Pharmacokinetics of d- and l-norfenfluramine following their administration as individual enantiomers in rats.

The effect of fenfluramine and norfenfluramine enantiomers in rodent seizure models and their correlation with the pharmacokinetics of d- and l-fenfluramine in rats have been reported recently. To complement these findings, we investigated the pharmacokinetics of d- and l- norfenfluramine in rat plasma and brain. Sprague-Dawley rats were injected intraperitoneally with 20 mg/kg and 1 mg/kg l- norfenfluramine. A 1 mg/kg dose of d-norfenfluramine was used because higher doses caused severe toxicity. The concentration of each enantiomer in plasma and brain was determined at different time points by liquid chromatography/mass spectrometry. Pharmacokinetic parameters were compared between norfenfluramine enantiomers, and with those reported previously for fenfluramine enantiomers after a 20 mg/kg, i.p., dose. All enantiomers were absorbed rapidly and eliminated, with half-lives ranging from 0.9 h (l-fenfluramine) to 6.1 h (l- norfenfluramine, 20 mg/kg) in plasma, and from 3.6 h (d-fenfluramine) to 8.0 h (l-fenfluramine) in brain. Brain-to-plasma concentration ratios ranged from 15.4 (d-fenfluramine) to 27.6 (d-norfenfluramine), indicating extensive brain penetration. The fraction of d- and l-fenfluramine metabolized to norfenfluramine was estimated to be close to unity. This work is part of ongoing investigations to determine the potential value of developing enantiomerically pure l-fenfluramine or l-norfenfluramine as follow-up compounds to the marketed racemic fenfluramine.

Effect of drug treatment changes and seizure outcomes on depression and suicidality in adults with drug-resistant focal epilepsy.

OBJECTIVE: To investigate changes in depressive and suicidality status and their relationship with seizure outcomes after the addition or substitution of another antiseizure medication (ASM) in adults with drug-resistant focal epilepsy. METHODS: Seven hundred seventy consecutively enrolled patients were assessed and followed prospectively for seizure outcome and depressive status over a 6-month period after starting treatment with a newly introduced ASM. The Neurological Disorders Depression Inventory for Epilepsy (NDDIE) was used to screen for depression and suicidality. Correlations of NDDIE results with clinical and treatment-related variables were assessed by using a stepwise logistic regression model. RESULTS: At baseline, 50% of patients had a positive screening test result for depression and 13% had a positive screening test result for suicidal ideation. A psychiatric comorbidity at baseline was associated with a 2.3 times increased risk of an initially negative NDDIE screening result becoming positive at re-assessment after 6 months. In addition, the number of ASMs taken at baseline correlated with an increased risk of a change in depression screening test results from negative to positive during follow-up, whereas no association was identified with sociodemographic and epilepsy-related variables, including seizure outcomes. Approximately 6% of patients who were initially negative at screening for suicidal ideation became positive at the 6-month re-assessment. The risk of switch from a negative to a positive screening test result for suicidal ideation was increased more than two-fold in individuals who screened positive for depression at baseline, and was unrelated to the type of ASM introduced, sociodemographic variables, or seizure outcomes. SIGNIFICANCE: Almost 1 in 5 adults with drug-resistant focal epilepsy who screen negative for depression become positive when re-assessed 6 months after a treatment change. At re-assessment 6 months later, 6.1% who screen initially negative for passive suicidal ideation become positive. These changes in screening status are independent of type of ASM introduced or seizure outcomes but correlate with psychiatric status at baseline.

Progress report on new medications for seizures and epilepsy: A summary of the 17th Eilat Conference on New Antiepileptic Drugs and Devices (EILAT XVII). I. Drugs in preclinical and early clinical development.

For >30 years, the Eilat Conference on New Antiepileptic Drugs and Devices has provided a forum for the discussion of advances in the development of new therapies for seizures and epilepsy. The EILAT XVII conference took place in Madrid, Spain, on May 5-8, 2024. Participants included basic scientists and clinical investigators from industry and academia, other health care professionals, and representatives from lay organizations. We summarize in this article information on treatments in preclinical and in early clinical development discussed at the conference. These include AMT-260, a gene therapy designed to downregulate the expression of Glu2K subunits of kainate receptors, in development for the treatment of drug-resistant seizures associated with mesial temporal sclerosis; BHV-7000, a selective activator of heteromeric Kv7.2/7.3 potassium channels, in development for the treatment of focal epilepsy; ETX101, a recombinant adeno-associated virus serotype 9 designed to increase NaV1.1 channel density in inhibitory γ-aminobutyric acidergic (GABAergic) neurons, in development for the treatment of SCN1A-positive Dravet syndrome; GAO-3-02, a compound structurally related to synaptamide, which exerts antiseizure activity at least in part through an action on cannabinoid type 2 receptors; LRP-661, a structural analogue of cannabidiol, in development for the treatment of seizures associated with Lennox-Gastaut syndrome, Dravet syndrome, and tuberous sclerosis complex; OV329, a selective inactivator of GABA aminotransferase, in development for the treatment of drug-resistant seizures; PRAX-628, a functionally selective potent sodium channel modulator with preference for the hyperexcitable state of sodium channels, in development for the treatment of focal seizures; RAP-219, a selective negative allosteric modulator of transmembrane α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor regulatory protein γ-8, in development for the treatment of focal seizures; and rozanolixizumab, a humanized anti-neonatal Fc receptor monoclonal antibody, in development for the treatment of LGI1 autoimmune encephalitis. Treatments in more advanced development are summarized in Part II of this report.

Progress report on new medications for seizures and epilepsy: A summary of the 17th Eilat Conference on New Antiepileptic Drugs and Devices (EILAT XVII). II. Drugs in more advanced clinical development.

The 17th Eilat Conference on New Antiepileptic Drugs and Devices took place in Madrid, Spain on May 5-8, 2024. As usual, the core part of the conference consisted of presentations on investigational drugs at various stages of development for epilepsy-related indications. Summaries of information on compounds in preclinical or early clinical development are included in an accompanying publication (Part I). In this article, we provide summaries for five compounds in more advanced clinical development, i.e. compounds for which some information on antiseizure activity in individuals with epilepsy is available. These investigational treatments include azetukalner (XEN1101), a potent, KV7.2/7.3-specific potassium channel opener in development for the treatment of focal seizures, generalized tonic-clonic seizures, and major depressive disorder; bexicaserin (LP352), a selective 5-HT2C receptor superagonist in development for the treatment of seizures associated with developmental and epileptic encephalopathies; radiprodil, a selective negative allosteric modulator of NR2B subunit-containing N-methyl-D-aspartate glutamate receptors, in development for the treatment of seizures and behavior manifestations associated with disorders caused by gain-of-function mutations in the GRIN1, -2A, -2B, or -2D genes; soticlestat (TAK-935), a selective inhibitor of cholesterol 24-hydroxylase in development for the treatment of seizures associated with Dravet syndrome and Lennox-Gastaut syndrome; and STK-001, an antisense oligonucleotide designed to upregulate Nav1.1 protein expression and improve outcomes in individuals with Dravet syndrome. The diversity in mechanisms of action of these agents illustrates different approaches being pursued in the discovery of novel treatments for seizures and epilepsy. For two of the compounds discussed in this report (azetukalner and soticlestat), clinical evidence of efficacy has already been obtained in a randomized placebo-controlled adjunctive-therapy trial. For the other compounds, adequately powered placebo-controlled efficacy trials have not been completed to date.

Call for the use of the ILAE terminology for seizures and epilepsies by health care professionals and regulatory agencies to benefit patients and caregivers.

The International League Against Epilepsy (ILAE) introduced a classification for seizure types in 2017 and updated the classification for epilepsy syndromes in 2022. These classifications aim to improve communication among healthcare professionals and help patients better describe their condition. So far, regulatory agencies have used different terminology. This paper stresses the crucial need for consistently adopting ILAE terminology in both regulatory processes and clinical practice. It highlights how language plays a significant role in healthcare communication and how standardized terminology can enhance patient comprehension. The ongoing review of guidelines by regulatory bodies offers a timely opportunity. Aligning regulatory terminologies holds the potential to facilitate discussions on future drug development and harmonize practices across diverse regions, ultimately fostering improved care and research outcomes in epilepsy treatment.

Which terms should be used to describe medications used in the treatment of seizure disorders? An ILAE position paper.

A variety of terms, such as "antiepileptic," "anticonvulsant," and "antiseizure" have been historically applied to medications for the treatment of seizure disorders. Terminology is important because using terms that do not accurately reflect the action of specific treatments may result in a misunderstanding of their effects and inappropriate use. The present International League Against Epilepsy (ILAE) position paper used a Delphi approach to develop recommendations on English-language terminology applicable to pharmacological agents currently approved for treating seizure disorders. There was consensus that these medications should be collectively named "antiseizure medications". This term accurately reflects their primarily symptomatic effect against seizures and reduces the possibility of health care practitioners, patients, or caregivers having undue expectations or an incorrect understanding of the real action of these medications. The term "antiseizure" to describe these agents does not exclude the possibility of beneficial effects on the course of the disease and comorbidities that result from the downstream effects of seizures, whenever these beneficial effects can be explained solely by the suppression of seizure activity. It is acknowledged that other treatments, mostly under development, can exert direct favorable actions on the underlying disease or its progression, by having "antiepileptogenic" or "disease-modifying" effects. A more-refined terminology to describe precisely these actions needs to be developed.

Development of an International Standard Set of Outcomes and Measurement Methods for Routine Practice for Adults with Epilepsy: The International Consortium for Health Outcomes Measurement Consensus Recommendations.

At present, there is no internationally accepted set of core outcomes or measurement methods for epilepsy clinical practice. Therefore, the International Consortium for Health Outcomes Measurement (ICHOM) convened an international working group of experts in epilepsy, people with epilepsy and their representatives to develop minimum sets of standardized outcomes and outcomes measurement methods for clinical practice that support patient-clinician decision-making and quality improvement. Consensus methods identified 20 core outcomes. Measurement tools were recommended based on their evidence of strong clinical measurement properties, feasibility, and cross-cultural applicability. The essential outcomes included many non-seizure outcomes: anxiety, depression, suicidality, memory and attention, sleep quality, functional status, and the social impact of epilepsy. The proposed set will facilitate the implementation of the use of patient-centered outcomes in daily practice, ensuring holistic care. They also encourage harmonization of outcome measurement, and if widely implemented should reduce the heterogeneity of outcome measurement, accelerate comparative research, and facilitate quality improvement efforts.

Development of an International Standard Set of Outcomes and Measurement Methods for Routine Practice for Infants, Children, and Adolescents with Epilepsy: The International Consortium for Health Outcomes Measurement Consensus Recommendations.

At present, there is no internationally accepted set of core outcomes or measurement methods for epilepsy clinical practice. The International Consortium for Health Outcomes Measurement (ICHOM) convened an international working group of experts in epilepsy, people with epilepsy, and their representatives to develop minimum sets of standardized outcomes and outcome measurement methods for clinical practice. Using modified Delphi consensus methods with consecutive rounds of online voting over 12 months, a core set of outcomes and corresponding measurement tool packages to capture the outcomes were identified for infants, children, and adolescents with epilepsy. Consensus methods identified 20 core outcomes. In addition to the outcomes identified for the ICHOM Epilepsy adult standard set, behavioral, motor, and cognitive/language development outcomes were voted as essential for all infants and children with epilepsy. The proposed set of outcomes and measurement methods will facilitate the implementation of the use of patient-centered outcomes in daily practice.

Safe delivery, perinatal outcomes and breastfeeding in women with epilepsy.

Safe delivery and optimal peripartum and postpartum care in women with epilepsy (WWE) is a major concern which has received limited attention in recent years. A diagnosis of epilepsy per se is not an indication for a planned cesarean section or induction of labor, even though epidemiological studies indicate that cesarean delivery is more common among WWE compared to the general population. Pregnancy in WWE is associated with an increased risk of obstetrical complications and increased perinatal morbidity and mortality, and these risks may be greater among WWE taking ASMs. Wherever feasible, pregnant WWE should be directed to specialist care. Risk minimization includes, when appropriate, dose adjustment to compensate for pregnancy-related changes in the pharmacokinetics of some ASMs. With respect to postpartum management, WWE should be advised that the benefits of breastfeeding outweigh the small risk of adverse drug reactions in the infant.

Stereoselective Analysis of the Antiseizure Activity of Fenfluramine and Norfenfluramine in Mice: Is l-Norfenfluramine a Better Follow-Up Compound to Racemic-Fenfluramine?

The aim of this study was to investigate the comparative antiseizure activity of the l-enantiomers of d,l-fenfluramine and d,l-norfenfluramine and to evaluate the relationship between their concentration in plasma and brain and anticonvulsant activity. d,l-Fenfluramine, d,l-norfenfluramine and their individual enantiomers were evaluated in the mouse maximal electroshock seizure (MES) test. d,l-Fenfluramine, d,l-norfenfluramine and their individual l-enantiomers were also assessed in the DBA/2 mouse audiogenic seizure model. All compounds were administered intraperitoneally. Brain and plasma concentrations of the test compounds in DBA/2 mice were quantified and correlated with anticonvulsant activity. In the MES test, fenfluramine, norfenfluramine and their enantiomers showed comparable anticonvulsant activity, with ED50 values between 5.1 and 14.8 mg/kg. In the audiogenic seizure model, l-norfenfluramine was 9 times more potent than d,l-fenfluramine and 15 times more potent than l-fenfluramine based on ED50 (1.2 vs. 10.2 and 17.7 mg/kg, respectively). Brain concentrations of all compounds were about 20-fold higher than in plasma. Based on brain EC50 values, l-norfenfluramine was 7 times more potent than d,l-fenfluramine and 13 times more potent than l-fenfluramine (1940 vs. 13,200 and 25,400 ng/g, respectively). EC50 values for metabolically formed d,l-norfenfluramine and l-norfenfluramine were similar to brain EC50 values of the same compounds administered as such, suggesting that, in the audiogenic seizure model, the metabolites were responsible for the antiseizure activity of the parent compounds. Because of the evidence linking d-norfenfluramine to d,l-fenfluramine to cardiovascular and metabolic adverse effects, their l-enantiomers could potentially be safer follow-up compounds to d,l-fenfluramine. We found that, in the models tested, the activity of l-fenfluramine and l-norfenfluramine was comparable to that of the corresponding racemates. Based on the results in DBA/2 mice and other considerations, l-norfenfluramine appears to be a particularly attractive candidate for further evaluation as a novel, enantiomerically pure antiseizure medication.

Comparative activity of the enantiomers of fenfluramine and norfenfluramine in rodent seizure models, and relationship with their concentrations in plasma and brain.

OBJECTIVES: To investigate the comparative antiseizure activity of the individual enantiomers of fenfluramine and its major active primary metabolite norfenfluramine in rodent seizure models, and its relationship with the pharmacokinetics of these compounds in plasma and brain. METHODS: The antiseizure potency of d,l-fenfluramine (racemic fenfluramine) was compared with the respective potencies of its individual enantiomers and the individual enantiomers of norfenfluramine using the maximal electroshock (MES) test in rats and mice, and the 6-Hz 44 mA test in mice. Minimal motor impairment was assessed simultaneously. The time course of seizure protection in rats was compared with the concentration profiles of d-fenfluramine, l-fenfluramine, and their primary active metabolites in plasma and brain. RESULTS: All compounds tested were active against MES-induced seizures in rats and mice after acute (single-dose) administration, but no activity against 6-Hz seizures was found even at doses up to 30 mg/kg. Estimates of median effective doses (ED50 ) in the rat-MES test were obtained for all compounds except for d-norfenfluramine, which caused dose-limiting neurotoxicity. Racemic fenfluramine had approximately the same antiseizure potency as its individual enantiomers. Both d- and l-fenfluramine were absorbed and distributed rapidly to the brain, suggesting that seizure protection at early time points (≤2 h) was related mainly to the parent compound. Concentrations of all enantiomers in brain tissue were >15-fold higher than those in plasma. SIGNIFICANCE: Although there are differences in antiseizure activity and pharmacokinetics among the enantiomers of fenfluramine and norfenfluramine, all compounds tested are effective in protecting against MES-induced seizures in rodents. In light of the evidence linking the d-enantiomers to cardiovascular and metabolic adverse effects, these data suggest that l-fenfluramine and l-norfenfluramine are potentially attractive candidates for a chiral switch approach leading to development of a novel, enantiomerically-pure antiseizure medication.

Should antiseizure medications be withdrawn after an extended period of seizure freedom in individuals with adult-onset epilepsy?

Unlike several epilepsies with onset in pediatric age, adult-onset epilepsies do not typically have a time course that is predictably self-remitting in the large majority of people. Still, about one-half of individuals with adult-onset epilepsy who have been seizure-free for an extended period (two years or longer) on antiseizure medications (ASMs) will remain in remission when their drug therapy is discontinued. Although a number of predictors of outcome have been identified (including specific adult-onset syndromes associated with a low probability of spontaneous remission), in most cases, the only way to establish whether the epilepsy has remitted in a given individual is to gradually withdraw ASMs. ASM withdrawal can be beneficial, particularly when the currently used treatment is not well tolerated, or could lead to adverse outcomes in the future (i.e., teratogenic effects should pregnancy occur in a female of childbearing potential). However, the risks associated with ASM withdrawal are significant. Relapse of seizures can have major adverse psychosocial consequences and also may carry a risk of morbidity and mortality. Most importantly, evidence suggests that in about 20% of individuals whose seizure relapsed following ASM withdrawal, re-institution of pharmacological therapy may not readily restore seizure control. Ultimately, management decisions should prioritize the preference of the well-informed person with epilepsy. Particularly, when adverse drug effects are a concern, options to be discussed should include not only withdrawal or continuation of the current treatment but also dose reduction or substitution with a different ASM.

Proposal for reference values for the developmental effects of valproate based on human data using a benchmark dose approach.

Following accidental release of valproate into ambient air during manufacture at a French production site in 2018, concerns were raised for inhabitants of the surrounding area. As no toxicological reference value (TRV) was available, the risks could not be properly assessed. The French Agency for Food, Environmental and Occupational Health and Safety (ANSES) was mandated to determine a TRV by inhalation to be used for risk assessment. Major congenital malformations (MCMs) in offsprings of mothers exposed to valproate during pregnancy have been reported in international scientific literature. As these adverse effects were the most sensitive effect identified, they were retained as the critical effect to be used for the TRV. The data from a robust registry on MCMs established by the International Registry of Antiepileptic Drugs and Pregnancy (EURAP) were modellized and support a strong DRR between the prevalence of MCMs in the fetus and in utero exposure. A benchmark dose (BMD) was then calculated as the dose that may trigger a 5% increase in this risk. A lower 95% confidence limit (BMD5%L95%) of 2.26 mg/kg/day, leading to an oral TRV of 0.08 mg/kg/day and a respiratory TRV of 0.26 mg.m-3 after applying an uncertainty factor of 30, was determined.

Progress report on new antiepileptic drugs: A summary of the Sixteenth Eilat Conference on New Antiepileptic Drugs and Devices (EILAT XVI): I. Drugs in preclinical and early clinical development.

The Eilat Conferences have provided a forum for discussion of novel treatments of epilepsy among basic and clinical scientists, clinicians, and representatives from regulatory agencies as well as from the pharmaceutical industry for 3 decades. Initially with a focus on pharmacological treatments, the Eilat Conferences now also include sessions dedicated to devices for treatment and monitoring. The Sixteenth Eilat Conference on New Antiepileptic Drugs and Devices (EILAT XVI) was held in Madrid, Spain, on May 22-25, 2022 and was attended by 157 delegates from 26 countries. As in previous Eilat Conferences, the core of EILAT XVI consisted of a sequence of sessions where compounds under development were presented and discussed. This progress report summarizes preclinical and, when available, phase 1 clinical data on five different investigational compounds in preclinical or early clinical development, namely GAO-3-02, GRT-X, NBI-921352 (formerly XEN901), OV329, and XEN496 (a pediatric granular formulation of retigabine/ezogabine). Overall, the data presented in this report illustrate novel strategies for developing antiseizure medications, including an interest in novel molecular targets, and a trend to pursue potential new treatments for rare and previously neglected severe epilepsy syndromes.

Progress report on new antiepileptic drugs: A summary of the Sixteenth Eilat Conference on New Antiepileptic Drugs and Devices (EILAT XVI): II. Drugs in more advanced clinical development.

The Sixteenth Eilat Conference on New Antiepileptic Drugs and Devices (EILAT XVI) was held in Madrid, Spain on May 22-25, 2022 and was attended by 157 delegates from 26 countries representing basic and clinical science, regulatory agencies, and pharmaceutical industries. One day of the conference was dedicated to sessions presenting and discussing investigational compounds under development for the treatment of seizures and epilepsy. The current progress report summarizes recent findings and current knowledge for seven of these compounds in more advanced clinical development for which either novel preclinical or patient data are available. These compounds include bumetanide and its derivatives, darigabat, ganaxolone, lorcaserin, soticlestat, STK-001, and XEN1101. Of these, ganaxolone was approved by the US Food and Drug Administration in March 2022 for the treatment of seizures associated with cyclin-dependent kinase-like 5 deficiency disorder in patients 2 years of age and older.

ILAE classification and definition of epilepsy syndromes with onset in neonates and infants: Position statement by the ILAE Task Force on Nosology and Definitions.

The International League Against Epilepsy (ILAE) Task Force on Nosology and Definitions proposes a classification and definition of epilepsy syndromes in the neonate and infant with seizure onset up to 2 years of age. The incidence of epilepsy is high in this age group and epilepsy is frequently associated with significant comorbidities and mortality. The licensing of syndrome specific antiseizure medications following randomized controlled trials and the development of precision, gene-related therapies are two of the drivers defining the electroclinical phenotypes of syndromes with onset in infancy. The principal aim of this proposal, consistent with the 2017 ILAE Classification of the Epilepsies, is to support epilepsy diagnosis and emphasize the importance of classifying epilepsy in an individual both by syndrome and etiology. For each syndrome, we report epidemiology, clinical course, seizure types, electroencephalography (EEG), neuroimaging, genetics, and differential diagnosis. Syndromes are separated into self-limited syndromes, where there is likely to be spontaneous remission and developmental and epileptic encephalopathies, diseases where there is developmental impairment related to both the underlying etiology independent of epileptiform activity and the epileptic encephalopathy. The emerging class of etiology-specific epilepsy syndromes, where there is a specific etiology for the epilepsy that is associated with a clearly defined, relatively uniform, and distinct clinical phenotype in most affected individuals as well as consistent EEG, neuroimaging, and/or genetic correlates, is presented. The number of etiology-defined syndromes will continue to increase, and these newly described syndromes will in time be incorporated into this classification. The tables summarize mandatory features, cautionary alerts, and exclusionary features for the common syndromes. Guidance is given on the criteria for syndrome diagnosis in resource-limited regions where laboratory confirmation, including EEG, MRI, and genetic testing, might not be available.

Methodology for classification and definition of epilepsy syndromes with list of syndromes: Report of the ILAE Task Force on Nosology and Definitions.

Epilepsy syndromes have been recognized for >50 years, as distinct electroclinical phenotypes with therapeutic and prognostic implications. Nonetheless, no formally accepted International League Against Epilepsy (ILAE) classification of epilepsy syndromes has existed. The ILAE Task Force on Nosology and Definitions was established to reach consensus regarding which entities fulfilled criteria for an epilepsy syndrome and to provide definitions for each syndrome. We defined an epilepsy syndrome as "a characteristic cluster of clinical and electroencephalographic features, often supported by specific etiological findings (structural, genetic, metabolic, immune, and infectious)." The diagnosis of a syndrome in an individual with epilepsy frequently carries prognostic and treatment implications. Syndromes often have age-dependent presentations and a range of specific comorbidities. This paper describes the guiding principles and process for syndrome identification in both children and adults, and the template of clinical data included for each syndrome. We divided syndromes into typical age at onset, and further characterized them based on seizure and epilepsy types and association with developmental and/or epileptic encephalopathy or progressive neurological deterioration. Definitions for each specific syndrome are contained within the corresponding position papers.

ILAE definition of the Idiopathic Generalized Epilepsy Syndromes: Position statement by the ILAE Task Force on Nosology and Definitions.

In 2017, the International League Against Epilepsy (ILAE) Classification of Epilepsies described the "genetic generalized epilepsies" (GGEs), which contained the "idiopathic generalized epilepsies" (IGEs). The goal of this paper is to delineate the four syndromes comprising the IGEs, namely childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy, and epilepsy with generalized tonic-clonic seizures alone. We provide updated diagnostic criteria for these IGE syndromes determined by the expert consensus opinion of the ILAE's Task Force on Nosology and Definitions (2017-2021) and international external experts outside our Task Force. We incorporate current knowledge from recent advances in genetic, imaging, and electroencephalographic studies, together with current terminology and classification of seizures and epilepsies. Patients that do not fulfill criteria for one of these syndromes, but that have one, or a combination, of the following generalized seizure types: absence, myoclonic, tonic-clonic and myoclonic-tonic-clonic seizures, with 2.5-5.5 Hz generalized spike-wave should be classified as having GGE. Recognizing these four IGE syndromes as a special grouping among the GGEs is helpful, as they carry prognostic and therapeutic implications.

International League Against Epilepsy classification and definition of epilepsy syndromes with onset in childhood: Position paper by the ILAE Task Force on Nosology and Definitions.

The 2017 International League Against Epilepsy classification has defined a three-tier system with epilepsy syndrome identification at the third level. Although a syndrome cannot be determined in all children with epilepsy, identification of a specific syndrome provides guidance on management and prognosis. In this paper, we describe the childhood onset epilepsy syndromes, most of which have both mandatory seizure type(s) and interictal electroencephalographic (EEG) features. Based on the 2017 Classification of Seizures and Epilepsies, some syndrome names have been updated using terms directly describing the seizure semiology. Epilepsy syndromes beginning in childhood have been divided into three categories: (1) self-limited focal epilepsies, comprising four syndromes: self-limited epilepsy with centrotemporal spikes, self-limited epilepsy with autonomic seizures, childhood occipital visual epilepsy, and photosensitive occipital lobe epilepsy; (2) generalized epilepsies, comprising three syndromes: childhood absence epilepsy, epilepsy with myoclonic absence, and epilepsy with eyelid myoclonia; and (3) developmental and/or epileptic encephalopathies, comprising five syndromes: epilepsy with myoclonic-atonic seizures, Lennox-Gastaut syndrome, developmental and/or epileptic encephalopathy with spike-and-wave activation in sleep, hemiconvulsion-hemiplegia-epilepsy syndrome, and febrile infection-related epilepsy syndrome. We define each, highlighting the mandatory seizure(s), EEG features, phenotypic variations, and findings from key investigations.

International League Against Epilepsy classification and definition of epilepsy syndromes with onset at a variable age: position statement by the ILAE Task Force on Nosology and Definitions.

The goal of this paper is to provide updated diagnostic criteria for the epilepsy syndromes that have a variable age of onset, based on expert consensus of the International League Against Epilepsy Nosology and Definitions Taskforce (2017-2021). We use language consistent with current accepted epilepsy and seizure classifications and incorporate knowledge from advances in genetics, electroencephalography, and imaging. Our aim in delineating the epilepsy syndromes that present at a variable age is to aid diagnosis and to guide investigations for etiology and treatments for these patients.