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Research: menstrual cycles affect seizure frequency

26 April, 2006

New research
suggests that having a longer or shorter menstrual cycle reduces
ovulation and, for women with epilepsy, lack of ovulation increases
seizure frequency.

The study was presented to the annual meeting of the American Academy of Neurology, and was led by Dr Andrew Herzog, from the Harvard Neuroendocrine Unit at Beth Israel Deaconess Medical Center in Boston, USA.

He commented:

"Ovulation
rates are lower among women with epilepsy than in the general
population. It has been suggested that these low 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.'

To
test these suggestions, the researchers studied menstrual cycle length,
ovulation occurrence and seizure frequency in 100 women. The frequency
of seizures during cycles with ovulation and cycles where no ovulation
occurred was compared in the 30 women who had at least one of each type
of cycle during the study.

Ovulation
occurred in 90 per cent of 26-32 day cycles, but declined steeply when
cycles were either longer or shorter, occurring in less than 40 per
cent of either 23- or 35-day cycles. Seizures occurred on average about
every four days in ovulatory cycles, and every three days in cycles
where ovulation did not happen.