Circalunar and ultralunar periodicities in women with partial seizures

Female sex steroids and epilepsy: Part 2. A practical and human focus on catamenial epilepsy

Catamenial epilepsy is the best described and most researched sex steroid-specific seizure exacerbation. Yet despite this there are no current evidence-based treatments, nor an accepted diagnostic tool. The best tool we currently have is tracking seizures over menstrual cycles; however, the reality of tracking seizures and menstrual cycles is fraught with challenges. In Part 1 of this two-part review, we outlined the often complex and reciprocal relationship between seizures and sex steroids. An adaptable means of tracking is required. In this review, we outline the extent and limitations of current knowledge on catamenial epilepsy. We use sample data to show how seizure exacerbations can be tracked in short/long and even irregular menstrual cycles. We describe how seizure severity, an often overlooked and underresearched form of catamenial seizure exacerbation, can also be tracked. Finally, given the lack of treatment options for females profoundly affected by catamenial epilepsy, Section 3 focuses on current methods and models for researching sex steroids and seizures as well as limitations and future directions. To permit more informative, mechanism-focused research in humans, the need for both a consistent classification of catamenial epilepsy and an objective biomarker is highlighted.

Cycles in epilepsy

Epilepsy is among the most dynamic disorders in neurology. A canonical view holds that seizures, the characteristic sign of epilepsy, occur at random, but, for centuries, humans have looked for patterns of temporal organization in seizure occurrence. Observations that seizures are cyclical date back to antiquity, but recent technological advances have, for the first time, enabled cycles of seizure occurrence to be quantitatively characterized with direct brain recordings. Chronic recordings of brain activity in humans and in animals have yielded converging evidence for the existence of cycles of epileptic brain activity that operate over diverse timescales: daily (circadian), multi-day (multidien) and yearly (circannual). Here, we review this evidence, synthesizing data from historical observational studies, modern implanted devices, electronic seizure diaries and laboratory-based animal neurophysiology. We discuss advances in our understanding of the mechanistic underpinnings of these cycles and highlight the knowledge gaps that remain. The potential clinical applications of a knowledge of cycles in epilepsy, including seizure forecasting and chronotherapy, are discussed in the context of the emerging concept of seizure risk. In essence, this Review addresses the broad question of why seizures occur when they occur.

Are there effects of lunar cycle on pediatric febrile seizure?: A single-center retrospective study (2005-2018)

BACKGROUND

Several studies have reported an association between seizure and the lunar cycle; however, results are conflicting. Thus, we investigated whether emergency department (ED) visits due to febrile seizure (FS) or FS plus were affected by lunar cycle.

METHODS

We reviewed the medical records of patients who were admitted to the ED with a main diagnosis of FS or FS plus from January 1, 2005 to August 31, 2018 (13 years 8 months), a period of 4991 days with 169 lunar cycles. During that period, we collected weather data such as mean temperature, average atmospheric pressure (AP), and humidity according to lunar phase (new moon, first quarter, full moon, and third or last quarter).

RESULTS

A total of 1979 patients were identified. We found male predominant with a mean age of 2.62 ± 2.09 years. Acute pharyngotonsillitis was the most common cause of fever, generalized tonic-clonic seizure was the most common type of seizure, and the mean peak body temperature was 38.77 ± 0.81 °C. The lunar cycle did not affect the onset or frequency of FS after adjustment; however, several factors, including season, O₃ and NO₂ concentrations, and holidays, were associated with FS.

CONCLUSION

We did not find an association between lunar cycle and FS or FS plus. However, several factors, including season, O₃, NO₂, and holidays were associated with FS or FS plus.

Progesterone receptor activation regulates seizure susceptibility

OBJECTIVE

Progesterone is a potent neuromodulator that exerts effects on the brain through neurosteroids, progesterone receptors (PRs), and other molecules. Whether PR activation regulates seizures is not known. We determined whether PR activation increased seizure susceptibility.

METHODS

Adult female rats that developed epilepsy following lithium-pilocarpine-induced status epilepticus (SE) were used. Seizures were recorded by continuous-video EEG and read by an individual blinded to the treatment of the animals. The animals were treated for a week with progesterone (50 mg/kg per day), and the effect of progesterone withdrawal on seizure frequency was assessed during the subsequent week. During the week of progesterone treatment, the animals were treated with PR antagonist RU-486 (10 mg/kg per day) or a vehicle control, which was administered 30 min before progesterone. In another set of animals, we determined the effect of the PR agonist Nestorone (3 mg/kg per day) on seizure frequency. The animals were treated with Nestorone or vehicle for a week, and seizure frequencies at baseline and during the treatment week were compared.

RESULTS

Progesterone withdrawal induced twofold increase in seizures in 57% of animals (n = 14). RU-486 treatment in combination with progesterone, prevented this increase, and a smaller fraction of animals (17%) experienced withdrawal seizures (n = 13). The specific activation of PRs by Nestorone also increased the seizure frequency. Forty-six percent (n = 14) of Nestorone-treated animals experienced at least a 50% increase in seizures compared to only 9% of the vehicle-treated animals (n = 11).

INTERPRETATION

PR activation increased seizure frequency in epileptic animals. Thus, PRs may be novel targets for treating catamenial epilepsy.

Neurosteroid regulation of GABAA receptors: A role in catamenial epilepsy

The female reproductive hormones progesterone and estrogen regulate network excitability. Fluctuations in the circulating levels of these hormones during the menstrual cycle cause frequent seizures during certain phases of the cycle in women with epilepsy. This seizure exacerbation, called catamenial epilepsy, is a dominant form of drug-refractory epilepsy in women of reproductive age. Progesterone, through its neurosteroid derivative allopregnanolone, increases γ-aminobutyric acid type-A receptor (GABAR)-mediated inhibition in the brain and keeps seizures under control. Catamenial seizures are believed to be a neurosteroid withdrawal symptom, and it was hypothesized that exogenous administration of progesterone to maintain its levels high during luteal phase will treat catamenial seizures. However, in a multicenter, double-blind, phase III clinical trial, progesterone treatment did not suppress catamenial seizures. The expression of GABARs with reduced neurosteroid sensitivity in epileptic animals may explain the failure of the progesterone clinical trial. The expression of neurosteroid-sensitive δ subunit-containing GABARs is reduced, and the expression of α4γ2 subunit-containing GABARs is upregulated, which alters the inhibition of dentate granule cells in epilepsy. These changes reduce the endogenous neurosteroid control of seizures and contribute to catamenial seizures.

Distribution of seizures across the menstrual cycle in women with epilepsy

The purpose of this study was to determine whether seizure frequency and cycle days with seizure occurrence vary across the menstrual cycle. The subjects were the first 100 women with intractable focal onset seizures, 13-45 years old, who completed the baseline phase of the National Institutes of Health (NIH) Progesterone Trial. Each subject recorded seizures and menses during a 3-month baseline phase. Data consisted of (1) seizure numbers for each cycle day and (2) cycle days with seizure occurrence. Statistical comparisons of seizure frequency and days with seizures were performed using generalized estimating equation one-way analysis of variance (ANOVA) and logistic regression followed by pairwise multiple comparisons of days based on the least square means. Seizure numbers and cycle days with seizure occurrence varied across the menstrual cycle. There was an approximately twofold difference between the highest (day 1) and lowest (day -8) values for both seizure frequency and days with occurrence. The demonstration of variation in seizure frequency and cycle days with seizure occurrence across the menstrual cycle, as well as identification of specific days that have substantially higher or lower frequencies than other days, supports the existence of catamenial epilepsy.

Catamenial epilepsy: Update on prevalence, pathophysiology and treatment from the findings of the NIH Progesterone Treatment Trial

PURPOSE

To extend our knowledge and practical application of the concept of catamenial epilepsy.

METHODS

The review focuses on the impact of the NIH Progesterone Trial on our understanding of the pathophysiology and treatment of catamenial epilepsy.

RESULTS

Catamenial epilepsy refers to the cyclic exacerbation of seizures in relation to the menstrual cycle. An interaction between seizures and the menstrual cycle is suggested by variations in seizure frequency according to the day, phase and ovulatory status of the menstrual cycle. There are three commonly recognized patterns: perimenstrual (C1: Day -3 to +3), peri-ovulatory (C2: Day 10 to 3) and entire luteal phase in anovulatory cycles (C3: Day 10 to 3). Pathophysiological determinants include 1) the neuroactive properties of reproductive steroids, 2) the variation of neuroactive steroid levels across the menstrual cycle and 3) the differential susceptibility of epileptic substrates to neuroactive steroid effects. Perimenstrual seizure exacerbation may result from the premenstrual withdrawal of progesterone which is accompanied by withdrawal of allopregnanolone, a potent positive allosteric modulator of the GABAA receptor, and changes in the subunit composition of the GABAA receptor to the α4 subtype which is insensitive to benzodiazepine and GABA. Bioidentical progesterone supplement is no better than placebo in the treatment of women with focal onset epilepsy overall but shows superior efficacy in women whose seizures show robust perimenstrual exacerbation.

CONCLUSION

There is sound evidence for the existence of catamenial epilepsy and class 3 evidence for adjunctive progesterone treatment of the perimenstrually exacerbated subtype.

Neuroendocrine considerations in the treatment of men and women with epilepsy

Complex, multidirectional interactions between hormones, seizures, and the medications used to control them can present a challenge for clinicians treating patients with epilepsy. Many hormones act as neurosteroids, modulating brain excitability via direct binding sites. Thus, changes in endogenous or exogenous hormone levels can affect the occurrence of seizures directly as well as indirectly through pharmacokinetic effects that alter the concentrations of antiepileptic drugs. The underlying structural and physiological brain abnormalities of epilepsy and the metabolic activity of antiepileptic drugs can adversely affect hypothalamic and gonadal functioning. Knowledge of these complex interactions has increased and can now be incorporated in meaningful treatment approaches for men and women with epilepsy.

Diagnosis and management of catamenial seizures: a review

Catamenial epilepsy is defined as a pattern of seizures that changes in severity during particular phases of the menstrual cycle, wherein estrogens are proconvulsant, increasing the neuronal excitability; and progesterone is anticonvulsant, enhancing GABA-mediated inhibition. Thus, changes in serum estradiol/progesterone ratio throughout a normal reproductive cycle bring about an increased or decreased risk of seizure occurrence. To date, there are no specific drug treatments for catamenial epilepsy however, non-hormonal and hormonal therapies have been proposed. The aim of this review is to report preclinical and clinical evidences about the relationship between female reproductive steroids and epileptic seizures, and to describe treatment approaches for catamenial epilepsy.

Variation of seizure frequency with ovulatory status of menstrual cycles

PURPOSE

To determine if seizure frequency differs between anovulatory and ovulatory cycles.

METHODS

The data came from the 3-month baseline phase of an investigation of progesterone therapy for intractable focal onset seizures. Of 462 women who enrolled, 281 completed the 3-month baseline phase and 92 had both anovulatory and ovulatory cycles during the baseline phase. Midluteal progesterone levels ≥5 ng/ml were used to designate cycles as ovulatory. Among the 92 women, average daily seizure frequency (ADSF) for all seizures combined and each type of seizure considered separately (secondary generalized tonic-clonic seizures - 2°GTCS, complex partial seizures - CPS, simple partial seizures - SPS) were compared between anovulatory and ovulatory cycles using paired t-tests. A relationship between the proportional differences in ADSF and estradiol/progesterone (EP) serum level ratios between anovulatory and ovulatory cycles was determined using bivariate correlational analysis.

KEY FINDINGS

ADSF was 29.5% greater for 2°GTCS during anovulatory than during ovulatory cycles. ADSF did not differ significantly for CPS or SPS or for all seizures combined. Proportional differences in anovulatory/ovulatory 2°GTCS ADSF ratios correlated significantly with differences in anovulatory/ovulatory EP ratios. Among the 281 women, the three seizure types did not differ in ovulatory rates, but EP ratios were greater for cycles with 2°GTCS than partial seizures only.

SIGNIFICANCE

Seizure frequency is significantly greater for 2°GTCS, but not CPS or SPS, during anovulatory cycles than ovulatory cycles. Because the proportional increases in 2°GTCS frequency during anovulatory cycles correlate with the proportional increases in EP level ratios, these findings support a possible role for reproductive steroids in 2°GTCS occurrence.

Seizure exacerbation and hormonal cycles in women with epilepsy

PURPOSE

To investigate seizure frequency in relation to menstrual cycles and seizure exacerbations with respect to various clinical factors in women with epilepsy.

METHODS

The authors prospectively evaluated premenopausal women with epilepsy aged 15-44. Catamenial epilepsy was defined as seizure frequency during the perimenstrual (C1), periovulatory (C2) or non-menstrual phase (C3) at least twice that during other phases.

RESULTS

In total 255 menstrual cycles, 231 ovulatory and 24 anovulatory cycles were registered in 79 patients (29.7+/-7.8 years old). Average seizure frequency was 0.13+/-0.29/day during the menstrual phase, 0.14+/-0.24 during the follicular, 0.18+/-0.61 in the ovulatory, and 0.14+/-0.33 during the luteal phases. Catamenial seizure exacerbation was observed in 37/79 (46.8%) patients and 108/255 (42.4%) cycles, more frequently during anovulatory (17/24, 70.8%) than ovulatory (91/231, 39.4%) cycles (p=0.003). During ovulatory cycles, seizure exacerbation was primarily C1 (42.9%) or C2 (45.1%) pattern. Myoclonic seizures were more frequently associated with the C1 pattern.

CONCLUSIONS

Overall, 46.8% of women had catamenial epilepsy. Seizure frequencies were greater during menstrual and ovulatory phases for ovulatory cycles, and during non-menstrual phases for anovulatory cycles.

Laterality and location influence catamenial seizure expression in women with partial epilepsy

OBJECTIVE

The temporal distribution of seizures in women with localization-related epilepsy occurs periodically according to a model "clock" with the peak phase of occurrence corresponding to menstrual onset. The location and laterality of the epileptic lesion as well as patient age may affect periodicity.

METHODS

Baseline data from seizure and menstrual diaries of approximately 3 months duration were obtained from 100 women enrolled in a trial of hormonal therapy for localization-related epilepsy. Durations of individual cycles were normalized to a common menstrual phase and period. Normalized data were then combined to create distributions evaluated by localization (lobar: temporal [TL], extratemporal [XL], multifocal [MF], unknown), lateralization (left, right, bilateral, unknown), and age. Distributions were evaluated with analysis of variance (ANOVA) and curve-fitted by nonlinear least squares cosinor analysis.

RESULTS

A total of 71 patients had TL (left = 25, right = 29, bilateral = 17), 10 XL, 14 MF, and 5 unknown seizure foci. XL and MF seizures occurred randomly across the 28-day cycle. TL seizures (left = 875, right = 706) occurred nonrandomly (ANOVA p = 0.0003) and cyclically with peak occurrence near onset of menses ([value +/- SD] peak = 1.6 +/- 2.3 days, period = 27.0 days). Left-side TL seizures peaked cyclically at onset of menses (ANOVA p = 0.04, peak = 0.0 +/- 3.0 days, period = 30 days); right-side TL seizures occurred randomly. Age did not have a cyclical effect. Women below the median age had a significantly higher seizure rate than those above the median age.

CONCLUSION

Circalunar rhythms of seizures in women, and therefore, possibly strategies of hormonal treatments of catamenial epilepsy, vary with the neuroanatomic substrate of the seizure focus.

Hormonal therapies: progesterone

Seizures do not occur randomly in the majority of people with epilepsy. They tend to cluster. Seizure clusters, in turn, commonly occur with a temporal rhythmicity that shows a readily identifiable and predictable periodicity. When the periodicity of seizure exacerbation in women conforms to that of the menstrual cycle, it is commonly known as catamenial epilepsy. This may be attributable to 1) the neuroactive properties of steroid hormones and 2) the cyclic variation in their serum levels. If hormones play a role in seizure occurrence, hormones may also have a role in treatment. Progesterone has potent GABAergic metabolites that may provide safe and effective seizure control in women who have catamenial epilepsy.