Abstracts

Estimates of the prevalence of catamenial epilepsy differ in definitions used to designate catamenial epilepsy. Past investigations have focused on the relationship between seizure occurrence and either menstrual phase or reproductive hormone levels. In contrast, few studies have evaluated the periodicity of seizures in women to test the hypothesis that they have circalunar or ultralunar patterns of occurrence independent of [italic]a priori[/italic] hormonal considerations. In the present study we determined seizure periodicity according to a [ldquo]menstrual clock[rdquo] provided by a common phase marker of the onset of menstrual bleeding., Baseline, pretreatment data from seizure and menstrual diaries of [sim] 3 months duration were obtained from women enrolled in a trial of hormonal therapy for localization-related epilepsy. Midluteal serum progesterone levels classified each cycle as ovulatory ([gt]5ng/ml) (OC) or anovulatory (AC). To group seizure data, durations of individual cycles were normalized to a common menstrual phase and period. The start for each cycle was identified as the onset on menstrual bleeding (day 1). Intervening days were then converted to 28 normalized cycle days. Normalized time series were then combined to create mean seizures per menstrual day divided between OC and AC. Rhythms of seizure occurrence were then characterized with cosinor-nonlinear least squares analysis that iteratively tested all potential rhythms for best-fit described by period, amplitude, phase, and mean within designated confidence limits. Rhythms were designated significant when the lower confidence limit of the amplitude [gt] 0 by single-tailed p-value [lt] 0.05., 100 patients provided 3344 seizures within 293 cycles. The duration of cycles before normalization ranged from 20-37 days (mean [plusmn] standard deviation, 27.92[plusmn]2.89). 77% cycles were OC (2587/3344); 20% were AC (673/3344). 3% of seizures occurred during cycles with indeterminate status and were discarded. Seizures during OC displayed a significant circalunar rhythm of occurrence of 31.7 days (26.9-36.5, 90% confidence interval) with peak phase of occurrence at onset of menses. Seizures during AC not only featured a circalunar rhythm of 28.6 (26.4-30.7) days that peaked at menses onset but were also characterized with ultralunar rhythms of 14.0 (13.6-14.3) days and 9.0 (8.9-9.1) days., This study determined that seizures in women with localization-related epilepsy occur in a circalunar rhythm during both ovulatory and anovulatory menstrual cycles. Ovulatory and anovulatory cycles differ in seizure timing with the seizures in the latter occurring in ultralunar rhythms in addition to the predominant circalunar rhythm. This finding supports the existence of catamenial epilepsy and differences in patterns of seizure occurrence between ovulatory and anovulatory cycles.,