Research Articles
Study Confirms Link Between Seizure
Frequency and Menstruation in Some Women
By Andrew N. Wilner, MD, FAAN, FACP
According to Andrew Herzog, M.D., MSc, Director of the
Harvard
Neuroendocrine Unit, Beth Israel Deaconess Medical Center, Boston, MA,
the idea of a relationship between seizure frequency and a woman’s
menstrual cycle, known as catamenial epilepsy, dates back more than a
century to Sir William Richard Gowers, an eminent British neurologist
who wrote a textbook considered at the time to be ‘The Bible of
Neurology’. Herzog’s presentation at the 58th Annual Meeting of the
American Academy of Neurology, San Diego, further characterizes the
relationship between seizures and a woman’s menstrual cycle.
In preparation for a National Institutes of Health
sponsored
multicenter trial of progesterone therapy for catamenial epilepsy,
Herzog and colleagues collected information for 3 months on the seizure
frequency and menstrual periods of 100 women, ages 13-45 years. When
women ovulate, there is an increase in progesterone in the latter part
of the cycle. When they fail to ovulate (anovulatory cycle),
progesterone doesn’t increase. To determine whether ovulation occurred,
progesterone levels were measured. A level of >5 ng/ml indicated
ovulation. Herzog proposed that the lack of progesterone increase
during anovulatory cycles may be related to an increase in seizures.
The results of the study indicated that women who have
menstrual
cycles lasting 26-30 days were the most likely to have ovulatory
cycles. However, women with short cycles (less than 26 days) or long
cycles (longer than 30 days) were less likely to ovulate. For example,
in cycles lasting longer than 35 days, ovulation occurred only a third
of the time. During cycles when they didn’t ovulate, women had 28% more
seizures than during cycles with ovulation.
“It has been recognized for quite a while that menstrual
disorders
are unusually common in women with epilepsy, occurring in about 36% of
women with epilepsy versus 12% in the general population. Menstrual
disorders are associated with failure of ovulation, which goes along
with lower fertility” said Herzog.
Robert Greene, M.D., a reproductive endocrinologist and
Assistant
Clinical Professor, University of California, Davis, College of Family
and Preventive Medicine, Davis, CA, commented, “One of the most
important things is for women to track their menstrual cycles and
seizures on the same calendar. If cycles are longer than 3 months or
excessive bleeding occurs, these are indications to see an obstetrician
gynecologist. If a woman doesn’t want to take a birth control pill to
regulate her cycle, one of the easiest things to do is to use
progesterone, because progesterone doesn’t cause birth defects, as it
doesn’t cross the placenta. However, some of the synthetic forms of
progesterone and estrogen can cause birth defects and shouldn’t be used
if a woman is trying to conceive.”
Herzog concluded, “There is very much a reciprocal
relationship
between seizures and hormones. The temporo-limbic system, which is the
site of origin for most adult epilepsy, has massive direct connections
to the hypothalamus, which regulates the pituitary, which in turn
regulates the ovaries. Anovulatory cycles feature estrogen without
progesterone, and estrogen is epileptogenic. If hormones play a role in
a woman’s seizures, they may be more likely to respond to progesterone
treatment. We expect to learn more about the role of hormones and
seizure frequency in our current trial of natural progesterone for
women with epilepsy.”
References:
- Herzog AG, Harden CL, Liporace JD, Pennell PB,
Schomer DL, Sperling
MR, Taylor G, Nikolov B, Newman ML, Fowler KM. Some relationships among
ovulation rates, menstrual cycle intervals and seizure frequency:
Preliminary data analysis in a prospective multicenter investigation.
Neurology 2006;66(Suppl 2):A342.
Submitted: 05/18/06
