EEG Beta functional connectivity decrease in the left amygdala correlates with the affective pain in fibromyalgia: A pilot study

Abstract

Fibromyalgia (FM) is a major chronic pain disease with prominent affective disturbances, and pain-associated changes in neurotransmitters activity and in brain connectivity. However, correlates of affective pain dimension lack. The primary goal of this correlational cross-sectional case-control pilot study was to find electrophysiological correlates of the affective pain component in FM. We examined the resting-state EEG spectral power and imaginary coherence in the beta (β) band (supposedly indexing the GABAergic neurotransmission) in 16 female patients with FM and 11 age-adjusted female controls. FM patients displayed lower functional connectivity in the High β (Hβ, 20–30 Hz) sub-band than controls (p = 0.039) in the left basolateral complex of the amygdala (p = 0.039) within the left mesiotemporal area, in particular, in correlation with a higher affective pain component level (r = 0.50, p = 0.049). Patients showed higher Low β (Lβ, 13–20 Hz) relative power than controls in the left prefrontal cortex (p = 0.001), correlated with ongoing pain intensity (r = 0.54, p = 0.032). For the first time, GABA-related connectivity changes correlated with the affective pain component are shown in the amygdala, a region highly involved in the affective regulation of pain. The β power increase in the prefrontal cortex could be compensatory to pain-related GABAergic dysfunction.

A systematic review of quantitative EEG findings in Long COVID, Fibromyalgia and Chronic Fatigue Syndrome

“…The high relative beta power was observed in frontal and central EEG measurement sites in Hargrove et al (2010), and generally across the scalp in López et al (2015). Makowka et al (2023)’s findings were limited to beta-1 and beta-2 sub-bands specifically in the left prefrontal cortex. One study found the opposite pattern, with FMS patients presenting with significantly decreased general beta activity compared to controls (Martín-Brufau et al, 2021).…”

“…No additional relevant articles were identified through manual searching. Eight of the selected studies compared resting-state EEG collected from healthy controls with a sample of FMS patients (González-Roldán et al, 2016; González-Villar et al, 2020; Hargrove et al, 2010; López et al, 2015; Makowka et al, 2023; Martín-Brufau et al, 2021; Vanneste et al, 2017; Villafaina et al, 2019), six involved CFS/ME patients (Billiot et al, 1997; Flor-Henry et al, 2009; Sherlin et al, 2007; Wu et al, 2016; Zinn and Jason, 2021; Zinn et al, 2018) and the remaining three studies focused on LC (Cecchetti et al, 2022; Kopańska et al, 2022; Ortelli et al, 2023). Table 1 shows a summary of the methodology and findings of the selected studies.…”

“…We first report the findings from studies on the spectral characteristics (frequency and power) of resting-state EEG signals. Ten of the selected studies reported results of spectral analysis of resting-state EEG signals: five in FMS (Hargrove et al, 2010; López et al, 2015; Makowka et al, 2023; Martín-Brufau et al, 2021; Villafaina et al, 2019), three in CFS/ME (Billiot et al, 1997; Flor-Henry et al, 2009; Wu et al, 2016) and two in LC (Cecchetti et al, 2022; Kopańska et al, 2022). The findings described in this section that map changes in each frequency band to broad brain regions are represented in Figure 2 (scalp map in the centre of each panel).…”

“…Villafaina et al (2019)’s study involving 31 females with FMS found significant differences only for alpha-2 power in electrodes located in central, temporoparietal and occipital regions. Regarding the higher-frequency EEG beta band, most studies in FMS reported a significant increase in beta power when compared to healthy controls (Hargrove et al, 2010; López et al, 2015; Makowka et al, 2023). The high relative beta power was observed in frontal and central EEG measurement sites in Hargrove et al (2010), and generally across the scalp in López et al (2015).…”

“…We outline the findings derived from functional connectivity analysis of resting-state EEG signals in this section, providing insights into network dynamics and functional interactions between brain regions. EEG functional connectivity was assessed in eight studies: six in FMS (González-Roldán et al,2016; González-Villar et al, 2020; Hargrove et al, 2010; Makowka et al, 2023; Martín-Brufau et al, 2021; Vanneste et al, 2017), one in CFS/ME (Zinn and Jason, 2021) and one in LC (Cecchetti et al, 2022).…”