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. Following traumatic injury, the pain usually begins above the collarbone and/or in the shoulder or neck and proceeds outward to the fingertips, and it has essentially the same qualities, as described above. When one side of the body is experiencing pain, the automatic response is to favor the unaffected side, causing similar pain to appear there over time. Given this plethora of symptoms, it can be difficult to arrive at a diagnosis. Involvement of the head, neck, arms, and front and back of the chest with pain and occasional swelling produces a clinical picture that is often difficult to integrate for the inexperienced physician.   .