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Papers of the Week


Papers: 20 Aug 2022 - 26 Aug 2022


Pharmacology/Drug Development


2022 Aug 03


Pain

Mechanisms of chronic pain in inflammatory rheumatism: the role of descending modulation.

Authors

Trouvin A-P, Simunek A, Coste J, Medkour T, Carvès S, Bouhassira D, Perrot S
Pain. 2022 Aug 03.
PMID: 35984362.

Abstract

Persistent pain despite satisfactory disease treatment is frequent in rheumatoid arthritis (RA) and spondyloarthritis (Spa) and may result from specific changes in central pain processing. We assessed these mechanisms further, by systematically comparing thermal pain thresholds and conditioned pain modulation (CPM) between patients with active RA or Spa and healthy controls.We included 50 RA and 50 Spa patients and 100 age- and sex-matched controls. Heat and cold pain thresholds (HPT-CPT) were measured on the dominant forearm, and CPM was assessed by applying conditioning stimuli (immersion in a cold water bath) to one foot and the non-dominant hand in two successive randomized sequences. Descending pain modulation was assessed as the difference in HPT (in °C) before and after conditioning. Larger HPT differences (i.e. a larger CPM effect) reflected more efficient descending inhibition. Potential associations between changes in CPM and clinical data, including disease activity, pain intensity, psychological and functional variables, were systematically assessed.HPT and CPT were similar in patients and controls. Mean CPM effect was significantly weaker in patients than controls for conditioning applied to either the foot (0.25°C ±2.57 vs. 2.79°C ±2.31; p<0.001) or the non-dominant hand (0.57°C ±2.74 vs. 2.68°C ±2.12; p<0.001).The smaller CPM effect in patients was correlated with average pain intensity, but not with disease activity or other clinical characteristics, suggesting a significant pathophysiological role for changes in endogenous pain modulation in the mechanisms of chronic pain associated with inflammatory rheumatism.