- Attacks, in a menstruating woman1, fulfilling criteria for 1.1 Migraine without aura and criterion B below
- Not fulfilling criterion B for A1.1.1 Pure menstrual migraine without aura or A1.1.2 Menstrually-related migraine without aura.
For the purposes of ICHD-3, menstruation is considered to be endometrial bleeding resulting from either the normal menstrual cycle or from the withdrawal of exogenous progestogens, as in the use of combined oral contraceptives or cyclical hormone replacement therapy.
This subclassification of 1.1 Migraine without aura is clearly applicable only to menstruating women as defined above.
Menstrual migraine attacks are mostly without aura. The importance of distinguishing between A1.1.1 Pure menstrual migraine without aura and A1.1.2 Menstrually-related migraine without aura is that hormone prophylaxis is more likely to be effective for the former.
Many women over-report an association between attacks and menstruation; for research purposes, diary-documented, prospectively-recorded evidence over a minimum of three cycles is necessary to confirm the diagnosis.
The mechanism(s) of migraine may be different with endometrial bleeding resulting from the normal menstrual cycle and bleeding due to the withdrawal of exogenous progestogens (as occurs with combined oral contraception and cyclical hormone replacement therapy). For example, the endogenous menstrual cycle results from complex hormonal changes in the hypothalamic-pituitary-ovarian axis resulting in ovulation, which is suppressed by use of combined oral contraceptives. Therefore research should separate these distinct subpopulations even though the diagnostic criteria do not. Management strategies may also differ for these subpopulations.
There is some evidence that menstrual migraine attacks, at least in some women, result from estrogen withdrawal, although other hormonal and biochemical changes at this time of the cycle may also be relevant. When pure menstrual migraine or menstrually-related migraine is considered to be associated with exogenous estrogen withdrawal, both codes A1.1.1 Pure menstrual migraine without aura or A1.1.2 Menstrually-related migraine without aura and 8.3.3 Estrogen-withdrawal headache should be used.
The menstrual relation may change over a woman’s reproductive lifetime.