By: Chad E Cook, Damian Keter, Ken Learman
Background
Myofascial Pain Syndrome (MPS) is hypothesized to be both a primary and/or a secondary chronic pain disorder that can refer symptoms to other parts of the body. MPS is relatively common, affecting millions of people worldwide, particularly those who have experienced muscle overuse, trauma, or stress [1]. MPS can significantly impact daily activities and quality of life, as the persistent pain and discomfort can be both physically and emotionally draining [2]. Despite its notable impact on health and wellness, MPS is a controversial diagnosis that mainly stems from the lack of consensus on its diagnostic criteria and the underlying mechanisms. The objective of this blog is to identify whether MPS meets current criteria as a unique diagnosis, using the four criteria from the World Health Organization (WHO).
Diagnostic Criteria
Historically, the WHO, through its International Classification of Diseases (ICD) criteria, provides a global standard for diagnostic health data, facilitating international comparisons and collaborations in healthcare. For each unique diagnosis, the WHO requires four criteria [3]: 1) specificity, 2) consistency, 3) significance and 4) diagnostic stability. These criteria have allowed them to differentiate two competing conditions such as influenza and COVID-19, and have allowed them to recognize new diseases/syndromes such as E-Cigs and Vaping-Associated Lung Injury or Post-Traumatic Stress Disorder (PTSD) due to Complex Trauma in Childhood.
Specificity suggests that the condition must have a clear and specific set of symptoms and characteristics that distinguish it from other conditions. Consistency requires that the symptoms and characteristics should be reliably observed across different patients and settings. Significance involves its impact on the individual’s health, functioning, or quality of life. Diagnostic Stability suggests that the diagnosis should remain stable over time, meaning that the condition does not frequently change or evolve into another condition.
Based on the WHO criteria, is MPS a stand-alone, primary diagnosis? The answer is both “yes” and “no”.
According to the WHO, MPS refers to a musculoskeletal disorder characterized by pain originating from tight muscles and the surrounding fascia, often presenting as sensitive “trigger points” that can cause localized pain and referred pain to other areas of the body; this pain can be chronic and is often associated with repetitive motions, poor posture, or stress [4]. Under the ICD-11, MPS is classified under chronic primary pain and chronic secondary musculoskeletal pain. The criteria for chronic primary pain
include persistent or recurrent pain for at least three months, with significant emotional distress or functional disability. For chronic secondary musculoskeletal pain, the pain is associated with a musculoskeletal condition, which persists beyond the usual recovery period. Despite these descriptions from the WHO, neither of the two (for chronic primary and chronic secondary) meets all four of the original WHO criteria.
Truthfully, it is well understood that MPS does not have a clear, routine set of signs and symptoms that distinguishes it from other diagnoses (lacks specificity). This influences consistency as well. These are reasons it is difficult to differentiate MPS from other diagnostic conditions such as fibromyalgia, tension type headaches, and chronic fatigue syndrome. MPS is also traditionally categorized as a nociceptive pain condition, but there’s growing evidence suggesting it can also involve neuropathic or nociplastic pain components. Further, due to the lack of specific laboratory indicators and imaging evidence, there is no unified diagnostic criteria for MPS, adding to the confusion with other diseases [5].
Summary
Given the prevalence of MPS it is likely that most physical therapists and chiropractors see a high percentage of these individuals in their outpatient practices. As currently defined by ICD coding MPS is highly likely to contribute to patients’ pain experience as a secondary condition [6], which can be very debilitating to the individual [7]. This is likely why other global healthcare groups such as the International Association for the Study of Pain, support the contribution of MPS, which they characterize as local and referred pain perceived as deep, dull, pressure, and aching, along with the presence of myofascial trigger points in any part of the body [8]. As the complex nature of pain and associated pain conditions are further unraveled perhaps MPS will find a better home as a primary pain condition, however, currently, MPS may be difficult to differentiate from other conditions and is likely a secondary contributor to most musculoskeletal conditions seen by rehabilitation providers.
References
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2. Jaeger B. Myofascial trigger point pain. Alpha Omegan. 2013;106(1–2):14–22.
3. Hebert O, Schlueter K, Hornsby M, Van Gorder S, Snodgrass S, Cook C. The diagnostic credibility of second impact syndrome: A systematic literature review. J Sci Med Sport. 2016 Oct;19(10):789-94.
4. Qureshi N, Hamoud AA, Gazzaffi IMA. Myofascial Pain Syndrome: A Concise Update on Clinical, Diagnostic and Integrative and Alternative Therapeutic
Perspectives. International Neuropsychiatric Disease Journal. 2019 Mar; 13(1): 1-14
5. Cao QW, Peng BG, Wang L, Huang YQ, Jia DL, Jiang H, Lv Y, Liu XG, Liu RG, Li Y, Song T, Shen W, Yu LZ, Zheng YJ, Liu YQ, Huang D. Expert consensus on the diagnosis and treatment of myofascial pain syndrome. World J Clin Cases. 2021 Mar 26;9(9):2077-2089. doi: 10.12998/wjcc.v9.i9.2077.
6. Plaut S. Scoping review and interpretation of myofascial pain/fibromyalgia syndrome: An attempt to assemble a medical puzzle. PLoS One. 2022 Feb 16;17(2):e0263087.
7. Lam C, Francio VT, Gustafson K, Carroll M, York A, Chadwick AL. Myofascial pain – A major player in musculoskeletal pain. Best Pract Res Clin Rheumatol. 2024 Mar;38(1):101944.
8. International Association of the Study of Pain. Myofascial Pain: Fact Sheet 14. Downloaded December 27, 2024 at: https://www.iasp-pain.org/wp-content/uploads/2022/10/14.-Myofascial-Pain-Fact-Sheet-Revised-2017.pdf.
