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APPENDIX A Ascription is offered here of the path~genesis, dwg- nostic criteria, and treatrnJent approaches to myotc~scial pate. The author, who was a member of the Institute of Medicine study committee, is one of the foremost propo- nents of the concept of trigger points in myoiclsczal pain syndromes arm a pioneer in developing treatment meth- ocis based on this vzewpozat. As indicated in Chapter 10, the concept of myoiclscicll trigger points is controversial and was the subject of debate by the committee. Myofascial Pain Syndromes Due to Trigger Points DAVID G. SIMONS, M.D. ]\~[yofascial trigger points are one of three '' musculoskeletal dysfunctions that are com- monly overlooked and deserve particular attention. The other two are fibromyaIgia or fibrositis, and articular dysfunction. None has a diagnos- tic laboratory or imaging test at this time. All three conditions presently require diagnosis by history and physical examination alone. In each case, the diagnosis would probably be missed on routine conventional examination. The examiner must know precisely what to look for, how to Took for it, and then must actually be looking for it. This appendix concentrates on myofascial pain syndromes because they now appear to be the most common end the feast well understood of the three conditions. MYOFASCIAL PAIN SYNDROMES: HOW COMMON ARE THEY? Recent reports indicate that myofascial pain syndromes are likely to be the major cause of pain that brings patients to chronic pain treatment centers. Among 283 consecutive admissions to a comprehen- 285
286 APPENDIX sive pain center, 85 percent were assigned a primary organic diagnosis of myofascial syndromes (Fishbain et al., 19861. This diagnosis was made independently by a neurosurgeon and a physiatrist based on physical examination for soft tissue findings as described by Travell (Travel! and Rinzler, 1952; Simons and Travell, 19831. Among 296 patients referred to a dental clinic for chronic head and neck pain of at least 6 months duration, the primary diagnosis was myofascial pain syndrome in more than half (55.4 percent) of the cases. Another 21 percent had pain due to disease of the temporomandibular joint (Fricton et al., 19851. Acute myofascial pain syndromes are also common in general medical practice. Among 61 consecutive consultation or follow-up patients in an internal medicine group practice, 10 percent of all patients and 31 percent of those presenting with a pain complaint had myofascial trigger points that were primarily responsible for their symptoms (Skootsky, 1986~. Why Are Myofascial Pain Syndromes So Common? Skeletal muscle is the largest organ of the body, making up nearly half of its total weight. Muscles are the motors of the body, working with and against the ubiquitous spring of gravity. They, together with cartilage, ligaments, and intervertebral discs, serve as the body's mechanical shock absorbers. Each one of approximately 500 skeletal muscles is subject to acute chronic strain and can develop myofascial trigger points, and each has its own characteristic pattern of referred pain. Myofascial pain may occur in conjunction with other common diseases. Reynolds (1981) compared the prevalence of signs of myo- fascial trigger points in 14 women who had early rheumatoid arthritis with the prevalence in 18 asymptomatic control women. The women with arthritis had twice as many trigger points. Every one of the women with arthritis had myofascial signs in muscles of the shoulder girdle. He found that the myofascial trigger points in these patients with rheumatoid arthritis were a significant source of additional pain. This component of their pain could be abated or relieved only when it was recognized and managed as being myofascial in origin. HISTORICAL BACKGROUND A study done by Kellgren in 1938 reported that pain was referred to remote locations from muscles throughout the body in response to intramuscular injection of hypertonic saline. This gave credibility to the large series of clinical papers published independently through the
APPENDIX 287 following decade by three authors on three continents. Gutstein (1938) in Europe, Kelly (1947) in Australia, and Travell (1949) in America reported that points of exquisite tenderness found in many muscles throughout the body were responsible for pain that projected to locations distant from--the point of tenderness. Injecting that spot with a local anesthetic eliminated the pain. Travell and Rinzler (1952) published the first summary of the specific patterns of pain and tenderness referred from trigger points in the most commonly involved muscles throughout the body. NATURAL HISTORY Myofascial pain syndromes are caused by trigger points in specific muscles (Travel! and Simons, 19831. Pain due to active myofascial trigger points often begins suddenly as an acute single-muscle syn- drome resulting from stress overload of the muscle. The pain also may develop insidiously because of chronic or repetitive muscle strain. In the absence of perpetuating factors, and in the presence of normal daily activities that stretch the muscle, active trigger points tend to revert to being latent trigger points. Examples of trigger point activation by acute gross trauma are activation of longissimus trigger points in the paraspinal muscles during a fall, or activation or sternocleidomastoid trigger points in the neck during a rear-end collision (one type of whiplash. injury). Some- times the acute overload occurs during what appears to be a trivial movement, such as activation of a quadratus Jumborum trigger point by bending over to one side to pick up a pin from the floor. An example of trigger point activation by microtrauma is unrelieved tension in the upper trapezius and levator scapulae muscles due to continued eleva- tion of the shoulders to reach a high keyboard without elbow support (Travel! and Simons, 19831. The pain and tenderness referred by a trigger point is usually projected at a distance, much as the trigger of a gun that is located one place causes the bullet to impact elsewhere. Trigger points refer pain and tenderness in a reproducible pattern characteristic of each muscle. That pain and tenderness are referred from muscles in this way should be no surprise. Four well-recognized neurophysiological mechanisms account for this phenomenon of referred pain; the question is, which mechanisms are responsible in specific situations. (See Chapter 7 on the neurophysiology of pain for more detail.) In the abovementioned examples, trigger points in the Tow thoracic Tongissimus muscle of the midback may refer pain and tenderness to the lower buttock, causing buttock pain when sitting. The sternoclei-
288 APPENDIX domastoid trigger points in the neck are likely to cause headache and facial pain. Together, the upper trapezius and levator scapulae mus- cles of the shoulder are likely to cause pain and tenderness extending down the back of the neck from the skull, across the back of the shoulder, and down along the vertebral border of the shoulder blade (Travel! and Simons, 19831. For reasons that are not well understood, one limited group of myofascial pain patients suffer greatly and are difficult to help. They exhibit a posttraumatic hyperirritability of their nervous system and of their trigger points. Each patient has suffered trauma, usually from an automobile accident or fall, severe enough to damage the sensory pathways of the central nervous system. This damage apparently acts as an endogenous perpetuating factor susceptible to augmentation by severe pain, additional trauma, vibration, loud noises, prolonged physical activity, and emotional stress. From the date of the trauma, coping with pain typically becomes the focus of life for these patients who previously paid little attention to pain. They are unable to increase their activity substantially without increasing their pain level. DIAGNOSIS Five cardinal features are characteristic of myofascial trigger points: 1. The history of the initial onset of pain and of its recurrences is strongly related to muscles. It usually relates to the length (prolonged shortening aggravates pain) and use (overload or sustained contrac- tion) of the specific muscles involved. 2. Reproducible, exquisite spot tenderness occurs in the muscle at the trigger point. 3. Pain is referred locally or at a distance on mechanical stimulation of the trigger point. This referred pain and tenderness projects in a pattern characteristic of that muscle and reproduces part of the patient's complaint. Patterns of referred pain are frequently different than those expected on the basis of nerve root innervation (Travel! and Rinzler, 1952; Travell, 19761. 4. There is palpable hardening of a taut band of muscle fibers passing through the tender spot in a shortened muscle (Simons, 19761. 5. A local twitch response of the taut band of muscle occurs when the trigger point is stimulated by snapping palpation or needle penetration. The last two features are completely objective findings, and the local twitch response is pathognomic of a myofascial trigger point. The lack of diagnostic laboratory studies emphasizes the importance
APPENDIX 289 of looking for myofascial trigger points and knowing how to identify them by history and physical examination. Both thermography (Fischer, 1984) and pressure threshold measurements (Fischer, 1986; Reeves et al., 1986) provide objective substantiation of clinical findings associated with myofascial trigger points. The trigger point itself generally registers by thermography as a circle of cutaneous warmth 5-10 cm in diameter and is a point of measurably reduced pressure tolerance (Fischer, 19841. A latent trigger point may have some or all of the other character- istics of an active trigger point, except that it does not cause pain with ordinary daily activities. Latent trigger points regularly cause some restriction of range of motion and are tender to digital palpation. An individual muscle may harbor latent trigger points for a period of time and then flare to become an acrid e source of referred pain in response to stress or perpetuating factors (Travel! and Simons, 1983~. Latent trigger points may (although they usually do not) have all the other characteristics of active trigger points (Travel!, 1976; Simons, 19851. Latent trigger points are common by early adulthood. Among 100 mate and 100 female 19-year-old asymptomatic Air Force recruits, Sola and associates found focal tenderness indicative of latent trigger points in the shoulder-girdle muscles of o4 percent of the women and 45 percent of the men (Sola et al., 1955~. Referred pain was demonstrated in 5 percent of these subjects. Myofascial trigger points tend to accumulate throughout a lifetime. In the presence of sufficiently severe perpetuating factors and if left untreated, an acute myofascial pain syndrome characteristically be- comes chronic. Mechanical or systemic perpetuating factors increase the susceptibility of muscles to trigger points; the severity of pain gradually increases, and less muscular activity is required to produce pain. Systemic factors increase the susceptibility of all muscles to the development of trigger points; additional muscles develop additional referred pain patterns (Travel! and Simons, 19831. Disability increases unnecessarily, weaving the complex web of chronic pain through all aspects of the patient's life. Myofascial pain is frequently overlooked in diagnosis and, as a consequence, inadequately treated. Clinicians often lack the training and experience necessary to recognize specific pain patterns referred by individual muscles, to identify trigger points by palpation, and to identify factors that may perpetuate the pain. The lack of standard diagnostic terms in this area and, until recently, of a published source consolidating the known information have contributed greatly to the problems of diagnosing and treating myofascial conditions. Over the past century, confusion developed because successive authors recognized different, often overlapping, aspects of the condi-
290 APPENDIX tion. Many authors contributed new names; some recognized symp- toms due to the involvement of muscles in one region of the body, whereas others recognized symptoms in other regions without noting their commonality. A few examples include soft-tissue rheumatism, nonarticular rheumatism, fibrositic nodules, fibrositis, fibromyaIgia, myogelosis, tension headache, tendonitis, and bursitis. Each term may be used to identify at least two conditions, one of which is often a myofascial pain syndrome. Approximately 100 years of this interna- tional confusion was reviewed for muscle pain syndromes generally in 1975 (Simons, 1975, 1976), and specifically for fibrositis in 1981 (Reynolds, 19811. PERPETUATING FACTORS These factors are rarely the same as the stress that activated the trigger point. Perpetuating factors may be mechanical or systemic (Fricton et al., 19851. Mechanical perpetuating factors include stress- fu] posture and body asymmetries (Travel! and Simons, 19831. For instance, a one-quarter inch discrepancy in leg length, present since childhood, may cause no symptoms until an awkward movement activates trigger points in the quadratus Jumborum muscle. The resultant myofascial low back pain often persists, regardless of appro- priate therapy, until the chronic excess strain on the muscle is relieved by correcting the leg length disparity (Simons and Travell, 19831. Similarly, systemic perpetuating factors may cause minimal symp- toms, including increased irritability of the muscles, that by them- selves escape attention. Irritable muscles are susceptible to strain. This susceptibility leads to the activation of trigger points. In the presence of unusually severe perpetuating factors, the activity of trigger points may be exacerbated, not relieved, by specific myofascial therapy. In most cases, unless the perpetuating factors are specifically dealt with, response to myofascial therapy is temporary, lasting only a few hours or days. The identification and management of common perpetuating factors, both mechanical and systemic, have been de- scribed in detail elsewhere (Travel! and Simons, 19831. TREATMENT Uncomplicated myofascial pain syndromes are highly responsive to simple treatment when appropriately directed (Sola, 1985; Travell and Simons, 19831. Specific myofascial therapy includes a variety of muscat stretching techniques (Lewis and Simons, 1984) and the injection of
APPENDIX 291 trigger points (Frost, 19861. Relief of chronic myofascial pain syn- dromes often requires resolution of all major perpetuating factors (they are commonly multiple) and application of myofascial therapy to the specific muscles involved. Satisfactory relief may require treat- ment of many muscles in several regions of the body in addition to restoration of well behaviors and a functional life-style. Trigger points cause the muscle to become tense and shortened (Travel!, 19761. Extension of the muscle to its full range of motion is blocked by pain. Any stretch technique that permits the tense short- ened muscle to reach its full stretch range of motion comfortably also inactivates its trigger points. Two effective methods are stretch and spray (Travel! and Simons, 1983) and postisometric relaxation (Lewis and Simons, 1984), which is similar to the contract-relax technique used by many physical therapists. A home self-stretch program often gives a patient control of the pain without drugs. Other treatments, such as muscle energy techniques, deep massage ultrasound, and specific relaxation techniques followed by stretch, are used with variable effectiveness depending on the practitioner's training and skill. Effective local injection of trigger points depends on physical disrup- tion of the trigger point mechanism by penetration with the needle and flushing the region with either a short-acting local anesthetic or saline. A recent study found that injecting trigger points with a prostaglandin inhibitor produced more pain relief than lidocaine (Frost, 19861. Less desirable is chemical destruction of the trigger point region with a long-acting, myotoxic local anesthetic (Travel! and Simons, 1983~. The effective management of an acute single-muscle myofascial pain syndrome without perpetuating factors can require simply the recog- nition of one referred pain pattern and a knowledge of the self-stretch technique for that muscle. This basic knowledge can be used by the patient to control recurrence and prevent chronic clisabl~ng pain. Conversely, the rehabilitation of a patient with chronic complex myofascial pain syndromes may require the multiple talents of a team approach and considerable time and ingenuity. REFERENCES Fischer, A. Diagnosis and management of chronic pain in physical medicine and rehabilitation. Chapter 8, In: Current Therapy in Physiatry (Ruskin, A.P., ed.). Philadelphia: W.B. Saunders, 1984. Fischer, A.A. Pressure threshold meter: its use for quantification of tender spots.
292 APPENDIX Archives of Physical Medicine and Rehabilitation 67:836~38, 1986. Fishbain, A.A., Goldberg, M., Meagher, B.R., Steele, R., and Rosomo£, H. Male and female chronic pain patients categorized by DSM-III psychiatric diagnostic criteria. Pain 26:181 - 197, 1986. Fricton, J.R., Kroening, R., Haley, D., and Siegert, R. Myofascial pain syndrome of the head and neck: a review of clinical characteristics of 164 patients. Oral Surgery 60:61~623, 1985. Frost, A. Diclofenac versus lidocaine as injection therapy in myofascial pain. Scandina- vian Journal of Rheumatology 15:153-156,1986. Gutstein, M. Diagnosis and treatment of muscular rheumatism. British Journal of Medicine 1:302~21, 1938. Kellgren, J.H. Observations on referred pain arising from muscle. Clinical Science 3:17~190, 1938. Kelly, M. Some rules for the employment of local analgesic in the treatment of somatic pain. Medical Journal of Australia 1:235-239, 1947. Lewit, K., and Simons, D.G. Myofascial pain: relief by post-isometric relaxation. Archives of Physical Medicine and Rehabilitation 65:452056, 1984. Reeves, J.L., Jaeger, B., and Graff-Radford, S.B. Reliability of the pressure algometer as a measure of myofascial trigger point sensitivity. Pain 24:313~21, 1986. Reynolds, M.D. Myofascial trigger point syndromes in the practice of rheumatology. Archives of Physical Medicine and Rehabilitation 62:111-114, 1981. Simons, D.G. Myofascial pain syndromes due to trigger points: 1. Principles, diagnosis, and perpetuating factors. 2. Treatment and single-muscle syndromes. Manual of Medicine 1:67-77, 1985. Simons, D.G. Muscle pain syndromes Parts I and II. American Journal of Physical Medicine 54:289 311, 1975; 55:1~42, 1976. Simons, D.G., and Travell, J.G. Myofascial origins of low back pain. Parts 1, 2, 3. Postgrad sate Med icine 73: 6~108, 19 83 . Skootsky, S. Incidence of myofascial pain in an internal medical group practice. Paper presented to the American Pain Society, Washington, OC, November ~9, 1986. Sola, A.E. Trigger point therapy. In: Clinical Procedures in Emergency Medicine (Roberts, J.R., and Hedges, J.R., eds.). Philadelphia: W.B. Saunders, 1985. Sola, A.E., Rodenberger, M.L., and Gettys, B.B. Incidence of hypersensitive areas in posterior shoulder muscles. American Journal of Physical Medicine 34:585~90, 1955. Travell, J. Myofascial trigger points: clinical view. In: Advances in Pain Research and Therapy, Vol. 1 (Bonica, J.J., and Alb - Fessard, D., eds.). New York: Raven Press, 1976. Travell, J. Basis for the multiple uses of local block of somatic trigger areas (procaine infiltration and ethyl chloride spray). Mississippi Valley Medical Journal 71:13-22, 1949. Travell, J.G., and Rinzler, S.H. The myofascial genesis of pain. Postgraduate Medicine 11:42~434, 1952. Travell, J.G., and Simons, D.G. Myofascial Pain and Dysfunction: The Trigger Point Manual. Baltimore, MD: Williams & Wilkins, 1983.