The role of systemic and nervous system factors in patients with shoulder pain: a perspective review

BackgroundPersistent shoulder pain is often driven by inflammatory conditions, including tendinopathy, bursitis, and frozen shoulder. Treatment remains uncertain, but targeting underlying mechanisms like inflammation, metabolic factors, and nervous system disturbances may be more effective.ObjectiveThis perspective review summarizes these underlying mechanisms' roles in patients with inflammatory-driven shoulder pain and potential effective treatments for these mechanisms.ResultsLiterature links inflammatory-driven shoulder pain to low-grade inflammation, obesity, hypertension, diabetes mellitus, and/or autonomic and central nervous system disturbances, which are interconnected. Both acute and chronic inflammation are evident in tissue around the shoulder joint, potentially compromising treatment outcomes and predisposing tissue to hyperresponsiveness. Persistent inflammation can disrupt endocrine and nervous system functions, leading to additional health issues. Metabolic factors, characterized by low-grade inflammation, increase the risk for developing inflammatory-driven shoulder pain. Patients with inflammatory-driven shoulder pain often exhibit autonomic and somatosensory dysregulation. The autonomic nervous system's involvement in the inflammatory pathway can be influenced by or influence inflammation when dysregulation precedes shoulder pain development. Its pathways overlap with pain processing, potentially affecting each other. Prolonged stress (mental or biological) can lead to a maladaptive state and trigger somatosensory dysregulation. Interventions targeting these mechanisms go beyond the joint and include pain neuroscience education, exercise therapy, graded motor imagery, stress management, lifestyle interventions, and combinations of these. However, evidence specific to shoulder pain is limited.ConclusionFuture research should prioritize understanding these underlying mechanisms in patients with inflammatory-driven musculoskeletal shoulder pain and evaluating targeted interventions' effects on shoulder disabilities.