Redes cerebrais evocadas em mulheres com fibromialgia: estudo transversal caso-controle

Abstract

Fibromyalgia is a chronic painful syndrome with a complex relationship with several other pathologies. Among these associations, cognitive impairment is frequently reported, especially in its interaction with brain areas involved in pain processing. The construction of functional brain networks using graph theory, specifically time-varying graphs (TVG), has shown consistent results in various studies, enabling an understanding of the coordination and integration of neural units. However, until now, networks for evoked potentials have not been developed, which could allow the integration of different study techniques and provide a deeper understanding of the cognitive dynamics involved in activities such as this. The aim of this study was to analyze the neural bioelectric behavior by constructing functional brain networks from evoked potentials in populations of healthy women compared to women with a clinical diagnosis of fibromyalgia. In this cross-sectional case-control observational study, 70 volunteers were allocated into two groups: the fibromyalgia group (Fibro) (n = 46) and the control group (Ctrl) (n = 24). After the inclusion and exclusion criteria for the groups were evaluated, and the socioeconomic and clinical questionnaires were answered, the volunteers were assessed through electroencephalogram (EEG) during the application of the event-related potential (ERP) test in the auditory P300 component. After constructing the networks using time- varying graphs (TVG) and the motif synchronization method, two moments of the weighted networks for each subject were compared: a baseline moment, prior to the stimulus, considering the sum of the edges in the time interval between -100 and -50ms; and a response moment, after the stimulus, considering the sum of the occurrences of edges in the interval between 250ms and 400ms, corresponding to the P300 potential. Finally, indices were produced to evaluate the synchronization and robustness of brain activity during the ERP, as well as the connections within and across each side of the brain. The analysis showed a reduction in brain connectivity in the frontal region, also highlighting a decrease in connections between the hemispheres in this same area in the fibromyalgia group (Fibro), compared to the control group. When investigating the baseline network and the proposed network for P300, it was observed that the baseline network did not present edges, supporting the findings for the definition of a specific network for stimulus processing. The Ctrl network had 32 edges, while the Fibro group had only two. It is important to highlight that the edges found in the Fibro group did not appear in the Ctrl group, suggesting that these edges may be associated with the fibromyalgia syndrome. The results of this study emphasize that fibromyalgia is related to a decrease in the complexity of brain activity, reinforcing the idea that the syndrome is a complex phenomenon. This finding represents a significant advancement in the understanding of the neural interaction necessary for human cognitive processing.