Catamenial epilepsy is a pattern in which seizures become more frequent at certain points in the menstrual cycle. It is linked to natural changes in hormones such as estrogen and progesterone, which can affect brain activity. Seizures may cluster around the start of a period, around ovulation, or during the days after ovulation. Keeping track of periods and seizures can help a clinician identify this pattern and plan care.
What does catamenial epilepsy mean?
Catamenial epilepsy describes a recurring increase in seizure activity related to the menstrual cycle. It occurs in people who have epilepsy and whose seizures follow a noticeable pattern during particular phases of the cycle. The pattern can occur with different types of epilepsy, including focal epilepsy, in which seizures begin in one area of the brain, and generalized epilepsy, which involves networks on both sides of the brain from the start.
The term does not mean that seizures must happen only during menstrual bleeding. Instead, the important feature is a repeated relationship between seizure frequency and particular points in the cycle. According to Epilepsy Action, the pattern may involve the days around menstruation, ovulation, or the phase after ovulation. Recognizing this timing can help healthcare professionals consider whether menstrual changes are contributing to a person's seizure pattern.
How can menstrual hormones affect seizures?
Estrogen and progesterone are reproductive hormones that naturally rise and fall during the menstrual cycle. These hormones can influence how nerve cells communicate in the brain, including processes involved in seizure activity. Their effects are not identical: estrogen may increase the brain's tendency toward seizure activity in some circumstances, while progesterone and certain substances produced from it may have seizure-reducing effects.
According to the Epilepsy Foundation, changes in these hormone levels are thought to help explain why some people experience more seizures at particular stages of their cycle. The relationship is complex, however, and hormonal changes do not affect everyone with epilepsy in the same way. Catamenial epilepsy is therefore understood through the combination of hormonal changes and an individual's underlying seizure condition, rather than through hormone levels alone.
When during the menstrual cycle do seizures tend to increase?
Clinicians commonly describe three patterns of catamenial seizure activity. These patterns refer to the timing of increased seizures, not to different types of seizures or a measure of how serious epilepsy is.
- Around menstruation: Seizures become more frequent in the days immediately before a period or during the first days of menstrual bleeding. This is often called the perimenstrual pattern.
- Around ovulation: Seizures increase near the middle of the cycle, when an ovary releases an egg. This is known as the periovulatory pattern.
- After ovulation: Seizures become more frequent during the later part of the cycle, before the next period. This pattern may be associated with cycles in which ovulation does not occur or progesterone exposure is inadequate.
These patterns can differ between individuals. Menstrual cycles that are irregular or do not consistently include ovulation can make the relationship harder to identify. The Epilepsy Society explains that changes in reproductive hormones can affect seizures at different stages of life, including puberty and the years when menstrual periods occur. A recurring pattern is more informative than an isolated increase in seizures.
How is catamenial epilepsy recognized?
There is no single routine test that confirms catamenial epilepsy. Healthcare professionals generally assess the timing of seizures alongside menstrual dates, medical history, and existing epilepsy treatment. They may also consider whether other factors, such as missed medication, changes in sleep, illness, stress, or other familiar seizure triggers, could explain an increase in seizures.
A seizure and menstrual diary is often a useful first step. Recording information over several menstrual cycles can help show whether seizures repeatedly increase during the same phase. The Epilepsy Action guidance recommends tracking periods and seizures over about three months to look for a pattern. This record can also help distinguish a recurring cycle-related change from a temporary fluctuation in seizure frequency.
What should a seizure and menstrual diary include?
A diary does not need to be complicated. Its purpose is to create an accurate record that can be reviewed with an epilepsy specialist. Helpful details may include:
- The first day of each menstrual period and the length of the cycle, when known.
- The date and approximate time of each seizure, including its observed features and duration.
- Whether prescribed antiseizure medication was taken as scheduled.
- Relevant changes in sleep, illness, stress, or other known seizure triggers.
- Any medication or hormonal contraception changes made during the tracking period.
When a person cannot reliably identify ovulation, a clinician may interpret the record alongside information about cycle regularity and, when appropriate, additional tests. Diary entries support the assessment but do not replace a clinical evaluation, particularly when seizures have recently changed or become more difficult to control.
What treatments may help catamenial epilepsy?
Treatment aims to improve seizure control while considering the timing of seizures, the person's existing medication, menstrual regularity, contraception needs, and reproductive plans. There is no single treatment that is appropriate for everyone. An epilepsy specialist may first review the current antiseizure medication regimen and determine whether adherence, dosing, side effects, or drug interactions need attention.
Depending on the pattern and individual circumstances, treatment options may include a prescribed additional antiseizure medicine during predictable high-risk days, selected hormone-based treatments, or approaches that suppress menstrual cycles. These options require individualized planning because their benefits and potential adverse effects differ, and some medicines can interact with hormonal contraception.
A 2021 Cochrane review found that the available randomized-trial evidence on hormonal treatments for menstrual-related seizures was limited. As a result, there is still uncertainty about which approach works best for different patterns of catamenial epilepsy. Treatment decisions should account for the available evidence as well as seizure control, fertility considerations, possible effects on bone health, and the person's preferences.
Why do medication and contraception choices need review?
Some antiseizure medicines can reduce the effectiveness of certain hormonal contraceptives, while some hormonal contraceptives can affect levels of particular antiseizure medicines. These interactions matter when considering contraception, menstrual suppression, or a change in epilepsy treatment. The Epilepsy Society's guidance for women and girls with epilepsy highlights the importance of reviewing these combinations with a healthcare professional. A neurologist or epilepsy specialist can coordinate care with a gynecologist or contraception specialist when needed.
Do not change the dose of an antiseizure medicine, start hormone treatment, or stop prescribed medication because seizures appear to follow a menstrual pattern. A clinician can determine whether a treatment adjustment is appropriate and explain how to make any changes safely.
When should you seek medical advice?
Speak with an epilepsy specialist if seizures seem to occur more often around periods, if a previously stable seizure pattern changes, or if seizures begin disrupting daily activities despite taking medication as prescribed. A diary of menstrual dates and seizures can make the discussion more productive, but it is not necessary to wait several months before seeking help when seizures are worsening or concerning.
Seek emergency medical help when a seizure lasts longer than five minutes, seizures occur repeatedly without recovery between them, breathing is difficult after a seizure, or an injury or other urgent concern occurs. Follow any seizure action plan provided by the person's healthcare team.
With careful tracking and individualized medical care, the relationship between seizures and the menstrual cycle may become clearer. Identifying a recurring pattern can help clinicians discuss suitable management options without assuming that every increase in seizure activity has a hormonal cause.