Myofascial Pain Syndrome

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Myofascial pain syndrome is characterised by the presence of myofascial trigger points (MTPs). MTPs are a palpable hypersensitive tender nodule in a taut skeletal muscle band with a twitch response.

Pressure can also cause a characterised referred pain pattern, motor dysfunction, and autonomic responses (e.g. vasodilation, vasoconstriction, piloerection). They are an indication of hyperalgesia or allodynia.

A MTP can be latent or active. Active MTPs are spontaneously painful. Latent MTPs are inactive until an activity activates them.

Clinical Features

Palpation: The MTP should be palpated perpendicular to the direction of the muscle fibre. When palpating over a firm or bony structure compress the muscle against it. In some areas the muscle can be grasped between the fingers with a pincer grip to allow for MTP palpation. Referred pain is most readily detected with palpation in the centre of the MTP. So move your fingers along the taut band to find the hardest and most tender spot.

Referred Pain: When found compress it for 5-10 seconds and ask the patient if there is local or referred pain. Referred pain is somewhat follows the myotome pattern of innervation. For example, infraspinatus is primarily innervated by C5, and tends to refer pain to other C5-innervated muscles, with also a spread to C4 and C6 muscles (Also see Deep Somatic Pain).

Twitch Response: A local twitch response can occur which is when pressure over the MTP causes localised contraction. It is a brief (25-250ms), high-amplitude, polyphasic electrical discharge. It is dependent on an intact spinal cord reflex arc. It isn't seen in healthy muscle.

Weakness and ROM Restriction: There may be increased tension and shortening with restricted range of motion and weakness with poor muscle activation patterns. MTPs typically occur in muscles that are fatigued, overloaded, weak, or activated because of failure of other muscles. Weakness can be temporarily reversed with inactivation of the trigger point.

Autonomic Changes: There can be vasodilation or vasoconstriction due to autonomic nervous system activation. This can be seen as erythema or blanching.

Investigations

Blood tests can include TSH, ferritin, vitamin D, and vitamin B12.

Diagnosis

The first three are essential for the diagnosis, the last five are not required.

1. Taut band within the muscle
2. Exquisite tenderness at a point on the taut band
3. Reproduction of the patient’s pain
4. Local twitch response
5. Referred pain
6. Weakness
7. Restricted range of motion
8. Autonomic signs: skin warmth or erythema, tearing, piloerection.

A pragmatic definition is the presence of a tender taut band that reproduces the patient's pain in full or in part.

Treatment

Manual Therapy

Manual therapy can be used to improve range of motion, but this may not necessarily improve pain.

• Ischaemic compression
• Stretching
• Strain-counterstrain technique
• Muscle energy technique
• Positional release technique
• Pressure release
• Transverse friction massage
• Joint manipulation

Treatment of an MTP depends on the cause

1. Muscle is weak and fatigues quickly: treatment is strengthening
2. Muscle is overactive and compensating for other muscles that aren't correctly activating: restore correct motor pattern for example scapula stabilisation
3. Muscle is inappropriately active: modify inappropriate activities that are overloading the muscle e.g. holding one's phone between the head and shoulder.

See Also

• triggerpoints.net
• Central Sensitisation
• Allodynia and hyperalgesia
• Fibromyalgia
• Deep Somatic Pain