What is myofascial pain syndrome?

What is Myofascial Pain Syndrome?

Myofascial pain syndrome (MPS) is a regional musculoskeletal pain disorder characterized by the presence of myofascial trigger points (TrPs) within taut bands of skeletal muscle and fascia, causing both localized and referred pain patterns. 1, 2

Clinical Definition and Prevalence

MPS represents one of the most common causes of chronic pain, affecting 30-93% of patients presenting to medical clinics with pain complaints, and up to 85% of adults during their lifetime 1, 3, 4. This wide prevalence range reflects the lack of uniformly accepted diagnostic criteria across specialties.

The condition is primarily a nociceptive pain disorder driven by peripheral input from trigger points, though it frequently coexists with or is secondary to other chronic pain conditions including bladder pain syndrome, endometriosis, fibromyalgia, and anxiety 4, 5.

Pathophysiology

The most comprehensive current theory is the expanded integrated hypothesis, which explains MPS as arising from:

• Mechanical overload (acute strain, repetitive movements, sustained abnormal postures)
• Development of localized taut bands within muscle fibers
• Formation of hypersensitive trigger points that generate both local and referred pain through central nervous system mechanisms 6, 7

A paradigm shift is emerging: Rather than viewing MPS purely as pathological dysfunction, recent evidence suggests it may represent a physiological protective response 6. The trigger point-taut band complex potentially serves dual protective functions by:

• Limiting harmful movements through sensitization mechanisms
• Enhancing joint stability by increasing muscle fiber tension and proprioceptive input

Diagnostic Criteria

Physical examination remains the primary diagnostic method, as there are no specific laboratory markers or imaging findings 2, 3. The generally accepted diagnostic criteria include:

1. Presence of palpable trigger points within taut muscle bands
2. Pain upon palpation of the trigger point
3. Referred pain pattern (cardinal sign indicating central nervous system involvement)
4. Local twitch response when the trigger point is stimulated
5. Restricted range of motion in the affected muscle 3, 7

Critical caveat: The Diagnostic Criteria for Temporomandibular Disorders are the most widely accepted guidelines for masticatory MPS, but their diagnostic capability is limited 7. No consensus exists on the optimal method for trigger point diagnosis or pain quantification 2, 7.

Clinical Presentation

MPS can present acutely or chronically and may exist independently or coexist with other musculoskeletal conditions 1. Pain patterns are well-characterized and can refer to:

• Eyebrows, ears, temporomandibular joints
• Maxillary sinus, tongue, hard palate
• Distant musculoskeletal regions depending on affected muscle groups 7

Important pitfall: MPS can mimic odontogenic pain and other dental conditions, leading to misdiagnosis and inappropriate treatment, including unnecessary endodontic procedures 7.

Treatment Approach

Management requires a multimodal strategy addressing both peripheral trigger points and any underlying central sensitization 6, 1, 2. The treatment hierarchy should include:

First-Line Interventions:

• Manual physical therapy with myofascial release techniques to resolve trigger points, lengthen muscle contractures, and release connective tissue restrictions 8, 9
• Trigger point injections with local anesthetics (with or without corticosteroids) 10, 1
• Exercise therapy focused on low-resistance strengthening to improve joint stability and muscle tone 11

Adjunctive Therapies:

• Pharmacologic options: NSAIDs, muscle relaxants, tricyclic antidepressants, SNRIs, anticonvulsants (gabapentin, pregabalin) 12, 13
• Topical agents: Lidocaine, capsaicin for localized pain 12
• Physical modalities: Heat, cold packs, massage, TENS 12, 14
• Botulinum toxin: May be considered for piriformis syndrome but should not be used routinely for general myofascial pain 14

Uncertain Benefit (Use Selectively):

• Acupuncture and dry needling 15
• Manual soft tissue techniques beyond myofascial release 15

Critical management principle: When MPS coexists with predominantly nociplastic pain conditions (e.g., fibromyalgia), address the central pain problem as the primary treatment goal while not ignoring the peripheral trigger point contribution, as TrP treatment can reduce sensitization-associated symptoms 5.

Avoid These Approaches:

• Pelvic floor strengthening exercises (Kegels) when pelvic floor tenderness is present—these worsen symptoms 9
• Routine use of sympathetic nerve blocks for non-CRPS neuropathic pain 14

Prognosis and Long-term Management

MPS has overarching effects on quality of life, physical and social functioning, emotional well-being, and healthcare costs 4. The condition remains challenging to treat due to incomplete understanding of its pathophysiology 3, 4.

The emerging protective response framework 6 suggests incorporating strategies that go beyond simple trigger point inactivation:

• Load modulation and functional training
• Addressing both peripheral and central sensitization
• Comprehensive multilevel treatment protocols

This approach may achieve more durable therapeutic outcomes and reduce pain-related disability associated with MPS 6.