August 8, 2012 — Extended-cycle dosing of an ultralow-dose contraceptive vaginal ring decreases the frequency of migraine aura and largely prevents menstrual-related migraine headache, results of a pilot observational study suggest.
"For me, this was an intuitive study to undertake," first author Anne H. Calhoun, MD, FAHS, partner and co-founder of the Carolina Headache Institute in Chapel Hill, North Carolina, told Medscape Medical News.
"Unlike many headache specialists, I have a background in clinical gynecology. If one understands the composition and action of the vaginal ring contraceptive and the relationships of aura and of menstrual migraine to estrogen, then our premise was quite logical, and the results expected," added Dr. Calhoun, adjunct professor in the departments of anesthesiology and psychiatry at the University of North Carolina in Chapel Hill.
Dr. Calhoun and colleagues report their results online July 12 in Headache.
Reduced Stroke Risk?
Migraine with aura (MwA) is known to increase the risk of stroke, and the risk seems to vary with the frequency of migraine aura, which, in turn, appears to be directly related to estrogen concentration (higher estrogen levels, more aura; lower levels, less aura).
Whether stroke risk will be similarly reduced with an extended-cycle ultralow-dose vaginal ring contraceptive remains to be determined, the authors note.
Traditionally, combined oral contraceptives have been suspected of increasing the frequency of aura and worsening menstrual-related migraine. Current guidelines recommend against their use in women with MwA because of concern regarding exacerbating stroke risk.
For their study, Dr. Calhoun's team reviewed the records of 23 women seen at a subspecialty menstrual migraine clinic. All patients had a history of MwA and a confirmed diagnosis of menstrual migraine and were treated with extended-cycle dosing of a transvaginal ring contraceptive containing 0.120 mg etonogestrel and 15 mg ethinyl estradiol.
"This product has been found to completely and effectively prevent ovulation, thereby preventing the attendant ovulatory spike in estradiol that represents the highest natural estrogen exposure encountered in healthy nonpregnant women," the authors note. "It also prevents the subsequent sustained estrogen surge of the luteal phase, whose abrupt decline precipitates [menstrual migraine]."
At baseline, women suffered 3.23 migraine auras per month on average (range, 0.1 to 12). With extended dosing of the vaginal ring contraceptive, median frequency fell to 0.23 auras per month following treatment, after a mean observation period of 7.8 months (P < .0005). None of the women reported an increase in aura frequency. In addition, menstrual migraine was eliminated in 91.3% of women, the researchers say.
The small sample size and the open-label retrospective design are limitations of the current study, the researchers say. The fact that all of the women were attending a specialty headache clinic and had a "higher than average" headache burden means that results may not be generalizable to the larger population of women who experience both MwA and menstrual migraine, they add.
"The next step should be a prospectively enrolled double-blind, placebo-controlled study to confirm these findings," Dr. Calhoun told Medscape Medical News.
Reached for comment on the study, Randolph W. Evans, MD, clinical professor of neurology at Baylor College of Medicine in Houston, Texas, said, "This is an interesting pilot study for a common and difficult problem."
He added, "I concur that confirmation of efficacy and safety will be of great benefit to our migraineurs with aura who also suffer from menstrual migraine."
The authors have disclosed no relevant financial relationships. Dr. Evans is a member of the Medscape editorial advisory board.
Headache. Published online July 12, 2012. Abstract
Medscape Medical News © 2012 WebMD, LLC
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Cite this: Vaginal Ring Contraceptive May Ease Migraine - Medscape - Aug 08, 2012.