Myofascial Pain Syndrome: An Update on Clinical Characteristics, Etiopathogenesis, Diagnosis, and Treatment

Myofascial pain syndrome (MPS) is a chronic regional pain condition that affects millions of people worldwide, yet it remains poorly understood and frequently underdiagnosed. The condition is characterized by the presence of myofascial trigger points (MTrPs) — hyperirritable spots within taut bands of muscle fibers that produce both localized pain and characteristic referred pain patterns. Despite being recognized as a major cause of musculoskeletal pain, MPS lacks internationally validated diagnostic criteria, and its symptoms often overlap with other common pain disorders such as fibromyalgia, neuropathic pain, and joint disorders. This diagnostic confusion leads to delayed or inappropriate treatment, causing significant suffering and disability for affected individuals.

The prevalence of MPS varies considerably depending on the population studied, with estimates ranging from 15% in occupational settings to as high as 93% in specialized pain clinics. Among middle-aged adults, prevalence reaches 37% in men and 65% in women, with even higher rates in adults over 65 years. Given this substantial burden, there is an urgent need for clearer understanding of MPS risk factors, mechanisms, diagnosis, and evidence-based treatments.

This narrative review synthesizes current knowledge across multiple domains of MPS. The authors conducted a comprehensive literature review examining the prevalence and risk factors for MPS, proposed pathogenic mechanisms, current diagnostic approaches and their limitations, differential diagnosis from related conditions, and both pharmacological and non-pharmacological treatments. For the treatment section, they evaluated evidence from randomized controlled trials, systematic reviews, and meta-analyses, classifying interventions based on the strength of supporting evidence. The review covers muscle relaxants, antidepressants, anticonvulsants, analgesics including NSAIDs and topical agents, opioids, trigger point injections with local anesthetics and botulinum toxin, dry needling, acupuncture, and various physical modalities including TENS, magnetic stimulation, ultrasound, laser therapy, extracorporeal shock wave therapy, manual therapy, and kinesio taping.

The authors applied standardized effectiveness statements to categorize evidence levels for each intervention.

The review identified multiple categories of risk factors for MPS. Physical and mechanical factors include muscle overuse, poor posture, acute trauma, and postural imbalances such as forward head posture or scoliosis. Systemic and metabolic conditions — particularly vitamin D deficiency, hypothyroidism, and iron deficiency — contribute to MPS development. Psychological factors, especially chronic stress, anxiety, and depression, create cycles of muscle tension and pain sensitization.

Lifestyle factors including sedentary behavior, sleep disturbances, and oral parafunctional behaviors like teeth grinding also increase risk.

Regarding pathogenesis, the review presents six major hypothetical mechanisms: the Cinderella hypothesis describing metabolic overload in smaller motor units during sustained low-level contractions; neuromuscular junction dysfunction with excessive acetylcholine release; Simons' integrated trigger point hypothesis involving persistent contraction and inflammatory mediator release; central sensitization amplifying pain signals in the spinal cord; neurogenic inflammation promoting peripheral and central sensitization; and fascial densification altering muscle biomechanics.

For diagnosis, the Simons criteria from 1999 remain most commonly used but show inter-practitioner variability. Emerging objective measures including quantitative sensory testing, algometry, ultrasound, vibration elastography, various imaging modalities, and electromyography show promise but are not yet widely adopted.

Treatment evidence revealed clear hierarchies. Local anesthetic injections have sufficient evidence for pain relief and functional improvement compared to placebo and alternatives. Some evidence supports dry needling, acupuncture, magnetic stimulation, ultrasound, laser therapy, extracorporeal shock wave therapy, and manual therapy — particularly compared to sham or placebo. However, NSAIDs, diclofenac, botulinum toxin, and TENS showed insufficient evidence.

Muscle relaxants, antidepressants, gabapentin, opioids, topical lidocaine, capsaicin, EMLA cream, and kinesio taping had inconclusive evidence.

This review carries significant implications for both patients and clinicians. For patients with chronic musculoskeletal pain, it highlights the importance of seeking clinicians familiar with MTrP examination, as proper diagnosis can distinguish MPS from commonly confused conditions like fibromyalgia or neuropathic pain. The emphasis on multimodal, patient-centered care suggests that effective management typically requires combining several approaches rather than relying on single interventions.

For clinicians, the review provides a practical evidence hierarchy to guide treatment selection. Local anesthetic injections emerge as the most reliably evidenced intervention, while dry needling offers short-term pain relief but may be superseded by other treatments for sustained improvement. The limited evidence for commonly prescribed medications like NSAIDs and muscle relaxants challenges routine pharmacological approaches. The review also underscores the importance of addressing modifiable risk factors including posture, activity levels, sleep quality, and psychological stress as part of comprehensive management.

The identified gaps in evidence — particularly the lack of standardized diagnostic criteria and limited high-quality comparative effectiveness research — point to priorities for future investigation. The authors explicitly call for more rigorous trials to establish definitive recommendations, especially regarding optimal treatment combinations and long-term outcomes.