This is a term that is used by Pellegrino who argues that this is non-generalized fibromyalgia whereby the chronic pain is just in to one or a few areas such as the upper body or the low back. He states: “The symptoms may wax and wane.” He claims that it is usually triggered by trauma. In says that he believes that “myofascial pain syndrome is part of this regional fibromyalgia, and both terms are essentially synonymous.”
“The similarities between myofascial pain syndrome and Fibromyalgia are far greater than their differences. They both have trigger points, tender points, ropey muscles…The treatments are essentially the same. He claims that people with people with “regional Fibromyalgia, over time, often develop generalized fibromyalgia.” He emphasizes the need for early identification and early treatment of regional fibromyalgia and this “can definitely help to prevent progression.” (The Fibromyalgia Spectrum - Part of the Big Picture in Understanding Fibromyalgia, Mark J. Pellegrino, www.ProHealth.com, June 8, 2010 available in full online at: http://www.prohealth.com/library/showarticle.cfm?libid=13042.
For further perspective see the entry Myofascial Pain Syndrome/MPS/Myofascial Syndrome in Fibro Wiki.