Abstracts

Seizures may vary during the menstrual cycle because hormones have neuroactive properties and hormone levels change during the course of the cycle. The purpose of this study was to determine if and how seizure frequency and occurrence varies across the menstrual cycle. The subjects were the first 100 women with clinical and EEG features of localization-related epilepsy, 13-45 years old, who participated in the baseline phase of a larger multicenter investigation of cyclic progesterone therapy for intractable seizures. Each subject participated in a 3-month baseline phase during which she recorded seizures and menses. Midluteal serum progesterone levels were measured with 5 ng/ml cutoff to indicate ovulation. The data consisted of 1) average seizure frequencies for each cycle day and 2) proportions of cycles with seizure occurrence on a given cycle day. Statistical comparisons of seizure frequency and occurrence were performed using generalized estimating equation one-way ANOVA and logistic regression followed by pairwise multiple comparisons of days based on the least square means. The results (pairwise p-values) were then plotted as tables for ease of visualization of resulting patterns. Data were available for 292 cycles: 229 (78.4%) were ovulatory; 54 (18.4%) were anovulatory; no sample was collected for 9 cycles. The distribution of both seizure frequencies and occurrence on particular days was not uniform across the cycle (ANOVA p[lt].001). There was a 2-fold difference between highest (day 1) and lowest (day -8 and day 7) frequencies for both seizure frequency and occurrence. Pairwise daily comparisons are shown in Fig. 1. Two-way ANOVA did not show a significant interaction between ovulation status and seizure patterns. Comparison of seizure distributions in cycles with high vs low progesterone levels, however, showed significant differences for both seizure frequency (ANOVA p[lt].001) and occurrence (p[lt].05). The distribution of seizure frequencies and days with seizure occurrence varies significantly over the course of the menstrual cycle with the highest likelihood perimenstrually and the lowest during the midluteal and midfollicular phases.[figure1] (Supported by NIH R01-NS39644.)