myofascial pain
Myofascial pain, as described by Travell and Simons, is a condition characterised by localised pain and discomfort arising from trigger points within muscles and their surrounding fascia.
Myofascial pain
There are four distinct distortions which can cause pain in myofascial tissue. These are:
Distortion Signs & Symptoms
Periosteal Trigger Point Pin point pain in one or more areas. The area of disruption can often be palpated as a small roughened area on the bone that is exquisitely tender.
Superficial Fascial Restriction Deep pain in a non-joint area, which cannot be reproduced by palpation. Pain jumping from one area to another. Tingling, numbness or paraesthesia throughout an entire extremity or area. Diffuse and nonspecific pain.
Myofascial Band Burning or pulling pain along a specific pathway
Muscle (Myofascial) Trigger Point Steady, deep, aching pain. Like a rope under the skin, with a nodule in that taut band.
Active TrP – reproduces a persons usual pain, and all referred pain and other symptoms.
Latent TrP – refers but does not reproduce persons usual pain.
The most common of these distortions is by far, the Muscle (Myofascial) Trigger Point.
A Myofascial Trigger point (MTrP) is a hyper irritable locus within a taut band of skeletal muscle. (Travell & Simons 1983)
A MTrP may be active and cause stiffness and pain, or latent and cause stiffness without pain. An active MTrP may be inactivated by treatment, and a latent MTrP may be activated by a number of precipitating factors.
MTrP’s tend to occur in rather constant positions within muscles, for example the anterior border of the upper fibres of the trapezius muscle shown in the diagram to the right.
The trigger point in the upper fibres of trapezius referring pain mainly to the neck and temporal region.
Incidence
MTrP’s are common, and most people develop one or more during their lifetime. In one study in primary care, MTrP’s were found in 30% of patients consulting for pain.
Aetiology
MTrP’s may be caused by muscle injury or strain, but they may also occur secondary to other painful conditions. A strain that causes an MTrP in one person may not bother a second person - or even the same person at another time, suggesting there are other factors that make MTrPs more likely to develop. The same factors may prevent them healing.
The commonest acute strain occurs when the muscle is overloaded, for example from lifting something too heavy, or at an awkward angle. Quadratus lumborum (see picture to the right) which is crucial in providing lateral support for the back, can easily be strained lifting a weight with one hand. In these cases, the onset of pain is usually rapid.
Myofascial pain of gradual onset is likely to be caused by chronic, cumulative strain.
This is common, for example, in the trapezius muscle when many hours are spent in a
poor working posture. A postural abnormality, such as kyphosis or scoliosis of the spine,
puts extra strain on the muscles of the trunk (e.g. quadratus lumborum) or neck
(trapezius). Constant mental tension can also produce prolonged muscle contraction:
for example, tightly hunched shoulders may cause MTrPs to develop in the neck muscles,
particularly trapezius.
Very occasionally, direct injury to the muscle can give rise to an MTrP, for example when
it is compressed for a long time (e.g. sitting in a chair where the front edge compresses the
hamstrings). Because of the way MTrPs are caused by injury, they are often unilateral,
though this is not always obvious in those that develop in the spinal muscles.
MTrPs can develop in painful conditions, and then cause added problems for a person. This is referred to as secondary myofascial pain. For example, arthritis of the hip is associated with MTrPs in the gluteal muscles, and MTrPs may develop in the pectoral muscles after myocardial infarction.
Sometimes, the history of injury appears to be too trivial to have produced an MTrP, in which case the muscles may have been in a particularly vulnerable state. This can happen for a variety of reasons:
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• Emotional: stress and anxiety, excitement
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• Physical: exhaustion, poor muscle fitness from lack of exercise or exposure to cold
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• Metabolic: poor nutritional status, low vitamin levels, hypothyroidism or chronic infection
These factors that precipitate an MTrP also perpetuate it, and will also interfere with the response to treatment. They may need to be corrected before treatment can be successful and lasting.
Common MTrPs in the head, face and neck: myofascial trigger points and pain reference zones.
Common MTrPs in the low back and hip girdle: myofascial trigger points and pain reference zones.
Most MTrPs are caused by muscle injury - acute or chronic.
Emotional, physical or metabolic factors can perpetuate a MTrP.
