I wonder if you find pain patterns as interesting as I
do? This is a subject that first drew me
medicine, the late James
Cyriax's system of identifying the precise anatomical locations generating
musculoskeletal pain. In addition to his
method of "systematic examination of the moving parts by selective tension" he
also showed that musculoskeletal pain
refers from specific structures in predictable patterns.
A knowledge of
anatomy was the key. For example,
pain referring down from the shoulder joint, i.e. in a C5 dermatomal
pattern would have to be coming from a gleno-humeral structure - joint, bursa
or tendon. On the other hand, pain
referring upward, to the upper shoulder or lower lateral neck would have
to be coming from the acromio-clavicular joint as it receives C4 innervation.
The systematic study of referred pain began long ago - in
the 1800s. Surgeons already knew that
pain could be referred from inflamed organs. Then in the late 1800s British
neurologist Sir Henry Head demonstrated that referred pain from organs followed
the body's ontogenetic segments in a systematic way. To this day these patterns are called "Head zones".
Kjellgren's experiments in the 1930s, using injections of
hypertonic solutions into muscles, ligaments and perisoteum demonstrated
referral of pain from somatic structures.
Janet Travel refined this
work by studying muscle trigger points.
Using injections of local anesthetic, she showed that myofascial pain
syndromes could be diagnosed and treated by identifying and injecting the
corresponding trigger points. Her
two-volume textbook Myofascial pain and dysfunction: The trigger point manual (now revised and updated by David
Simons) remains the standard reference on this subject.
George Hackett, a Cleveland
trauma surgeon, did similar work in the 1940s and 50s on ligament trigger
points. He demonstrated that ligaments
stabilizing the pelvic ring and lumbar spine were common generators of referred
pain (in consistent patterns for each ligament) into the groin, hip and/or down
the leg. Hackett went on to become one
of the pioneers of prolotherapy (or sclerotherapy), a method of treating
ligament "laxity" and pain by injecting "proliferating" solutions such as
dextrose into fibro-osseous junctions.
Pain referral patterns overlap from muscle trigger points, ligament
trigger points, and no doubt from injured periosteum. It is
interesting how pain from adjacent or related
somatic structures can refer in similar ways. Notice the similar referral patterns of two
phylogenetically related structures: the ilio-lumbar ligament and the inferior
quadratus lumborum muscle.