Seizure precipitants and inhibiting factors in mesial temporal lobe epilepsy

Exploring shared triggers and potential etiopathogenesis between migraine and idiopathic/genetic epilepsy: Insights from a multicenter tertiary-based study

INTRODUCTION

Migraine and epilepsy are two episodic disorders that share common pathophysiological mechanisms. The aim of our research was to assess the possible shared etiopathogenesis by analyzing the relations of headache, and seizure triggers, based on information obtained from a national cohort surveying the headache characteristics of 809 patients who had been diagnosed with idiopathic/genetic epilepsy.

MATERIAL AND METHODS

Our study utilized data from a multi-center, nationwide investigation of headaches in 809 patients with idiopathic/genetic epilepsy. Out of these, 508 patients reported complaints related to any type of headache (333 Migraines, 175 Headaches of other types). In the initial phase of the study encompassing the entire sample of 809 epilepsy patients, differences in seizure triggers were assessed between the migraine group (n = 333) and the non-migraine group (n = 476). Additionally, the subsequent part of the study pertains to a subgroup of the entire patient group, namely those affected by all types of headaches (n = 508), and differences in headache triggers were assessed among migraine patients (n = 333) and those with other types of headaches (n = 175). Similar differences were observed between epilepsy patients with and without a family history of epilepsy.

RESULTS

The most frequently reported seizure triggers in all I/GE group (n = 809) were stress (23%), sleep deprivation (22%) and fatigue (18%), respectively. The most frequently reported headache triggers in migraine patients were stress (31%), sleep deprivation (28%), and noise (26%). The occurrence of menstruation-triggered seizures in individuals with migraine and I/GE was found to be considerably higher than those without migraine. The most common triggers for seizure and headache among the individuals with a positive family history of epilepsy were determined to be light stimuli and sleep deprivation.

CONCLUSION

In conclusion, our study provides valuable insights into the overlapping triggers including sleep patterns, stress levels, and menstrual cycles, etc. and potential shared etiology of migraine and I/GE. Recognizing these connections may facilitate the development of more precise therapeutic strategies and underscore the significance of adopting a holistic, multidisciplinary approach to the management of these intricate neurological conditions. Further research is essential to explore in greater depth the shared mechanisms underpinning these associations and their implications for clinical practice.

Perceptions of Modulatory Factors in Migraine and Epilepsy: A Multicenter Study

Background: Migraine and epilepsy are both common episodic disorders, typically precipitated or inhibited by some modulatory factors (MFs). Objective: To assess the self-perception of MFs in patients with migraine (PWM) compared to patients with epilepsy (PWE) with a standardized protocol in different countries. Methods: Transcultural multicenter comparative cross-sectional study. All consecutive patients who fulfilled the ICHD-3 criteria for migraine and ILAE's criteria for epilepsy, with at least 1 year of follow-up were interviewed with a semi-structured questionnaire on clinical and epidemiological data and were asked to identify all experienced MFs from a provided list. Results: A total of 608 individuals were surveyed at five university referral centers in Brazil, Guatemala, Lithuania and Turkey. Two hundred and nineteen (91.6%) PWM and 305 (82.7%) PWE identified attack precipitating factors (PFs; p < 0.001). The most frequent three PFs reported by epilepsy patients were: "lack of sleep" (56.6%), "emotional stress" (55.3%), "negative feelings" (53.9%), while among migraine patients "emotional stress" (81.6%), "lack of sleep" (77.8%), "negative feelings" (75.7%) were cited. Inhibitory factors (IFs) for the episodes were reported by 68 (28.5%) PWM and 116 (31.4%) PWE. "Darkness" was the most common one, described by 35.6% of PWM whereas "positive feelings" reported by 10.6% of PWE. Most MFs are concordant across the countries but some transcultural differences were noted. Conclusion: The MFs of migraine and epilepsy attacks and their varying frequencies according to different countries were investigated with the same standardized questionnaire, for the first time. MFs were recognized very often in both migraine and epilepsy cohorts, but in distinct disease-specific prevalence, being more frequent in migraine. Recognition of self-perceived MFs may be helpful for the management of both illnesses.

Behavioral and EEGraphic Characterization of the Anticonvulsant Effects of the Predator Odor (TMT) in the Amygdala Rapid Kindling, a Model of Temporal Lobe Epilepsy

Background: Clinical and experimental evidence indicates that olfactory stimulation modulates limbic seizures, either blocking or inducing ictal activity.

Objective: We aim to evaluate the behavioral and electroencephalographic (EEGraphic) effects of dihydro-2,4,5-trimethylthiazoline (TMT) olfactory exposure on limbic seizures induced by amygdala rapid kindling (ARK).

Materials and Methods: Wistar male rats (280–300 g) underwent stereotaxic surgery for electrode implantation in piriform cortex (PC), hippocampal formation (HIP), and amygdaloid complex (AMYG). Part of the animals was exposed to a saturated chamber with water or TMT, while others had ARK and olfactory exposure prior to the 21st stimulus. Behavioral responses were measured by traditional seizure severity scales (Racine and Pinel and Rovner) and/or by sequential analysis/neuroethology. The electrographic activity of epileptogenic limbic networks was quantified by the occurrence of the first and second EEG afterdischarges, comparing the 1st and 21st stimulus. The spectral analysis [Fast Fourier Transform (FFT)] of the first afterdischarge was performed at the 21st stimulus.

Results: TMT olfactory exposure reduced the seizure severity in kindled rats, altering the displayed behavioral sequence. Moreover, TMT decreased the occurrence of first and second afterdischarges, at the 21st stimulus, and altered the spectral features.

Conclusions: Both behavioral and EEGraphic evaluations indicated that TMT, a potent molecule with strong biological relevance, in fact, “predator odor,” suppressed the epileptiform activity in limbic networks.

How are results of EEG activation procedures associated with patient perception of seizure provocative factors? A single-center cross-sectional pilot study

PURPOSE

The purpose of this study was to examine the relationship between subjectively perceived seizure provocative factors or inhibitors and objectively recorded changes in epileptiform activity (EA) during EEG activation procedures.

MATERIAL AND METHODS

Consenting epilepsy patients (≥18 years old) were asked to complete a questionnaire by indicating whether items on a list provoke, inhibit or have no effect on their seizures. A scalp EEG was recorded afterwards to evaluate baseline epileptiform activity and its change (increase/decrease in frequency) during a set of activation procedures. These included hyperventilation, intermittent photic stimulation (IPS), eye-closing/eye-opening, tasks of reading aloud in a native and a foreign language, solving a Rubik's cube and crossing-out letters. We used correlation and multiple regression analysis to search for associations between the sum of self-reported provocative/inhibiting items and changes in EA.

RESULTS

Of the 90 patients recruited 75 (83.3%) indicated at least one seizure provocative factor. Sleep deprivation, emotional stress, negative emotions and alcohol use were most frequently selected as provoking seizures. Positive feelings, focused thinking, mental calculation and exercising were the most predominant seizure inhibitors. EEG data revealed a weak, but statistically significant correlation with the sum of items in distinct questionnaire groups (0.20 ≤ Spearman's ρ ≤ 0.39). Sensory stimuli (olfactory, gustatory, auditory and visual), cognitive phenomena (thoughts and feelings) and substance use were found to be significantly correlated with EEG results by being self-reported as both provoking and inhibiting seizures. A statistically significant relationship was also found between the increase in EA while reading aloud in a native language and the number of physiological states (sleep deprivation, stress etc.) indicated as provoking seizures (Spearman's ρ = 0.320, P = 0.005). A suitable stepwise multiple regression model was feasible for this finding (F(3, 71) = 7.396, P < 0.001, adjusted R squared = 0.206) with the additional inclusion of EA change during IPS and epilepsy type as explanatory variables.

CONCLUSION

Our pilot study indicates that there is a previously non-explored association between patients' self-perception of seizure provocative/inhibiting factors and objectively recorded changes in epileptiform activity during activation EEGs. Distinct EEG tests might be useful in activating ictogenic networks that are sensitive to indirect influence by hormonal, emotional or diurnally variable factors.

Hyperthermia-induced seizures followed by repetitive stress are associated with age-dependent changes in specific aspects of the mouse stress system

Stress is among the most frequently self-reported factors provoking epileptic seizures in children and adults. It is still unclear, however, why some people display stress-sensitive seizures and others do not. Recently, we showed that young epilepsy patients with stress-sensitive seizures exhibit a dysregulated hypothalamic-pituitary-adrenal (HPA)-axis. Most likely, this dysregulation gradually develops, and is triggered by stressors occurring early in life (early-life stress [ELS]). ELS may be particularly impactful when overlapping with the period of epileptogenesis. To examine this in a controlled and prospective manner, the present study investigated the effect of repetitive variable stressors or control treatment between postnatal day (PND) 12 and 24 in male mice exposed on PND10 to hyperthermia (HT)-induced prolonged seizures (control: normothermia). A number of peripheral and central indices of HPA-axis activity were evaluated at pre-adolescent and young adult age (ie, at PND25 and 90, respectively). At PND25 but not at PND90, body weight gain and absolute as well as relative (to body weight) thymus weight were reduced by ELS (vs control), whereas relative adrenal weight was enhanced, confirming the effectiveness of the stress treatment. Basal and stress-induced corticosterone levels were unaffected, though, by ELS at both ages. HT by itself did not affect any of these peripheral markers of HPA-axis activity, nor did it interact with ELS. However, centrally we did observe age-specific interaction effects of HT and ELS with regard to hippocampal glucocorticoid receptor mRNA expression, neurogenesis with the immature neurone marker doublecortin and the number of hilar (ectopic) granule cells using Prox1 staining. This lends some support to the notion that exposure to repetitive stress after HT-induced seizures may dysregulate central components of the stress system in an age-dependent manner. Such dysregulation could be one of the mechanisms conferring higher vulnerability of individuals with epilepsy to develop seizures in the face of stress.

Seizure-precipitating factors in dogs with idiopathic epilepsy

Background

Stress, sleep deprivation, and infectious diseases are important seizure‐precipitating factors in human epilepsy patients. However, these factors have not been thoroughly studied in epileptic dogs.

Objective

Seizure‐precipitating factors are common in dogs with idiopathic epilepsy and the occurrence of these factors associate with the dogs' signalment, personality, and epilepsy‐related factors.

Animals

Fifty dogs with diagnosed idiopathic epilepsy from the hospital populations of University Veterinary Teaching Hospital of University of Helsinki and Referral Animal Hospital Aisti.

Methods

In a retrospective cross‐sectional observational study, owners were interviewed about their dogs' possible seizure‐precipitating factors according to a predefined questionnaire. The dogs were identified and selected by searching the medical records of the participating animal hospitals.

Results

The prevalence of seizure‐precipitating factors in the study population was 74% (37/50). The most frequently reported factors included stress‐related situations, sleep deprivation, weather, and hormonal factors. In dogs with focal onset seizures, the number of precipitating factors was 1.9 (95% CI 1.1‐3.4) times higher compared to dogs with generalized seizures.

Conclusions and Clinical Importance

Seizure‐precipitating factors are common in dogs with idiopathic epilepsy, and the nature of these factors is consistent with those of human patients. Aside from antiepileptic medication, acknowledging and avoiding seizure‐precipitating factors could help veterinarians achieve better treatment outcomes.

Who are the individuals diagnosed with epilepsy using the Public Health System in the city of Pelotas, southern Brazil?

The aim of this study was to describe sociodemographic, clinical, behavioral, nutritional, and health-related variables from people with epilepsy. A descriptive observational study was carried out in the city of Pelotas, southern Brazil. Sociodemographic, clinical, behavioral, nutritional, and health-related variables were collected. A univariate analysis was performed, calculating the measures of central tendency for continuous variables and proportions for categorical ones. The sample consisted of 101 people, age ranging from 12 to 75years, mostly male (50.5%) and white (59.4%). Only 37.2% from the sample was employed, and the average income was R$ 788.00 Brazilian Reais (US$ 245.90 at the moment of the interview). From all the subjects, 65.6% was in treatment with monotherapy, 62.9% presented more than 15 seizures during the life, 67.3% showed active epilepsy, 64.6% were physically inactive, 52.5% presented normal body mass index, and 50% showed generalized seizures. The most used antiepileptic drug was the carbamazepine. The average score of depression was 12.6±4.1 points and 34.6% showed severe depressive symptoms (equal or higher than 15 points). The mean score of trait and state anxiety was 12.2±3.6 and 15.1±3.4 points, respectively (ranging from 6 to 24 points). The mean score of quality of life and stress was 63.2±18.2 (ranging from 0 to 100 points) and 21.2±7.1 points (ranging from 0 to 40 points), respectively. Considering the medication side effects, the mean score was 42.4±8.9 points, 38.5% showing high rates (higher than 45 points), and only 16% showing good sleep quality. In conclusion, these results are important to improve understanding of these individuals' disease and to subsidize the specific public policies in countries of low and middle income.

The Wistar Audiogenic Rat (WAR) strain and its contributions to epileptology and related comorbidities: History and perspectives

In the context of modeling epilepsy and neuropsychiatric comorbidities, we review the Wistar Audiogenic Rat (WAR), first introduced to the neuroscience international community more than 25years ago. The WAR strain is a genetically selected reflex model susceptible to audiogenic seizures (AS), acutely mimicking brainstem-dependent tonic-clonic seizures and chronically (by audiogenic kindling), temporal lobe epilepsy (TLE). Seminal neuroethological, electrophysiological, cellular, and molecular protocols support the WAR strain as a suitable and reliable animal model to study the complexity and emergent functions typical of epileptogenic networks. Furthermore, since epilepsy comorbidities have emerged as a hot topic in epilepsy research, we discuss the use of WARs in fields such as neuropsychiatry, memory and learning, neuroplasticity, neuroendocrinology, and cardio-respiratory autonomic regulation. Last, but not least, we propose that this strain be used in "omics" studies, as well as with the most advanced molecular and computational modeling techniques. Collectively, pioneering and recent findings reinforce the complexity associated with WAR alterations, consequent to the combination of their genetically-dependent background and seizure profile. To add to previous studies, we are currently developing more powerful behavioral, EEG, and molecular methods, combined with computational neuroscience/network modeling tools, to further increase the WAR strain's contributions to contemporary neuroscience in addition to increasing knowledge in a wide array of neuropsychiatric and other comorbidities, given shared neural networks. During the many years that the WAR strain has been studied, a constantly expanding network of multidisciplinary collaborators has generated a growing research and knowledge network. Our current and major wish is to make the WARs available internationally to share our knowledge and to facilitate the planning and execution of multi-institutional projects, eagerly needed to contribute to paradigm shifts in epileptology. This article is part of a Special Issue entitled "Genetic and Reflex Epilepsies, Audiogenic Seizures and Strains: From Experimental Models to the Clinic".

Stress as a seizure precipitant: Identification, associated factors, and treatment options

Stress is a common and important seizure precipitant reported by epilepsy patients. Studies to date have used different methodologies to identify relationships between epilepsy and stress. Several studies have identified anxiety, depression, and childhood trauma as being more common in patients with epilepsy who report stress as a seizure precipitant compared to patients with epilepsy who did not identify stress as a seizure precipitant. In one survey study it was found that a majority of patients with stress-triggered seizures had used some type of stress reduction method on their own and, of those who tried this, an even larger majority felt that these methods improved their seizures. Additionally, small to moderate sized prospective trials, including randomized clinical trials, using general stress reduction methods have shown promise in improving outcomes in patients with epilepsy, but results on seizure frequency have been inconsistent. Based on these studies, we recommend that when clinicians encounter patients who report stress as a seizure precipitant, these patients should be screened for a treatable mood disorder. Furthermore, although seizure reduction with stress reduction methods has not been proven in a randomized controlled trial, other important endpoints like quality of life were improved. Therefore, recommending stress reduction methods to patients with epilepsy appears to be a reasonable low risk adjunctive to standard treatments. The current review highlights the need for future research to help further clarify biological mechanisms of the stress-seizure relationship and emphasizes the need for larger randomized controlled trials to help develop evidence based treatment recommendations for our epilepsy patients.

Comparison of precipitating factors for mania and partial seizures: Indicative of shared pathophysiology?

OBJECTIVES

Mania in bipolar disorder (BD) and partial (focal) seizures (PS) arising from the temporal lobes, have a number of similarities. Typically, a chronic course of the disorders is punctuated by acute illness episodes. Common features of episodes may include sensory, perceptual, cognitive and affective changes. Both respond to anticonvulsant treatment. Common mechanisms imputed include neurotransmitters and kindling processes. Further investigation may improve understanding of the occurrence of both mania and PS, casting light on the relevance of temporal lobe mediated processes and pathology. One avenue of investigation is to compare aetiological factors and determine the extent of overlap which may indicate shared brain localization or pathophysiology. Aetiology includes predisposing, precipitating or perpetuating factors. This paper examines the literature on precipitating factors of mania, first or subsequent episode, and of PS in diagnosed epilepsy, which is the second or subsequent seizure, to identify the extent and nature of their overlap.

METHOD

Narrative review based on a literature search of PubMed and Google Scholar.

RESULTS

Precipitating factors for both mania and PS were stress, sleep deprivation, antidepressant medication and, tentatively, emotion. For mania alone, goal-attainment events, spring and summer season, postpartum, and drugs include steroids and stimulants. For PS alone, winter season, menstruation and specific triggers in complex reflex epilepsies. Those not substantiated include lunar phase and menopause. A wide range of chemicals may provoke isolated seizures but by definition epilepsy requires at least two seizures.

CONCLUSIONS

The overlap of precipitating factors in mania and PS imply that common brain processes may contribute to both, consistent with findings from neuroscience research.

Do reflex seizures and spontaneous seizures form a continuum? - triggering factors and possible common mechanisms

Recent changes in the understanding and classification of reflex seizures have fuelled a debate on triggering mechanisms of seizures and their conceptual organization. Previous studies and patient reports have listed extrinsic and intrinsic triggers, albeit their multifactorial and dynamic nature is poorly understood. This paper aims to review literature on extrinsic and intrinsic seizure triggers and to discuss common mechanisms among them. Among self-reported seizure triggers, emotional stress is most frequently named. Reflex seizures are typically associated with extrinsic sensory triggers; however, intrinsic cognitive or proprioceptive triggers have also been assessed. The identification of a trigger underlying a seizure may be more difficult if it is intrinsic and complex, and if triggering mechanisms are multifactorial. Therefore, since observability of triggers varies and triggers are also found in non-reflex seizures, the present concept of reflex seizures may be questioned. We suggest the possibility of a conceptual continuum between reflex and spontaneous seizures rather than a dichotomy and discuss evidence to the notion that to some extent most seizures might be triggered.

Why do seizures occur when they do? Situations perceived to be associated with increased or decreased seizure likelihood in people with epilepsy and intellectual disability

Seizure precipitants are commonly reported in the general population of people with epilepsy. However, there has been little research in this area in people with epilepsy and intellectual disability (ID). We conducted a survey of the situations associated with increased or decreased seizure likelihood in this population. The aim of the research was to identify situations of increased seizure likelihood (SISLs) and situations of decreased seizure likelihood (SDSLs) reported by carers of people with an ID and epilepsy. Three study groups were investigated: two groups comprising individuals with ID associated with a specific genetic diagnosis - Rett syndrome or fragile X syndrome - and one group consisting of individuals with a range of other etiologies. Responses relating to 100 people were received: 44 relating to people with Rett syndrome, 25 to people with fragile X syndrome, and 31 to people whose ID had some other etiologies. Ninety-eight percent of the respondents reported at least one SISL, and 60% reported at least one SDSL. Having more seizure types and greater seizure frequency were associated with a higher number of SISLs reported. The most commonly reported SISLs and SDSLs for each of the three groups are presented. The most common SISL overall was illness, which was reported as an SISL by 71% of the respondents. There was less consensus with regard to SDSLs. These findings provide a greater understanding of when seizures occur in those with ID and epilepsy, with possible implications for adjunctive behavioral management of seizures in those with treatment-refractory epilepsy.

Early life stress in epilepsy: a seizure precipitant and risk factor for epileptogenesis

Stress can influence epilepsy in multiple ways. A relation between stress and seizures is often experienced by patients with epilepsy. Numerous questionnaire and diary studies have shown that stress is the most often reported seizure-precipitating factor in epilepsy. Acute stress can provoke epileptic seizures, and chronic stress increases seizure frequency. In addition to its effects on seizure susceptibility in patients with epilepsy, stress might also increase the risk of epilepsy development, especially when the stressors are severe, prolonged, or experienced early in life. Although the latter has not been fully resolved in humans, various preclinical epilepsy models have shown increased seizure susceptibility in naïve rodents after prenatal and early postnatal stress exposure. In the current review, we first provide an overview of the effects of stress on the brain. Thereafter, we discuss human as well as preclinical studies evaluating the relation between stress, epileptic seizures, and epileptogenesis, focusing on the epileptogenic effects of early life stress. Increased knowledge on the interaction between early life stress, seizures, and epileptogenesis could improve patient care and provide a basis for new treatment strategies for epilepsy.

Seizure precipitants (triggering factors) in patients with epilepsy

AIM

adult epilepsy clinic population: (a) to identify the frequency of seizure precipitants (triggering factors) and their relative frequency in those with psychiatric disorders, and in those in remission or with active epilepsy, differences in frequency with regard to gender, seizure duration, number of drugs taken; (b) to determine which precipitants patients most commonly report; and (c) to identify differences in the distribution of precipitants among generalized, temporal, and extratemporal epilepsies.

METHODS

Consecutive patients attending a tertiary-care epilepsy clinic were prospectively and an open personal interview to identify and characterize seizure precipitants. Information about the epilepsy and clinical characteristics of patients was collected during the interview and from medical records.

RESULTS

Of 104 patients, 97% cited at least one precipitant. Stress, sleep deprivation, and fatigue were the most frequently reported precipitants. Patients with psychological comorbidities reported a greater percentage of seizures with seizure precipitants. Patients with idiopathic generalized epilepsy seemed to be more sensitive to seizures during awakening and sleep deprivation, patients with extratemporal epilepsy reported more frequent seizures during sleep. There were no differences in frequency or type of seizure precipitants with regard to gender, seizure duration or frequency, and the number of antiepileptic drugs taken.

CONCLUSION

The findings may have implications for the better management of epilepsy by increasing a focus on nonpharmacological therapy. The implications of the findings for nosology and causation of epilepsy are also briefly discussed.

Conceptual distinctions between reflex and nonreflex precipitated seizures in the epilepsies: a systematic review of definitions employed in the research literature

Seizure precipitation is a defining characteristic of reflex seizures and epilepsies, but seizure precipitants are also commonly reported for patients with epilepsies not considered to be reflex in nature. This raises the questions of exactly how reflex and nonreflex epilepsies with seizure precipitants are defined, and how these concepts are differentiated from one another in current practice. In this systematic literature review, definitions of reflex seizures, reflex epilepsies, and precipitation in a nonreflex context were extracted from published primary research papers. Content analysis was applied to these definitions to identify their main features, allowing comparisons to be made between definitions of the different concepts. Results indicated that there was little consistency within definitions of a given term, and that although some differences in definition content were found between terms, it was evident that clear defining characteristics to differentiate them from one another were lacking. These findings are discussed in the context of current debates regarding classification of the reflex epilepsies and the extent to which the distinction between reflex and nonreflex epilepsies is a meaningful one. Suggestions are made for how clarity might be increased in ongoing research in this area.

Stress sensitivity of childhood epilepsy is related to experienced negative life events

PURPOSE

To evaluate the effect of stress on seizure frequency in childhood epilepsy, and to assess possible differences between children in whom seizures are precipitated by stress and those in whom they are not.

METHODS

Parents or caregivers of children with active epilepsy (aged 2-16 years) were sent questionnaires on developmental and epilepsy characteristics, life-time stress exposure, and the effect of stressful periods and moments of acute stress on seizure frequency in their child. Further information was extracted from patient files.

KEY FINDINGS

Parents or caregivers of 153 children with a median age of 8.8 years responded to the questionnaires. Thirty-nine percent reported an increase in seizure frequency during periods of stress, with a median increase of 2.5 times the frequency compared to nonstressful periods. Thirty-seven percent reported that seizures were precipitated by acute stress, with stress being a precipitating factor in 33% (median value) of the seizures. Overall, 51% of the patients reported stress sensitivity of seizures. A higher number of negative life events experienced in total life was related to an increase in seizure frequency in stressful periods (odds ratio [OR] 1.3, p = 0.01) as well as to the precipitation of seizures by acute stress (OR 1.3, p = 0.02).

SIGNIFICANCE

Stress sensitivity is reported in half of the children with epilepsy. Results of this study suggest a relation between experienced negative life events and stress sensitivity of childhood epilepsy. One possible explanation could be that experiencing negative life events may cause a larger response to daily stressors, thereby increasing the likelihood to induce epileptic activity.