The overlapping roles of neuropathic and nociplastic pain in non-traumatic shoulder disorders: Implications for pain mechanisms and functional loss

Background: This study aims to investigate the prevalence of neuropathic pain in shoulder pain, its relationship with nociplastic pain, and the effects of both pain types on functional outcomes. Materials and Methods: Between May 2024 and December 2024, a total of 73 patients with non-traumatic shoulder pain persisting for more than three months were included in this multi-center, prospective, cross-sectional study. Participants were classified according to diagnoses of rotator cuff disorders, subacromial impingement, adhesive capsulitis, osteoarthritis, or calcific tendinitis. Assessments were performed using the Visual Analog Scale (VAS), the Short Form of the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS-SF), the Central Sensitization Inventory (CSI), and the Shoulder Pain and Disability Index (SPADI). Results: Of the patients, 28 were male and 45 were female with a mean age of 54.89±10.24 (range, 32 to 70) years. Neuropathic pain was present in 26% of patients, while 28.8% exhibited central sensitization (CS), indicating nociplastic pain. Patients with both neuropathic and nociplastic pain had significantly higher SPADI scores ( p < 0.05), indicating greater functional impairment. However, nociplastic pain alone was not significantly associated with disability. Patients with CS had higher VAS scores and longer symptom duration ( p < 0.05), indicating its role in pain chronicity. Conclusion: In non-traumatic shoulder disorders, neuropathic and nociplastic pain mechanisms overlap; however, their clinical impacts differ. Nociplastic pain increases pain perception, whereas neuropathic pain is more strongly associated with functional impairment. These findings highlight the importance of multidisciplinary treatment strategies that target both pain components rather than focusing solely on CS.