Massage Therapy / Pain

What is a Trigger Point and Why it Causes Pain

trigger_point_chart2

Many people suffer from “muscle knots” that can produce pain locally or in a referral pattern to another spot on the body away from the actual site of the “muscle knot”. These hard spots in the muscle are usually sensitive when pressure is applied and can be hyper-irritable. A common name for these “muscle knots” is Myofascial Trigger Points, and you may have heard this term from your massage therapist.

Of course, this trigger point (TrP) does not involve any actual knots. The theory of the formation of trigger points is discussed as being a small sustained contractile activity in the muscle fibers. This small area of contracted muscle blocks off its own blood supply, which irritates the local nociceptors (nerve cell endings that initiate the sensation of pain), a vicious cycle called an “energy crisis”.

Many people suffer from aches and pains, a common medical complaint, resulting in different diagnosis and treatment. Muscle pain is an important problem, and is the reason for many peoples pain in their bodies.  The daily clinical practice of massage therapists, physical therapists and physicians indicate that most of our common aches and pains – and many other strang physical complaints- are actually caused by trigger points.

Myofascial trigger points are a frequently overlooked and misunderstood source of musculoskeletal aches and pains, Why? Because most medical doctors are unqualified to care properly for most common pain and injury problems, and this has been proven by other doctors. (Stockard found that 82% of graduates lacked “basic competency in musculoskeletal medicine”  according to his study (http://www.jaoa.org/cgi/content/full/106/6/350)

“Muscle is an orphan organ. No medical speciality claims it. As a consequence, no medical specialty is concerned with promoting funded research into the muscular causes of pain, and medical students and physical therapists rarely receive adequate primary training in how to recognize and treat myofascial trigger points.” (2) Muscle tissue is the “primary target of the wear and tear of daily activities, but it is the bones, joints, bursae and nerves on which physicians usually concentrate their attention.” (3)

Diagnosis and treatment of acute single-muscle myofascial pain syndromes can be easier if the problem is dealt with right away. When an acute myofascial TrP syndrome is neglected and allowed to become chronic, it becomes unnecessarily complicated, more painful and it becomes increasingly time-consuming, frustrating and expensive to treat.

Trigger points are a key factor in headaches, neck pain, low back pain and many more pain conditions. Trigger points are clinically important for three reasons, they cause pain  problems, complicate pain problems and mimic other pain problems.

travell_trapezius_trigger_point3_38005_1_1_7234

Trigger points can cause pain directly: those common aches and pains; the reason is often a TrP. When we work in an office chair all day, through many other work related tasks and labour, or with activities and hobbies, sooner or later almost everyone is certain to get a trigger point. Trigger points just seem to be a natural part of life, we use our muscle (or abuse our muscles) and in turn, they develop the little areas of muscle contractions that cause us so much pain.

Trigger points can complicate injuries: When you get an acute injury, this predisposes you to developing TrPs, or activating a latent TrP. When you get the initial injury, you will likely protect this area by guarding the limb or area of injury. This perpetuates TrPs because a muscle held in a shortened position will aggravate the TrP, causing you more pain.  Stresses such as wrenching movements, automobile accidents, falls, fractures, joint sprains, dislocations or direct blow to the muscle are examples of injuries or accidents that can cause TrPs. Most of the time, myofascial TrPs due to such one-time gross trauma are easily inactivated as soon as any associated soft tissue injury has heeled; however, the TrPs may persist for years if untreated.

Trigger points can mimic other problems: Many trigger points can produce pain or symptoms and are often mistaken and diagnosed as being something else. It is interesting to read about some of the unusual symptoms of TrP pain that are experienced in another area of the body distant to the site of the TrP. This phenomenon of pain spreading from the area of the TrP to another location is called “referred pain”. Some examples include: Sciatica: often caused by the referred pain in the piriformis or other gluteal muscles, and not by irritation of the sciatic nerve. Many other trigger point referred pain patterns are mistaken for a nerve problem. Carpal tunnel syndrome may actually be a referred pattern from a TrP in subscapularis (a rotator cuff muscle located in the armpit).  Low back pain is often caused by TrP referred pain so low that it is not even in the low back; gluteal muscles or lateral rotators of the hip cause the common aches and pains in the low back. Trigger point referred pain is also often mistaken for arthritis, bursitis, or ligament pain. Other unusual symptoms include earaches, sinusitis, toothaches, tinnitus (ringing in the ears), dizziness, nausea, heartburn or false heart pain.

However, the majority of symptoms caused by myofascial pain syndromes are simply the familiar aches and pains of humanity — a sore back, shoulders and neck. Some of which can become quite serious.

In the rest of this article, we will be focusing on the trigger points that cause pain directly, and discussing the common symptoms and definitions of a TrP. Although a lengthy discussion of the other two topics, (trigger points complicate injuries and trigger points can mimic other problems) would provide you with further information about your pain problem, we will start with the basics for now. Other articles on pain problems and TrPs to come.

What do I mean when I say an “active TrP” and a “latent TrP”

Active TrPs produce a clinical complaint, this is usually pain. The TrP will usually cause referred pain with a predictable pattern specific to the muscle, the TrP is rarely located where the client feels pain (ex. Tension headaches are caused by TrPs in the upper back and neck). An active TrP can be identified by a taut band of muscle, spot tenderness of a nodule in a taut band, pain by pressure on the tender nodule, limited range of motion due to pain, and observation of a local twitch response by visual or tactile methods.

The thing that makes TrPs even more difficult to find and figure out is a phenomenon that occurs with an active TrP and referral patterns called satellite trigger points. For this example, an active TrP will be called a key TrP.  A key TrP and satellite TrP are related TrPs, so when you have a key Trp, this predisposes you to developing a satellite TrP in the referred pattern of the key Trp. (ex. A TrP in the scalene muscle – front of your neck, lower region, causes a referral pattern on the same side of your upper back, and the same side of your chest. This referred pain can cause TrPs in the muscles in this area – upper back: serratus posterior superior, chest: pectoralis major and minor.) Knowledge of these TrP relationships is important in reducing a clients pain, clinically, a key TrP must be inactivated in order to effectively inactivate the satellite TrP (in relation to the above example; the TrP in the scalene’s muscle must be inactivated in order to fully inactivate the TrP in serratus posterior superior, and reduce the clients complaint of upper back pain). In another example taken from the book “The Trigger Point Manual” by Travell and Simons’, “ Whiteside described an interesting example of a three-step satellite TrP phenomenon. A final year physiotherapy student complained of a toothache that developed in the right upper jaw along with an ache in her right upper trapezius muscle when she studied for long periods of time. She had received extensive dental treatment including a root canal without relief. In response to firm pressure on a TrP in the right lower trapezius she said, “I am getting a dull ache in the upper trapezius that I get when I study.” In response to pressure on an upper trapezius TrP she said, “I am now getting pain in the right temporal region, but I’ve not had pain in that area before.” In response to pressure on a right temporal TrP she responded, “Now I’m getting pain in the tooth that bothers me when I study.” (p122-123)

Latent TrPs do not produce spontaneous pain, but they can produce other effects characteristic of a TrP including increased tension and muscle shortening, which can cause restricted range of motion. A nodular area will be palpable and is associated with taut bands of muscle. The client becomes aware of pain originating from a latent TrP only when pressure is applied to it. Spontaneous referred pain appears with increased irritability of the TrP and it then is identified as active.

Both active and latent TrPs can cause motor dysfunction (action of a muscle or nerve). The patient is aware of the pain caused by an active TrP, but may or may not be aware of the dysfunction it causes.

The presence of a TrP in a muscle may cause these additional symptoms:

  • Limited Range of Motion: readily identified by the pain that develops as the muscle approaches full stretch ROM. Limitations of motion and increased stiffness are worse in the morning and recur after periods of overactivity or immobility during the day.

  • Weakness with certain movements, as when pouring milk from a carton, turning a door knob or carrying groceries in one arm. This yields clues as to which muscles are involved. The muscle learns to limit the force of its contraction below the pain threshold of the central and attachment TrPs, weakness may also be a reflection of inhibition referred from a TrP in another muscle (ex. inhibition of ant. deltoid by a TrP in the infraspinatus muscle)

  • Other: excessive lacrimation, nasal secretion, pilomotor activity and occasionally changes in sweat patterns, limb may feel cold d/t reflex vasoconstriction, symptoms of postural dizziness, spatial disorientation and disturbed weight perception.

The pain associated with a TrP will feel like a steady, deep (subcutaneous and muscular), and aching pain, rarely as burning. Occasionally a TrP will refer sharp, lancinating or lightening like stabs of pain. It is to be distinguished from prickling pain and numbness associated with nerve root irritation or peripheral nerve entrapment. Throbbing pain is more likely due to vascular disease or dysfunction.

The patterns of pain referred from TrPs in a muscle are reproducible and knowledge of these patterns are used to locate the muscle most likely to be causing the pain. The referral pattern can be classified as peripheral (away from the center of the body), mostly central (predominantly in the direction of the center of the body) and local (only in the immediate vicinity and surrounding the TrP).

Myofascial TrPs may cause constant pain, intermittent pain or no pain. Clients with constant pain are usually unaware of activities that aggravate the pain because the pain is so intense, they cannot perceive an increase and so cannot distinguish what makes it worse. Most clients have intermittent pain that is aggravated by specific movements and may be alleviated temporarily by a certain position. They may have sum relatively pain free days and can usually identify what position or situation provides relief. A TrP that does not produce pain is called a latent TrP, and will not give any primary pain clues. These TrPs must be identified by other clues such as an increased muscle tension and muscle shortening.

The activation of a TrP is usually associated with some degree of mechanical abuse of the muscle in the form of muscle overload, which may be acute, sustained and/or repetitive. In addition, leaving a muscle in a shortened position can convert a latent TrP to an active TrP and this process is greatly aggravated if the muscle is contracted while in the shortened position (certain sleeping positions shorten muscles, or in an individual who concentrates on an activity, such as writing or reading, so intensely that they forget to change positions regularly and their muscles stay contracted in a shortened position for too long.)

With acute onset, the mechanical stress that often activates TrPs will include injuries, accidents, or an episode of excessive or unusual exercise, such as packing and handling boxes when moving. With abrupt onset, the patient remembers clearly the first date of the pain and can usually describe the exact event or movement, such as reaching back for something.

Pain of gradual onset is usually due to chronic overload of muscles (sustained contraction, repetitive motion or emotional stressors), this must be identified and treated because when chronic strain continues to affect a certain muscle, this will perpetuates and may intensify the TrPs. Typical cases of sustained postural overload are poor work habits such as a slouched posture or a keyboard operator lifting the shoulders to reach an elevated keyboard.

If the source of strain is not obvious, the client should be instructed in the kind of movements that would overload the involved muscle and then watch for daily activities that use that motion. The client should also note any movement or activity that increases the referred pain and then avoid it or learn how to perform the activity (if essential) without overloading the muscles. Synergistic muscles (muscles that perform the same action as the affected muscle) that are overloaded by substituting for an involved muscle or are in sustained contraction to protectively splint an involved muscle are themselves likely to develop secondary TrPs.

Myofascial pain may also appear during or after a period of viral infection, visceral disease or psychogenic stress and may develop in association with radiculopathy of its nerve supply.

It is important to determine in detail what activities and postures aggravates the pain and which ones relieve it. This will help your therapist identify which muscles are affected by a TrP.

“ Myofascial pain is characteristically aggravated by:

  1. Strenuous use of the muscle, especially in the shortened position (Defining the precise movement that increases pain will identify the muscle)

  2. By passively stretching the muscle, active stretch by voluntary contraction of antagonist rarely causes pain because the patient subconsciously limits this movement. The patient is aware of restricted ROM and “weakness” but may not think the affected muscle as painful.

  3. By pressure on the TrP

  4. By placing the involved muscle in a shortened position for prolonged period. Pain and stiffness are often at their worst when the patient gets out of bed in the morning or when getting up from an armchair after sitting immobile for a while.

  5. By sustained or repeated contraction of the involved muscle

  6. by cold, damp weather, viral infections, periods of marked nervous tension.

  7. By exposure to a cold draft, especially when the muscle is fatigued

Myofasical pain is decreased

  1. by a short period of rest

  2. By slow, steady passive stretching of the involved muscles, particularly when seated under a warm shower or in a warm bath

  3. When moist heat is applied over the TrP. The pain is decreased much less when the heat is applied over the reference zone.

  4. By short periods of light activity with movement (not by isometric contraction)

  5. By specific myofascial therapy ” (2)

Clients must learn to respect their muscles. Muscles are designed to contract, relax and be kept mobile through their full range of motion. They are not designed to be held for long periods in sustained contraction or in a fixed position, particularly not in the fully shortened position. Most clients need to apply some myofascial therapy at home such as moist heat, stretch exercises and TrP pressure release. Clients also need to practice good movement postures that prevent excessive muscle tension and stress.

See my article on What Perpetuates Pain and TrPs  for ways to identify what may be causing your pain and how to deal with this.

Treatment of Trigger Points; Specific Myofascial Therapy

Trigger Point Pressure Release: the TrP is compressed with a thumb or finger until the finger encounters a definite increase in tissue resistance. This pressure is maintained until the therapist feels a relief of tension under the palpating finger and the pain has decreased. This pressure is increased to encounter the next barrier and the TrP gradually releases.

Muscle Stripping: this technique uses deep-stroking massage along the taut band of muscle. The purpose is to elongate the shortened muscle fibers to release their tension.

Voluntary Contraction and Release Method: these techniques use voluntary (active) contraction followed by relaxation. A reduction in muscle stiffness (tension) following the contraction provides an increase in range of motion during the period of relaxation. The techniques include: contract-relax, post-isometric relaxation, a combination of post-isometric relaxation and reciprocal inhibition, hold-relax and muscle-energy techniques.

Most Registered Massage Therapists have knowledge on Trigger Points and their referral patterns and will be able to identify which muscles are affected and how to treat the affected area to alleviate the pain and discomfort.  They are also trained to give proper homecare exercises to help further decrease the tension and pain in the affected area.

 

Health Into Perspective: Articles to get you thinking about Your Health

Sarnia, ON

 

(1) Stockard. Wesley Allen. 2006. Journal of the American Osteopathic Association. Competence Levels in Musculoskeletal Medicine: Comparison of Osteopathic and Allopathic Medical Graduates. (2) Travell. Simons. 1999. Myofascial Pain and Dysfunction. Vol 2. (3) Mense. Simons. Russell. Muscle Pain: Understanding Its Nature, Diagnosis, and Treatment. p208.

(Other) Daniels JM, Ishmael T, Wesley, MA. Managing Myofascial Pain Syndrome Phys Sportsmed 2003 Oct:31(10):39-45. Bennett R. Myofascial pain syndromes and their evaluation  Best Pract Res Clin Rheumatol. 2007 Jun:21(3)427-45.

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