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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
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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
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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-
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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
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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-
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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
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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.
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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.
Representative terms from entire chapter:
perpetuating factors
