Seizure Frequency May Be Tied To Menstrual Cycle

August 22, 2011

The ebb and flow of reproductive hormones can have effects outside the reproductive process. Indeed, research has shown that the neuroactive properties of reproductive steroids can affect neuronal excitability and therefore may be associated with seizures. To better understand this phenomenon, Dr Andrew G. Herzog, professor of neurology at Harvard Medical School and director of the neuroendocrine unit at Beth Israel Deaconess Medical Center, Boston, and colleagues looked at seizure experience in anovulatory versus ovulatory cycles.

The ebb and flow of reproductive hormones can have effects outside the reproductive process. Indeed, research has shown that the neuroactive properties of reproductive steroids can affect neuronal excitability and therefore may be associated with seizures. To better understand this phenomenon, Dr Andrew G. Herzog, professor of neurology at Harvard Medical School and director of the neuroendocrine unit at Beth Israel Deaconess Medical Center, Boston, and colleagues looked at seizure experience in anovulatory versus ovulatory cycles.

The researchers conducted a multicenter, prospective observational study of 92 women who had at least 2 documented intractable focal-onset seizures per month. These women had both anovulatory and ovulatory cycles. Women were excluded if they were taking any reproductive medications; for inclusion, the researchers also required that women were on a stable antiepileptic drug regimen for at least 1 month.

During the study, women were asked to chart their seizure occurrences, and during midluteal phase of each cycle, a blood sample was taken to measure serum estradiol and progesterone levels. Average daily seizure frequency between the days of anovulatory and ovulatory cycles for each seizure type (ie, secondary generalized tonic-clonic seizures, complex partial seizures, and simple partial seizures), as well as all seizures combined, were then calculated. The study was designed to have the women serve as their own controls; to do so, the researchers had the women chart across both anovulatory and ovulatory cycles.

Complex partial seizures were found to be the most common, occurring in 72.8% of all participants; secondary generalized tonic-clonic seizures occurred in 29.3% and simple partial seizures occurred in 33.7%. Demographics, epilepsy, and drug regimen did not differ among the patients with secondary generalized tonic-clonic seizures, complex partial seizures, and simple partial seizures. 

No significant differences were found in average daily seizure frequency for complex partial seizures, simple partial seizures, or all seizures combined across anovulatory and ovulatory cycles. They did find a significant difference for secondary generalized tonic-clonic seizures, with a 29.5% higher average daily frequency during anovulatory than during ovulatory cycles. Herzog and colleagues further noted a correlation with proportional increases in midluteal estradiol/progesterone serum level ratios, suggesting a possible role for reproductive steroids in secondary generalized tonic-clonic seizures.

“If hormones play a role in seizure occurrence, there may also be a role for hormones in seizure therapy,” the researchers noted.

By gaining a better understanding of how the hormones affect seizures, it is possible researchers are one step closer to finding solutions. “If you don’t ovulate, you don’t make progesterone, hence the importance of estrogen-to-progesterone ratio,” Dr Herzog explained in a statement to the press. “Estrogen tends to promote seizure occurrence and progesterone has a metabolite that has powerful antiseizure properties comparable to barbiturates and benzodiazepines.”

More Information

Epilepsy.com: Menstrual Cycle Epilepsy and Your Changing Hormones

References:

References
Herzog AG, Fowler KM, Sperling MR, et al.Variation of seizure frequency with ovulatory status of menstrual cycles.  Epilepsia. 2011; doi: 10.1111/j.1528-1167.2011.03194.x
Anderson P. Seizure activity linked to ovulation cycles. Medscape News. July 21, 2011.