The best way of establishing whether the patient's seizures tend to worsen at certain points of the menstrual cycle is to have her keep a careful seizure diary in relation to her menstrual cycle. Using the first day of menstrual bleeding as the first day of the cycle, the menstrual cycle is divided into four phases:

  1. menstrual, days -3 to +3
  2. follicular, days +4 to +9
  3. ovulatory, days +10 to +16
  4. luteal, days +17 to -4

The number of seizures in each phase is counted. The average daily number of seizures for each menstrual phase is then compared with the average daily number of seizures for the rest of the cycle to look for a pattern of exacerbation or remission at certain phases of the menstrual cycle. A useful definition of seizure exacerbation is a twofold or greater increase in average daily seizure frequency during the affected part of the cycle in comparison to the remainder of the cycle.

If a catamenial pattern of seizure exacerbation is established from this record, additional steps in the evaluation will help to guide treatment:13

  • Establish the menstrual pattern: normal or abnormal menstrual cycles.
  • Check midluteal serum progesterone levels (for example, on day 22 of a 28-day menstrual cycle) to see whether the luteal phase is inadequate.
  • If the woman has perimenstrual (type I) catamenial seizure exacerbation, check trough AED levels on day 22 (when estradiol and progesterone levels are high and the AED level should be "normal") and day 1 (when estradiol and progesterone levels are low). Low AED levels at this time (perhaps related to increased drug metabolism) could be the cause of perimenstrual seizure exacerbation.

Adapted from: Klein P and Herzog AG. Endocrine aspects of partial seizures. In: Schachter SC, Schomer DL, eds. The comprehensive evaluation and treatment of epilepsy. San Diego, CA: Academic Press; 1997. p. 207-232.
With permission from Elsevier (

Authored By: 
Pavel Klein MD
Andrew G. Herzog MD
Reviewed By: 
Cynthia L. Harden MD
Sunday, February 1, 2004