The role of purity and frequency in the classification of perimenstrual headache

Among all menstruation-associated headaches, only menstrual migraine has classification criteria in the International Classification of Headache Disorders 3rd edition (ICHD-3). Other menstruation-associated headaches are not generally described. The ICHD-3 classifies menstrual migraine according to headache type, timing(on days -2 to +3 of menstruation), frequency (whether headache occurs in at least two out of three menstrual cycles), and purity(whether headache occurs at other times of the menstrual cycle), and provides a reference for research on menstruation-associated headache. However, the role of frequency and purity in the classification of menstruation- associated headache is not clear Moreover, the potential risk factors for high-frequency and pure headaches have not been explored. The study was a secondary analysis of an epidemiological survey on menstrual migraine among nurses. Among nurses who had a headache on days -2 to +3 of menstruation, headache frequency, purity, and type were described. High-frequency vs. low-frequency and pure vs. impure headache were compared according to headache features, demographics, occupation-related factors, menstruation-related factors, and lifestyle factors. Of all respondents, 254(18.3%) nurses who had headaches on days -2 to +3 of menstruation were included in the study. In the 254 nurses with perimenstrual headache, the proportions of migraine, tension type headache (TTH), high-frequency headache, and pure headache were 24.4%, 26.4%, 39.0%, and 42.1%, respectively. High-frequency and impure perimenstrual headache was more severe and similar to migraine. High-frequency headache was associated with more perimenstrual extremity swelling and generalized pain. Other variables were not significantly different between the groups. Headache except for menstrual migraine accounts for a certain proportion of menstruation-associated headache and should not be ignored in research. Headache frequency and purity are related to headache type and should be equally considered in the classification of menstruation- associated headache. Perimenstrual extremity swelling and generalized pain are potential indicators of high-frequency perimenstrual headache. ChiCTR2200056429.