Despite affecting one in seven of the UK population, migraine is underdiagnosed and undertreated. 1 Prevalence is highest during the peak reproductive years with a female predilection, affecting one in five women compared with one in 13 men. 1 The diagnosis of migraine is based on recurrent episodic headaches lasting between four and 72 hours associated with photophobia, nausea and limitation of normal function in an otherwise healthy person. 2
Prevalence of menstrual migraineMenstruation is a significant risk factor for attacks of migraine without aura, with 50-60 per cent of women reporting a link between their menstrual periods and migraine. [3][4][5] Most women with menstrual exacerbation of migraine also experience attacks at other times of the month ('menstrually-related' migraine). 6,7 Fewer than 10 per cent of women report migraine exclusively with menstruation ('pure' menstrual migraine). [5][6][7][8][9] Characteristics of menstrual migraine Timing of attacks Compared with all other phases of the menstrual cycle, attacks of migraine without aura are most likely to occur during a five-day window that starts two days before the onset of menses and continues through the first three days of menstruation. 8,10-12 Studies suggest that women are over 70 per cent more likely to have migraine in the two days before menstruation and more than 2.5 times more likely to have attacks during the first three days of bleeding. 12 How attacks differ from non-menstrual attacks Menstrual attacks last longer, are more severe, are more likely to relapse, are less responsive to treatment, and are associated with greater disability when compared with attacks at other times of the cycle. 5,[11][12][13][14][15][16][17][18][19]
DiagnosisThe International Headache Society (IHS) recognises two types of menstrual migraine: menstrually-related migraine, which is migraine without aura that regularly occurs on or between two days before menstruation and third day of bleeding (days -2 to +3), with additional attacks of migraine with or without aura at other times of the cycle; and pure menstrual migraine, which is migraine without aura that occurs only on or between days -2 to +3, ie with no attacks at any other time during the cycle. 6,20 To confirm the diagnosis, migraine attacks during the day -2 to +3 window must occur in at least two of three menstrual cycles to establish a relationship that is greater than chance alone. Relying on the history to confirm the diagnosis can be misleading. 21 Use of a three-month diar y to record migraine patterns can reveal the predictable patterns associated with menstrual migraine, aiding diagnosis.
PathophysiologyResearch has found an increased risk of migraine associated with oestrogen 'withdrawal'. This occurs during the late luteal phase of the natural menstrual cycle and also during the hormone-free interval of combined hormonal contraceptives. 17,22 Prostaglandins have also been implicated in menstrual migraine. There is a three-fold increase in prostaglandin levels in the uterine endometriu...