Response to letter to the editor by Dr. Cohen and Dr. Quintner.

Dear Editor, I appreciate the opportunity to respond to the letter to the editor of Drs. Cohen and Quintner (the authors), prompted by the reviewof theMuscle and Myofascial Pain section of the 2005 IASP Core Curriculum (IASP CC) [1]. The authors are acknowledged for their persistence in challenging inconsistencies in the constructs of the myofascial syndrome (and fibromyalgia). Indeed, and unfortunately, they have offered essentially similar comments to this journal when it was called the Clinical Journal of Pain as early as 1994 [2]. Their position is that the myofascial pain syndrome (MPS) is ill conceived and does not represent a true clinical phenomenon, and that the signs and symptoms attributed to myofascial pain and trigger points (TrPs) are better explained by the concept of regions of secondary hyperalgesia of peripheral nerve origin, which the authors stated in 1994, as a hypothesis that is testable to achieve external validity. Their studies have not been carried out and their theory has not been validated, but many studies have been produced supporting the existence of the mechanisms underlying pain of muscular origin [3,4].The authors challenge and attribute to Mense the concept of altered end-plate potentials in the pathophysiology of TrPs. As David Simons is the actual author of this theory, he has offered to respond in a separate letter below. The authors refer to the IASP CC book review of Leano and Kalauokalani [1]. The section alluded to actually says