October 29th 2004 - Pain is a complex physical and psychological experience that may or may not reflect injury or tissue damage. In fact, the paradox of pain is that it may often exist without recent injury or tissue damage. Acute pain is usually a sign of actual or potential injury or trauma, often associated with anxiety or sympathetic nervous system hyperactivity, lasting a short time – from one to six months, according to different definitions. Chronic pain lasts longer than this period taken for the healing of acute tissue damage. Other symptoms commonly become associated with the chronic stage of pain: anxiety, depression, insomnia, weight loss, appetite disturbance, constipation and decreased libido. Pain can have a somatogenic or organic cause, involving a physiological mechanism, or can be psychogenic, caused by psychological issues. Unfortunately, doctors too often ascribe chronic pain to psychological causes when organic pathology is not apparent; the correct description in this case should be idiopathic pain, i.e. pain of unknown origin. Somatogenic pain can be further classified as nociceptive, involving activation of somatic or visceral pain-sensitive nerve fibers, or neuropathic, from dysfunction of the peripheral or central nervous system. In the case of nociception, organ pain can be felt as an aching or pressure sensation, as in cancer pain. Neuropathic pain can be from compression of a peripheral nerve or central nervous system pathology, such as stroke or spinal cord injury. There may be peripheral polyneuropathies, as in diabetes. Several of these factors can co-exist in a chronic pain problem such as headache or cancer pain, which can involve, at the same time, nociception and psychological issues. (1) In a medical evaluation, an organic cause is always sought first, through physical exam, laboratory testing and X-ray, MRI or CATSCAN imaging. In evaluation of a chronic pain disorder, one would also have to take into consideration cultural, social and economic factors and the possibility of secondary gain (for example, from disability payments).
The Gate Control Theory of pain, formulated by Melzack and Wall in 1965, postulated a valve or gate for pain perception, through a specialized cluster of nerve cells in the substantia gelatinosa of the spinal column, probably involving activation of the endorphins, the natural morphine-like substance. Gating occurs also through the activation by such pain control techniques as acupuncture, acupressure, masssage or electrical stimulation of large-diameter (A-beta) nerve fibers that suppress the slower transmission of pain impulses through small diameter (A-delta and C) nerve fibers, mediated by the pro-inflammatory Substance P (2). A higher level gate may operate in the reticular or limbic structures of the brain, involving the sensory discrimination, cognitive and emotional interpretation of the experience (3).
SIGNS AND SYMPTOMS
Since pain is predominantly a subjective experience, the best reflection of the existence and severity of the condition is the list of words commonly used to describe pain, compiled by the psychological researchers Melzack and Torgerson and classified by them as sensory (throbbing, pounding, shooting, pricking, sharp, stabbing, pinching, pressing, gnawing, crushing, burning, searing, stinging, smarting, wrenching, etc.); affective or emotional (sore, tender, sickening, blinding, etc.); or evaluative (excruciating, intense, unbearable, etc.) (4)
Conventional treatment of pain has been primarily through pharmaceutical medications. Non-opioid analgesics, including acetaminophen and non-steroidal anti-inflammatory drugs (NSAID’s), such as ibuprofen, naproxen and apirin, treat mild to moderate pain. Excess doses can cause toxic effects on the liver and kidney. Opioid (narcotic) agents bind to opioid receptors in the central nervous system and can control severe, acute pain after injury or surgery, or chronic pain, such as cancer pain. For acute pain, morphine is usually delivered intravenously or intramuscularly. Other opioids include codeine and the synthetic agents methadone and oxycodone. Opioids are administered with caution for the elderly, infants and those with kidney, respiratory or liver disease, and in all cases dosage is guided by frequent monitoring of pain levels, respiratory rate and blood pressure. Excess or adverse effects of morphine and other opioids can be constipation, nausea or respiratory depression. Physical dependence can also be a danger (5).
Non-drug alternatives for pain relief in conventional medicine can range from non-invasive approaches like physical therapy, including manual therapy, therapeutic exercise and modalities like ultrasound, to spinal surgery and surgical implants of electrical stimulators.
Acupuncture has provided analgesia for acute and chronic pain for thousands of years in China and elsewhere. Clinical and experimental studies generally show a 70 percent level of pain control in comparison to placebo (6) (7). Objective evidence of this analgesic effect has also been provided by EEG evoked-potential studies (8). Electrical stimulation of different types has been used successfully for pain control, and in particular transcutaneous electrical nerve simulation (TENS) has become increasingly popular for home therapy, utilizing pads attached over the area of pain, or clips attached to the ear lobe (for central nervous system control), and a small control unit attached to the belt. (9).
Massage and other manual therapy methods probably work similarly to acupuncture and TENS through autonomic nervous system control of pain, according to a counter-stimulus mechanism such as that postulated in the Gate Control Theory.
Psychological strategies for pain management include cognitive and behavioral skills, such as attention focusing and relaxation training, as well as preparatory information, to develop control in conditions like chronic low back pain, irritable bowel syndrome, cancer, migraine headaches and rheumatic conditions (10). Hypnosis has also been successful in inducing a deep relaxation state that can be directed specifically to an area of pain (11).
Botanical agents have traditionally been used to provide pain relief throughout the world for thousands of years and now provide safer alternatives to pharmaceutical drugs. Capsaicin, the active ingredient of cayenne or red pepper has been successfully applied topically (0.025% or 0.075% in a cream base) in a number of pain conditions. Research supports its effectiveness in reducing the pain of post-herpetic neuralgia (the chronic pain
persisting after the healing of shingles lesions), trigeminal neuralgia (facial pain), post-mastectomy pain, pain due to chemotherapy or radiation, diabetic neuropathy, cluster headaches, and arthritis (12). Kava, an herb known for its sedative effect, was demonstrated also to have analgesic effect, although through a mechanism different from opiate or non-steroidal anti-inflammatory drugs (13). The anagesic effect of ginger in experimental studies on animals is thought to operate like capsaicin in inhibiting the release of the neurotransmitter Substance P (14). In studies on rheumatoid arthritis and migraine headache, ginger had marked anti-inflammatory effect, with 75% of arthritis patients and 100 % of patient with muscular discomfort experiencing relief in pain or swelling (15). Curcumin, the active ingredient of turmeric, has been used in the Ayurvedic medical tradition of India as a topical pain-reliever, also operating like capsaicin to deplete the nerve endings of Substance P (16). The Chinese herb angelica (known in Chinese as tang-kuei), through its pain-relieving and muscle-relaxing acitivity, has demonstrated analgesic action 1.7 times that of aspirin (17). Historically, angelica has treated such conditions as uterine cramps, trauma, headaches and arthritis (18). The Chinese herb yan hu suo or corydalis has traditionally acted like opiates such as morphine and codeine to control neurological pain, and pain of headaches, low back, abdomen, arthritis and dysmenorrhea (19). The active ingredient of white willow bark is salicin, from which aspirin (acetylsalicylic acid) is formed. White willow bark has been a traditional native American herbal agent for control of painful conditions like osteoarthritis (20).
The amino acid D-phenylalanine, through its promotion of the endorphin pathway, has demonstrated positive effects in relieving post-surgical low back pain, osteoarthritis, whiplash, rheumatoid arthritis, fibrositis and migraine headaches (21). L-tryptophan, another amino acid, has raised pain tolerance threshold in numerous experimental and clinical studies of acute and chronic pain conditions (22).
Traditional Chinese herbal formulas are prescribed for pain according to a pattern described in the language of traditional Chinese medicine. For example, the formula Du Huo Ji Sheng Wan, which includes the herb angelica, is indicated for the traditionally described syndrome of Wind Dampness and Kidney Deficiency, or the Western biomedical symptoms of chronic joint and muscle pain, stiffness, spasm and cramp associated with osteoarthritis of the low back or lower limb or sciatica (23).
Homeopathic remedies are similarly prescribed according to distinctive symptom patterns, for example pain with stiffness or cramping or on movement, or accompanied by tearfulness, or aggravated by injury, or better with continued movement (24).
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17 Tanaka S., Kuno Y, Tabata M., Konoshima M. Effects of “toki” (angelica acutiloba Kitagawa) extracts on writhing and capillary permeability in mice:analgesic and anti-inflammatory effects. Yakugaku Zasch 1071; 91: 1098-1104.
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19 Yeung H. Handbook of Chinese herbs and formulas, vol. I. Institute of Chinese medicine. 1983: 566.
20 Mills SY, Jacoby RK, Chackfield M, Willoughby M. Effect of a proprietary herbal medicine on the relief of chronic arthritic pain: a double-blind study. Br. J. Rheum 1996; 35: 874-8.
21 Ehrenpreis S et al. Naloxone reversible analgesia in mice produced by D-phenylalanine and hydrocinnamic acid, inhibitors of carboxypeptidase A. Adv Pain Res & Therapy, vol 3. 1978.
22 Werbach M. Nutritional influences on illness. Keats. 1988: 344-5.
23 Maclean W. The clinical manual of Chinese herbal patent medicines. Pangolin.2000: 268.
24 Locke A. and Geddes N. The complete guide to homeopathy. Darling Kindesley. 1995: 154-7.
Dr. Richard Kitaeff - New Health Medical Center
23700 Edmonds Way
Edmonds, WA 98026
appears on the website Progressive Health.com