Estrogen withdrawal may trigger migraine

Fluctuations in estrogen levels during the menstrual cycle are related to the incidence of migraine. Researchers from the City of London Migraine Clinic studied 38 women (average age 43 years) with menstrual migraine and regular menstrual cycles. The participants kept a daily migraine diary and provided the study team with an early morning urine sample each day. It was found that if timed correctly, transdermal estrogen therapy might prevent these migraines. Over three menstrual cycles, the incidence of migraine peaked on the first full day of bleeding and on the preceding day, which correlated with a drop in estrogen levels. As estrogen levels began to rise, migraine incidence began to decline. This confirmed the hypothesis that estrogen withdrawal acts as a trigger for migraine. However, it was surprising that rising levels of estrogen appeared to offer some protection. In a second study with the same group of women, the researchers confirmed that treatment with estrogen supplements, around the time the menstrual cycle begins could reduce the severity and duration of menstrual migraine attacks. During six menstrual cycles, the women began treatment with an estrogen gel or placebo 10 days after day 1 of peak fertility and continued daily through the second full day of bleeding. Estrogen gel was associated with a 22-percent reduction in migraine days. Migraine attacks were also less severe and less likely to be associated with nausea. However, in the 5 days after estradiol was discontinued, migraine incidence increased by 40 percent, consistent with a delayed estrogen withdrawal. The findings suggest that estrogen supplements are effective and if continued into the next cycle, they can avoid the problem of deferring attacks.