Abstracts

Rationale: Seizures do not occur randomly in the majority of people with epilepsy. In women, seizure occurrence often varies with the menstrual cycle (catamenial epilepsy, CE). The laterality and focality of the epileptic focus may be relevant variables for the frequency of CE as well as the level of catameniality. Methods: The data are taken from the seizure charts of 168 women, 13-48 years old, who had unilaterally localized intractable partial onset seizures and completed the 3-month baseline phase of a prospective multicenter investigation of progesterone therapy. CE designation was made if at least 2 of 3 baseline cycles qualified using the formulas and cut-off scores proposed by Herzog et al. (Epilepsia 1997;38:1082-1088). The level of catameniality was taken to be the actual score derived from the application of the defining formula that compares average daily seizure frequency (ADSF) during the phase of seizure exacerbation with ADSF during the mid-follicular and mid-luteal phases. Only those cycles (C1: N=186 ovulatory cycles, C2: N=183 ovulatory cycles, C3: N=86 anovulatory cycles) that had seizures during the phase of exacerbation were considered. Epilepsy laterality and focality were designated using all available localizing tests including EEG, MR, SPECT & PET. Cases were excluded if results were incongruent. Frequencies of catamenial epilepsy with unilateral left (L) and right (R) sided temporal (T) and non-temporal (NT) foci were compared using χ2 analysis. Scores for each of the 3 types of CE (C1:perimenstrual, C2:pre-ovulatory, C3:Days 10-3 in anovulatory cycles) were compared for the various epilepsy localizations using the Mann Whitney U test. Results: CE frequencies by laterality and focus were as follows: LT - 45.2%, LNT - 33.0%, RNT - 30.1%, RT - 28.6%. CE was more frequent with L than R sided epilepsy overall (L:R = 43.5%:28.9%; χ2 = 3.878, df = 1, p=.0489) and especially greater with LT than RT localization (45.2% v 28.6%; χ2 = 4.239, df = 1, p=.0395). There were no significant differences in CE occurrence between other laterality and focality combinations. CE frequency did not differ significantly in relation to T v NT foci overall (37.1% v 32.0%; χ2 = 0.236, df = 1, p=.6272). The levels of catameniality without regard to CE designation were significantly greater with LT than RT for the C1 and C2, but not C3 patterns (C1: L:2.5 [quartiles: 1.0,3.75] v R:1.25 [0.76,2.50] p=.010; C2: L:1.67 [1.05,3.75] v R: 1.13 [0.75,1.88] p=.004; C3: L:1.82 [0.66,5.00] v R: 1.66 [0.76,5.0] p = .949). Conclusions: Catamenial epilepsy is significantly more common with L than R sided epilepsy, especially with temporal foci. The level of catameniality, regardless of CE designation, is significantly greater with a LT than RT focus for the C1 and C2, but not the C3, patterns. Although the three patterns of CE may all result from changes in neuroactive reproductive steroid effects on an epileptic brain substrate, the possibility exists that the C3 pattern may depend less on epilepsy localization than the C1 and 2 patterns. Supported by NIH R01 NS39466