Is the menstrual cycle affecting Epilepsy?

Menstrual cycles appear to influence seizure frequency in women with epilepsy, a U.S. study finds.
In women with epilepsy, having a shorter or longer menstrual cycle reduces ovulation, and a lack of ovulation boosts the frequency of seizures, the study authors found.

The findings were presented Thursday at the American Academy of Neurology annual meeting, in San Diego.

"Ovulation rates are much lower among women with epilepsy than in the general population," study author Dr. Andrew Herzog, of the Harvard Neuroendocrine Unit at Beth Israel Deaconess Medical Center in Boston, noted in a prepared statement.

"It has been suggested that these lower ovulation rates may be due in part to menstrual cycles that are longer or shorter than normal, and that lack of ovulation may in turn correlate with increased frequency of seizures, but prospective data are lacking in this population," Herzog said.

Researching further, his team conducted a study of menstrual cycle length, ovulation occurrence, and seizure frequency in women with epilepsy. The researchers compared frequency of seizures during cycles with ovulation and cycles with no ovulation in women who had at least one of each cycle during the study.

Ovulation occurred in 90 percent of 26- to 32-day cycles but sharply decreased in shorter or longer menstrual cycles. For example, ovulation occurred in less than 40 percent of 23- or 35-day cycles. On average, seizures occurred every four days in ovulatory cycles and about every three days during cycles with no ovulation.

"These results support the hypothesis that seizure frequency is affected by ovulation and ovulation is correlated with cycle length," Herzog said.

More information

The Epilepsy Foundation has more about women and epilepsy.