Effects of 8-weeks acupuncture on eyes-closed resting state natural EEG frequency components in endometriosis: AcuENDO trial sub-study

Objective: The aim of this study was to examine changes in resting electroencephalography (EEG) activity associated with an 8-week acupuncture intervention for women with endometriosis and chronic pelvic pain. Methods: Eighteen women aged 18–45 years with laparoscopic diagnosis of endometriosis completed this study. The treatment group (n = 13) received 16 acupuncture sessions over eight weeks, administered in 45-min sessions twice weekly. Self-reported daily pain ratings and eyes-closed resting state EEG were obtained pre- and post-intervention (T1, T2). The control group was insufficient and omitted. Frequency principal components analysis (fPCA) was used to decompose EEG data for each timepoint. Results: Four fPCA component pairs showed suitable correspondence between T1 and T2: Alpha-II (9 Hz), alpha-III/IV (~10–11 Hz), beta-I (19 Hz), and beta-II (~26 Hz). From T1 to T2, global alpha-II amplitude increased, peak alpha-III/IV frequency increased and amplitude decreased, whilst beta-I amplitude decreased. The relative alpha-III/IV amplitude reduction was associated with the relative reduction in pain severity scores. Conclusions: Changes in alpha-III/IV peak frequency and amplitude, and the relationship with chronic pelvic pain suggest that ~10–11.5 Hz alpha may index pain severity in women with endometriosis. However, the potential acupuncture-related modulation of alpha could not be determined due to the lack of a suitable control group. Significance: Resting state EEG may be a viable tool to further characterise changes in chronic pain states in a clinical setting and provide objective quantification of responsivity to treatment. Further research with an appropriate control group is recommended to test this.