What is Referred pain?
Referred pain, also called reflective pain, is pain perceived at a location other than the site of the painful stimulus. An example is the case of ischemia brought on by a myocardial infarction (heart attack), where pain is often felt in the neck, shoulders, and back rather than in the chest, the site of the injury. The International Association for the Study of Pain, as of 2001, has not officially defined the term; hence several authors have defined the term differently.
Radiation is different from referred pain. The pain related to a myocardial infarction could either be referred pain or pain radiating from the chest. Classically the pain associated with a myocardial infarction is located in the mid or left side of the chest where the heart is actually located. The pain can radiate to the left side of the jaw and into the left arm. Referred pain is when the pain is located away from or adjacent to the organ involved. Referred pain would be when a person has pain only in their jaw or left arm, but not in the chest. Myocardial infarction can rarely present as referred pain and this usually occurs in people with diabetes or older age.
Physicians and scientists have known about referred pain since the late 1880s. Despite an increasing amount of literature on the subject, the mechanism of referred pain is unknown, although there are several hypotheses.