A Biopsychosocial Model-Based Clinical Approach in Myofascial Pain Syndrome: A Narrative Review

Myofascial pain syndrome (MPS) is one of the most prevalent chronic musculoskeletal pain conditions, affecting between 13.5% and 47% of the world's population. This narrative review examines how the biopsychosocial model can revolutionize the therapeutic approach to this complex condition, integrating biological, psychological, and social factors into diagnosis and treatment. MPS is characterized by the presence of trigger points, which are taut, hypersensitive muscle bands capable of generating local and referred pain, restricted movement, and muscle weakness. Prevalence varies significantly, reaching 30-93% among patients with musculoskeletal pain and as high as 85% in older adults.

The pathophysiology of MPS involves the 'integrated hypothesis' of Mense and Simons, which proposes an abnormal increase in acetylcholine production at the neuromuscular junction. Muscle injuries, repetitive movements, poor posture, and stress amplify this mechanism, leading to increased motor end-plate activity, continuous calcium release, and sustained sarcomere shortening. This vicious cycle results in decreased muscle blood flow, tissue hypoxia, accumulation of metabolic byproducts, and local inflammation. The biopsychosocial model, proposed by Engel and Romano in 1977, demonstrates how biological factors interact with psychological and social aspects in the perpetuation of pain.

Studies reveal a strong correlation between genetic predisposition, polymorphisms in genes related to pain perception, hormonal differences between sexes, and pain sensitivity. Psychological factors such as depression, anxiety, stress, and catastrophizing activate brain regions associated with the emotional processing of pain, including the bilateral amygdala, orbitofrontal cortex, and hippocampus. Social isolation, low socioeconomic status, and insomnia also contribute to trigger point activation by reducing the descending pain modulatory system. Diagnosis is based on detailed physical examination, identifying palpable taut bands, local hypersensitivity, referred pain patterns, and the 'jump sign' — a characteristic behavioral response to pressure on the trigger point.

Clinical management integrates myofascial release techniques, ischemic compression, and dry needling with a pharmacologic approach including muscle relaxants, antidepressants, and anti-inflammatory drugs. Myofascial release applies prolonged pressure (120-300 seconds) directly or indirectly to restricted fascial layers, promoting changes in blood flow and removal of inflammatory mediators. Dry needling induces local mechanical depolarization, automatic contraction (twitch effect), and subsequent relaxation of muscle fibers. Treatment of psychosocial aspects includes management of depression with tricyclic antidepressants or selective serotonin reuptake inhibitors, cognitive restructuring techniques to modify pain perception, social skills training, and problem-solving strategies.

Meditation contributes to mental relaxation, reduced cortisol levels, and activation of brain areas responsible for emotional regulation. Physical exercise increases muscle blood flow, facilitates the diffusion of pro-inflammatory markers, and provides essential metabolic resources for trigger point deactivation. The review proposes a holistic clinical protocol that considers mechanical stressors, nutritional deficiencies, biopsychosocial factors, and metabolic and endocrine inadequacies during evaluation. Personalized treatment, based on each patient's individual needs and grounded in the biopsychosocial model, demonstrates greater efficacy in improving function and quality of life.

Limitations include the heterogeneity of diagnostic criteria and the need for more randomized controlled studies to validate the proposed interventions.