Musculoskeletal disorders and orofacial pain: a narrative review

Background and Objective: Musculoskeletal disorders comprise the largest subset of chronic pain conditions, contributing to great disability, lost productivity and increased utilization of healthcare services. Temporomandibular disorders (TMDs) are one of the most common chronic musculoskeletal disorders in the orofacial region. The term is inclusive of temporomandibular joint disorders (TMJDs) and masticatory muscle disorders (MMDs). The condition may occur in isolation affecting the components of the masticatory system locally, or it may be a component of multi -system condition. The objective of the article is to provide an overview of etiopathogenesis, risk factors, diagnosis and management of MMD and the global pain condition fibromyalgia. Methods: A search was conducted on indexed databases (PubMed, Embase, Ovid Medline, Cochrane, Web of Science, Scopus) using keywords temporomandibular disorder, myofascial pain, fibromyalgia from 1st January 1959-31st May 2021 and 476 relevant full text articles in English were analysed and included in the narrative review. Key Content and Findings: MMD and fibromyalgia are complex conditions with multiple risk factors and a the etiopathogenesis are yet to be completely elucidated. MMDs may involve multiple risk factors and currently it is suggested that multiple biopsychosocial factors interacting with genetic factors may act in cohort with environmental factors and enhance individual susceptibility to developing incident TMDs. Varying degrees of peripheral and central sensitization, upregulation of ascending pain pathways coupled with downregulation of descending modulatory pathways may be also be involved in their genesis. Various classification systems including International Classification of Orofacial Pain (ICOP), Diagnostic Criteria for TMD (DC-TMD), International Classification of Disease -11 (ICD-11) are currently in use. Conclusions: MMDs and fibromyalgia are complex conditions. First line management for MMD may include patient education, counselling, home care, risk factor and behavioral modification, pharmacotherapy, short term intra oral appliances, nerve blocks, trigger point injections, physiotherapy, and psychotherapy. Distinction of acute and chronic MMDs, localized vs. systemic forms degree of peripheral and central sensitization and preventing transition of acute to chronic MMD is crucial to management. Fibromyalgia is a global systemic disorder and management of MMDs in fibromyalgia is primarily palliative and multidisciplinary or interdisciplinary management may have enhanced success rates. Precision medicine may enhance success rates.