Purpose: On the basis of the neuroactive properties of estradiol and progesterone and the menstrually related cyclic variations of their serum concentrations, we propose the existence of three hormonally based patterns of seizure exacerbation. Because previous reports both support and refute the concept of catamenial epilepsy, we test the hypothesis by charting seizures and menses and measuring midluteal serum progesterone levels to estimate the frequency of epileptic women with catamenial seizure exacerbation.
Methods: One hundred eighty-four women with intractable complex partial seizures (CPS) charted their seizure occurrence and onset of menstruation on a calendar for one cycle during which they had a midluteal blood sample taken for serum progesterone determination on day 22. Levels >5 ng/ml were considered ovulatory. The cycle was divided into four phases with onset of menstruation being day 1: menstrual (M) = -3 to +3, follicular (F) = 4 to 9, ovulatory (O) = 10 to -13, and luteal (L) = -12 to -4. Average daily seizure frequency for each phase was calculated and compared among phases by repeated-measures analysis of variance (ANOVA) and the Student-Newman-Keul's test, separately for ovulatory and anovulatory cycles.
Results: The 1,324 seizures recorded during 98 ovulatory cycles occurred with significantly greater (p < 0.001) average daily frequency during the M (0.59) and O (0.50) phases than during the F (0.41) and L (0.40) phases, offering support for perimenstrual (catamenial 1) and preovulatory (catamenial 2) patterns of seizure exacerbation. The 1,523 seizures recorded during 86 anovulatory cycles occurred with significantly lower (p < 0.001) average daily frequency during the F phase (0.49) than during all other phases (M = 0.78, O = 0.74, L = 0.74), offering support for seizure exacerbation throughout the second half of inadequate luteal phase cycles (catamenial pattern 3). Although 71.4% of the women with ovulatory cycles and 77.9% with inadequate luteal phase cycles had seizure exacerbation in relation to one of the three patterns of catamenial epilepsy, approximately one third of the women showed at least a twofold increase in average daily seizure frequency. We propose a twofold or greater increase as a reasonable definition of catamenial epilepsy.
Conclusions: Charting of seizures and menses and determination of day 22 progesterone levels during each cycle may be sufficient to establish the existence of three distinct patterns of catamenial epilepsy. Approximately one third of women with intractable CPS may have catamenial epilepsy.