Pain Referral Patterns

Myofascial Referred Pain

Referred Pain is pain that is caused by a trigger point but is experienced at a distance. It is quite often can be entirely remote from the source TrP. The pattern of this pain is every time reproducible and connected to its locus of origin. However, its distribution seldom coincides completely with the distribution of a relevant dermatomal segment or peripheral nerve.

Referred Pain and Referred Autonomic Responses

Referred pain is part of more generic Referred (Trigger-Point) Phenomena.

Apart from pain, the latter include Referred Autonomic Phenomena:

• tenderness;
• increased motor unit activity (spasm)*;
• vasoconstriction – blanching;
• vasodilatation – the widening of blood vessels;
• coldness;
• sweating;
• pilomotor response – “goose flesh”;
• ptosis - the upper eyelid droops over the eye;
• hypersecretion.

* There is an example in research literature (Headley BJ) when pressure on a trigger point in a right soleus gave rise to a strong spasm response in the right lumbar paraspinal muscles.

These phenomena also usually appear at a remote distance from the trigger point, in the same general zone to which a certain trigger point refers pain.
The intensity and expanse of the referred pain depends on the level of irritability of the trigger point, and not on the size of the harboring muscle. Trigger points in small muscles can be as upsetting to the patient as those in large muscles.

Essential Zone of Reference

The region of the body, where phenomena caused by the myofascial TrP are observed is called Essential Zone of Reference. The essential referred pain area is indicated by solid red in pain charts.

Spillover Pain Zone

The area where certain, but not all, patients feel referred pain outside the essential pain area, due to greater irritability (hyperirritability) of a trigger point is called Spillover Pain Zone. In the pain-pattern trigger point charts it is indicated by red stippling or solid pink to be distinguished from an essential referred pain area (solid red).

The pain referral pattern is characteristic for each muscle. Some patients feel numbness or paresthesia (‘pins and needles’) rather than pain.