Fibromyalgia (FM) and myofascial pain syndrome (MPS) are both commonly diagnosed forms of chronic musculoskeletal pain and in many ways are clinically comparable.
FM is defined by widespread, chronic musculoskeletal pain with the presence of palpable tender points (TPs – distinct areas of soft tissue which are painful under palpatory pressure of less than 4 kg, but otherwise indistinguishable from surrounding tissue). MPS, on the other hand, is defined by regional muscle pain associated with abnormalities in both motor and sensory function, and the presence of myofascial trigger points (MTrPs – hyperirritable spot/nodules within a taut band of skeletal muscle, patient pain recognition and painful limitation in ROM [note twitch response and predicted pain referral pattern are no longer required]). Because these conditions are clinically similar, MPS is commonly misdiagnosed as FM. Misdiagnosis is largely attributed to similarities in clinical presentation between MTrPs and TPs, a lack of reliable laboratory tests and the potential co-morbidity of FM with MPS. The overlapping lexicon used to describe the clinical manifestation and diagnostic criteria for these conditions may also be a significant source of confusion.
The purpose of this scoping review was to determine the current lexicon of diagnostic criteria used to diagnose FM and MPS in published studies. The authors further aimed to identify any potential inconsistencies in diagnostic terminology to contribute to the development of a standardized vocabulary for the diagnosis of FM and MPS, which would hopefully promote consistency across both clinical and research settings…LOG IN OR SUBSCRIBE TO ACCESS THIS REVIEW!
“Fibromyalgia & Myofascial Pain Syndrome – Comparison of Diagnostic Criteria”
This paper was published in Musculoskeletal Care (2019) and this Review is posted in Recent Reviews, Trigger Points, Pain - Chronic Pain and the 2019 Archive.
Exerpt from Conclusion:

Generally speaking, a wider range of diagnostic criteria was used for the diagnosis of myofascial pain syndrome (MPS) in the literature compared to fibromyalgia (FM). This may partly explain the lack of reliability pertaining to the diagnosis of MPS. MTrPs are generally seen as the defining characteristic of MPS; however, there is currently no gold standard (ex. EMG, ultrasound, biomarkers etc.) for identifying MTrPs other than palpation of a tender spot/nodule in a taut band, patient pain recognition and painful limitation in range of motion. In addition, MTrPs are clinically associated with a wider range of medical conditions. Therefore, the identification of MTrPs cannot be assumed to be consistent across practitioners (evidence for reproducibility of MTrPs identification via palpation is moderate at best) or to be specific to MPS. In contrast, the criteria for the diagnosis of FM are more widely known and accepted due to extensive study and acceptable reliability.