Catamenial epilepsy refers to seizures that vary in severity according to the menstrual cycle. In people with this type of epilepsy, seizures can worsen from fluctuations in estrogen and progesterone.

Catamenial epilepsy affects around 40% of females with epilepsy. To make a diagnosis, doctors ask people to keep a diary of when their seizures and periods occur. This can show whether the seizures coincide with critical changes in hormone levels.

Keep reading to learn more about the causes, symptoms, diagnosis, and treatment of catamenial epilepsy.

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Catamenial epilepsy refers to epileptic seizures that worsen at certain points in the menstrual cycle. It is common in people with epilepsy who menstruate and can significantly impact quality of life.

Doctors divide catamenial epilepsy into three subtypes according to the pattern of symptoms a person experiences. These subtypes are:

  • Type 1 pattern: People with this type of catamenial epilepsy experience worsened symptoms in the days before or during a period.
  • Type 2 pattern: In this symptom pattern, a person’s seizures get worse around ovulation, when the ovaries release an egg. Ovulation occurs in the middle of the menstrual cycle for most individuals — around 10–16 days before a period.
  • Type 3 pattern: In this pattern, seizures generally worsen in the second half of the menstrual cycle. This is known as the luteal phase of the cycle and includes the days in between ovulation and the next period.

The main symptom of catamenial epilepsy is seizures that get more intense or frequent at certain points in the menstrual cycle. The pattern varies according to the subtype a person has, but the pattern will be repetitive, with symptoms worsening at the same time during each menstrual cycle.

The seizure symptoms will depend on the type of seizure a person has. For example, a focal seizure only affects one part of the brain and may cause:

  • twitching
  • a strange smell or taste
  • confusion
  • an inability to respond to questions

In contrast, generalized seizures affect both sides of the brain. Symptoms may include:

  • rapid blinking
  • becoming unresponsive for a few seconds
  • crying out
  • muscle jerks or spasms
  • a loss of consciousness
  • falling to the ground

Learn more about the types of epilepsy.

Catamenial seizures happen due to changes in estrogen and progesterone levels that occur throughout the menstrual cycle.

Estrogen and progesterone are the main sex hormones responsible for regulating ovulation and menstruation. Around the time of ovulation, estrogen levels increase substantially before gradually declining as a person approaches their period.

As this occurs, progesterone levels increase, rising before a person’s period and then falling once the period begins.

Scientists believe catamenial seizures occur due to the impact of these fluctuations on the brain and nervous system, although the exact mechanism is still unclear. However, there are several theories, depending on symptom patterns:

  • Type 1 pattern: The Epilepsy Foundation suggests a worsening of seizures during ovulation may be due to estrogen’s ability to excite neurons. This is especially true for estradiol, a type of estrogen the ovaries produce. Also, progesterone may have anticonvulsant properties, so as this hormone rises, the seizures improve again.
  • Type 2 pattern: People who experience worsened seizures just before and during a period may be responding to a decline in progesterone.
  • Type 3 pattern: This pattern has a greater association with irregular periods. Sometimes, people have irregular periods because they do not ovulate. When this happens, estrogen remains high from the midpoint of the menstrual cycle until the days before menstruation. This could explain why people with type 3 catamenial seizures have worsened symptoms for the whole second half of their cycle.

Another theory is that catamenial seizures affect those with a progesterone deficiency or those who have excess estrogen in relation to progesterone levels. Doctors refer to this as estrogen dominance.

However, scientists have not proven any of these theories, so exactly how hormone levels influence seizures in those with epilepsy is still unclear. More research is necessary to understand the condition.

Diagnosing catamenial epilepsy involves a person maintaining a seizure diary for at least 3 months. The United Kingdom epilepsy charity, Epilepsy Action, recommends using the diary to record:

  • the date, time, and type of seizures a person has
  • how long seizures last
  • when menstruation occurs
  • other possible seizure triggers
  • potential side effects of medications or any recent medication changes

In addition to tracking seizures, it is also worth tracking the menstrual cycle itself, particularly how long it lasts from month to month. This is because the regularity of periods can influence the treatment for catamenial epilepsy. The first day of a period marks the first day of a new menstrual cycle.

A person should also bring their seizure diary to an appointment with a doctor. A healthcare professional will be able to determine if the pattern of seizures is catamenial. They may also check mid-luteal progesterone levels using a blood test.

There is a range of treatments that doctors can try for catamenial epilepsy.

Treatment for people with regular cycles

For those with regular periods, doctors may suggest increasing the dose of antiseizure medications a person already takes. They could also recommend taking them at times when seizures occur.

Another approach is to take additional medications that control seizures during times in the cycle when they usually get worse. This may include clobazam (Onfi) or acetazolamide (Diamox).

Clobazam is a type of benzodiazepine, a class of drug with a high risk of misuse. People will need to speak with a doctor about the potential benefits and risks to decide which approach is best for them.

Another treatment option involves progesterone therapy. An older 2012 review suggests taking progesterone through the luteal phase may reduce seizures — this may be especially beneficial to those with low progesterone levels at this stage in the cycle.

However, the studies on this approach are not conclusive. A 2021 review found that, out of four clinical trials, there was no evidence that progesterone was more effective than a placebo for reducing seizure symptoms. However, the researchers noted that the evidence was generally low quality, making this finding uncertain.

Additionally, oral contraceptive pills do not appear to be beneficial for catamenial epilepsy. However, they also do not appear to make seizures worse.

Treatment for people with irregular cycles

There are other treatment options for people who cannot always predict when their period will occur and therefore do not know when they are most likely to get seizures.

These include medications that stop hormonal fluctuations from occurring. A doctor may suggest medroxyprogesterone injections, otherwise known as the Depo-Provera shot, to prevent ovulation and menstruation.

Gonadotropin‐releasing hormone analogs, such as triptorelin (Trelstar) and goserelin (Zoladex), are also options. These work by stopping the production of sex hormones.

Before prescribing these medications, a doctor will test a person’s hormone levels and perform other blood tests to assess whether these treatments will be useful.

Research on whether menopause helps with catamenial epilepsy is mixed. According to an older 2012 review, some studies suggest that for many females, seizures are just as frequent in premenopause as they are in menopause. Others show an improvement, but some indicate that the seizures may worsen.

The effect of menopause on seizures may vary from person to person, depending on their symptom pattern. For some, raised estrogen during perimenopause — the first stage of menopause — may worsen symptoms. For others, a lack of estrogen or progesterone after menopause may worsen them.

However, some evidence suggests that, unlike hormonal birth control, hormonal replacement therapy (HRT) may have a positive impact on those going through menopause who have catamenial epilepsy. The authors of the 2012 review suggest this might be because, after menopause, a person’s reproductive hormones stop rising and falling.

As a result, the effect of HRT may be different from the effect of taking oral contraceptives. Additionally, HRT may reduce the risk of osteoporosis, which may be especially important for those taking certain epilepsy drugs. Some antiseizure medications may accelerate the breakdown of vitamin D, which is necessary for strong bones.

Catamenial epilepsy involves seizures that increase in frequency or intensity due to the menstrual cycle. Due to a lack of research, scientists are not sure exactly how or why they occur. However, they likely develop due to changes in progesterone or estrogen levels, which affect the brain and nervous system.

People can have one of three subtypes of catamenial epilepsy, and this on their symptom pattern. Keeping a seizure diary can help individuals and doctors understand the pattern and whether there is a correlation with ovulation or menstruation.

Treatment for catamenial epilepsy may involve progesterone therapy, taking additional or increased antiseizure medications at certain points in the menstrual cycle, or trying drugs that stop hormonal fluctuations. However, much more research on the condition is necessary.