Myofascial pain syndrome (MPS) is a common cause of chronic musculoskeletal pain characterized by myofascial trigger points and fascial constrictions. MPS often occurs in conjunction with other conditions and can be overlooked, leading to misdiagnosis and inappropriate treatment.
There is currently no consensus on the etiology and diagnostic criteria for Myofascial pain syndrome. This has motivated the Chinese Association for the Study of Pain to develop an expert consensus to standardize the diagnosis and management of MPS in clinical practice.
Methods
The expert consensus was formulated based on a review of relevant domestic and international literature on MPS. The literature search focused on research related to the definition, epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of Myofascial pain syndrome.
The key findings from the literature were analyzed by a panel of medical experts to develop evidence-based recommendations.
Definition and Epidemiology
MPS is defined as recurring pain in muscles, fascia or related tissues that may be accompanied by emotional disorders or dysfunction. Myofascial pain syndrome is estimated to occur in 30-93% of patients with musculoskeletal pain. The most common sites are the neck, shoulders, and back.
Pathogenesis
Integrated Hypothesis
The integrated hypothesis proposed by Mense and Gerwin provides a unifying explanation for the development of myofascial trigger points and pain in Myofascial pain syndrome. It posits that excessive acetylcholine release at the neuromuscular junction leads to sustained contracture of muscle fibers.
This persistent activation depletes ATP and causes localized hypoxia and ischemia. The resulting biochemical milieu triggers release of inflammatory mediators and sensitized nociceptors, creating a pain stimulus. Substance P, CGRP, bradykinin, serotonin, and proton buildup activate and sensitize muscle nociceptors. The integrated hypothesis accounts for the main clinical features of MPS, including local and referred pain, twitch response, and muscle stiffness.
Fascial Pathology
Fascial pathology provides an alternative model, positing that collagenous changes and fibrosis in muscular fascia contribute to the pain and dysfunction of Myofascial pain syndrome. Fibroblasts interact with the extracellular matrix and may promote adhesive crosslinking between collagen fibers in response to tissue injury or mechanical strain.
This alters fascial mobility and viscosity, which could potentially irritate fascial nociceptors directly or affect muscle mechanics in a way that generates pain. Restrictions identified clinically at fascial interfaces may arise from these pathological fibrous changes, though definitive evidence is still lacking. Youthful, healthy fascia exhibits free gliding between layers, which appears disturbed in MPS.
Central Sensitization
Central sensitization has been demonstrated in MPS, manifesting as expanded referred pain zones, allodynia, and temporal summation to repeated stimuli. Enhanced nociceptive input from muscle and fascia results in hyperexcitability of dorsal horn neurons via activation of NMDA and metabotropic glutamate receptors.
Loss of inhibitory interneuron function also contributes. This central amplification helps explain the spread and persistence of pain beyond the initial peripheral insult. Reduced descending inhibition from periaqueductal gray and rostroventral medulla may further disinhibit spinal transmission.
Other factors
Other factors probably contribute in a subset of MPS patients. Spinal cord neuromodulation from dorsal root reflexes may be involved. Small fiber neuropathy has been observed in some cases. Positional nerve compromise or mechanical neural provocation could play a role.
Genome-wide association studies have linked HLA markers to chronic muscle pain. Much remains to be elucidated regarding contributors to MPS pathophysiology and how they interrelate. An integrated perspective incorporating neural, fascial, and psychosocial components will be needed.
Clinical Manifestations
- Pain (aching, burning, stabbing, numbness) that is induced by cold, fatigue, or muscle overload and relieved by heat or mild activity
- Stiffness, weakness, reduced muscle endurance and coordination
- Referred pain and tenderness at myofascial trigger points
- Local twitch response at trigger points
- Restricted range of motion
- Autonomic features like sweating, pallor, and hair changes
Diagnostic Criteria
- Relevant medical history and precipitating factors
- Characteristic symptoms (pain, stiffness, limited mobility)
- Signs on examination including restricted movement, trigger points, and local tenderness
- Imaging and electromyography may assist diagnosis
Treatment Recommendations
- Patient education on causes, management, and prognosis
- Identification and elimination of contributing factors
- Physical therapy including stretching, massage, and thermal modalities
- Pharmacological therapy with NSAIDs, muscle relaxants, antidepressants
- Trigger point needling and injection techniques
- Pulsed radiofrequency treatment
- Psychological counseling and pain management education
Conclusion
MPS is a common cause of musculoskeletal pain that is often under-recognized. This Chinese expert consensus provides evidence-based recommendations on the diagnosis and management of Myofascial pain syndrome to guide clinical practice. Key highlights include the role of physical examination in diagnosis, multimodal treatment approaches, and need to address psychosocial factors. Further research is needed to better understand MPS pathophysiology and refine diagnostic criteria.
Discussion
This expert consensus provides a comprehensive overview of the current state of knowledge on MPS and offers practical clinical recommendations based on evidence appraisal. The diagnostic criteria emphasize detailed history and physical examination, which reflects the lack of definitive laboratory or imaging findings for Myofascial pain syndrome.
The treatment guidelines highlight the benefits of a multifaceted approach utilizing pharmacological, physical, psychological and procedural interventions.
The consensus reflects continued uncertainty about MPS pathogenesis. The hypotheses around fascial pathology and central sensitization mechanisms need further exploration. There is also a need to validate the proposed diagnostic criteria through additional research. Longitudinal studies evaluating treatment outcomes would help refine best practices.
The consensus represents an important step toward improving recognition and management of this common pain disorder in China. Additional expert perspectives from other regions could provide valuable insights into any geographic variations in MPS patterns and practices.
The article mentions there is no consensus on the underlying causes of MPS. What theories seem most promising in explaining the pathogenesis? Are there any emerging hypotheses not discussed in the article?
The integrated hypothesis proposed by Mense and Gerwin provides a compelling explanation for MPS pathogenesis involving acetylcholine upregulation at motor endplates, muscle ischemia, release of algesic substances, and central sensitization. Emerging research implicates fascial fibrosis, mechanotransduction, spinal cord neuromodulation, and genetic factors, but more work is needed to integrate these into cohesive models.
Advanced neuroimaging and biochemical analyses in MPS patients could elucidate pathogenic mechanisms.
The diagnostic criteria rely heavily on physical examination due to the lack of definitive laboratory or imaging findings. What novel techniques or biomarkers show potential for improving MPS diagnosis in the future?
Ultrasound elastography and shear wave imaging show promise for characterizing altered tissue stiffness and fascial fibrosis in MPS. High-resolution MRI and PET scanning may identify unique signatures of muscle ischemia and inflammation. Biomarker analysis could screen for proteomic, genomic, and metabolic profiles associated with MPS.
Novel electrodiagnostic techniques like surface EMG arrays and electrical impedance myography may aid MPS diagnosis. These technologies require further validation to determine clinical utility.
The treatment recommendations cover a wide range of modalities but evidence quality is not discussed. What approaches have the strongest evidence so far in treating MPS? What types of comparative effectiveness studies would help identify optimal treatment algorithms?
Active trigger point needling has the strongest evidence thus far, however quality data on modalities like massage, fascial manipulation, dry needling, and pulsed radiofrequency is lacking.
Large RCTs comparing single vs multimodal approaches over both short and long-term timeframes are needed. Cost-effectiveness research could help refine optimal sequencing or selection of therapies. Responder analyses may identify predictive factors to personalize MPS treatment.
The article focuses on expert consensus in China. How might diagnostic patterns, management practices, and access to therapies differ in other countries and settings? What implications might this have for generalizing the recommendations globally?
Care delivery models, provider training, access to interventional modalities, and cultural factors likely differ widely between China and Western countries. The generalizability of the diagnostic and therapeutic recommendations would need to be verified through studies in other geographic and practice settings. Adaptation may be required based on available resources, knowledge, and patient preferences in a given context.
The consensus highlights the need for patient education and addressing psychosocial factors. What programs or models have proven most effective for MPS patient education and counseling? How might we better integrate these with interventional approaches?
Cognitive-behavioral therapy and mindfulness-based stress reduction have shown efficacy for improving coping, catastrophizing, and disability in Myofascial pain syndrome patients. Web-based education platforms and self-care apps may enhance accessibility and engagement.
Strategies are needed to optimally integrate psychosocial approaches with physical therapy and medical treatments. Stepped care models could provide algorithms to match intensity of behavioral interventions to patient needs.
Are there any patient subgroups, comorbidities, or risk factors that require special diagnostic or treatment considerations for MPS? How might the approach need to be tailored for certain populations?
Myofascial pain syndrome symptoms may be more severe in the context of cervical spinal pathology, fibromyalgia, or headache disorders. Elderly and sedentary populations are at higher risk. Patients with hypersomnia or severe depression may require adjusted treatment timelines and monitoring.
Future studies should examine tailored diagnostic and treatment algorithms for high-risk or complex MPS patient subgroups.
What obstacles have hindered past MPS research and how can we advance understanding of this disorder? What types of studies or infrastructure would be needed to make breakthroughs?
Challenges in MPS research include heterogeneity of musculoskeletal disorders, lack of specific diagnostic criteria, and difficulty isolating treatment effects. Large, multi-site studies with centralized coordination could obtain generalizable data. Longitudinal observational cohorts could track natural history.
Leveraging integrated health systems could allow high-quality comparative effectiveness research. Genomic and proteomic analyses require substantial biobanking infrastructure and computational power.
Beyond pain relief and function, how should outcomes be measured to capture overall efficacy and patient experience? What patient-centered outcomes merit more attention in MPS research?
In addition to pain and function, validated patient-reported outcomes like quality of life, emotional well-being, fatigue, sleep quality, and satisfaction with care should be captured.
Novel mobile health technologies can provide more continuous real-world data on physical activity, social participation, and treatment adherence. Patient input is critical when designing clinical trials and practice guidelines to ensure relevance to those living with MPS.
MD, PhD. Physical Medicine & Rehabilitation Physician from São Paulo - Brazil. Pain Fellowship in University of São Paulo.