Menstrual Seizures and Progestin Only Contraceptives
Frederick R. Jelovsek MD
"I am trying to find a birth control pill consisting of only natural progesterone, (not synthetic). Is there such a thing?
Also, would a natural progesterone pill (or the cremes for that matter), protect you against getting pregnant?
I am 34 yrs old and suffer from endometriosis, and seizures. I was put on the pill to help with the painful cramps, but the estrogen in these pills causes me to have seizures. I have catamenial epilepsy, and am taking Neurontin® for it." Lori
Catamenial epilepsy refers to a condition of seizures whose frequency increases during a woman's menstrual period. It is not a matter of no seizures until the period and then a bunch of them. It is usually a matter of having twice as many seizures (eg., 2 a day instead of 1 a day) on the days of menses versus the other days in the menstrual cycle.
How do reproductive hormones affect epileptic seizures?
Estrogens lower the threshold for seizures in the nerve pathways of the brain. In other words they permit a smaller electrical impulse along the nerve to start a complex cascade of electrical impulses that results in an epileptic seizure then would be necessary in the absence of estrogen. Progesterone has the opposite effect. It raises the threshold for electrical nerve conduction. With progesterone aboard, it takes more electrical stimulation to cause the convulsion. If you lower estrogens to menopausal levels using gonadotropin releasing factor ( eg., Lupron®) there is a significant reduction of seizure frequency.
Taking estrogen medications may cause an increase is seizure activity in some women prone to this and taking progesterone may lessen seizures. It is interesting that at the time of menses there is a decrease in both estrogen AND progesterone. Therefore it is the lack of progesterone that was preventing some seizures that is the primary force leading to increased seizures in catamenial epilepsy. And since progesterone is only naturally secreted in the last two weeks of the menstrual cycle, there may be a decrease in seizures at that time but the "decrease" disappears at the time of menses just as progesterone also disappears.
How does the seizure frequency vary with a menstrual cycle?
There can be several different effects of the normally cycling reproductive hormones on seizure frequency in women with epilepsy. In women with ovulatory cycles, there can be an increase in seizures right around ovulation at midcycle when estrogen levels spike higher. There also can be an increase during menses when progesterone (and estrogen levels) decrease. Finally, in women who are anovulatory, there seems to be a lower seizure incidence in the first two weeks of the cycle and an increased incidence after the first two weeks when there should be progesterone around but it is not present because ovulation did not occur.
Is there a birth control pill consisting of only natural progesterone, not synthetic progestins?
No, not at the current time. It sounds enticing to take a progesterone only birth control pill which should keep constant progesterone levels throughout the entire cycle. Thus seizure activity should be decreased all of the time and not vary in frequency throughout the days of a menstrual cycle. In fact progesterone supplements have been shown to reduce catamenial epileptic seizures on the average by about 55%. The main problem is that natural progesterone alone is not a contraceptive. Synthetic progestins like medroxyprogesterone acetate (Provera®, DepoProvera®) can also reduce seizure activity but not as effectively as natural progesterone.
Progesterone CreamWould a natural progesterone pill or the natural progesterone cremes for that matter, protect you against getting pregnant?
There are no natural progesterone containing birth control pills that I know of at the present time. Historically when researchers first developed oral contraceptives, they were looking for a way to manufacture progesterone from Mexican yams and when they first discovered the contraceptive effects of their manufactured progestins, they were very excited. As they purified the compounds to contain only progestins and not the contaminant estrogen (specifically mestranol) they lost the contraceptive effect of the pills. Thus the discovery that you needed both progestin and estrogen to have an effective contraceptive pill by mouth.
Now we know that progestin only pills can function as contraceptives, not by inhibiting ovulation but by making the cervical mucous hostile to sperm penetration and the endometrium hostile to fertilized egg implantation. But they are not as effective as combined oral contraceptives in preventing pregnancy. The typical use failure rate of progestin only pills is about 5%.
Catamenial EpilepsyWhat would be the best birth control for a woman with catamenial epilepsy?
There is no best answer for this. I could not find studies of DepoProvera® used for contraception in women with epilepsy, nor with just progestin only pills. It is not even clear that regular oral contraceptives containing estrogens worsen seizure activity; they may not. In the absence of clinical trials and data, we need to reason using the studies and physiology that we do know about.
I think in the next patient I see who describes catamenial epilepsy, I might suggest one of several approaches:
- if a woman has had one or more children, the use of a progesterone IUCD and continuous oral micronized progesterone at about 100mg or 200 mg twice a day should provide birth control as well as decrease the seizures as much as reproductive hormones can.
- The above is also an option for a woman who has not had any children but if tolerating the IUCD was a problem, then using a very low dose estrogen containing oral contraceptive (20 mcg dose) with a supplement of oral micronized progesterone at about 100-200 mg twice a day could be tried.
The twice a day dose of oral progesterone should be better to lower neuron sensitivity since the blood level of progesterone from an oral dose peaks at about 3 hours with therapeutic levels for 6 hours and clearing by 24 hours. I do not know if the current non prescription progesterone creams(25 mg/tsp) would provide this level of progesterone unless you used at least 1-2 teaspoons a day (7). No woman should use the progesterone cream as a contraceptive.
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