Migraine headaches are much more frequent among women than men. While it is unlikely that the discrepancy is totally due to sex hormones, they definitely are a factor. UCLA researchers have shown that migraines may begin as a problem of brain excitability, dramatic waves of activity that spread across the surface of the brain. They suggest that women may have a faster trigger than men for activating the waves of brain activity thought to underlie migraines. Regardless of the underlying cause, a new study has reported that a hormonal preparation in the form of an ultralow dose vaginal ring contraceptive can decrease the frequency of migraine aura and prevent menstrual-related migraine (MRM). Researcher affiliated with the University of North Carolina (Chapel Hill) published their findings on July 12 in the journal Headache.
The researchers note that many women are denied therapy with combined hormonal contraceptives due to published guidelines that recommend against their use in migraine with aura (MwA). The concern is that these products might increase the risk of ischemic stroke that accompanies aura. They note that stroke risk has been reported to vary directly with aura frequency, and aura frequency in turn has been shown to have a direct relationship to estrogen levels. With the evolution of increasingly lower dosed combined hormonal contraceptives, formulations are now available that result in lower peak estrogen levels than the concentrations that are normally present during the menstrual cycle. They explain that these formulations would be expected to result in a lower frequency of migraine aura; furthermore, because extended-cycle therapy eliminates monthly estrogen withdrawals, this therapy would likewise be expected to prevent MRM.
The researchers accessed data of 830 women seen in a subspecialty menstrual migraine clinic to identify women who met all inclusion criteria: (1) current history of MwA; (2) confirmed diagnosis of MRM; and (3) treatment with extended-cycle dosing of a transvaginal ring contraceptive containing 0.120 mg etonogestrel/15 µg ethinyl estradiol. All the patients were required to maintain a calendar that specifically documented bleeding patterns, headache details, and occurrence of aura.
The investigators found that 28 women met the study criteria. Of note, none of them were smokers, which has been reported to increase the frequency of migraine attacks. Of this group of 28 women, 5 discontinued use of etonogestrel/ethinyl estradiol within the first month, leaving 23 subjects for evaluation. At baseline, subjects averaged 3.23 migraine auras/month (range: 0.1-12). With extended dosing of the vaginal ring contraceptive, the median frequency was reduced to 0.23 auras per month following treatment after an average observation of 7.8 months. No subject reported an increase in aura frequency. On this regimen, MRM was eliminated in 91.3% of the evaluable subjects.
The authors concluded that in this sample of women with both MwA and MRM, use of an extended-cycle vaginal ring contraceptive was associated with a reduced frequency of migraine aura and with resolution of MRM. They cautioned that their findings cannot be extrapolated to suggest that stroke risk in MwA will be similarly reduced. They recommend that further studies are indicated.
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