Women who have epilepsy often experience an increase in seizure frequency around the time of their menstruation each month, referred to as catamential epilepsy. Researchers at Emory University and other centers are investigating what causes this frequency and the patterns in which the seizures develop. Epilepsy is a chronic medical condition produced by temporary changes in the electrical function of the brain, causing seizures that affect awareness, movement or sensation. One percent of the population has epilepsy at any given time. Catamenial epilepsy occurs in about one-third of all women with epilepsy.
"In this study, we have enrolled 87 women with epilepsy at the four sites thus far, including 17 at Emory, who also had intractable partial seizures - or seizures that develop in one part of the brain," says Page Pennell, of Emory University School of Medicine. "This is a real physiological phenomenon, and we want to find out why seizure frequency occurs during monthly hormonal changes and how we can better treat our patients."
Past research has shown that women can develop an increase in seizure frequency during at least three patterns around their menstrual cycle. The patterns during normal cycles are perimenstrual (the few days before and after before the onset of the menstruation cycle) and periovulatory (in the middle of the cycle at ovulation). These patterns are present if women ovulate monthly.
"If women ovulate, their seizures get worse around ovulation, then get better, then get worse again around menses," explains Dr. Pennell, who is leading the study at Emory. "If women do not ovulate, their seizures increase during the entire second half of their cycle. Women who have epilepsy tend to have more non-ovulatory cycles than normal cycles because seizures affect the regulation of hormones and alter signals sent from the brain. One out of three cycles in women with certain forms of epilepsy is non-ovulatory."
Among the 87 women studied, nearly 40 percent showed catamential patterns where seizures fluctuated with their menstrual cycles and they were diagnosed as having catamenial epilepsy. "We know seizures get worse with monthly hormonal changes in women with epilepsy," says Dr. Pennell. "This study is helping us identify the three patterns in which seizure frequency is the most intense and why."
Researchers gave all study participants either natural progesterone lozenges or placebo lozenges beginning at the time of ovulation. Based on laboratory research, progesterone has strong anti-seizure properties. It has been known to reduce the frequency and severity of seizures. Participants tapered their medication before stopping it at the end of their cycles.
