Abstracts

Past observations in small studies have suggested that seizures may not occur randomly in the majority of women with epilepsy. They often tend to cluster (Tauboll et al. 1991; Bauer et al. 2001; Haut S et al. 2006). Systematic investigations in large prospective investigations, however, are lacking. The purpose of this investigation was to determine the distribution of seizure occurrence in women with localization related epilepsy., The present data come from the first 100 women, aged 13-45, who were participating in the baseline phase of a multicenter investigation of supplemental progesterone therapy for the treatment of intractable seizures in women with localization related epilepsy. The women recorded seizures and menses during 3 baseline menstrual cycles. A midluteal progesterone level [ge] 5 ng/ml was used to identify ovulatory cycles. The goodness of fit of the Poisson distribution to the distribution of seizures during the combined three-cycle observation period in each woman with [ge]10 seizures was tested by chi square analysis. [chi]² values [gt]5.99 identified women with nonrandom seizure distributions. Nonrandom distributions were further categorized as uniform (variance/mean [lt]1) or clustered (variance/mean [gt]1). Results were similar to an alternative method of testing nonrandom distributions against a uniform distribution for each subject using the Pearson chi square statistic with categorization as clustered if p value was [le] .05., 75 women had [ge]10 seizures over the 3 month observation period. Seizure distributions in these 75 women were random in 29 (38.7%). Among the remaining 46 (61.3%) who had non-random distributions, 6 (8.0%) had uniform distributions and 40 (53.3%) had clustered distributions. Clustering was significantly more pronounced among women with anovulatory cycles than among women with ovulatory cycles (variance/mean [plusmn] 2 SD = 6.1 [plusmn] 5.3 vs 2.2 [plusmn] 1.7; t-test for independent samples: p = .006). No correlation was demonstrated between clustering and age of subjects, age of epilepsy onset, duration of epilepsy, EEG laterality and individual AEDs., The preliminary findings of this prospective study suggest that the majority (53.3%) of women with localization related epilepsy have clustered seizure distributions and that clustering may be significantly more common with anovulatory than ovulatory cycles., (Supported by NIH RO1 NS39466.)