University Center of João Pessoa, João Pessoa PB, Brazil.
Clinics (Sao Paulo). 2013 Jul;68(7):901-8. doi: 10.6061/clinics/2013(07)03.
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.
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.
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.
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.
本研究旨在识别月经周期不同阶段的正常月经妇女和口服避孕药使用者的神经阈值变化。
进行了一项观察性研究，包括 56 名志愿者，其中 30 名正常月经妇女未服用口服避孕药，26 名服用口服避孕药。使用电刺激器评估他们的神经阈值，以固定频率 2500 Hz 施加脉冲，以 50 Hz 调制，相位变化为 20 μs、50 μs 和 100 μs。在五个月经周期阶段评估敏感性、运动和疼痛阈值：阶段 1-月经，阶段 2-卵泡，阶段 3-排卵，阶段 4-黄体和阶段 5-经前期。
结果表明，未服用口服避孕药的妇女在第 5 阶段的 100 μs 有较低的敏感性阈值，服用口服避孕药的妇女为 50 μs。未服用口服避孕药的妇女在第 5 阶段观察到 20 μs、50 μs 和 100 μs 的低运动阈值，而服用口服避孕药的妇女的运动阈值为 100 μs。最后，仅在口服避孕药组中观察到第 5 阶段的低疼痛阈值为 100 μs。
无论是否使用口服避孕药，神经阈值在月经周期的各个阶段都会系统地变化。在对女性进行研究时，应考虑这些变化。
