Referred Pain vs. Origin of Pain Pathology
by James Woessner, MD, PhD
 Referred pain, as defined by Anderson, is “pain felt at a site
different from the injured or diseased organ or body part.”1 Radiating
pain, however, is not defined by Anderson; radiating pain is more commonly used in
connection with pain perceived in somatic nerve and spinal nerve root distributions (i.e.
the dermatomes that all physicians learn early in their training). Merskey and Bogduk
specify that “referred pain is pain perceived in a region that has a nerve supply
different from that of the source of pain,”2 which indicates that
radiating pain is completely different (the author does not find that excluding radiating
pain from referred pain useful; radiating pain is just a subcategory of referred pain).
Bellenir adds “Antidromic” into the definition, noting that visceral and
somatic nerve cells may synapse on the same neuron at the spinal cord.3 With
chronic stimulation, “the impulse will spill over. . . . into the somatic
nerve.” Warfield and Fausett also calls it “heterotopic” pain and state
that “referred pain is a phenomenon that is frequently encountered and is most
baffling.”4 Added meaning is conveyed by Khalsa, who defines referred pain
as “pain that exists in a location other than the immediate area of the spasm”5
without defining limits, or specific distributions. However, according to Khalsa, the
range of the main pain should not be larger than the receptive field, which varies in size
depending on the area of the body.
It has been said by the IASP Subcommittee on Classification that “Pain is always
subjective. . .”2 Yet if the clinician does not understand a presenting
pain pattern, where the pain is already considered “subjective,” the chances of
justly handling and treating the patient are limited. Indeed, if psychogenic (eg.
“subjective”) pain and referred pain become synonymous, then the physician may
stop looking for the originating pathology and not provide proper treatment or any
treatment at all. The patient is likely to slip into a downward spiral of “doctor
shopping.”
However, it must be said that all pain “is always real.” Thus, diagnosing
pain pathology — in the face of referred pain that may be perceived as worse than the
origin of the pain — becomes a daunting challenge. An understanding of the pain
pathophysiology with familiarity of referred pain possibilities, coupled with a thorough
history and physical examination, is essential in making an appropriate and potentially
correct diagnosis.
Please refer to the Nov/Dec 2003 issue for the complete text. In the event you need to order a back issue, please click here.
— Nov/Dec 2003
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