Caracterização clínica, comportamental, sensorial e eletrofisiológica de crianças e adolescentes com dor reumatológica crônica: estudo transversal comparativo

Abstract

Rheumatic conditions comprise a diverse group of diseases that predominantly affect the joints, but also muscles, bones, connective tissues, and internal organs, arising from immune-mediated, inflammatory, infectious, or degenerative mechanisms, characterized by a prolonged, painful, and function-limiting course, and which also affect children and adolescents. Among pediatric rheumatic conditions, juvenile idiopathic arthritis (JIA), of inflammatory and autoimmune nature, and juvenile fibromyalgia syndrome (JFS), of non-inflammatory nature and associated with central sensitization mechanisms, potentially involving cognitive, autonomic, and sensory dysfunction, stand out. In this context, electroencephalography (EEG) stands out as a tool for objectively characterizing the neurological processes underlying pediatric chronic pain. However, studies detailing the physiological mechanisms involved in JFS and JIA remain scarce. Objective: To characterize the clinical, behavioral, sensory, and electrophysiological profile of children and adolescents with chronic rheumatic pain resulting from juvenile fibromyalgia syndrome or juvenile idiopathic arthritis, compared with a healthy control group matched by sex and age range. Materials and Methods: This was an analytical, observational, cross-sectional study including children and adolescents of both sexes, aged 7 to 18 years, allocated into two groups: a pain group (JFS and JIA) and a control group. The groups were assessed using socioeconomic questionnaires, pain intensity (11-point numerical rating scale), mechanical detection threshold (esthesiometry), electrophysiological profile (electroencephalogram), and cognitive profile (auditory P300 event-related potential). Results: The sample consisted of 54 participants, 27 in the pain group and 27 in the control group, stratified into children and adolescents (24 children and 30 adolescents). A mean diagnostic delay of 21.3 months was observed in children and 50.7 months in adolescents. Children in the pain group showed generalized mechanical hypersensitivity to light touch at a site distant from the affected joint (p=0.004; d=−1.297), and adolescents in the pain group showed greater pain sensitivity to mechanical pressure (p=0.013 and p=0.045) and greater self-reported pain intensity (p=0.001) compared with controls. No intergroup EEG differences were identified under the resting-state condition. During the P300 paradigm, adolescents in the pain group showed greater relative amplitude in the theta band and lower relative amplitude in the beta3 band in the right anterior and posterior regions compared with controls (p<0.05; d ranging from 0.94 to 1.41), a finding significant under the uncorrected primary criterion adopted in this exploratory study; in a Benjamini-Hochberg sensitivity analysis restricted to relative-amplitude variables and applied per age subgroup within each experimental condition (m=24), right posterior theta power remained significant (q=0.015). In children, a differentiated pattern of right posterior relative amplitude was observed during exposure to educational and recreational screen conditions. The topographic pain contrast between diagnoses was statistically significant for back pain, leg pain, and headache, all more frequent in JFS (FDR-adjusted p<0.01). Conclusion: In response to the overall objective, the electrophysiological profile of children and adolescents with JFS and JIA, compared with healthy controls, was characterized by the absence of EEG differences at rest and by specific alterations under active cognitive and sensory demand. Children and adolescents with JFS and JIA present measurable sensory alterations and specific electrophysiological changes during conditions of active cognitive and sensory demand, though not generalized to the resting state, consistent with early stages of central sensitization and pain-related cognitive interference. These findings reinforce the relevance of early diagnosis as a possible therapeutic window and point to the need for longitudinal studies investigating the progression of these alterations throughout development.