Catamenial Epilepsy: When Your Menstrual Cycle Affects Your Seizures

For some women with epilepsy, seizures follow a predictable pattern linked to their menstrual cycle. This phenomenon, known as catamenial epilepsy, affects between 10% and 70% of women with epilepsy at some point in their lives.

Understanding the relationship between hormones and seizures can help women recognise patterns, track changes effectively, and have informed discussions with their neurologist about treatment options.

What is Catamenial Epilepsy?

Catamenial epilepsy describes epilepsy in which seizures cluster around specific phases of the menstrual cycle.

The link between hormones and seizure activity has been recognised for decades. Research shows that:

• Oestrogen tends to increase neuronal excitability (potentially increasing seizure risk)
• Progesterone has a calming effect on the brain (potentially reducing seizure risk)

It is the changing ratio between these hormones throughout the menstrual cycle—rather than absolute hormone levels—that appears to influence seizure frequency in susceptible women.

Not every seizure that happens to occur during menstruation indicates catamenial epilepsy. A pattern must be established over multiple cycles before this relationship can be confirmed.

The Three Recognised Patterns

Medical research has identified three distinct patterns of catamenial epilepsy, each linked to different hormonal fluctuations:

Pattern 1: Perimenstrual (C1)

When it occurs: The three days before menstruation begins through to the first three days of the period (days -3 to +3).

Why it happens: Just before menstruation, progesterone levels drop sharply while oestrogen remains relatively stable. This sudden change in the hormone ratio can increase seizure susceptibility.

Most common pattern: This is the most frequently observed form of catamenial epilepsy.

Pattern 2: Ovulatory (C2)

When it occurs: Days 10 to 15 of the cycle, corresponding with ovulation.

Why it happens: Oestrogen surges at ovulation, creating a temporary spike in neuronal excitability.

Less common: Fewer women experience this pattern, but it is well-documented.

Pattern 3: Luteal Phase (C3)

When it occurs: From day 10 through to three days before the next period begins.

Why it happens: During the second half of the cycle (luteal phase), progesterone should rise. In some cycles—particularly anovulatory cycles where no egg is released—progesterone levels remain inadequate. This creates an extended period of oestrogen dominance.

Variable pattern: This pattern tends to occur in cycles where ovulation does not happen.

Some women may experience more than one pattern, or patterns may shift over time.

How to Track Seizure Patterns

Identifying catamenial epilepsy requires careful record-keeping over at least two to three menstrual cycles. Healthcare professionals look for a pattern showing at least a two-fold increase in seizure frequency during vulnerable phases compared to other times in the cycle.

Information to Record

To help establish whether a pattern exists, track:

• Seizure details: Date, time, type, duration, and severity
• Menstrual cycle: First day of each period
• Cycle day: Number each day of your cycle (day 1 = first day of bleeding)
• Other factors: Sleep quality, stress levels, missed anti-seizure medications (ASMs), alcohol consumption

Methods of Tracking

• Paper diary: A simple calendar or seizure diary works well for many people
• Apps: Several epilepsy apps allow combined tracking of seizures and menstrual cycles
• Spreadsheet: Some women find visual patterns easier to spot in a spreadsheet format

Bring this information to neurology appointments. Clear documentation over multiple cycles provides valuable evidence when discussing treatment adjustments.

Treatment Approaches

If a clear catamenial pattern is established, several treatment approaches may be considered. All decisions should be made in consultation with a neurologist.

Anti-Seizure Medication Adjustments

Some neurologists may recommend:

• Temporary dose increases: Raising the dose of current anti-seizure medications (ASMs) during high-risk days
• Intermittent additional medication: Adding a short-acting ASM such as clobazam during vulnerable phases
• Medication timing changes: Adjusting when daily medications are taken to optimise levels during high-risk periods

Hormone-Based Approaches

For some women, hormone therapy may be explored:

• Progesterone supplementation: Natural progesterone taken during the luteal phase has shown benefit for some women
• Contraceptive options: Certain hormonal contraceptives that suppress ovulation or stabilise hormone levels may reduce seizure clustering
• Medroxyprogesterone: Injectable contraception that eliminates periods entirely may help some women

Hormone therapy requires careful consideration, as some anti-seizure medications (ASMs) can reduce the effectiveness of hormonal contraception. Any hormone-based treatment must be coordinated between the neurologist and GP or gynaecologist.

Lifestyle Factors

While not treatments in themselves, certain practices may help reduce overall seizure risk:

• Consistent sleep: Maintaining regular sleep patterns, particularly during vulnerable cycle phases
• Stress management: Stress can be a seizure trigger, and many women report increased stress around menstruation
• Medication adherence: Never miss doses of prescribed anti-seizure medications (ASMs)

When to Discuss This With Your Neurologist

Consider raising catamenial epilepsy with your specialist if:

• You notice seizures consistently cluster around your period
• Seizure frequency varies noticeably throughout your cycle
• You have documented patterns over at least two to three cycles
• Your seizures have become harder to control since starting or stopping hormonal contraception
• You are planning pregnancy and want to understand hormone-related seizure changes

Come prepared with your tracking records. Documented patterns provide clearer evidence than memory alone.

Safety Planning

If catamenial patterns are confirmed, practical safety planning becomes especially important during high-risk days:

• Inform close contacts: Let family, housemates, or colleagues know about your higher-risk periods
• Adjust activities: Consider avoiding high-risk activities (swimming, using heavy machinery, cooking at the hob) during vulnerable days
• Rescue medication planning: Ensure anyone who may need to administer rescue medication knows when you are at higher risk
• Sleep prioritisation: Protect sleep quality even more carefully during these times

Catamenial Epilepsy Across Life Stages

Hormone-related seizure patterns can change significantly across a woman’s life:

• Adolescence: Patterns may emerge when menstruation begins or stabilise as cycles become regular
• Reproductive years: Patterns may shift with pregnancy, postpartum, or changes in contraception
• Perimenopause and menopause: Changing hormone levels can alter or eliminate catamenial patterns

Regular review with a neurologist ensures treatment remains appropriate as these changes occur.

Key Points to Remember

• Catamenial epilepsy describes seizures that cluster around specific menstrual cycle phases
• Three recognised patterns exist, linked to hormonal fluctuations
• Tracking seizures alongside cycle information over multiple months is essential for diagnosis
• Treatment options include anti-seizure medication (ASM) adjustments and hormone-based approaches
• All treatment decisions should be made in consultation with a neurologist
• Safety planning during high-risk days is an important practical measure

Understanding the relationship between your menstrual cycle and seizures can help you work with your healthcare team to optimise seizure management throughout the month.

If you notice patterns emerging, keep detailed records and bring them to your next neurology appointment. Clear documentation supports informed discussions about the most appropriate treatment approach for your individual circumstances.