"Myofascial trigger points are among the most common, yet poorly recognised and inadequately managed causes of musculoskeletal pain seen in medical practice." Ex White House physician Janet Travell 1976.

Over the last two decades Travell's call for improved recognition and treatment of myofascial trigger points has begun to be answered. Relatively rapid changes in our knowledge have begun to accrue, particularly since the establishment of a standardised nomenclature and the usage of pain diagnostic tools.

These advances have led to a major exploration of the epidemiology, pathogenesis of and therapeutic options for pain states caused by muscular trigger points, which are now specifically known as myofascial pain syndromes.

The delineation of chronic benign intractable pain syndromes of the neck and back as being myofascial pain syndromes is of particular importance. These chronic benign intractable pain syndromes constitute a large proportion of the chronic pain population, who, because the diagnosis chronic benign intractable pain syndromes carried considerable psychological overtones, were frequently exposed to psychologically based therapies, which usually had little effect on pain reduction. Thus the finding that these patient's have a physical cause for their pain is of great significance as it allows for treatments that target the tissue and reflexes that cause and maintain their pain state.

Myofascial pain syndromes can be thought of as pain syndromes that are caused by and are maintained by one or more active trigger points and their associated reflexes. The trigger point is the actual tissue causing the pain state. The trigger point is the pain generator.

Myofascial trigger points (MTrPs) may be active or latent.

An active myofascial trigger point is a focus of hyper-irritability in a muscle or its fascia that causes pain and tenderness at rest or with motion that stretches or loads the muscle. It prevents full lengthening of the muscle, as well as causing fatigue and decreased strength. Pressure on an active MTrP induces/reproduces some of the patient's pain complaint and is recognised by the patient as being some or all of his or her pain.

A latent myofascial trigger point does not cause pain during normal activities. It is locally tender, but causes pain only when palpated. It also refers pain on pressure. It can be associated with a weakened shortened more easily fatigued muscle.

Unselected and Control Groups

• A Danish study of 1504 randomly selected people, aged 30-60,

• found that 37% of males and 65% of females had localised myofascial
• pain.

• An American study of 100 male and 100 female airforce personnel

• (Av. age 19) determined that 45% of males and 54% females had focal
• neck muscle tenderness (latent trigger points).

• 269 female student nurses were examined. 45% had TrPs in masseter,

• 35% had TrPs in trapezious. 28% had myofascial pain at the time of
• examination.

• Lumbogluteal muscles: Assessment of 100 asymptomatic control

• subjects. Revealed latent TrPs in 45% of Quadratus Lumborum, 41% of
• Gluteus Medius, 11% of Gluteus Minimus, 5% of Piriformis.

Patient Groups

• Community Pain Medical Center. 96 patients studied by a
• neurologist: 93% had at least part of their pain caused by myofascial
• TrPs and in 74% of the patients myofascial TrPs were considered to be
• the primary source of pain.

• Comprehensive Pain Center: 283 consecutive admissions to a

• comprehensive pain center: The diagnosis made independently by a
• neurosurgeon and a physiatrist based on physical examination as
• described by Travell and Simons assigned a primary organic diagnosis
• of myofascial pain in 85% of the cases.

• Additionally several studies have determined that MTrPs are

• frequently associated with and contribute to the patient's pain in
• the conditions summarised in the table below.

Spot Tenderness: A very tender small spot, which is found in a taut band.

A taut band: A ropelike swelling found within the muscle probably due to sustained shortening of muscle fibres. Increasing the tension on the muscle fibers of the taut band can increase the sensitivity of the MTrP.

Jump Sign: Pressure on the tender spot causes the patient to physically react to the precipitated pain by exclaiming or moving. This reaction indicates the level of tenderness but is also dependent on the pressure exerted by the examiner.

Pain Recognition: Digital pressure on or needling of the tender spot induces/reproduces some of the patient's pain complaint and is recognised by the patient as being some or all of his or her pain. This finding by definition identifies an active trigger point. (This replication of the patient's pain may require sustained pressure (5 - 60 seconds) on the MTrP.)

Twitch Response: A transient contraction of the muscle fibers of the taut band containing the trigger point. The twitch response can be elicited by "snapping" palpation of the trigger point. Or more commonly by precise needling of the trigger point.

Elicited referred pain: An active MTrP refers pain in a pattern characteristic of that muscle -Usually to a site distant to the MTrP. 85% of TrPs project distally. [The area of the referred pain is often tender and may contain satellite trigger points.]

Latent TrPs also refer pain on pressure but usually require more pressure to do so.

Restricted Range of Movement: Full stretching of the affected muscle is often involuntarily restricted by pain.

Muscle Weakness: The patient is unable to demonstrate normal muscle strength on static testing of the affected side as compared to the contralateral non-affected side. The involved muscle is also more easily fatigued.

• Overwork - Fatigue (Including postural stress)
• Chilling
• Gross Trauma
• Other Trigger Points
• Emotional distress
• Joint or nerve damage
• Visceral disturbance

Perpetuating Factors

• Mechanical: Structural inadequacies e.g. The short leg syndrome, the small hemipelvis, the long second metatarsal, short upper arms.
• Clothes. Tight constrictive clothing can produce MTrPs due to sustained muscle compression. E.g. Jeans related buttock pain, bra strap headache, and wallet sciatica.
• Systemic. Metabolic, endocrine, toxic, inflammatory etc. Commonly found systemic factors include hypothyroidism, folic acid and iron deficiency.
• Toxic: alcohol.
• Metabolic - Inflammatory: gout.
• Relative Growth Hormone deficiency has recently been suggested as playing a pivotal role in MTrPs syndromes. (As growth hormone is necessary for muscle repair and its secretion is related to deep sleep which is frequently disturbed in patients with pain. )

• The energy crisis theory
• The muscle spindle concept
• The motor endplate hypothesis

• MTrPs have specific pain referral patterns.
• The actual trigger point is frequently outside the area of the patient's perceived pain.
• Trigger point activity stimulates regional/segmental sympathetic outflows.
• The area of the perceived (referred) pain is usually cool or cold.
• The muscle containing the active trigger point is frequently found by recognising the patient's pain pattern.
• Comparison of the patient's pain diagram with Travell and Simons' trigger point charts greatly aids diagnosis.

Myofascial Trigger Points Emerging Criteria for Diagnosis:
Circumscribed local tenderness
Patient recognition (pain replication on palpation or needling)
Jump sign
Local twitch response (with needling or snapping palpation)
Taut band

Traditional Chinese Medicine

"When pressed on the patient winces, or suddenly starts and exclaims AAGH is The POINT!" from Acupuncture a Comprehensive Text: Shanghai College of Traditional Chinese Medicine.

"Ah Shi - Oh Yes!" as the patient's pain complaint is reproduced by palpation. Nanking College of Traditional Chinese Medicine, Nanking, China 1978.

  Traditional Chinese medicine groups myofascial pain syndromes under the heading of Cold Bi syndromes. Traditional Chinese medicine's pathogenic factors include:

• Over-exertion
• Invasion by "cold" Eg. Chilling of a muscle by wind or cold following exertion.
• Prolonged inactivity
• Visceral disturbance

Cold Bi syndromes have these common characteristics: inhibition of blood supply, fondness and alleviation of pain with warmth and a worsening of pain severity with cold and damp.

Traditional Chinese medicines aim in the treatment of Cold Bi is to remove the obstruction to the flow of Chi and blood and warm and nourish the tissues.

In Western terms, remove the trigger point and its associated muscle spasm/shortening, diminish the over active sympathetic outflows and thereby restore normal blood flow.

The near and far method of acupuncture, where the tender point/trigger point, plus distal analgesia producing sympatholytic acupuncture points below the elbow or knee are needled with the Bu technique, is an ancient method for the treatment of myofascial pain syndromes that is currently used in China today.

The Bu needling technique or the warming method, where the needle is painlessly inserted and gently manipulated until needle grasp is obtained provokes stimulation of large sensory nerve fibres. The consequences of large fibre afferent activity are inhibition of small fibre activity (pain gate), relaxation of segmental muscle tone (muscle gate), and inhibition of sympathetic segmental outflow (sympathetic gate).

The exact effects of trigger point needling are not known. Relaxation of 'stuck' myofibrils, segmental release of endogenous opiods (dynorphin, encephalin), and localised trauma induced vasodilatation have all been postulated to explain the return to normal of an exquisitely tender circumscribed muscle area.

The effect of needling the analgesia producing distal points (points that are either muscle motor points or have dense cutaneous / muscle nerve innervation) has been well researched. The analgesic effects are mediated by the endogenous opioid substances as well as a host of other neurotransmitters and modulators including 5HT, and nor adrenaline. The sympatholytic effects of acupuncture have also been well detailed and have been shown to be associated with decreased pain scores in both sympathetically maintained and trigger point related pain states.

The success of the near and far acupuncture technique and indeed of most treatment techniques that target the trigger point relies on the accurate localisation of the relevant trigger point. Consequently a rigorous physical examination including palpation must be carried out.

The practitioner's level of skill and training also appear to be influential as does the adherence to classical treatment schedules. These factors seem to have been alluded to by Richardson and Vincent in their review article "Acupuncture for the Treatment of Pain: a Review of Evaluative Research" PAIN, 24 (1986) 15 - 40, when discussing the long term pain relieving effects of acupuncture; "The controlled study by Coan et al., where traditional acupuncturists were given the freedom to follow their normal practices, presents a more promising picture- with improvements in 58% of the initial sample of low back pain patients being maintained at a 10 month follow-up." That these factors may be of lesser importance in the short term effectiveness of acupuncture may be deduced from their statement, "The above review indicates that there is good evidence from controlled studies for the short-term effectiveness of acupuncture in relieving clinical pain in each of the areas examined. The extent of the therapeutic effects produced has varied from study to study but the proportion of patients helped has commonly fallen in the 50 - 80% range. This applies to both acute and chronic painful conditions." as many of the trials surveyed used acupuncture regimes that bear little resemblance to acupuncture as it is practiced in China today.

However, before being able to effectively treat myofascial pain syndromes (and evaluate that treatment's efficacy) the trigger point must first be identified, quantified and its associated reflexes delineated. Pressure algometry, thermography and EMG studies, as well as electrical stimulation pain provocation studies and differential local anaesthetic blocks, have been used with varying success to provide objective measurement of trigger point activity. Additionally much can be gained in clinical practice by the use of subjective pain assessment tools including, visual analogue pain scales, The McGill pain questionnaire and pain diagrams.

The wide importance of pain assessment is highlighted by the following statement: "One of the most dramatic developments in pain research and therapy has been the recent proliferation of techniques for the measurement and assessment of pain", -R. Melzack.

My own view is that every patient complaining of chronic pain deserves to be examined. Palpation and the utilisation of pain assessment tools including pain diagrams, the McGill pain questionnaire, visual analogue pain scale are all a necessary part of this process and should always be carried out before referral for psychologically based therapies. (Simon Strauss unsubstantiated opinion.)

Subjective

Visual Analogue Scale (VAS)

McGill Pain Questionnaire

Pain Diagram

  Objective

Pressure Threshold Algometry

Differential Local Anesthetic Blocks

Thermography, EMG etc.

Treatment Efficacy Controlled trials have shown; dry needling, acupuncture (The near and far technique), trigger point injection with saline, steroids, local anesthetics and Botulinum Toxin, to be effective treatment strategies. Biofeedback and dental splints have also proven to be effective in the context of myofascial tempero-mandibular joint syndromes.

The case for spinal manipulation, neuromyotomy and low-level laser irradiation has not yet been established.