People with musculoskeletal shoulder pain demonstrate no signs of altered pain processing

Abstract

[eng] Background: Central sensitization may contribute to persistent musculoskeletal shoulder pain. Few studies have provided a comprehensive sensory and psychosocial evaluation of this population. Objective: To comprehensively assess whether sensory function and psychosocial aspects are impaired in people with shoulder pain and whether age, gender, and clinical outcomes are related to impaired sensory function. Study design: Observational case-control study. Methods: Twenty-three participants with musculoskeletal shoulder pain and 23 age- and gender-matched healthy participants were included. Static (pressure and thermal pain thresholds) and dynamic (temporal summation) quantitative sensory testing were performed bilaterally at the shoulder and remote tibialis anterior muscle. Conditioned pain modulation was measured at the affected/matched shoulder. Shoulder function (SPADI), depression, anxiety and stress (DASS-21), and health-related quality of life (EQ-5D-5L) were also measured. Comparisons were performed between body regions and groups. Age and gender were included as factors in analyses. Clinical outcomes were tested for correlation with sensory measures. Results: Shoulder pain group had higher local pressure pain threshold (i.e., hypoalgesia; p=0.03; Z=0-5.04), higher SPADI score (p < 0.01; Z=−5.76) and higher EQ-5D-5L (p < 0.01; Z=5.23) compared to the control group. There was no difference between groups for thermal pain sensitivity, dynamic sensory testing or psychological measures. Conclusion: People with shoulder pain demonstrated mechanical hypoalgesia, increased upper limb disability, and poorer quality of life compared with healthy controls. Central sensitization seems not be a characteristic of musculoskeletal shoulder pain although it could be present in a subgroup of patients.