Catamenial epilepsy: what it means

Catamenial epilepsy describes seizures that cluster around specific days of the menstrual cycle instead of happening at random. Researchers use the term to describe a pattern within an existing epilepsy diagnosis. An estimated 40% of women with epilepsy show one of these patterns [1, 4].

Progesterone and estrogen act directly on brain cells, which is why mapping seizures against menstrual cycle hormones can reveal a pattern that feels random day to day.

Catamenial epilepsy and PMDD are separate diagnoses that share a hormone mechanism. Progesterone breaks down into allopregnanolone, a neurosteroid that calms brain cells through the GABA system. When progesterone falls before a period, allopregnanolone falls with it [2, 6, 7].

That same drop plays out differently depending on which system it reaches:

• In the C1 and C3 patterns, that progesterone drop is thought to lower the seizure threshold [1, 4]; in the C2 pattern, a pre-ovulatory estrogen surge is implicated instead.
• In PMDD, the same drop is linked to mood symptoms in people whose brains react differently to it, not to abnormal hormone levels (see what causes PMDD).

The two conditions aren't the same, but a seizure-vulnerable week and a mood-vulnerable week often land in the same stretch of the cycle, the luteal phase into the period. If you live with epilepsy and also notice heavier mood symptoms beforehand, both are worth tracking on one calendar.

Treatment for catamenial epilepsy depends on which pattern fits and whether periods are regular. None of it is something to start or stop without a doctor.

One large trial of natural progesterone found a benefit specifically for the C1 (perimenstrual) pattern, not the others [8]. Confirming which pattern applies usually means:

1. Keeping a seizure diary alongside period dates.
2. Marking cycle day for each seizure over several cycles.
3. Looking for clustering around bleeding, ovulation, or the luteal phase with a doctor.

That's why a doctor needs your exact pattern before choosing a treatment.

A few terms show up often alongside catamenial epilepsy:

• Luteal phase: the second half of the cycle, after ovulation, when progesterone should rise then fall.
• Corpus luteum: the structure that makes progesterone after ovulation. See corpus luteum.
• Allopregnanolone: progesterone's calming metabolite, linked to both seizure threshold and mood. See allopregnanolone.

Niyora is a PMS and PMDD support app, and it doesn't track seizures. But if the same week brings a harder mood alongside a harder time for your epilepsy, Niyora's estimated PMS window can sit next to a seizure diary, so you're reading one calendar instead of two. For more on the hormone research behind both conditions, see PMS and PMDD research.