GABAergic inhibition

Pediatric epileptic encephalopathies represent a clinically challenging and often devastating group of disorders that affect children at different stages of infancy and childhood. With the advances in genetic testing and neuroimaging, the etiologies of these epileptic syndromes are now better defined. The various encephalopathies that are reviewed in this article include the following: early infantile epileptic encephalopathy or Ohtahara syndrome, early myoclonic encephalopathy, epilepsy of infancy with migrating focal seizures, West syndrome, severe myoclonic epilepsy in infancy (Dravet syndrome), Landau-Kleffner syndrome, Lennox-Gastaut syndrome, and epileptic encephalopathy with continuous spike-and-wave during sleep. Their clinical features, prognosis as well as underlying genetic etiologies are presented and updated. Semin Pediatr

Pediatric epileptic encephalopathies represent a clinically challenging and often devastating group of disorders that affect children at different stages of infancy and childhood. With the advances in genetic testing and neuroimaging, the etiologies of these epileptic syndromes are now better defined. The various encephalopathies that are reviewed in this article include the following: early infantile epileptic encephalopathy or Ohtahara syndrome, early myoclonic encephalopathy, epilepsy of infancy with migrating focal seizures, West syndrome, severe myoclonic epilepsy in infancy (Dravet syndrome), Landau-Kleffner syndrome, Lennox-Gastaut syndrome, and epileptic encephalopathy with continuous spike-and-wave during sleep. Their clinical features, prognosis as well as underlying genetic etiologies are presented and updated. Semin Pediatr

Anxiety-associated symptoms following acute stress usually become extinct gradually within a period of time. However, the mechanisms underlying how individuals cope with stress to achieve the extinction of anxiety are not clear. Here we show that acute restraint stress causes an increase in the activity of GABAergic neurons in the CeA (GABA CeA ) in male mice, resulting in anxiety-like behaviors within 12 hours; meanwhile, elevated GABA CeA neuronal CX3CL1 secretion via MST4 (mammalian sterile-20-like kinase 4)-NF-κB-CX3CL1 signaling consequently activates microglia in the CeA. Activated microglia in turn inhibit GABA CeA neuronal activity via the engulfment of their dendritic spines, ultimately leading to the extinction of anxiety-like behaviors induced by restraint stress. These findings reveal a dynamic molecular and cellular mechanism in which microglia drive a negative feedback to inhibit GABA CeA neuronal activity, thus facilitating maintenance of brain homeostasis in response to acute stress. Anxiety caused by acute stress is likely an evolutionary adaptation for maintaining heightened vigilance and sustained attention to stimuli that require close attention or for avoiding repeated exposure to dangerous conditions 1-3 . It is well-known that the acute anxiety can gradually become extinct with the removal of stress stimuli. However, in this dynamic extinction process, the mechanisms of how individuals cope with acute stress and drive anxiety extinction to avoid the irreversible effects induced by persistent anxiety are still unclear. Microglia and neurons in the brain can communicate bidirectionally. Upon receiving external stimuli, neurons respond first and mediate a cascade of responses throughout the brain, including modulating the activity of neural immune cells, such as microglia, via secretion of soluble factors (e.g., chemokines, cytokines, and neurotransmitters) 4,5 . As resident macrophages in the brain, microglia perform essential functions required for the maintenance of brain homeostasis, for instance, removing dying neurons, pruning nonfunctional synapses, or producing ligands that support neuronal survival . Microglial activation is also known to participate in triggering anxiety in animal models of chronic stress . Despite several decades of intensive research focusing on neuronal remodeling in the brain after acute or chronic stress, our understanding of the dynamic mechanisms regulating neuron-microglia interactions, and their role in recovery from acute stress-induced anxiety, remains incomplete. Acute or chronic exposure to stress can lead to several longlasting adaptive changes in stress-sensitive brain regions such as the amygdala, which has been shown to undergo radical changes in

Anxiety-associated symptoms following acute stress usually become extinct gradually within a period of time. However, the mechanisms underlying how individuals cope with stress to achieve the extinction of anxiety are not clear. Here we show that acute restraint stress causes an increase in the activity of GABAergic neurons in the CeA (GABACeA) in male mice, resulting in anxiety-like behaviors within 12 hours; meanwhile, elevated GABACeA neuronal CX3CL1 secretion via MST4 (mammalian sterile-20-like kinase 4)-NF-κB-CX3CL1 signaling consequently activates microglia in the CeA. Activated microglia in turn inhibit GABACeA neuronal activity via the engulfment of their dendritic spines, ultimately leading to the extinction of anxiety-like behaviors induced by restraint stress. These findings reveal a dynamic molecular and cellular mechanism in which microglia drive a negative feedback to inhibit GABACeA neuronal activity, thus facilitating maintenance of brain homeostasis in response to acute stress.

Quinidine (QND) is an old antimalarial drug that was used in the early 20th century as an antiarrhythmic agent. Currently, QND is receiving attention for its use in epilepsy of infancy with migrating focal seizures (EIMFS) due to potassium sodium-activated channel subfamily T member 1 (KCNT1) genetic variants. Here, we report the application of Therapeutic Drug Monitoring (TDM) in pediatric patients carrying KCNT1 genetic variants and orally treated with QND for developmental and epileptic encephalopathies (DEE). We measured plasma levels of QND and its metabolite hydroquinidine (H-QND) by using a validated method based on liquid chromatography coupled with mass spectrometry (LC-MS/MS). Three pediatric patients (median age 4.125 years, IQR 2.375–4.125) received increasing doses of QND. Cardiac toxicity was monitored at every dose change. Reduction in seizure frequency ranged from 50 to 90%. Our results show that QND is a promising drug for pediatric patients with DEE due to KCNT1 ge...

Objective: Epilepsy of infancy with migrating focal seizures (EIMFS) is one of the most severe developmental and epileptic encephalopathies. We delineate the genetic causes and genotype-phenotype correlations of a large EIMFS cohort. Methods: Phenotypic and molecular data were analyzed on patients recruited through an international collaborative study. Results: We ascertained 135 patients from 128 unrelated families. 93/135 (69%) had causative variants (42/55 previously reported) across 23 genes, including 9 novel EIMFS genes: de novo dominant GABRA1, GABRB1, ATP1A3; X-linked CDKL5, PIGA; and recessive, ITPA, AIMP1, KARS, WWOX. The most frequently implicated genes were KCNT1 (36/135, 27%) and SCN2A (10/135, 7%). Mosaicism occurred in two probands (SCN2A, GABRB3) and three unaffected mothers (KCNT1). Median age of seizure onset was 4 weeks, with earlier onset in the SCN2A, KCNQ2, and BRAT1 groups. Epileptic spasms occurred in 22% patients. 127 patients had severe to profound developmental impairment. All but 7 patients had ongoing seizures. Additional features included microcephaly, movement disorders, spasticity, and scoliosis. Mortality occurred in 33% at median age 2 years 7 months. Interpretation: We identified a genetic cause in 69% of patients with EIMFS. We highlight the genetic heterogeneity of EIMFS with 9 newly implicated genes, bringing the total number to 33. Mosaicism was observed in probands and parents, carrying critical implications for recurrence risk. EIMFS pathophysiology involves diverse This article is protected by copyright. All rights reserved. molecular processes from gene and protein regulation to ion channel function and solute trafficking.

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...

myoclonic epilepsy, five de novo Lennox-Gastaut syndrome (LGS), four symptomatic LGS and two had symptomatic epilepsy. Three had responded to rufinamide. Compared to the rest, they had no infantile spasms or clonic seizures, and their first seizure was later (2, 3, 4 years). Their learning disabilities were mild without autistic features. Rufinamide was started at earlier age in two with de novo LGS (4, 5 years) with fewer failed AED (3−4). One had complete resolution of DA, the other had one cluster. The third case (symptomatic LGS) commenced on rufinamide later (16 1 / 2 yrs) with less marked improvement (50−70% reduction in DA). Rufinamide had ameliorated other seizure types except their brief nocturnal tonic seizures. The non responders stopped rufinamide after 3 months, no side effects. Conclusion: Use of rufinamide in children with relatively late onset epilepsy is safe and might be more effective with early administration for cessation of DA.

Aim of the study: To determine the effect of VNS therapy on seizure frequency and daily activities in children and adolescents with pharmaco-resistant epilepsy. Patients and Methods: Medical records of 15 patients, who received VNS implantation from 2001 to 2008, were reviewed retrospectively. In January 2009, all families received questionnaire to assess the period before and after VNS. Seizure frequency and the following daily activities were assessed: alertness, interest in play, learning and memory, independency in feeding /drinking, dressing, independency in the bathroom and toilette, the recognition and avoidance of dangerous situations, communication with peers, behaviour and quality of sleep. Results: Age at epilepsy onset ranged from 1 to 12 y, age at VNS implantation from 4 to 25 y. Aetiology of epilepsy was as follows: Lennox Gastaut syndrome (3), large cortical dysplasias (3 cases), mitochondrial (2), cong. CVI (2), remote symptomatic (post-radiation encephalopathy in 2, meningitis in 1) and undetermined in 2 patients. At follow up the 49% seizure frequency reduction (range from 0 to 93%) was reported. Sleep quality improved in 6 and play/communication skills in 5 out of 15 patients. In 3 patients improvement was noticed in learning/memory, unchanged in 8 pts (changes in alertness). Only 2 patients became completely independent in all daily activities. Deterioration in learning was described in 3, presumably due to the progression of the underlying disease itself. Behavioural improvement was observed in 9 patients. Conclusion: The main benefit of VNS therapy was seizures reduction and improvement in sleep could be the result of seizure reduction during sleep. Patients with no change in daily activities had severe neurological and mental handicap before VNS. Overall, VNS therapy has positive effect on daily quality of life.

The syndrome of malignant migrating partial seizures in infancy was first described by Coppola and colleagues in 1995. The International League Against Epilepsy defines this form of epilepsy as a seizure onset in the first 6 months of life, occurrence of almost continuous migrating polymorphous focal seizures, combined with multifocal ictal EEG discharges, and progressive deterioration of psychomotor development. Most cases are pharmacoresistant and have poor outcomes. A lot of publications described the trial of several medications such as Stiripentol, Rufinamide, Cannabidiol, and finally Ketogenic diet, to control the refractory devastating seizures. We describe a 13-month-old girl with malignant migrating partial seizures in infancy who was started on Quinine for the control of her refractory seizures after the trial of multiple antiepileptic medications that failed to control her seizures, including Clonazepam, Carbamazepine, Phenobarbitone, Phyntion, Midazolam, Valproate, Perampanel & Ketogenic diet, all were tried by different combination at different times. Finally, as malignant migrating partial seizures in infancy are sometimes linked to K channelopathy, a trial of Quinine was given in a dose of 30mg/kg/d. Patients showed an excellent response with control of clinical & electrographic seizures. Now she is seizure-free for five months and undergoing physiotherapy. She started rolling over but doesn't have much improvement in motor milestones, is not following or cooing, and is unable to say clear words.

Objectives To analyze the efficacy and safety of Brivaracetam in pediatric patients with epileptic encephalopathy or unresponsive focal epilepsy. Materials & Methods This retrospective study included eight pediatric patients with EE or unresponsive focal epilepsy. Inclusion criteria: (1) ≤14 years, (2) history of refractory epilepsy, (3) at least one month of continuous therapy with BRV, and (4) at least six months of follow-up. Exclusion criteria: (1) variation of concomitant antiepileptic drugs during the previous and/or subsequent four weeks of the BRV introduction, (2) levetiracetam in therapy, (3) epilepsy secondary to the progressive cerebral disease, tumor, or any other progressive neurodegenerative diseases, and (4) a status epilepticus a month before screening or during the baseline period. The efficacy of BRV was defined as ≥50% of seizure frequency reduction at the end of the follow-up, compared to baseline. Results: All patients showed ≥50% seizure frequency reduction, o...

N eonatal convulsions are one of the most common emergency neurological diseases in the neonatal period. Since the potential adverse effects of convulsions on the brain are known, they must be treated urgently. In recent years, many studies have examined the use of anticonvulsant drugs in the newborn period; however, there is currently no standardized treatment protocol for neonatal convulsion management. A convulsion is defined as a transient change in neurological function caused by a sudden, paroxysmal depolarization of a group of neurons. In cases of convulsions seen in the neonatal period, it is important to consider the seriousness of potential underlying diseases, the treatments that might be applied targeted at the etiology, and to remember that repetitive convulsions may have a permanent effect on the brain. [1,2] The frequency of neonatal convulsion has been reported to be 1.5 to 3 in 1000 live births. [3] Pathophysiology Neonates have immature neurons and differences in neurotransmitter levels make them susceptible to seizures. [4] Immature neurons contain a larger number of excitatory N-methyl-D-aspartate and α-amino-3-hydroxy-5-methyl-4isoxazolpropionic acid (AMPA) receptors, and fewer gamma-aminobutyric acid (GABA) receptors, which is one of the reasons for a low convulsion threshold in neonates. In addition, unlike in adults, GABAA receptors in neonates work as excitators through sodium-potassium-chloride cotransporter 1 (NKCC1), which also contributes to a low convulsion threshold. [5] (Fig. 1) In addition, in cases of hypoxia, the NKCC1 channel is upregulated and the convulsion threshold is decreased even more. Neonatal convulsions are one of the most common emergency neurological events in the early period after birth. The frequency has been reported to be 1.5 to 3 in 1000 live births. It has been established that the convulsion threshold is lower in infants due to immature neonatal neurons and differences in neurotransmitters. Hypoxic ischemic encephalopathy is the most common etiology in neonatal convulsions. Other causes vary, and may be related to the level of development of the country. Convulsions are classified into 4 different types according to the clinical findings. The most common is the subtle (undefined) type of seizure; the other types are defined as clonic, tonic, and myoclonic seizures. Non-epileptic paroxysmal movements frequently seen in the neonatal period, should not be confused with seizures. The most common non-epileptic paroxysmal movements are jitteriness, benign neonatal sleep myoclonus, and hyperekplexia. A newborn that experiences convulsions should be hospitalized and monitored with continuous video electroencephalogram, if possible. If an initial rapid evaluation detects an acute metabolic disorder, treatment is provided, and, if warranted, it will be followed by a plan for further treatment with anticonvulsant drugs. Phenobarbital is still currently recommended as first-line therapy, though there are studies of other anticonvulsant drugs. Levetiracetam and phenytoin are commonly used as second-step anticonvulsant drugs. The aim of treatment should be not only to stop acute symptomatic seizures, but also to reduce the risk of brain damage and to minimize the possible negative effects of epilepsy and neurological deficits.

Background: Hemimegalencephaly (HME) is a hamartomatous malformation of one cerebral hemisphere, resulting in refractory epilepsy, intellectual disability, and autistic features. Hemispherectomy is the definitive treatment, but there is risk of high morbidity and mortality, especially when done in early infancy. Various preclinical studies have shown that dysregulation of the mTOR pathway has an integral role in the development of various epilepsy syndromes, including tuberous sclerosis complex (TSC), focal cortical dysplasia and HME. Recently, mTOR inhibitors were proven to be effective in treating seizures in TSC. Methods: We present a case of a 6 day old female with refractory epilepsy despite the trial of 9 anti-seizure medications and the ketogenic diet. As the patient was awaiting epilepsy surgery, an mTOR inhibitor, rapamycin was initiated. Results: After 1 week of the initiation, she had over a 50% reduction in seizures. At two weeks, the parents felt that for the first time...

We read with interest the paper of Kimizu et al. [1] on a patient with Early Onset Epileptic Encephalopathy (EOEE) and de novo mutation in SLC35A2 presenting with tonic partial seizures evolving to infantile spasms and hypsarrhythmia. We recently reported four children with EOEE and variable electroclinical features, including myoclonic and clonic focal seizures followed by tonic-clonic, myoclonic seizures, and infantile spasms, in association with generalized, focal, multifocal, and burst-suppression EEG patterns. Metabolic and genetic analyses led to the diagnosis of four different Congenital Disorders of Glycosylation (CDG): ALG1-CDG, ALG3-CDG, ALG6-CDG, and DPM2-CDG [2]. CDG are a rapidly growing group of genetic defects that will increasingly be diagnosed particularly due to the wider use of NGS techniques (CDG panel analysis, WES, WGS). On the other hand, in infants investigated for epilepsy, alterations of CDG-related genes can be incidentally found. Other N-glycosylation disorders with severe and treatment-resistant epilepsy, besides the above mentioned are ALG2-CDG, ALG8-CDG, ALG9-CDG, ALG11-CDG, ALG12-CDG. Only a few patients are known with each of these CDG. It is important to raise awareness for these rare CDG among child neurologists and epilepsy specialists.

We read with interest the paper of Kimizu et al. [1] on a patient with Early Onset Epileptic Encephalopathy (EOEE) and de novo mutation in SLC35A2 presenting with tonic partial seizures evolving to infantile spasms and hypsarrhythmia. We recently reported four children with EOEE and variable electroclinical features, including myoclonic and clonic focal seizures followed by tonic-clonic, myoclonic seizures, and infantile spasms, in association with generalized, focal, multifocal, and burst-suppression EEG patterns. Metabolic and genetic analyses led to the diagnosis of four different Congenital Disorders of Glycosylation (CDG): ALG1-CDG, ALG3-CDG, ALG6-CDG, and DPM2-CDG [2]. CDG are a rapidly growing group of genetic defects that will increasingly be diagnosed particularly due to the wider use of NGS techniques (CDG panel analysis, WES, WGS). On the other hand, in infants investigated for epilepsy, alterations of CDG-related genes can be incidentally found. Other N-glycosylation disorders with severe and treatment-resistant epilepsy, besides the above mentioned are ALG2-CDG, ALG8-CDG, ALG9-CDG, ALG11-CDG, ALG12-CDG. Only a few patients are known with each of these CDG. It is important to raise awareness for these rare CDG among child neurologists and epilepsy specialists.

Drug-resistant epileptic encephalopathy such as Dravet syndrome presents with autistic symptoms. Three cases with autism spectrum disorder with comorbid Dravet syndrome were assessed. All the cases presented with onset of seizures before a year and with autistic features. The patients responded to a combination of antiepileptic drugs (AEDs), resulting in reduced frequency of seizures and behavioral issues. Contrary to the belief that both epilepsy and use of AEDs have adverse impact on the cognition of children with an early onset of epilepsy, we found improvement in the symptoms of our patients who presented with autism and epilepsy. Primary treatment approaches such as occupational therapy, special education, speech therapy, and behavioral therapy; effective diagnosis of comorbidities such as epilepsy; and aggressive treatment might help with behavioral improvement. Early diagnosis followed by treatment with AEDs can improve seizures, electroencephalography abnormalities, and behavioral problems.

Case introduction: In this work we present a female infant patient with epilepsy of infancy with migrating focal seizures (EIMFS). Although many pharmacological schemes were attempted, she developed an encephalopathy with poor response to antiepileptic drugs and progressive cerebral dysfunction.Aim: To present the pharmacological response and therapeutic drug monitoring of a paediatric patient with a severe encephalopathy carrying a genetic variant in KCNT1 gene, whose identification led to include quinidine (QND) in the treatment regimen as an antiepileptic drug.Case report: Patient showed slow rhythmic activity (theta range) over left occipital areas with temporal propagation and oculo-clonic focal seizures and without tonic spasms three months after birth. At the age of 18 months showed severe impairments of motor and intellectual function with poor eye contact. When the patient was 4 years old, a genetic variant in the exon 24 of the KCNT1 gene was found. This led to the diagnos...

Developmental and epileptic encephalopathies are a heterogeneous group of early-onset epilepsy syndromes dramatically impairing neurodevelopment. Modern genomic technologies have revealed a number of monogenic origins and opened the door to therapeutic hopes. Here we describe a new syndromic developmental and epileptic encephalopathy caused by bi-allelic loss-of-function variants in GAD1, as presented by 11 patients from six independent consanguineous families. Seizure onset occurred in the first 2 months of life in all patients. All 10 patients, from whom early disease history was available, presented with seizure onset in the first month of life, mainly consisting of epileptic spasms or myoclonic seizures. Early EEG showed suppression-burst or pattern of burst attenuation or hypsarrhythmia if only recorded in the post-neonatal period. Eight patients had joint contractures and/or pes equinovarus. Seven patients presented a cleft palate and two also had an omphalocele, reproducing t...

ObjectiveMolecular genetic etiologies in epilepsy have become better understood in recent years, creating important opportunities for precision medicine. Building on these advances, detailed studies of the complexities and outcomes of genetic testing for epilepsy can provide useful insights that inform and refine diagnostic approaches and illuminate the potential for precision medicine in epilepsy.MethodsWe used a multi‐gene next‐generation sequencing (NGS) panel with simultaneous sequence and exonic copy number variant detection to investigate up to 183 epilepsy‐related genes in 9769 individuals. Clinical variant interpretation was performed using a semi‐quantitative scoring system based on existing professional practice guidelines.ResultsMolecular genetic testing provided a diagnosis in 14.9%‐24.4% of individuals with epilepsy, depending on the NGS panel used. More than half of these diagnoses were in children younger than 5 years. Notably, the testing had possible precision medic...

The aim of this study was to evaluate the predictive value of the features of neonatal seizures for pharmacoresistant epilepsy in children. Method: This is a retrospective study that involved all children diagnosed as having epilepsy who had neonatal seizures and who were hospitalized at the Neurology Department of the Mother and Child Healthcare Institute in Belgrade from January the 1st 2017 until December 31st 2017. The following parameters and their impact on the outcome were investigated: perinatal data, the characteristics of epileptic seizures in the neonatal period, and the response to anticonvulsant treatment. The presence of pharmacoresistance was observed as an outcome parameter. Univariate and multivariate logistic regression analyses were used to define predictors of drug-resistant epilepsy. Results: The study involved 55 children, 35 (63.6%) male and 20 (36.4%) female. The average age of the children at the end of the observation period was 5.17 years (min: 0.25, max: 17.75, iqr (interquartile range): 6.92). Pharmacoresistant epilepsy was found in 36 (65.5%) children. The most common type of epilepsy was focal, which affected 30 patients (54.5%), than generalized, which affected 15 patients (27.3%), and combined generalized and focal, which affected 8 patients (14.5%). At the end of the observation period, 28 patients (50.9%) had no seizures, while 14 (25.5%) had daily seizures. It was found that the pharmacoresistant neonatal seizures and metabolic-genetic disorders were predictive factors of the occurrence of pharmacoresistant epilepsy. Conclusion: Patients prone to developing pharmacoresistant epilepsy might be identified as early as the neonatal and early infant period. High incidence of asphyxia cooccurring with established genetic-metabolic disease further emphasizes need for genetic testing in infants with neonatal seizures including in the presence of hypoxicischemic injury.

GABAergic inhibition via local interneurons may play a role in enhancing spike timing precision in principal cells, since it tends to eliminate the influence of initial conditions. However, both the number and the timing of inhibitory synaptic events may be variable across repeated trials. How does this variability affect the spike timing precision in principal neurons ? In this paper, we derive an analytical expression for the spike output jitter as a function of the variability of the received inhibition. This study predicts that variable inhibition is especially tolerated as the number of inhibitory cells is large, which is consistent with experimental data from early olfactory systems (antennal lobe for insects, olfactory bulb for vertebrates).

Identifying individuals with rare epilepsy syndromes in electronic data sources is difficult, in part because of missing codes in the International Classification of Diseases (ICD) system. Our objectives were the following: (1) to describe the representation of rare epilepsies in other medical vocabularies, to identify gaps; and (2) to compile synonyms and associated terms for rare epilepsies, to facilitate text and natural language processing tools for cohort identification and population-based surveillance. We describe the representation of 33 epilepsies in 3 vocabularies: Orphanet, SNOMED-CT, and UMLS-Metathesaurus. We compiled terms via 2 surveys, correspondence with parent advocates, and review of web resources and standard vocabularies. UMLS-Metathesaurus had entries for all 33 epilepsies, Orphanet 32, and SNOMED-CT 25. The vocabularies had redundancies and missing phenotypes. Emerging epilepsies (SCN2A-, SCN8A-, KCNQ2-, SLC13A5-, and SYNGAP-related epilepsies) were underrepresented. Survey and correspondence respondents included 160 providers, 375 caregivers, and 11 advocacy group leaders. Each epilepsy syndrome had a median of 15 (range 6-28) synonyms. Nineteen had associated terms, with a median of 4 (range 1-41). We conclude that medical vocabularies should fill gaps in representation of rare epilepsies to improve their value for epilepsy research. We encourage epilepsy researchers to use this resource to develop tools to identify individuals with rare epilepsies in electronic data sources.

Epilepsy of infancy with migrating focal seizures (EIMFS) is a rare early-onset developmental epileptic encephalopathy resistant to anti-epileptic drugs. The most common cause for EIMFS is a gain-of-function mutation in the KCNT1 potassium channel gene, and treatment with the KCNT1 blocker quinidine has been suggested as a rational approach for seizure control in EIMFS patients. However, variable results on the clinical efficacy of quinidine have been reported. In the present study, we provide a detailed description of the clinical, genetic, in vitro, and in vivo electrophysiological profile and pharmacological responses to quinidine of 2 EIMFS unrelated patients with a heterozygous de novo KCNT1 mutation: c.2849G>A (p.R950Q) in patient 1 and c.2677G>A (p.E893K) in patient 2. When expressed heterologously in CHO cells, KCNT1 channels carrying each variant showed gain-offunction effects, and were more effectively blocked by quinidine when compared to wild-type KCNT1 channels. On the basis of these in vitro results, add-on quinidine treatment was started at 3 and 16 months of age in patients 1 and 2, respectively. The

Epileptic encephalopathies (EEs) are the severe form of childhood epilepsy and phenotypically heterogeneous disorders with different underlying genetic defects. EEs are always accompanied with developmental delay/mental retardation and behavior problems. Finding the genetic basis of epileptic encephalopathies with developmental delay/mental retardation can be valuable not only for diagnosis but also for guiding treatment and providing disease prognosis. Methods and Results A customized panel of 90 genes related to epileptic encephalopathies was utilized to screen for potential genetic variants via targeted next generation sequencing (NGS). A total of 78 children with epilepsy and developmental delay/mental retardation were analyzed with an average read depth of 265.3 ± 68.3X. Mutations were found in 23 (9 boys and 14 girls) probands, and the overall mutation identification rate was 29.5% (25.0% for males and 33.3% for females). Fifteen (65.2%) mutations involve ion channels, including SCN1A, KCNT1, SCN2A, SCN8, KCNB1 and KCNQ2. The other (34.8%) mutations involve CDKL5, ALG13, GFAP, SNAP25, STXBP1 and SYNGAP1. Sixteen (69.6%) of the identified mutations were confirmed to be de novo and one (4.3%) was found to be paternal mosaicism. Channelopathies were found to be the major cause of both early onset (≤6 months) and later onset of unclassified EE as well as febrile seizure cases. On the contrary, patients with infantile spasms or West syndrome were mainly caused by mutations in non-ion channel proteins, whereas patients of epilepsy with developmental delays and/or mental retardation were caused by mutations in both channel and non-channel genes. Conclusion NGS is a valuable and reliable diagnostic tool to detect the gene mutation in epileptic children with developmental delay/mental retardation. This cost-effective method shortens the course from seizure onset to genetic diagnosis. By understanding the gene mutations and genotypephenotype correlation better, clinical practitioners could provide the optimal anticonvulsant and treatment.

SCN2A mutations have been identified in various encephalopathy phenotypes, ranging from benign familial neonatal-infantile seizure (BFNIS) to more severe forms of epileptic encephalopathy such as Ohtahara syndrome or epilepsy of infancy with migrating focal seizure (EIMFS). Thus far, no particularly effective treatment is available for severe epileptic encephalopathy caused by SCN2A mutations in children. We present the case of a boy who developed seizures on the third day of life and received a diagnosis of EIMFS based on his clinical presentations and electroencephalography reports. Antiepileptic drugs, namely oxcarbazepine, phenytoin, valproate, levetiracetam, and clonazepam, as well as adrenocorticotropic hormone therapy failed to reduce the severity of the seizures. Seizure pattern changed to infantile spasm with extensor thrust since 5 months of age. A ketogenic diet consisting of a medium-chain triglyceride recipe was introduced at 8 months of age and the seizures were resolved in the following 10 months. A de novo mutation in SCN2A (c.573G > T; p.W191C) was proven through next-generation sequencing.

We sought to investigate the diagnostic yield and mutation spectrum in previously reported genes for early-onset epilepsy and disorders of severe developmental delay. In 400 patients with these disorders with no known underlying aetiology and no major structural brain anomaly, we analysed 46 genes using a combination of targeted sequencing on an Illumina MiSeq platform and targeted, exon-level microarray copy number analysis. We identified causative mutations in 71/400 patients (18%). The diagnostic rate was highest among those with seizure onset within the first two months of life (39%), although overall it was similar in those with and without seizures. The most frequently mutated gene was SCN2A (11 patients, 3%). Other recurrently mutated genes included CDKL5, KCNQ2, SCN8A (six patients each), FOXG1, MECP2, SCN1A, STXBP1 (five patients each), KCNT1, PCDH19, TCF4 (three patients each) and ATP1A3, PRRT2 and SLC9A6 (two patients each). Mutations in EHMT1, GABRB3, LGI1, MBD5, PIGA, U...

In tuberous sclerosis complex (TSC), a substantially increased risk of developing epilepsy is present very early in life. Epilepsy is characterized by early onset and intractable seizures in the majority of children. Vigabatrin (VGB) proved efficacy in determining cessation of spasms associated with TSC. The aim of this retrospective study is to assess the longterm epilepsy and cognitive outcome in a larger series of TSC patients who presented seizure onset in the first year of life and received a very prompt treatment with VGB. Methods: Due to an early diagnosis we were able to start VGB at the very early onset of seizures in 23 children, who subsequently underwent a long-term neurodevelopmental follow-up. Key findings: At the final evaluation, a seizure free status was observed in 65% of patients. Furthermore, 39% of individuals had a normal or borderline mental development, and only 9% developed severe mental retardation and autism spectrum disorder. Significance: Our data suggest that a very prompt control of focal seizures and epileptic spasms could prevent the subsequent epileptic encephalopathy, reducing the cognitive and behavioral consequences of seizures in children with TSC.

Poster sessions S89 performed. Other measurements including demographics and monitoring of serum 25-hydroxyvitamin D were taken. Results: Seventeen (7 male, 10 female) patients had DXA performed at a mean age of 88.8 months, SD 33.7 months. The mean duration from starting the KD to the DXA was 20.8 months, SD 16.3 months (range 4 to 60 months). Ten patients utilised wheeled ambulation and 16 were on multiple anticonvulsant medication. None of the patients sustained skeletal fractures while on the KD. Nine patients had low DXA Z scores <−2. They consisted of 6 females and 3 males aged 4 to 12 years. All were on appropriate supplementation although 2 had insufficient vitamin D levels on monitoring. Intervention varied from adjustment of diet, calcium and vitamin D supplements, follow up DXA and bisphosphonate treatment in 2. Three patients had repeat DXA, all of which showed improvement. Conclusions: Children on the KD for epilepsy have a high prevalence of low bone mineral density demonstrated by DXA. Pre diet conselling should include risk and advice in optimising skeletal health.

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Developmental, cellular, and subcellular variations in the direction of neuronal Cl− currents elicited by GABAA receptor activation have been frequently reported, and we found a corresponding variance in the reversal potential (EGABA) for individual interneurons synapsing on a single pyramidal cell. These findings suggest a corresponding variance in the cytoplasmic concentration of Cl− ([Cl−i]). We determined [Cl−]i by: 1) two-photon imaging of the Cl− sensitive, ratiometric fluorescent protein SuperClomeleon (sCLM); 2) Fluorescence Lifetime IMaging (FLIM) of the Cl− sensitive fluorophore MEQ; and 3) electrophysiological measurements of EGABA. These methods collectively demonstrated stable [Cl−]i microdomains in individual neurons in vivo. Fluorometric and electrophysiological estimates of local [Cl−]i were highly correlated. [Cl−]i microdomains persisted after pharmacological inhibition of cation-chloride cotransporters (CCCs) but steadily decreased after inhibiting the polymerizat...

In tuberous sclerosis complex (TSC), a substantially increased risk of developing epilepsy is present very early in life. Epilepsy is characterized by early onset and intractable seizures in the majority of children. Vigabatrin (VGB) proved efficacy in determining cessation of spasms associated with TSC. The aim of this retrospective study is to assess the longterm epilepsy and cognitive outcome in a larger series of TSC patients who presented seizure onset in the first year of life and received a very prompt treatment with VGB. Methods: Due to an early diagnosis we were able to start VGB at the very early onset of seizures in 23 children, who subsequently underwent a long-term neurodevelopmental follow-up. Key findings: At the final evaluation, a seizure free status was observed in 65% of patients. Furthermore, 39% of individuals had a normal or borderline mental development, and only 9% developed severe mental retardation and autism spectrum disorder. Significance: Our data suggest that a very prompt control of focal seizures and epileptic spasms could prevent the subsequent epileptic encephalopathy, reducing the cognitive and behavioral consequences of seizures in children with TSC.

The term "epileptic encephalopathy" is used to describe a possible relationship between epilepsy and developmental delay. The pathogenesis of developmental encephalopathies, independent of epilepsy, can be de ned by genetic control mechanisms. The aim of this study was to investigate the use of miRNAs as serum biomarkers for the determination and discrimination of epileptic encephalopathies. Methods Whole blood samples obtained from 54 individuals in 2 groups designated as epileptic encephalopathy patients group (n=24) and healthy controls (n=30) were included in this study. The expression levels of 10 miRNAs were determined using qRT-PCR. After the determination of expression levels the correlation of upregulated miRNA levels and Ki67 index was calculated using Pearson correlation test. Results The comparison of epileptic encephalopathy patients group with healthy controls revealed the upregulation of one miRNAs (hsa-miR-324-5p) and downregulation of three miRNAs (hsa-miR-146a-5p, hsa-miR-138-5p, hsa-miR-187-3p). Conclusion It has been determined that miRNAs with altered expression are an important factor in the formation of epileptic seizures and seizure-induced neuronal death. The fact that processes that play a key role in epiloptogenesis are under the control of miRNAs causes miRNAs to become metacontrollers of gene expression in the brain. We thouhgt that further studies are needed to prove that especially, hsa-miR-146a-5p, hsa-miR-138-5p and hsa-miR-187-3p can be used as epileptic encephalopathy biomarkers. Detection of disease-speci c miRNAs could contribute to the development of presicion treatments.

In Kazakhstan, there is insufficient data on genetic epilepsy, which has its own clinical and management implications. Thus, this study aimed to use whole genome sequencing to identify and evaluate genetic variants and genetic structure of early onset epilepsy in the Kazakhstani pediatric population. In this study, for the first time in Kazakhstan, whole genome sequencing was carried out among epilepsy diagnosed children. The study involved 20 pediatric patients with early onset epilepsy and no established cause of the disease during the July–December, 2021. The average age at enrolment was 34.5 months, with a mean age at seizure onset of 6 months. Six patients (30%) were male, and 7 were familial cases. We identified pathogenic and likely pathogenic variants in 14 (70%) cases, among them, 6 novel disease gene variants (KCNQ2, CASK, WWOX, MT-CO3, GRIN2D, and SLC12A5). Other genes associated with the disease were SCN1A (x2), SLC2A1, ARX, CACNA1B, PCDH19, KCNT1, and CHRNA2. Identifica...

The term "epileptic encephalopathy" is used to describe a possible relationship between epilepsy and developmental delay. The pathogenesis of developmental encephalopathies, independent of epilepsy, can be de ned by genetic control mechanisms. The aim of this study was to investigate the use of miRNAs as serum biomarkers for the determination and discrimination of epileptic encephalopathies. Methods Whole blood samples obtained from 54 individuals in 2 groups designated as epileptic encephalopathy patients group (n=24) and healthy controls (n=30) were included in this study. The expression levels of 10 miRNAs were determined using qRT-PCR. After the determination of expression levels the correlation of upregulated miRNA levels and Ki67 index was calculated using Pearson correlation test. Results The comparison of epileptic encephalopathy patients group with healthy controls revealed the upregulation of one miRNAs (hsa-miR-324-5p) and downregulation of three miRNAs (hsa-miR-146a-5p, hsa-miR-138-5p, hsa-miR-187-3p). Conclusion It has been determined that miRNAs with altered expression are an important factor in the formation of epileptic seizures and seizure-induced neuronal death. The fact that processes that play a key role in epiloptogenesis are under the control of miRNAs causes miRNAs to become metacontrollers of gene expression in the brain. We thouhgt that further studies are needed to prove that especially, hsa-miR-146a-5p, hsa-miR-138-5p and hsa-miR-187-3p can be used as epileptic encephalopathy biomarkers. Detection of disease-speci c miRNAs could contribute to the development of presicion treatments.

The intraneuronal ionic composition is an important determinant of brain functioning. There is growing evidence that aberrant homeostasis of the intracellular concentration of Cl ([Cl]) evokes, in addition to that of Na and Ca, robust impairments of neuronal excitability and neurotransmission and thereby neurological conditions. More specifically, understanding the mechanisms underlying regulation of [Cl] is crucial for deciphering the variability in GABAergic and glycinergic signaling of neurons, in both health and disease. The homeostatic level of [Cl] is determined by various regulatory mechanisms, including those mediated by plasma membrane Cl channels and transporters. This review focuses on the latest advances in identification, regulation and characterization of Cl channels and transporters that modulate neuronal excitability and cell volume. By putting special emphasis on neurons of the olivocerebellar system, we establish that Cl channels and transporters play an indispensa...

Chloride homeostasis determines the impact of inhibitory synaptic transmission and thereby mediates the excitability of neurons. Even though cerebellar Purkinje cells (PCs) receive a pronounced inhibitory GABAergic input from stellate and basket cells, the role of chloride homeostasis in these neurons is largely unknown. Here we studied at both the cellular and systems physiological level the function of a recently discovered chloride channel, SLC26A11 or kidney brain anion transporter (KBAT), which is prominently expressed in PCs. Using perforated patch clamp recordings of PCs, we found that a lack of KBAT channel in PC-specific KBAT KO mice (L7-KBAT KOs) induces a negative shift in the reversal potential of chloride as reflected in the GABAA-receptor-evoked currents, indicating a decrease in intracellular chloride concentration. Surprisingly, bothin vitroandin vivoPCs in L7-KBAT KOs showed a significantly increased action potential firing frequency of simple spikes, which correlat...

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BACKGROUND AND PURPOSE Vasoactive intestinal peptide (VIP) is an important modulator of hippocampal synaptic transmission that influences both GABAergic synaptic transmission and glutamatergic cell excitability through activation of VPAC 1 and VPAC 2 receptors. Presynaptic enhancement of GABA release contributes to VIP modulation of hippocampal synaptic transmission. EXPERIMENTAL APPROACH We investigated which VIP receptors and coupled transduction pathways were involved in VIP enhancement of K +-evoked [ 3 H]-GABA release from isolated nerve terminals of rat hippocampus. KEY RESULTS VIP enhancement of [ 3 H]-GABA release was potentiated in the presence of the VPAC 1 receptor antagonist PG 97-269 but converted into an inhibition in the presence of the VPAC 2 receptor antagonist PG 99-465, suggesting that activation of VPAC 1 receptors inhibits and activation of VPAC 2 receptors enhances, GABA release. A VPAC 1 receptor agonist inhibited exocytotic voltage-gated calcium channel (VGCC)-dependent [ 3 H]-GABA release through activation of protein G i/o , an effect also dependent on PKC activity. A VPAC 2 receptor agonist enhanced both exocytotic VGCC-dependent release through protein G s-dependent, PKA-dependent and PKC-dependent mechanisms and GABA transporter 1-mediated [ 3 H]-GABA release through a G s protein-dependent and PKC-dependent mechanism. CONCLUSIONS AND IMPLICATIONS Our results show that VPAC 1 and VPAC 2 VIP receptors have opposing actions on GABA release from hippocampal nerve terminals through activation of different transduction pathways. As VPAC 1 and VPAC 2 receptors are located in different layers of Ammon's horn, our results suggest that these VIP receptors underlie different modulation of synaptic transmission to pyramidal cell dendrites and cell bodies, with important consequences for their possible therapeutic application in the treatment of epilepsy.

Objective: The principal aim of the present study was to assess the importance of multidrug transporter; P-glycoprotein (P-gp) as a potential therapeutic target in patients with epilepsy. Can P-gp transporter expression modulation by memantine add to the standard antiepileptic drugs (AEDs) response? Methods: A cohort of 56 epilepsy patients was included in a 4 monthly visits prospective study. Patients were on levetiracetam (LEV) 1000 mg/ day alone or combined with other AEDs. They were randomly assigned into two groups; LEV only group including LEV-treated patients and LEV + memantine group including patients on LEV with add-on oral memantine 10 mg/day until the end of the study. During monthly follow-up visits, therapeutic responses were evaluated for each patient by recording the monthly seizures frequency. Blood samples were drawn from every patient twice (on the first and last visits) for assessment of P-gp mRNA expression level. Results: Fifty patients completed the study. At the end of 4 th month, LEV only group showed a non-significant decrease in P-gp expression and seizure frequency compared to the 1 st month, whereas, in LEV + memantine group, P-gp expression was significantly reduced and associated with significant seizure control. Conclusion: Memantine by hindering P-gp overexpression was apt to enhance LEV efficacy and exhibit a better seizure control.

Purpose/Aim: Ehlers-Danlos syndrome (EDS) is a hereditary connective tissue disease. Epilepsy is not a common neurological finding in EDS. Here we report a pediatric patient with EDS comorbid with STXBP1 related epileptic encephalopathy as 'electrical status epilepticus during slow-wave sleep (ESES)' and whose refractory epileptic seizures were controlled with ketogenic diet. Case Report: A 6-year-old girl who had EDS presented with refractory seizures and worsening cognitive functions. Her sleep electroencephalography (EEG) revealed electrical status epilepticus during slow-wave sleep (ESES). The epileptic encephalopathy panel revealed a de novo c.560C> T (p.pro187Leu) heterozygous mutation in the STXPB1 gene. Ketogenic diet treatment was started for her refractory seizures and seizures stopped in the third month of the 3:1 classical ketogenic diet. Conclusion: Our case is remarkable due to the coexistence of EDS and epileptic encephalopathy as well as ESES findings in STXBP1-associated epileptic encephalopathy and is therefore presented. Ketogenic diet would be beneficial on the management of refractory seizures in STXBP1-related epileptic encephalopathy and ESES.

Objective: This study is aimed to evaluate the effectiveness and tolerability of rufinamide as add-on therapy in patients with intractable epilepsies. Methods: We retrospectively reviewed the medical records of 94 patients treated with rufinamide in Asan Medical Center, children's hospital. Twenty-five cases with less than 3 months of medication and 4 cases with incomplete medical records were excluded and total 65 cases were enrolled. Rufinamide was added on the existing antiepileptic drugs and the total seizure frequency at pre-medication, 3 months and 12 months were examined. Results: The mean age of 65 patients (44 male) were was 10 yrs (range, 1e24yrs). At 3 months after rufinamide initiation, 5 patients achieved freedom from seizures and 38 (58%) achieved a 50% seizure reduction. At 12 months, 8 of 55 patients achieved seizure freedom and 60% (23/55) achieved 50% seizure reduction. There was no significant difference of sex, age at seizure onset, duration of epilepsy, seizure types, and the diagnosis of Lennox-Gastaut syndrome (LGS) between responders and non-responders. The retention rate was hold up to 72% at 3 months, 64% at 12 months of study. Total 21 patients reported adverse events in order of somnolence, seizure aggravation, insomnia, common cold, nausea and vomiting and 3 cases of seizure aggravation, 1 case of somnolence, 1 case of visual hallucination had to stop the medication of rufinamide. Conclusion: In this study, rufinamide is effective and tolerable in patients with intractable epilepsy of childhood onset. The effectiveness is not significantly different according to their epileptic syndrome diagnosis of LGS. Further research is required to define the efficacy of rufinamide in intractable epilepsy other than LGS.