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Journal of Neurology Aug 2017This paper reviews advances in epilepsy in recent years with an emphasis on therapeutics and underlying mechanisms, including status epilepticus, drug and surgical... (Review)
Review
This paper reviews advances in epilepsy in recent years with an emphasis on therapeutics and underlying mechanisms, including status epilepticus, drug and surgical treatments. Lessons from rarer epilepsies regarding the relationship between epilepsy type, mechanisms and choice of antiepileptic drugs (AED) are explored and data regarding AED use in pregnancy are reviewed. Concepts evolving towards a move from treating seizures to treating epilepsy are discussed, both in terms of the mechanisms of epileptogenesis, and in terms of epilepsy's broader comorbidity, especially depression.
Topics: Animals; Epilepsy; Humans
PubMed: 28120042
DOI: 10.1007/s00415-017-8394-2 -
Epilepsia Apr 2017The International League Against Epilepsy (ILAE) Classification of the Epilepsies has been updated to reflect our gain in understanding of the epilepsies and their...
The International League Against Epilepsy (ILAE) Classification of the Epilepsies has been updated to reflect our gain in understanding of the epilepsies and their underlying mechanisms following the major scientific advances that have taken place since the last ratified classification in 1989. As a critical tool for the practicing clinician, epilepsy classification must be relevant and dynamic to changes in thinking, yet robust and translatable to all areas of the globe. Its primary purpose is for diagnosis of patients, but it is also critical for epilepsy research, development of antiepileptic therapies, and communication around the world. The new classification originates from a draft document submitted for public comments in 2013, which was revised to incorporate extensive feedback from the international epilepsy community over several rounds of consultation. It presents three levels, starting with seizure type, where it assumes that the patient is having epileptic seizures as defined by the new 2017 ILAE Seizure Classification. After diagnosis of the seizure type, the next step is diagnosis of epilepsy type, including focal epilepsy, generalized epilepsy, combined generalized, and focal epilepsy, and also an unknown epilepsy group. The third level is that of epilepsy syndrome, where a specific syndromic diagnosis can be made. The new classification incorporates etiology along each stage, emphasizing the need to consider etiology at each step of diagnosis, as it often carries significant treatment implications. Etiology is broken into six subgroups, selected because of their potential therapeutic consequences. New terminology is introduced such as developmental and epileptic encephalopathy. The term benign is replaced by the terms self-limited and pharmacoresponsive, to be used where appropriate. It is hoped that this new framework will assist in improving epilepsy care and research in the 21st century.
Topics: Epilepsy; Humans; International Agencies; Terminology as Topic
PubMed: 28276062
DOI: 10.1111/epi.13709 -
Current Opinion in Neurology Apr 2017Epilepsy genetics is shifting from the academic pursuit of gene discovery to a clinical discipline based on molecular diagnosis and stratified medicine. We consider the... (Review)
Review
PURPOSE OF REVIEW
Epilepsy genetics is shifting from the academic pursuit of gene discovery to a clinical discipline based on molecular diagnosis and stratified medicine. We consider the latest developments in epilepsy genetics and review how gene discovery in epilepsy is influencing the clinical classification of epilepsy and informing new therapeutic approaches and drug discovery.
RECENT FINDINGS
Recent studies highlighting the importance of mutation in GABA receptors, NMDA receptors, potassium channels, G-protein coupled receptors, mammalian target of rapamycin pathway and chromatin remodeling are discussed. Examples of precision medicine in epilepsy targeting gain-of-function mutations in KCNT1, GRIN2A, GRIN2D and SCN8A are presented. Potential reasons for the paucity of examples of precision medicine for loss-of-function mutations or in non-ion channel epilepsy genes are explored. We highlight how systems genetics and gene network analyses have suggested that pathways disrupted in epilepsy overlap with those of other neurodevelopmental traits including human cognition. We review how network-based computational approaches are now being applied to epilepsy drug discovery.
SUMMARY
We are living in an unparalleled era of epilepsy gene discovery. Advances in clinical care from this progress are already materializing through improved clinical diagnosis and stratified medicine. The application of targeted drug repurposing based on single gene defects has shown promise for epilepsy arising from gain-of-function mutations in ion-channel subunit genes, but important barriers remain to translating these approaches to non-ion channel epilepsy genes and loss-of-function mutations. Gene network analysis offers opportunities to discover new pathways for epilepsy, to decipher epilepsy's relationship to other neurodevelopmental traits and to frame a new approach to epilepsy drug discovery.
Topics: Animals; Epilepsy; Genetic Association Studies; Humans; Mutation; Phenotype; Potassium Channels
PubMed: 28212175
DOI: 10.1097/WCO.0000000000000433 -
The Indian Journal of Medical Research Nov 2016Epilepsy is a highly prevalent chronic neurologic disorder and leads to social, behavioural, health and economic consequences. 'Treatment gap' varies from 10 per cent in... (Review)
Review
Epilepsy is a highly prevalent chronic neurologic disorder and leads to social, behavioural, health and economic consequences. 'Treatment gap' varies from 10 per cent in developed countries to 75 per cent in low-income countries. Stigma and discrimination related to epilepsy are prevalent worldwide. Electroencephalography (EEG) is considered the most important tool for evaluating the patient with epilepsy. Video-EEG monitoring is an important tool for confirming the seizure type and estimating the epileptogenic zone in the brain. Neuroimaging evaluation is important to determine the aetiology of the epilepsies. Genetic testing has increased the probability of identifying the causes of some types of epilepsies. Epilepsy can be treated in an affordable way with low-cost medications. Refractory epilepsies occur in approximately one-third of recently diagnosed patients with epilepsy. For this group of patients, there are options of surgical treatment, diets and neurostimulation to improve seizure control and quality of life. In poorly organized societies, there is a lack of prioritization of epilepsy in national health policies, limited resources for trained personnel and a shortage of basic antiepileptic medications. There is evidence of improvement in the understanding of epilepsy and a clear progress in the management of epileptic seizures in recent times.
Topics: Anticonvulsants; Electroencephalography; Epilepsy; Humans; Seizures
PubMed: 28361817
DOI: 10.4103/ijmr.IJMR_1051_16 -
Brain : a Journal of Neurology Nov 2022Brain voltage-gated sodium channel NaV1.1 (SCN1A) loss-of-function variants cause the severe epilepsy Dravet syndrome, as well as milder phenotypes associated with...
Brain voltage-gated sodium channel NaV1.1 (SCN1A) loss-of-function variants cause the severe epilepsy Dravet syndrome, as well as milder phenotypes associated with genetic epilepsy with febrile seizures plus. Gain of function SCN1A variants are associated with familial hemiplegic migraine type 3. Novel SCN1A-related phenotypes have been described including early infantile developmental and epileptic encephalopathy with movement disorder, and more recently neonatal presentations with arthrogryposis. Here we describe the clinical, genetic and functional evaluation of affected individuals. Thirty-five patients were ascertained via an international collaborative network using a structured clinical questionnaire and from the literature. We performed whole-cell voltage-clamp electrophysiological recordings comparing sodium channels containing wild-type versus variant NaV1.1 subunits. Findings were related to Dravet syndrome and familial hemiplegic migraine type 3 variants. We identified three distinct clinical presentations differing by age at onset and presence of arthrogryposis and/or movement disorder. The most severely affected infants (n = 13) presented with congenital arthrogryposis, neonatal onset epilepsy in the first 3 days of life, tonic seizures and apnoeas, accompanied by a significant movement disorder and profound intellectual disability. Twenty-one patients presented later, between 2 weeks and 3 months of age, with a severe early infantile developmental and epileptic encephalopathy and a movement disorder. One patient presented after 3 months with developmental and epileptic encephalopathy only. Associated SCN1A variants cluster in regions of channel inactivation associated with gain of function, different to Dravet syndrome variants (odds ratio = 17.8; confidence interval = 5.4-69.3; P = 1.3 × 10-7). Functional studies of both epilepsy and familial hemiplegic migraine type 3 variants reveal alterations of gating properties in keeping with neuronal hyperexcitability. While epilepsy variants result in a moderate increase in action current amplitude consistent with mild gain of function, familial hemiplegic migraine type 3 variants induce a larger effect on gating properties, in particular the increase of persistent current, resulting in a large increase of action current amplitude, consistent with stronger gain of function. Clinically, 13 out of 16 (81%) gain of function variants were associated with a reduction in seizures in response to sodium channel blocker treatment (carbamazepine, oxcarbazepine, phenytoin, lamotrigine or lacosamide) without evidence of symptom exacerbation. Our study expands the spectrum of gain of function SCN1A-related epilepsy phenotypes, defines key clinical features, provides novel insights into the underlying disease mechanisms between SCN1A-related epilepsy and familial hemiplegic migraine type 3, and identifies sodium channel blockers as potentially efficacious therapies. Gain of function disease should be considered in early onset epilepsies with a pathogenic SCN1A variant and non-Dravet syndrome phenotype.
Topics: Humans; Arthrogryposis; Epilepsies, Myoclonic; Epilepsy; Gain of Function Mutation; Migraine with Aura; Movement Disorders; NAV1.1 Voltage-Gated Sodium Channel; Phenotype; Spasms, Infantile; Infant, Newborn; Infant
PubMed: 35696452
DOI: 10.1093/brain/awac210 -
Epilepsy & Behavior : E&B Jul 2022Dravet Syndrome is a genetic epileptic syndrome characterized by severe and intractable seizures associated with cognitive, motor, and behavioral impairments. The... (Review)
Review
Dravet Syndrome is a genetic epileptic syndrome characterized by severe and intractable seizures associated with cognitive, motor, and behavioral impairments. The disease is also linked with increased mortality mainly due to sudden unexpected death in epilepsy. Over 80% of cases are due to a de novo mutation in one allele of the SCN1A gene, which encodes the α-subunit of the voltage-gated ion channel Na1.1. Dravet Syndrome is usually refractory to antiepileptic drugs, which only alleviate seizures to a small extent. Viral, non-viral genetic therapy, and gene editing tools are rapidly enhancing and providing new platforms for more effective, alternative medicinal treatments for Dravet syndrome. These strategies include gene supplementation, CRISPR-mediated transcriptional activation, and the use of antisense oligonucleotides. In this review, we summarize our current knowledge of novel genetic therapies that are currently under development for Dravet syndrome.
Topics: Epilepsies, Myoclonic; Epilepsy; Epileptic Syndromes; Humans; Mutation; NAV1.1 Voltage-Gated Sodium Channel; Seizures; Spasms, Infantile
PubMed: 35653814
DOI: 10.1016/j.yebeh.2022.108741 -
International Journal of Molecular... Oct 2020Epilepsy, a neurological disease characterized by recurrent seizures, is highly heterogeneous in nature. Based on the prevalence, epilepsy is classified into two types:... (Review)
Review
Epilepsy, a neurological disease characterized by recurrent seizures, is highly heterogeneous in nature. Based on the prevalence, epilepsy is classified into two types: common and rare epilepsies. Common epilepsies affecting nearly 95% people with epilepsy, comprise generalized epilepsy which encompass idiopathic generalized epilepsy like childhood absence epilepsy, juvenile myoclonic epilepsy, juvenile absence epilepsy and epilepsy with generalized tonic-clonic seizure on awakening and focal epilepsy like temporal lobe epilepsy and cryptogenic focal epilepsy. In 70% of the epilepsy cases, genetic factors are responsible either as single genetic variant in rare epilepsies or multiple genetic variants acting along with different environmental factors as in common epilepsies. Genetic testing and precision treatment have been developed for a few rare epilepsies and is lacking for common epilepsies due to their complex nature of inheritance. Precision medicine for common epilepsies require a panoramic approach that incorporates polygenic background and other non-genetic factors like microbiome, diet, age at disease onset, optimal time for treatment and other lifestyle factors which influence seizure threshold. This review aims to comprehensively present a state-of-art review of all the genes and their genetic variants that are associated with all common epilepsy subtypes. It also encompasses the basis of these genes in the epileptogenesis. Here, we discussed the current status of the common epilepsy genetics and address the clinical application so far on evidence-based markers in prognosis, diagnosis, and treatment management. In addition, we assessed the diagnostic predictability of a few genetic markers used for disease risk prediction in individuals. A combination of deeper endo-phenotyping including pharmaco-response data, electro-clinical imaging, and other clinical measurements along with genetics may be used to diagnose common epilepsies and this marks a step ahead in precision medicine in common epilepsies management.
Topics: DNA Copy Number Variations; Epilepsy; Epilepsy, Absence; Epilepsy, Generalized; Genetic Markers; Humans; Pharmacogenomic Testing; Precision Medicine; Prognosis; Seizures; Time Factors
PubMed: 33096746
DOI: 10.3390/ijms21207784 -
Seizure Apr 2020In clinical practice, the diagnosis of focal vs generalized epilepsy dictates the management of the patient. The distinction between generalized and focal epilepsy is at... (Review)
Review
In clinical practice, the diagnosis of focal vs generalized epilepsy dictates the management of the patient. The distinction between generalized and focal epilepsy is at times imperfect and some epilepsies have features that fall in between these two extremes. An example is the occurrence of focal interictal and focal ictal abnormalities in generalized epilepsies. As a part of the special issue on "The epileptogenic zone in pediatric epilepsy surgery", this focused narrative review will discuss different focal abnormalities seen in generalized epilepsy. An overlap of focal and generalized epileptiform abnormalities may support a continuum between focal and generalized epilepsy. When evaluating patients in the "gray zone", other factors such as ictal semiology, neuroimaging, genetic testing and functional deficits may need to be considered to reach an accurate diagnosis. Being aware of possible occurrence of focal clinical and EEG features in generalized epilepsy will help clinicians select more preferred AED (s), avoiding potential iatrogenic side effects and inappropriate consideration for epilepsy surgery.
Topics: Adult; Child; Electroencephalography; Epilepsies, Partial; Epilepsy, Generalized; Female; Humans; Male
PubMed: 31882201
DOI: 10.1016/j.seizure.2019.12.013 -
Revue Neurologique Mar 2015Surgical removal of the epileptogenic zone provides an effective therapy for several focal epileptic syndromes. This surgery offers the opportunity to study pathological... (Review)
Review
Surgical removal of the epileptogenic zone provides an effective therapy for several focal epileptic syndromes. This surgery offers the opportunity to study pathological activity in living human tissue for pharmacoresistant partial epilepsy syndromes including temporal lobe epilepsies with hippocampal sclerosis, cortical dysplasias, epilepsies associated with tumors and developmental malformations. Slices of tissue from patients with these syndromes retain functional neuronal networks and may generate epileptic activities. The properties of cells in this tissue may not be greatly changed, but excitatory synaptic transmission is often enhanced and GABAergic inhibition is preserved. Typically epileptic activity is not generated spontaneously by the neocortex, whether dysplastic or not, but can be induced by convulsants. The initiation of ictal discharges in the neocortex depends on both GABAergic signaling and increased extracellular potassium. In contrast, a spontaneous interictal-like activity is generated by tissues from patients with temporal lobe epilepsies associated with hippocampal sclerosis. This activity is initiated, not in the hippocampus but in the subiculum, an output region, which projects to the entorhinal cortex. Interictal events seem to be triggered by GABAergic cells, which paradoxically excite about 20% of subicular pyramidal cells while simultaneously inhibiting the majority. Interictal discharges thus depend on both GABAergic and glutamatergic signaling. The depolarizing effects of GABA depend on a pathological elevation in levels of chloride in some subicular cells, similar to those of developmentally immature cells. Such defect is caused by a perturbed expression of the cotransporters regulating intracellular chloride concentration, the importer NKCC1 and the extruder KCC2. Blockade of NKCC1 actions by the diuretic bumetanide restores intracellular chloride and thus hyperpolarizing GABAergic actions and consequently suppressing interictal activity.
Topics: Epilepsy; Hippocampus; Humans; Neurons; Seizures
PubMed: 25724711
DOI: 10.1016/j.neurol.2015.01.563 -
Brain : a Journal of Neurology Oct 2021Epilepsies of early childhood are frequently resistant to therapy and often associated with cognitive and behavioural comorbidity. Aetiology focused precision medicine,...
Epilepsies of early childhood are frequently resistant to therapy and often associated with cognitive and behavioural comorbidity. Aetiology focused precision medicine, notably gene-based therapies, may prevent seizures and comorbidities. Epidemiological data utilizing modern diagnostic techniques including whole genome sequencing and neuroimaging can inform diagnostic strategies and therapeutic trials. We present a 3-year, multicentre prospective cohort study, involving all children under 3 years of age in Scotland presenting with epilepsies. We used two independent sources for case identification: clinical reporting and EEG record review. Capture-recapture methodology was then used to improve the accuracy of incidence estimates. Socio-demographic and clinical details were obtained at presentation, and 24 months later. Children were extensively investigated for aetiology. Whole genome sequencing was offered for all patients with drug-resistant epilepsy for whom no aetiology could yet be identified. Multivariate logistic regression modelling was used to determine associations between clinical features, aetiology, and outcome. Three hundred and ninety children were recruited over 3 years. The adjusted incidence of epilepsies presenting in the first 3 years of life was 239 per 100 000 live births [95% confidence interval (CI) 216-263]. There was a socio-economic gradient to incidence, with a significantly higher incidence in the most deprived quintile (301 per 100 000 live births, 95% CI 251-357) compared with the least deprived quintile (182 per 100 000 live births, 95% CI 139-233), χ2 odds ratio = 1.7 (95% CI 1.3-2.2). The relationship between deprivation and incidence was only observed in the group without identified aetiology, suggesting that populations living in higher deprivation areas have greater multifactorial risk for epilepsy. Aetiology was determined in 54% of children, and epilepsy syndrome was classified in 54%. Thirty-one per cent had an identified genetic cause for their epilepsy. We present novel data on the aetiological spectrum of the most commonly presenting epilepsies of early childhood. Twenty-four months after presentation, 36% of children had drug-resistant epilepsy (DRE), and 49% had global developmental delay (GDD). Identification of an aetiology was the strongest determinant of both DRE and GDD. Aetiology was determined in 82% of those with DRE, and 75% of those with GDD. In young children with epilepsy, genetic testing should be prioritized as it has the highest yield of any investigation and is most likely to inform precision therapy and prognosis. Epilepsies in early childhood are 30% more common than previously reported. Epilepsies of undetermined aetiology present more frequently in deprived communities. This likely reflects increased multifactorial risk within these populations.
Topics: Causality; Child, Preschool; Cohort Studies; Drug Resistant Epilepsy; Epilepsy; Female; Follow-Up Studies; Humans; Infant; Infant, Newborn; Male; Prospective Studies; Retrospective Studies; Scotland; Socioeconomic Factors
PubMed: 34687210
DOI: 10.1093/brain/awab162