Temporal relations in hormone-withdrawal migraines and impact on prevention- a diary-based pilot study in combined hormonal contraceptive users.

Background: Menstrually related migraine (MRM) in the hormone-free interval (HFI) of combined hormonal contraceptives (CHC) are according to the ICHD definition also estrogen withdrawal migraines (EWH). MRMs are less responsive to acute medication. Therefore short-term prevention, initiated 1-2 days before onset of the anticipated bleeding and continued for 6 days, is recommended. Such a long prophylactic triptan use might increase the risk for medication overuse headache in women suffering in addition from non-menstrual migraines. In CHC users onset of hormone decline is predictable. It is however unknown, whether the EWHs are rather associated with onset of hormone withdrawal or onset of bleeding. Improved understanding of this relation might contribute to better define and shorten the time interval for prevention.

Methods: For this observational diary-based pilot study we collected data from daily conducted headache diaries of CHC users with MRM in at least two of three cycles, visiting our clinic from 2009 to 2015. We analyzed frequency of migraines for each hormone free day, onset of migraine, onset of bleeding and the relation of migraine to onset of bleeding in the 7-day period following estrogen withdrawal. We identified in addition the onset of migraine attacks lasting more than 1 day (episodes).

Results: Forty patient charts met the inclusion criteria, what allowed us to analyze 103 cycles. The mean number of migraine days in the HFI was 2.2 ± 1.6. Migraine started typically on days 1-5 and bleeding on days 3-5. In relation to first day of bleeding, migraines started on days -1 to 4. Almost half of the migraine attacks lasted longer than 24 h, despite the use of rescue medication.

Conclusion: MRM in CHC users starts on bleeding days -1 to 4, what differs from findings in the natural cycle. Referring to the HFI interval migraine started mostly on days 1-5. According to these data, it seems to be reasonable to initiate short-term prevention at the last day of pill use or the first day of the HFI and continue for 5 days.