Perfil eletrofisiológico das ondas cerebrais de mulheres com fibromialgia : estudo transversal caso-controle

Abstract

Fibromyalgia (FM) is a syndrome characterized by chronic diffuse musculoskeletal pain associated with psychosomatic disorders, having hyperexcitability of neural circuits (central sensitization) as the main pathophysiological hypothesis. Electroencephalography is a technique for direct measurement of neural activity through electrical oscillations, which detects brain dysfunctions, including those related to pain. However, few studies investigate these mechanisms in FM patients. Thus, the aim of the study was to investigate the electrophysiological profile of brain waves in women diagnosed with fibromyalgia. In this cross-sectional observational case-control study, 40 volunteers were allocated into two groups: fibromyalgia group (n=20) and control group (n=20). After evaluating the fulfillment of the inclusion and exclusion criteria for the groups and answering the socioeconomic and clinical questionnaires, volunteers were assessed using an electroencephalogram and event-related potential in the P300 hearing component. The electrophysiological analysis showed that FM patients showed a greater relative amplitude of alpha waves (8-12 Hz) in the anterior brain quadrants, right and left (p ≤ 0.05), and lower amplitudes of beta 3 waves (24-30 Hz) in the right anterior quadrant (p ≤ 0.05). When analyzing the electrodes individually, greater alpha amplitudes were observed in the electrodes F7, F4, F8 and T4 (p ≤ 0.05), beta 1 (12-18Hz) in Fp2, F3, Fz, F4, F8, Cz, C4, Pz, P4 and T6 (p ≤ 0.05), and lower beta 3 and gamma amplitudes (> 30 Hz) at the electrode of the frontal region F4 (p ≤ 0.05). P300 amplitudes were reduced in the Fz, Cz and Pz electrodes (p ≤ 0.001) in FM subjects when compared to healthy women. In FM group, there was also an increase in the latency of the peak P200 (p ≤ 0.05) and N200 (p ≤ 0.01) in the parietal region Pz. Changes in brain activity for high frequency waves such as alpha and beta have already been reported in the literature in the involvement in several painful pathologies and it seems that this is also the case for FM. Reduced P300 potentials in the frontal, central and parietal regions, and increased latencies in the parietal region may reflect on the dysfunctional cognitive character experienced by patients with the syndrome. The predilection for the right hemisphere and anterior cerebral region evidenced in this work may represent a modification of the allostatic reference produced by the chronicity of the painful sensation produced by maladaptive nociplastic changes.