Evaluation of sensitivity, motor and pain thresholds across the menstrual cycle through medium-frequency transcutaneous electrical nerve stimulation

Abstract

OBJECTIVES:The aim of this study was to identify variations in nervous thresholds in different phases of the menstrual cycle in eumenorrheic women and users of oral contraceptives.METHOD:An observational study was performed including 56 volunteers, consisting of 30 eumenorrheic women who were non-users of oral contraceptives and 26 users of oral contraceptives. An electrical stimulator was employed to assess their nervous thresholds, with pulses applied at a fixed frequency of 2,500 Hz, modulated at 50 Hz, with phase variances of 20 μs, 50 μs and 100 μs. Sensitivity, motor and pain thresholds were evaluated during five menstrual cycle phases: phase 1 - menstrual, phase 2 - follicular, phase 3 - ovulatory, phase 4 - luteal and phase 5 - premenstrual.RESULTS:The results indicated low sensitivity thresholds of 100 μs for non-users of oral contraceptives and 50 μs for oral contraceptive users in phase 5. Low motor thresholds of 20 μs, 50 μs and 100 μs were observed for non-users of oral contraceptives in phase 5, while that of oral contraceptive users was 100 μs. Finally, a low pain threshold of 100 μs was observed in phase 5, but only in the oral contraceptive group.CONCLUSION:Nervous thresholds vary systematically across the phases of the menstrual cycle, with or without the use of oral contraceptives. These variations should be taken into account during research performed in women.

Sex and the migraine brain

“…The complexity of the interaction of gonadal hormones and pain processing (103) is illustrated by studies that show that oscillations in hormonal levels during the 5 phases of the menstrual cycle (menstrual, follicular, ovulatory, luteal, and premenstrual) influence experimental sensitivity to thermal pain (126) in healthy women (see Figure 6) and to experimental muscle pain in women with dysmenorrhea (127). Other studies that show that changes in pressure, electrical, and cold pain thresholds, which occur over the menstrual cycle with higher thresholds to pressure and electrical pain stimuli on day 22 and to cold on day 14, are not correlated with changes in gonadal hormones (128).…”

EEG alpha activity increased in response to transcutaneous electrical nervous stimulation in young healthy subjects but not in the healthy elderly

“…The influence of the menstrual cycle and using oral contraceptives on the EEG alpha activity was investigated in relation to hormonal changes. Some studies demonstrated that menstrual cycle and use of the oral contraceptives could effect the nervous thresholds of women (Barbosa, Guirro & Nunes, 2013;Brötzner et al, 2014;Bazanova, Nikolenko & Barry, 2017). One of the limitations of the present study is that the menstrual cycle of the young female subjects was not evaluated.…”

Inter- and Intra-Examiner Reliability Study of Two-Point Discrimination Test (TPD) and Two-Point Estimation Task (TPE) in the Sacral Area of Pain-Free Individuals

“…Considering that the study only included healthy women and healthy men, a certain limitation of the study was the lack of taking into account the phase of the cycle among the studied group of women. As is known, in the second phase of the cycle, water is retained in the female body, including subcutaneous tissue, which changes the conditions for the sensitivity of the sense of touch [49,50]. In the second phase of the cycle, tactile hyperesthesia temporarily occurs.…”