Recognition of central nervous system sensitization and its risk factors in patients with unilateral musculoskeletal shoulder pain

Abstract

BACKGROUND: Overall, inferences from the majority of the literatures reviewed provide increasing evidence on the presence of central nervous system sensitization in unilateral shoulder pain. The possibility of presence of central sensitization (CS) among patients with unilateral musculoskeletal shoulder pain has not been adequately explored till date. The term “unilateral shoulder pain” in this study will be used to refer to nonneuropathic shoulder pain of different etiologies including rotator cuff pathology, adhesive capsulitis, or labral lesion. OBJECTIVES: The purpose of this study was to determine the presence of a subgroup of patients among patients with unilateral musculoskeletal shoulder pain and to further explore what extent the central nervous system sensitization correlates with other clinical measures. METHODS: Ninety-one patients with unilateral musculoskeletal shoulder pain participated in this cross-sectional study. Standardized outcome measures such as Central Sensitization Inventory-Gujarati (CSI-G) for the presence of CS, pressure pain threshold by pressure algometry, and Shoulder Pain and Disability Index for disability were administered as per standardized protocol. RESULTS: The results of the present study showed that 17 (18.7%) patients had CS. The CSI score had mild correlation with the demographic and clinical outcome measures and comorbidities such as gender (r = 0.208), duration of the condition (r = 0.208), hypertension (r = −0.238), sleep disturbance (r = −0.327), numbness (r = −0.238), and fatigue perception (r = −0.314) by the pain and disability score also had mild correlation with CSI score (P, 0.05). The risk ratio for sensitization was 2.40 for female gender, 3.07 for hypertension, 3.19 for sleep disturbance, 2.06 for numbness, and 3.87 for perceived fatigue in patients with unilateral musculoskeletal shoulder pain. CONCLUSION: The present study showed that the central nervous system becomes hypersensitive in a subgroup of patients and weakly related to factors such as female gender, chronicity of shoulder pain, hypertension, pain and disability, sleep disturbance, and perceived fatigue in patients with unilateral musculoskeletal shoulder pain.