Seizures do not occur randomly. They tend to cluster in the majority of men and women with epilepsy. Seizure clusters, in turn, often show a temporal periodicity. When the periodicity of seizure exacerbation aligns itself with that of the menstrual cycle, it is designated catamenial epilepsy. The neuroactive properties of reproductive steroids and the cyclic variation in their serum concentrations are important pathophysiologic factors. There is evidence for the existence of at least 3 patterns of catamenial seizure exacerbation: perimenstrual and periovulatory in ovulatory cycles, and entire luteal phase in anovulatory cycles. A rational mathematical basis for this categorization of catamenial epilepsy has been developed. It identifies over one-third of women as having catamenial epilepsy. If seizures show hormonal sensitivity in their occurrence, they may also respond to hormonal treatment. A randomized, double-blind, placebo-controlled National Institute of Health (NIH) progesterone trial found that cyclic progesterone supplement is no better than placebo overall, but did reduce seizure frequency significantly in the subset of women with perimenstrual seizure exacerbation. There have also been successful open-label trials using depomedroxyprogesterone and depot gonadotropin-releasing hormone analogues.

Keywords: Catamenial, epilepsy, hormones, progesterone, reproductive, seizures