# Quantitative Electroencephalographic Analysis in Women with Migraine during the Luteal Phase
## 5 Discussion  
It has been reported that migraine is three times more frequent in women than in men of reproductive age. This fact is associated with the changes of hormonal mechanisms that occur in females throughout the menstrual cycle [35]. A specific phase of the menstrual cycle that is related to psychological, cognitive, and physical changes is the luteal phase. The symptoms and signs of this period are distinct and have been named pre-menstrual syndrome. During this period, a persistent headache of the migraine type that decreases after three days of menstruation has been reported [36]. The present study showed that women with no migraine presented the following relevant encephalographic characteristics during the luteal phase: alpha occurrence over the parieto-occipital area, a predominance of beta rhythm over the whole scalp, theta increase over the frontcentral and parietooccipital area, and an increase in delta for the temporal areas. Figure 5: Total averaged absolute power for delta, theta, alpha, and beta bands. The \({}^{\star}\) means a statistically significant difference (\(p<\) 0.05). In the case of women with migraine, we observed an increase in alpha in the frontocentral area and a reduction in alpha in occipitoparietal area. Few studies have been carried out in patients with migraine, and the results have not been very consistent. However, the first studies reported an increase in alpha rhythm variability in the headache-free phase [21; 22; 37; 38; 39; 40]. In our study, we observed a reduction in beta in all the considered cortical areas except the frontopolar leads. This result is in contrast with studies that reported an excess of beta activity during attacks [41], in migraine patients. [PERSON] [42], reported an excess of high-frequency beta activity (21-30 Hz) in all four cortical areas in a group of migraine patients in neurofeedback therapy in comparison with a group of patients using drug therapy. We also found a focal decrease in the theta band in the left central-parietal leads (C3 and P3) and a local delta decrease in the left temporal and right occipital leads (T3 and O2). Past research has also shown that individuals with chronic pain exhibit increased beta and decreased alpha activity, with additional increased theta/delta [43]. Much evidence suggests the involvement of delta oscillations during sustained pain as a reflex of autonomic processes linked to efforts of homeostatic processes [44]. However, our study is more specifically focused on a phase of the menstrual period that begins with pain and not the pain itself. [PERSON] et al. [45], suggested that EEG activity in migraine patients is related to a predisposition to painful or high-risk stimuli. In line with [PERSON] et al. [45], we observed power differences between the considered groups in the frontal channels (see Figure S1). Some authors suggest that migraine is related to a lack of habituation to environmental stimuli due to inadequate information processing [46]. Our study supports the suggestion that the differences in EEG patterns in women with migraine could be involved in pain related to migraine and the regulation of input processing. In other words, chronic pain can change the responsiveness of brain regulatory systems and the emotional processing of somatosensory information; this could be a reason why we found that in somatosensory areas such as C3 and C4, the delta and beta band were larger in the control group than the experimental group. This type of EEG pattern could be related to allostatic load, which also includes the participation of the hypothalamic-pituitary-gonadal axis and the negative feedback regulation of the endogenous opioid system during the release of luteinizing hormone. The cyclic surges of gonadal hormones may directly alter neuronal, glial, and astrocyte function throughout the brain [47]. The irregular EEG patterns found in our study could be used not only for diagnosis criteria, but also for the improvement of pharmacological and psychological therapeutic targets.