Functional and Neural Correlates Associated with Conditioned Pain Modulation in Patients with Chronic Knee Osteoarthritis Pain: A Cross-Sectional Study

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Simis, Marcel ; Pacheco-Barrios, Kevin ; Vasquez-Avila, Karen ; Rebello-Sanchez, Ingrid ; Parente, Joao ; Castelo-Branco, Luis ; Marduy, Anna ; de Melo, Paulo S. ; Imamura, Marta ; Battistella, Linamara ; Fregni, Felipe

• Document type: Journal article
• Source: LIFE-BASEL; v. 13, n. 8, p. 13-pg., 2023-08-01.

Abstract

In this study, we aimed to assess the factors that predict a dysfunctional conditioned pain modulation (CPM) in chronic knee OA. Methods: This is a cross-sectional analysis of patients with chronic knee OA from a prospective cohort study in Brazil (n = 85). We performed linear and logistic multivariate regression models using the purposeful selection approach to test the relationship between the CPM in both knees (average) as a dependent variable and demographics, clinical, and neurophysiological as independent variables. Results: A significant negative association between WOMAC pain scores and CPM (beta: 0.13) was found. This association was modified by the subjects' race, being stronger in the non-white subjects. In our logistic regression models, pain intensity indexed with the WOMAC pain scale remained a significant association with dichotomized CPM. Furthermore, a significant CPM association with balance, indexed with the Berg Balance score, was evidenced ( beta: 0.04). Neurophysiological variables showed a significant negative relationship with CPM, such as the relative power of delta oscillations in the frontal area ( beta: 3.11) and central area ( beta: 3.23). There was no significant relationship between CPM and the following domains: cognitive, emotion, sleep, opioid receptor polymorphisms, and intrinsic variables of OA disease. There was no association of CPM with TMS-indexed inhibitory markers. Conclusions: These results may indicate that less function of the pain descending inhibitory system in patients with OA is correlated with higher activity-related pain (WOMAC), less balance, and cortical plasticity especially with increased low-frequency (delta) brain oscillations. These associations seem modified by race. (AU)

• FAPESP's process: 17/12943-8 - Inhibitory deficit as a marker of neuroplasticity in rehabilitation
• Grantee: Felipe Fregni
• Support Opportunities: Research Projects - SPEC Program