivation on labor pain was effectively demonstrated in a prospective study of maternal attitudes toward pregnancy in 8,000 American women. One of the factors found to be strongly related to maternal attitude toward having a baby was the need for analgesics in labor.12
Cultural conditioning may also be fundamental to the labeling of childbirth as painful. Throughout most of the world, analgesics are not required for labor; in fact, a Japanese anesthesiologist suggests that the idea of “painless delivery” is a strange one to his culture.13 American women, on the other hand, “live through a largely self-fulfilling prophecy of birth as a painful, terrifying ordeal, and/or as a medical, drugged process over which they have no control”.11 This relates to body fantasies of injury, brought about in a hospital environment where distress is an expected response to the expulsive reflex.2
Moderating variables and psychological techniques
The psychological strategies recommended for control of labor pain, many of them part of prepared childbirth programs, generally aim to provide control, communication, relaxation, attention focus, and support, as well as physical counter-stimuli. There is considerable psychological research supporting the use of these in the development of pain tolerance.
The significance of various characteristics of an individual’s psychological profile has been studied by evaluating the effects on pain perception of such parameters as:
• field dependence18,19
For example, on the repression-sensitization axis, repressors may be characterized as those who avoid having to cope with pain, while sensitizers have an obsessive need to cope. They like to be informed in advance about the situation and to have control over it. The superior initial tolerance exhibited by repressors in response to heat and pressure stimuli disappears in repeated trials, showing that the sensitizers’ predilection for challenge enables them to endure long-term pain better.
The importance of individual difference variables is also illustrated by the observation that one-third of patients undergoing surgical operations do not request pain-killing medication.23 This common ability to suppress pain indicates that not all surgical patients consider themselves passive victims. In fact, during the postoperative period, pain persists longer for those who accept medication.
The impetus for devising cognitive strategies to promote tolerance of pain has been particularly supported by investigations showing that pain tolerance increases with greater predictability and perception of control.24-28 Similarly, preparatory communications and information received prior to the onset of experimental or surgical pain consistently decreases the subjects’ perception of pain.29-31
Animal studies have demonstrated higher rates of instrumental responses when painful shocks are signaled than when they are unsignaled.32 Kanfer & Seidner33 found that subjects who could advance slides of travel pictures at their own rate tolerated ice-water immersion of the hand longer than yoked subjects whose slides were changed by the experimenter.
When surgery patients are given a sense of control by providing them with preparatory information concerning post-surgery discomforts and operative care, in combination with training in rehearsal of realistic, positive aspects of the surgical experience, they showed a significant reduction in postsurgical anxiety (as indicated by nurses’ observations), requests for sedatives, and length of hospital stay.34 Furthermore, preparation for repeated periodontal surgery by auditory and visual messages classified as “control enhancement” was associated with reduction of pain after a second surgery.35 Subjects who could cognitively redefine a threat of electric shocks as interesting new physiological sensations also reduced stress to a greater extent than subjects not provided with this coping strategy.36
A typical cognitive behavioral procedure utilizes “stress inoculation”, beginning with an educational phase (in which subjects are given a conceptual framework for understanding the nature of their stressful reactions), followed by rehearsal of behavioral and cognitive coping skills, based on a set of coping self-statements generated by the client in collaboration with the therapist. Such cognitive-behavioral techniques, sometimes in combination with EMG biofeedback control, have been found successful in treatment of chronic low back pain.37-39 Also, cognitive-behavioral strategies have been effective in alleviating the pain of irritable bowel syndrome,40 temporomandibular joint syndrome,41, 42 cancer,43 migraine headaches,44 rheumatic conditions,45-47 fibromyalgia,48 and complex regional pain syndrome.49 This emphasis on conceptualization, preparatory information, and cognitive transformation seems to have been incorporated into the Read method of natural childbirth, which replaces fear with knowledge about birth.12 Sheila Kitzinger,2 in her method of prepared childbirth, similarly emphasizes the necessity of “acquiring knowledge and understanding of what labor involves, the terminology used by obstetricians and midwives, and information about what happens in hospitals”.
A study by Stevens & Heide50 conducted at the University of Wisconsin used ice water to test perception and endurance of pain in subjects who had been taught methods used in childbirth education classes. The controls for this training and an additional control group offered only distraction during the tests. Those who had been taught the techniques reported only about half the pain of the controls and endured it 2.5 times longer. The prepared childbirth strategies improved with practice, were effective for pain lasting longer than most contractions in labor, and were more effective than distraction techniques.50 However, this later finding introduces some confusion, since some prepared childbirth methods include either distraction techniques or some other deliberate disposition of one’s attention.
Distraction or focused attention, mostly utilizing the rhythms of the breath, is essential to the Lamaze method, the most popular prepared childbirth program in America, and important in the Bradley and other methods. Sheila Kitzinger describes the controlled attention focusing as:
…concentration on what is happening, one’s response to it as a task, and visualization of what is being achieved by the work of the uterus during contractions. The focus may be on the fantasy of the contractions as a shape provided by actual objects (furniture, architectural details, flowers, a painting) in the room, or a combination of these factors.2
Stevens & Heide50 found that attention-focusing functions effectively as an analgesia for labor pain. Such strategies are strongly supported by much psychological research. Hospitalized children with chronic illnesses who were taught distraction techniques were able to reduce measures of distress before and during medical procedures such as intramuscular and intravenous injections.51 In a study of patients with burn pain, sensory focusing techniques were more successful than distraction techniques in controlling pain, and both were more successful than standard care.52 The focus may be on a competing response, as in the Kanfer & Goldfoot53 study showing that when attention was directed to self-presented external slides, individuals were able to increase their tolerance of the pain of cold water. Focus on a competing response is also shown in the use of hypnosis as an analgesic and in the meditative states of Raj yogis, who pinpoint attention on the tip of their nose or a point on the back of their skull, and then do not react physiologically to cold water, bright lights, or sudden sounds.54,55 Other adepts in unusual feats of pain tolerance, such as having spikes stuck through their skin, either maintain an unfocused attitude, without evaluation, or pinpoint attention totally on the pain, but without evaluation.56 In such cases, the attitude of detachment from the pain can be reflected by an undisturbed EEG pattern of alpha or beta waves throughout performance of the feat.
Relaxation training is another essential element of pain control, and is found in all childbirth training programs. A considerable body of literature supports its importance in pain control, since a state of lowered autonomic arousal is incompatible with anxiety. While progressive muscular relaxation, systematic desensitization, and autogenic training are all well-established physiological approaches to muscular relaxation, meditation traditions provide quicker methods to achieve what Benson57 has called, the “relaxation response”. One of the simplest meditation practices – maintaining a focal awareness of the flow of the breath – is taught by Rahima Baldwin in Special Delivery and is identical to the ancient Buddhist practice of vipassana or insight meditation.
Hypnosis or auto-hypnosis is another method utilized to induce deep relaxation for pain control. It incorporates many of the therapeutic elements already referred to – focused attention, positive expectation, and a supportive or permissive attitude – in making suggestions that alleviate anxiety. Thus, its success in pain management may be viewed from a cognitive-behavioral perspective.58 In one technique, “glove anesthesia” is induced in one hand and the “numb, heavy wooden feeling” so produced is transferred to the other hand, the face, and eventually to the abdomen in order to “relieve the discomfort” of uterine contractions (the word “pain” is never used, as this would be counter-suggestive).59 Pain modulation in “high hypnotizable” subjects has been confirmed through brain measurement of somatosensory event-related potentials (SERP’s) to noxious stimuli, with highest amplitudes for these subjects recorded at frontal and temporal scalp sites.60
Control of environmental stress
Kitzinger2 cites animal research to show how environmental stress can interfere with the physiological processes of labor and delivery. Education for childbirth therefore promotes verbal and non-verbal support from husband, obstetrician, midwife or anyone else who is part of the birthing environment. Touch relaxation and coaching techniques combine the essential elements of relaxation, massage counter-stimulus, and the direct supportive communication of a partner.11 Several studies agree that comfort in labor is also enhanced by a more vertical position such as the squatting posture that is adopted in many other cultures.61-63
Counter-stimulus methods: massage, acupuncture, TENS
The hand reflexology method of grasping combs during labor to activate points on the fingertips and balls of the hand that relate to uterine functioning is one example of counter-stimulus strategy.11 Foot reflexology, acupressure, acupuncture and transcutaneous electrical nerve stimulation (TENS) might also share a common autonomic nervous mode of operation.
Transcutaneous electrical nerve stimulation (TENS)
The use of TENS to control pain during delivery has been evaluated by several studies. The method used in a Swedish study, which was subsequently replicated in Germany and Britain, was originally developed in the US by Shealy for the control of acute and chronic pain.64,65 In a controlled study of experimentally induced cold-presssor pain, the effect of electrical stimulation with TENS electrodes at two traditional acupoints in 20 subjects had an analgesic effect with statistical significance comparable to morphine, and the combined effect of TENS with morphine was stronger than TENS alone.66 A series of controlled randomized double-blind studies on carpal tunnel syndrome pain found that the combination of low-level laser and micro-current TENS on distant and local points significantly decreased McGill Pain Questionnaire Score, sensory and motor latencies, and Phanel and Tinel signs, compared to sham treatment. 67 A British study investigated the relative hypoalgesic effects of differenct TENS parameters upon experimentally induced mechanical pain, and found that low-frequency, high intensity, extrasegmental stimulation (i.e. over an acupuncture point rather than over a nerve distribution) produced a rapid onset hypoalgesic effect, which increased during the stimulation period and was sustained for 30 minutes post-stimulation.68 Generally, the electrodes are placed over the painful area in order to stimulate the cutaneous nerves in that area. For use in labor, four electrodes are placed on either side of the midline of the spine to stimulate the posterior primary rami of the spinal segments (T11–L1 and S2–S4) receiving the painful stimuli during labor. It is interesting to note that these are the loci of acupuncture points (BL-20, BL-27, and BL-28) which are traditionally thought to reflect female reproductive function.
The selection of this area for stimulation is based on Bonica’s account of the neurological mechanism of delivery pain.69 During the first stage, pain receptors are assumed to be activated by contractions of the uterus and dilation of the cervix. The evoked impulses are mediated in afferents which run in the hypogastric nerves and reach the spinal cord via the dorsal roots T10–L1. The pain is referred to large areas of the abdomen and back. During the second stage, pain is also caused by distension and stretching of the delivery canal, the pelvic floor, the vulva, and the perineum. The pain is localized, and the impulses reach the spinal cord mainly via the pudendal nerves and the dorsal roots S2–S4. The pain during the first stage is characterized as an ache considered to be mediated in small-diameter C fibers. During the second stage, the pain has the more localized intensive nature usually identified with the delta-afferent fibers.69,70
In the typical application of this technique for control of pain during labor, low-intensity stimulation is given continuously and a high-intensity stimulation could be initiated by the parturient herself whenever pain increased. Stimulation via the thoracic electrodes is maintained throughout the delivery at an amplitude that is maximal for a pleasant sensation, whereas sacral stimulation is added from the later part of the first stage. Table 56.1 summarizes the uniformly good results which have been reported.
Those patients who complained of backache have especially appreciated it. An Austrian study compared the analgesic effects of TENS, pethidine and placebos on labor pain in 30 parturient women during the first stage of labor. No significant difference was found between the placebo, unspecific TENS, and control groups in the increase in pain during the test period. Patients who had received pethidine and those who had been given TENS experienced considerable relief of pain.75 It is curious that apart from a passing reference by Shealy to its use in labor, no research on its obstetric application appeared for many years in any of the US literature. A 1996 review of 30 studies on TENS stimulation of acupuncture points in labor substantiated the conclusions of earlier research.76
In view of the relatively good results and lack of complications, the consensus of all the above studies is that the TENS method is recommended as a primary pain-relieving measure, to which conventional methods can be added as needed. Robson77 comments that TENS is non-invasive and is believed to be safe for both mother and baby. It is easy to apply and can be operated throughout labor by doctor, midwife, father, or mother. Augustinsson et al64 were most impressed by the lack of complications, since the conventional methods, including analgesic and sedative drugs, N2O inhalation, epidural anesthesia and local blockades, all possess a varying degree of potential risks.64 Another advantage is that TENS, since it does not give complete analgesia, does not eliminate pain as a diagnostic tool; it can be interrupted whenever needed for clinical evaluation. More importantly, perhaps, from the point of view of the woman in labor is the fact that her consciousness is not altered to the point of excluding her own active participation in, and experience of, the delivery.
Both Stewart72 and Augustinsson et al65 reported the method to be inadequate alone for analgesia in the second stage of labor. Augustinsson et al see this difference as possible support for the assumption that C-fiber-mediated pain is more amenable to blocking by electrical stimulation than is A-fiber-mediated pain. Stewart mentions simply that many patients did not wish to use the stimulator at that time as it proved a distraction from their efforts to bear down. In this connection, it is interesting to note that “those who were well prepared and keen on natural childbirth were not always the most enthusiastic and, in fact, two of the early failures were patients who had been to relaxation classes.”72 Robson77 explains that TENS could distract some patients from their breathing or other focus of attention learned in courses.
A related issue in the TENS literature is introduced by the comment of Andersson et al71 that there was a correlation between the degree of hypnotizability and pain relief in their subjects. Such a correlation may, of course, imply only a susceptibility to any type of therapeutic effect. Neumark et al75 tested this effect by including a placebo group that was given no current through the electrodes, and found that the result for the placebo group was not different from TENS applied non-specifically (i.e. incorrectly), but was significantly different from the effect of TENS placed over the relevant nerve distribution and from that of pethidine. Robson,77 while making no attempt to assess a patient’s degree of susceptibility to hypnosis, switched off the machine for at least two contractions. All patients asked for it to be switched on again, indicating that the technique was providing pain relief. Augustinsson et al64 consider the suggestive effect, if it occurs, to be of minor significance, since several investigators have found the pain-reducing effect of TENS to be achieved through demonstrable neurophysiological mechanisms. Stewart72 points out that the increased personal contact between patient and attendant essential to the use of this method may introduce an element of suggestibility or distraction affecting the pain experience.
Hundreds of studies have investigated the efficacy and mechanisms of acupuncture analgesia for acute and chronic pain, in surgical operations, and in childbirth. In a review article of 24 studies, Lewith & Machin78 found that the typical clinical trial showed a 70% efficacy when compared with placebo treatment. Reichmanis & Becker79 found similar results in a review of 17 studies of acupuncture analgesia in experimentally induced pain. Based on a thorough review of the clinical and experimental research on acupuncture pain control, Pomerantz and Stux concluded that acupuncture analgesia helps from 55% to 85% of chronic pain patients, comparing favorably with the effects of potent pain medication (such as morphine, 70% effective), and clearly distinct from the placebo effect, which helps 30-35%. 80 At the same time, somatosensory EEG-evoked potential studies have provided objective evidence of the analgesic effect of acupuncture.81-83 Recent randomized and double-blinded controlled studies have demonstrated clinical effectiveness of acupuncture in treating chronic lateral epcondylitis84 and chronic neck pain .85 In the latter study, stimulation at distant points of the neck-related meridians were more effective than sham acupuncture points and “dry needle” injections of local myofascial trigger points, reducing motion-related pain by one third after a single treatment. A single-blinded randomized controlled trial showed that electro-acupuncture is superior to manual acupuncture in treating patients with tennis elbow.86 A review article on treatment of fibromyalgia pain for patients at a hospital in Brazil showed improvement using traditional acupuncture, measured on subjective scales and number of tender points.87 Preoperative electroacupuncture has led to a reduced intraoperative and postoperative requirement of analgesic medications (alfentanil and morphine) in patients receiving gynecologic lower abdomen surgery.88 In fact, surgery requiring general anesthesia in Western countries is routinely performed in Chinese hospitals with the combination of acupuncture and local anesthesia, providing a considerable decrease in risk for surgical patients.
Hyodo & Gega12 of the Osaka Medical College have reviewed the literature (summarized in Table 56.2) on acupuncture anesthesia and analgesia in normal delivery and found mixed results. For example, Wallis et al89 reported that while 19 of the 21 volunteer parturients considered acupuncture unsuccessful in providing analgesia for labor, one-third of them indicated that they would choose acupuncture analgesia in labor again. Some authors criticize the technique as being inconsistent, unpredictable, incomplete, time-consuming, and interfering with movement and electronic monitoring.
In their own study, Hyodo & Gega12 tested 32 patients, equally divided between primaparas and multiparas. Low-frequency electrical current was introduced through needles at LI-4, ST-36, and SP-6, a standard therapeutic repertory for sedation of the reproductive organs. The result, as assessed by relief noted by the patient as well as by the obstetrician’s observation, was 62.5% finding good or excellent effect on the subjective scale, and 62.6% good or excellent on the objective scale among the primapara; and 93.8% subjective relief, and 93.7% objective relief among the multipara. Overall, 90% of the cases experienced relief of pain within 20 minutes of initiation of acupuncture anesthesia They noted the considerable disparity in reports of effectiveness of acupuncture from Japan and America, and explained it as a novelty effect. It is natural that in Japan, where no analgesic methods are normally used, the scoring in favor of acupuncture will be high compared with that in America.
They concluded that it is useful for delivery, especially because of its safety, despite more erratic and less potent results than conventional anesthetic techniques.12 More recently, a randomized controlled trial investigating acupuncture treatment as a compliment or an alternative to conventional analgesia for labor in a Swedish hospital found that acupuncture significantly reduced the need for epidural analgesia, and parturients receiving acupuncture assessed a better degree of relaxation compared with the control group. 90
A considerable amount of research has focused on determining a mechanism for acupuncture analgesia. A 1995 review of studies on acupuncture effects in pain and disease pointed out that, like exercise, acupuncture produces rhythmic discharges in nerve fibers and causes the release of endogenous opioids and oxytocin. Furthermore, “experimental and clinical evidence suggests that acupuncture may affect the sympathetic system via mechanisms of the hypothalamic and brain-stem levels”.91 Animal studies continue to demonstrate that acupuncture analgesia is mediated in the central and peripheral nervous systems by opioid peptides.92-94 The cortex and hippocampus appear to participate in the modulation of chronic pain, and the analgesic action of electroacupuncture seems to operate along this pathway.93 A study carried out on dogs seems to verify the traditional theory of points of tonification and sedation, by differential production of sympathomimetic and parasympathomimetic effects on the cardiovascular system upon stimulation of different points. Carlsson, a Swedish research, concludes that a mechanism for therapeutic acupuncture must include peripheral events that release neuropeptides, spinal mechanisms such as gate control, and supra-spinal mechanisms through the descending pain inhibitory system, the sympathetic nervous system and the HPA axis. He cautions that much of animal and human experimental acupuncture research shows only short-term hypoalgesia; that almost all such experimental research has been performed with electro-acupuncture rather than the more gentle manual style of therapeutic acupuncture; and that pain threshold elevation in human experimental research does not necessarily predict the clinical outcome.95
In a study of labor induction and inhibition by electroacupuncture, Tsuei et al96 utilized SP-6 and SP-4 points, located in the territory of the L-4 dermatome. The spleen meridian, to which these loci belong, runs across the dermatomes of L-4, L-5, L-2, and L-1, and then upward from T-12 to T-5. Since the sympathetic nerve controlling the uterus through the pelvic plexus receives preganglionic fibers from T-5 to L-4, Tsuei et al concluded that it is highly possible that stimulation of the electropermeable loci within this area may alter the physiologic function of the uterus.96 The LI-4 points of the upper extremities, often added to the spleen meridian points in the acupunctural control of labor pain, perhaps represent the central approach to the autonomic nervous system, since these loci control pain to the head and neck. It should be noted, however, that Motoyama97 has attempted to verify the traditional subtle anatomy of meridian pathways through tests of electrocutaneous resistance at meridian points, and claims that these effects cannot be adequately explained in terms of the conventional sympathetic dermatomes, but imply an alternative bioelectric transmission system.
The discovery of the Head McKenzie sensory zones has shown the possible mediation of the invisible meridians and points of traditional Eastern medicine between internal organs and corresponding skin areas. Nakatani98 was able to detect the electropermeable line as an apparent viscerocutaneous autonomic nerve reflex when organic diseases are involved. Hyodo99 has explained acupuncture stimulation as the transmission of impulses centrally from the reactive electropermeable loci, via a sympathetic afferent fiber, and the autonomic nerve in the viscera is stimulated to response by the reverse of the McKenzie theory. An exciting recent development in acupuncture research has been the finding by functional neuroimagery of neuronal correlates in the human brain of acupuncture stimulation. In a controlled study of electoacupuncture (EA) stimulation of GB 34 on the left leg, compared to mock and minimal EA, the real EA elicited significantly higher activation over the hypothalamus and primary somatosensory motor cortex, showing that the hypothalamic-limbic system was significantly modulated by EA at acupoints.100
The scope of this article does not permit detailed discussion of other promising methods of pain control, but mention can be made of massage, biofeedback, nutritional and botanical agents for treatment of pain. A literature search led to the conclusion that massage is effective for low-back pain, particularly acupressure, especially when combined with exercises and education, with beneficial effects lasting at least one year after the end of treatment.101 There is a vast literature available on biofeedback training for pain. An article suggesting a future direction in pain medicine describes ‘off-the shelf’, low-cost, and low-bandwidth telemedicine equipment used to deliver clinical biofeedback treatment when the patient and provider are in two different locations. 102 In a randomized double-blind trial of 30 patients with chronic maxillofacial pain, significant reduction in pain scores and increase in tolerance of experimentally induced dental pain were achieved with administration of 3 gm of the amino acid tryptophan and a high carbohydrate, low fat, low protein diet compared to placebo.103 Among botanical agents for pain, corydalis rhizome or tuber (yanhusuo) is well known in the Chinese material medica for its analgesic effect, containing combined alkaloids found to be 40% as effective as morphine. Acting probably through inhibition of the reticular activating system, corydalin has been shown in one clinical study of 44 patients with dysmenorrhea to decrease or relieve pain in 32 patients.104
This chapter has presented many of the current non-pharmacological strategies for control of pain. Since the mechanism of pain perception has been shown to involve both physiological and psychological components, the optimal treatment might combine psychological factors of preparatory information, attention focus, relaxation, and supportive communication, in conjunction with the physical stimuli of transcutaneous electrical nerve stimulation or acupuncture. In fact, such a multidisciplinary approach to patients with chronic back pain was evaluated following a 4- week program which included back schooling, psychological intervention, and treatment by acupuncture, chiropractic, the Alexander technique and a pain specialist. Significant improvement was maintained for a period of 6 months.105
Dental researchers of the Pediatric Pain Program of the UCLA School of Medicine searched several data-bases for reports of randomized, controlled clinical trials of complimentary and alternative medical modalities used to treat chronic facial pain. Three acupuncture trials, eight biofeedback trials, and three relaxation trials met the authors’ inclusion criteria, suggesting that these modalities were comparable to conventional treatment, such as an intraoral appliance. 106 Increasingly, the multidisciplinary pain management team, incorporating a variety of nonpharmacologic treatment modalities is being considered “the optimal method for delivery of comprehensive treatment to patients in pain.” 107 The incorporation of “alternative” forms of pain management, including acupuncture, relaxation techniques, hypnosis, biofeedback and guided imagery is acknowledged by the Children’s Hospital of the Medical College of Wisconsin to complement pharmacologic pain management of children’s pain. 108
The selection, balance, and application of these treatment components should be based on consideration of an individual’s coping styles. Such a treatment program could be developed to provide a more consistently effective analgesia than the individual components can provide separately. Relieving the pain of childbirth, for example, without diminishing or distorting the full consciousness of the experience for the mother, would be consistent with the goals of the contemporary physician of natural medicine.
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Table 56.1The results of the use of TENS for pain control in labor
Study n Good Moderate None
(%) (%) (%)
Augustinsson et al64 147 44 44 12
Andersson et al71 27 48 37 15
Kanfer & Goldfoot53 35 20 62 18
Stewart72 67 31 56 13
Kubista et al73 102 55 24 21
Bundsen et al74 347 47 42 11
Table 56.2Results of acupuncture analgesia in the control of labor pain
Study n Good Poor or none
Hyodo & Gega13
Primapara 16 62.5 37.5
Multipara 16 93.7 7.3
Ito109 80 85 15
Wallis et al89 9-33 67-91
Abouleish & Depp91 80.5 19.5
Dr. Richard Kitaeff - New Health Medical Center
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published in the Textbook of Natural Medicine