Does the menstrual cycle affect the rate of seizures in women with epilepsy?

Yes. Approximately half the women of childbearing age who have epilepsy report an increase in seizures around the time of their monthly menstrual period. Seizures occurring predominantly around the time of menstruation are referred to as catamenial epilepsy. Studies reveal that the premenstrual and ovulatory phases are associated with the highest seizure frequencies.

Why are certain phases of the ovulatory cycle associated with an increase in seizures?

The hormonal changes associated with the menstrual cycle are the most likely cause of changes in seizure frequency. The brain contains numerous nerve cells that are directly affected by estrogen and progesterone, the main sex hormones in women. Studies in animals have shown that high doses of estrogen can cause or worsen seizures, whereas high doses of progesterone can act like an antiepileptic drug.

What strategies can doctors use that may reduce seizures associated with the menstrual cycle?

The following strategies may help reduce seizures associated with the menstrual cycle:

• Slightly increasing the dosage of the antiepileptic drugs before the time of increased seizure frequency. (Note: This applies only to women with regular cycles.)
• Reducing the water retention that occurs in the premenstrual period.
• Taking an additional antiepileptic drug such as lorazepam (Ativan) for several days around the most vulnerable time of the menstrual cycle.
• Using hormonal agents such as progesterone or birth control pills for women with catamenial epilepsy may help. However, the effectiveness and safety of hormonal therapy for this type of epilepsy remains to be established.

Topic Editor: Steven C. Schachter, M.D.
Last Reviewed:12/15/06