A long-term follow-up study of Dravet syndrome up to adulthood

A systematic literature review on the global epidemiology of Dravet syndrome and Lennox-Gastaut syndrome: Prevalence, incidence, diagnosis, and mortality

Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS) are rare developmental and epileptic encephalopathies associated with seizure and nonseizure symptoms. A comprehensive understanding of how many individuals are affected globally, the diagnostic journey they face, and the extent of mortality associated with these conditions is lacking. Here, we summarize and evaluate published data on the epidemiology of DS and LGS in terms of prevalence, incidence, diagnosis, genetic mutations, and mortality and sudden unexpected death in epilepsy (SUDEP) rates. The full study protocol is registered on PROSPERO (CRD42022316930). After screening 2172 deduplicated records, 91 unique records were included; 67 provided data on DS only, 17 provided data on LGS only, and seven provided data on both. Case definitions varied considerably across studies, particularly for LGS. Incidence and prevalence estimates per 100 000 individuals were generally higher for LGS than for DS (LGS: incidence proportion = 14.5-28, prevalence = 5.8-60.8; DS: incidence proportion = 2.2-6.5, prevalence = 1.2-6.5). Diagnostic delay was frequently reported for LGS, with a wider age range at diagnosis reported than for DS (DS, 1.6-9.2 years; LGS, 2-15 years). Genetic screening data were reported by 63 studies; all screened for SCN1A variants, and only one study specifically focused on individuals with LGS. Individuals with DS had a higher mortality estimate per 1000 person-years than individuals with LGS (DS, 15.84; LGS, 6.12) and a lower median age at death. SUDEP was the most frequently reported cause of death for individuals with DS. Only four studies reported mortality information for LGS, none of which included SUDEP. This systematic review highlights the paucity of epidemiological data available for DS and especially LGS, demonstrating the need for further research and adoption of standardized diagnostic criteria.

Long-term predictors of developmental outcome and disease burden in SCN1A-positive Dravet syndrome

Dravet syndrome is a severe infantile onset developmental and epileptic encephalopathy associated with mutations in the sodium channel alpha 1 subunit gene SCN1A. Prospective data on long-term developmental and clinical outcomes are limited; this study seeks to evaluate the clinical course of Dravet syndrome over a 10-year period and identify predictors of developmental outcome. SCN1A mutation-positive Dravet syndrome patients were prospectively followed up in the UK from 2010 to 2020. Caregivers completed structured questionnaires on clinical features and disease burden; the Epilepsy & Learning Disability Quality of Life Questionnaire, the Adaptive Behavioural Assessment System-3 and the Sleep Disturbance Scale for Children. Sixty-eight of 113 caregivers (60%) returned posted questionnaires. Developmental outcome worsened at follow-up (4.45 [SD 0.65], profound cognitive impairment) compared to baseline (2.9 [SD 1.1], moderate cognitive impairment, P < 0.001), whereas epilepsy severity appeared less severe at 10-year follow-up (P = 0.042). Comorbidities were more apparent at 10-year outcome including an increase in autistic features (77% [48/62] versus 30% [17/57], χ2 = 19.9, P < 0.001), behavioural problems (81% [46/57] versus 38% [23/60], χ2 = 14.1, P < 0.001) and motor/mobility problems (80% [51/64] versus 41% [24/59], χ2 = 16.9, P < 0.001). Subgroup analysis demonstrated a more significant rise in comorbidities in younger compared to older patients. Predictors of worse long-term developmental outcome included poorer baseline language ability (P < 0.001), more severe baseline epilepsy severity (P = 0.003) and a worse SCN1A genetic score (P = 0.027). Sudden unexpected death in epilepsy had not been discussed with a medical professional in 35% (24/68) of participants. Over 90% of caregivers reported a negative impact on their own health and career opportunities. Our study identifies important predictors and potential biomarkers of developmental outcome in Dravet syndrome and emphasizes the significant caregiver burden of illness. The negative impact of epilepsy severity at baseline on long-term developmental outcomes highlights the importance of implementing early and focused therapies whilst the potential impact of newer anti-seizure medications requires further study.

Clinical and Genetic Features of Dravet Syndrome: A Prime Example of the Role of Precision Medicine in Genetic Epilepsy

Dravet syndrome (DS), also known as severe myoclonic epilepsy of infancy, is a rare and drug-resistant form of developmental and epileptic encephalopathies, which is both debilitating and challenging to manage, typically arising during the first year of life, with seizures often triggered by fever, infections, or vaccinations. It is characterized by frequent and prolonged seizures, developmental delays, and various other neurological and behavioral impairments. Most cases result from pathogenic mutations in the sodium voltage-gated channel alpha subunit 1 (SCN1A) gene, which encodes a critical voltage-gated sodium channel subunit involved in neuronal excitability. Precision medicine offers significant potential for improving DS diagnosis and treatment. Early genetic testing enables timely and accurate diagnosis. Advances in our understanding of DS's underlying genetic mechanisms and neurobiology have enabled the development of targeted therapies, such as gene therapy, offering more effective and less invasive treatment options for patients with DS. Targeted and gene therapies provide hope for more effective and personalized treatments. However, research into novel approaches remains in its early stages, and their clinical application remains to be seen. This review addresses the current understanding of clinical DS features, genetic involvement in DS development, and outcomes of novel DS therapies.

Determining the Relationship Between Seizure-Free Days and Other Predictors of Quality of Life in Patients with Dravet Syndrome and Their Carers from FFA Registration Studies

INTRODUCTION

Dravet syndrome (DS) is a rare, lifelong epileptic encephalopathy characterised by frequent and severe seizures associated with premature mortality. Typically diagnosed in infancy, patients also experience progressive behavioural, motor-function and cognitive decline. Twenty percent of patients do not reach adulthood. Quality of life (QoL) is impaired for both patients and their carers. Reducing convulsive seizure frequency, increasing convulsive seizure-free days (SFDs) and improving patient/carer QoL are primary treatment goals in DS. This study explored the relationship between SFDs and patients' and carers' QoL to inform a cost-utility analysis of fenfluramine (FFA).

METHODS

In FFA registration studies, patients (or their carer proxies) completed the Paediatric QoL inventory (PedsQL). These data were mapped to EuroQol-5 Dimensions Youth version (EQ-5D-Y) to provide patient utilities. Carer utilities were collected using EQ-5D-5L and mapped to EQ-5D-3L to align patient and carer QoL on the same scale. Linear mixed-effects and panel regression models were tested and Hausman tests identified the most appropriate approach for each group. On this basis, a linear mixed-effects regression model was used to examine the relationships between patient EQ-5D-Y and clinically relevant variables (age, frequency of SFDs per 28 days, motor impairments and treatment dose). A linear panel regression model examined the relationship between SFDs and carer QoL.

RESULTS

After adjustment for age and underlying comorbidities, the patient regression model showed that SFDs per 28 days was a significant predictor of QoL. Each additional patient-SFD increased utility by 0.005 (p < 0.001). The carer linear panel model also showed that increasing SFDs per 28 days was a significant predictor of improved QoL. Each additional SFD increased carer utility by 0.014 (p < 0.001).

CONCLUSION

This regression framework highlights that SFDs are significantly correlated with both patients' and carers' QoL. Treatment with effective antiseizure medications that increase SFDs directly improves QoL for patients and their carers.

Reintroducing Fenfluramine as a Treatment for Seizures: Current Knowledge, Recommendations and Gaps in Understanding

Despite the introduction of new anti-seizure medications in recent years, approximately one-third of the epileptic population continues to experience seizures. Recently, the anti-obesity medication fenfluramine (FFA) has been successfully repurposed, and it has received approval from various regulatory agencies for the treatment of seizures associated with Dravet syndrome and Lennox-Gastaut syndrome. The potential antiseizure effects of FFA were initially observed in patients with photosensitive epilepsy in the 1980s but it was not rigorously explored as a treatment option until 30 years later. This narrative review aims to provide an overview of the historical progression of FFA's use, starting from initial clinical observations to preclinical studies and, ultimately, successful clinical trials in the field of epilepsy.

Optogenetic modulation of hippocampal oscillations ameliorates spatial cognition and hippocampal dysrhythmia following early-life seizures

There is increasing human and animal evidence that brain oscillations play a critical role in the development of spatial cognition. In rat pups, disruption of hippocampal rhythms via optogenetic stimulation during the critical period for memory development impairs spatial cognition. Early-life seizures are associated with long-term deficits in spatial cognition and aberrant hippocampal oscillatory activity. Here we asked whether modulation of hippocampal rhythms following early-life seizures can reverse or improve hippocampal connectivity and spatial cognition. We used optogenetic stimulation of the medial septum to induce physiological 7 Hz theta oscillations in the hippocampus during the critical period of spatial cognition following early-life seizures. Optogenetic stimulation of the medial septum in control and rats subjected to early-life seizures resulted in precisely regulated frequency-matched hippocampal oscillations. Rat pups receiving active blue light stimulation performed better than the rats receiving inert yellow light in a test of spatial cognition. The improvement in spatial cognition in these rats was associated with a faster theta frequency and higher theta power, coherence and phase locking value in the hippocampus than rats with early-life seizures receiving inert yellow light. These findings indicate that following early life seizures, modification of hippocampal rhythms may be a potential novel therapeutic modality.

Gene mutations in comorbidity of epilepsy and arrhythmia

Epilepsy is one of the most common neurological disorders, and sudden unexpected death in epilepsy (SUDEP) is the most severe outcome of refractory epilepsy. Arrhythmia is one of the heterogeneous factors in the pathophysiological mechanism of SUDEP with a high incidence in patients with refractory epilepsy, increasing the risk of premature death. The gene co-expressed in the brain and heart is supposed to be the genetic basis between epilepsy and arrhythmia, among which the gene encoding ion channel contributes to the prevalence of "cardiocerebral channelopathy" theory. Nevertheless, this theory could only explain the molecular mechanism of comorbid arrhythmia in part of patients with epilepsy (PWE). Therefore, we summarized the mutant genes that can induce comorbidity of epilepsy and arrhythmia and the possible corresponding treatments. These variants involved the genes encoding sodium, potassium, calcium and HCN channels, as well as some non-ion channel coding genes such as CHD4, PKP2, FHF1, GNB5, and mitochondrial genes. The relationship between genotype and clinical phenotype was not simple linear. Indeed, genes co-expressed in the brain and heart could independently induce epilepsy and/or arrhythmia. Mutant genes in brain could affect cardiac rhythm through central or peripheral regulation, while in the heart it could also affect cerebral electrical activity by changing the hemodynamics or internal environment. Analysis of mutations in comorbidity of epilepsy and arrhythmia could refine and expand the theory of "cardiocerebral channelopathy" and provide new insights for risk stratification of premature death and corresponding precision therapy in PWE.

Cys-loop receptors on cannabinoids: All high?

Endocannabinoids (eCBS) are endogenously derived lipid signaling molecules that serve as tissue hormones and interact with multiple targets, mostly within the endocannabinoid system (ECS). The ECS is a highly conserved regulatory system involved in homeostatic regulation, organ formation, and immunomodulation of chordates. The term “cannabinoid” evolved from the distinctive class of plant compounds found in Cannabis sativa, an ancient herb, due to their action on CB1 and CB2 receptors. CB1/2 receptors are the primary targets for eCBs, but their effects are not limited to the ECS. Due to the high interest and extensive research on the ECS, knowledge on its constituents and physiological role is substantial and still growing. Crosstalk and multiple targeting of molecules are common features of endogenous and plant compounds. Cannabimimetic molecules can be divided according to their origin, natural or synthetic, including phytocannabinoids (pCB’s) or synthetic cannabinoids (sCB’s). The endocannabinoid system (ECS) consists of receptors, transporters, enzymes, and signaling molecules. In this review, we focus on the effects of cannabinoids on Cys-loop receptors. Cys-loop receptors belong to the class of membrane-bound pentameric ligand gated ion channels, each family comprising multiple subunits. Mammalians possess GABA type A receptors (GABAAR), glycine receptors (GlyR), serotonin receptors type 3 (5-HT3R), and nicotinic acetylcholine receptors (nAChR). Several studies have shown different modulatory effects of CBs on multiple members of the Cys-loop receptor family. We highlight the existing knowledge, especially on subunits and protein domains with conserved binding sites for CBs and their possible pharmacological and physiological role in epilepsy and in chronic pain. We further discuss the potential for cannabinoids as first line treatments in epilepsy, chronic pain and other neuropsychiatric conditions, indicated by their polypharmacology and therapeutic profile.

Adaptive behaviour in adolescents and adults with Dravet syndrome

AIM

To explore the feasibility of using an adaptive behaviour profile (ABP) assessment generated from a well-known measure-the Vineland Adaptive Behavior Scales, Second Edition (VABS-II)-as an instrument for outcome measures in adolescents and adults with Dravet syndrome.

METHOD

We administered the VABS-II to 35 adolescents and adults with Dravet syndrome (15 males; mean age 24 years, SD 8 years, range: 12-46 years) and collected epilepsy history and neurological features at the time of assessment. We conducted a cross-sectional analysis of VABS-II raw scores and performed cluster analysis to identify different subgroups. We then explored possible relationships between clinical and epilepsy features, ABPs, and age.

RESULTS

Most participants obtained the minimum standard scores in the various VABS-II subdomains, while the raw score analysis outlined interindividual and intraindividual differences among skills. We found two subpopulations: one with a 'lower' ABP and one with a 'higher' ABP, corresponding respectively to individuals in whom myoclonic seizures or generalized spike-and-wave activity were present ('complete phenotype') or absent ('incomplete phenotype') on electroencephalography.

INTERPRETATION

This study further delineates the natural history of Dravet syndrome. The assessment of an ABP through the VABS-II raw score analysis provides a means by which to illustrate profiles of adaptive behaviour in adolescents and adults with Dravet syndrome but shows limitations related to poor sensitivity in measuring fine clinical details. There is a need for new and more specific tools to monitor patients with developmental and epileptic encephalopathies.

Genetics and gene therapy in Dravet syndrome

Dravet syndrome is a well-established electro-clinical condition first described in 1978. A main genetic cause was identified with the discovery of a loss-of-function SCN1A variant in 2001. Mechanisms underlying the phenotypic variations have subsequently been a main topic of research. Various genetic modifiers of clinical severities have been elucidated through many rigorous studies on genotype-phenotype correlations and the recent advances in next generation sequencing technology. Furthermore, a deeper understanding of the regulation of gene expression and remarkable progress on genome-editing technology using the CRISPR-Cas9 system provide significant opportunities to overcome hurdles of gene therapy, such as enhancing Na_V1.1 expression. This article reviews the current understanding of genetic pathology and the status of research toward the development of gene therapy for Dravet syndrome. This article is part of the Special Issue "Severe Infantile Epilepsies".

The effectiveness of intravenous benzodiazepine for status epilepticus in Dravet syndrome

PURPOSE

We aimed to evaluate choice and efficacy of intravenous antiepileptic drugs (AEDs) for status epilepticus (SE) in Dravet syndrome and to find predictable clinical features demonstrating the effectiveness of benzodiazepine (BZD) for SE.

METHODS

We retrospectively investigated the medical records in patients with Dravet syndrome and evaluated the effectiveness rate of intravenous AEDs and the rate of adverse effects. To find the clinical features of BZD-effective SE, we divided the SE episodes into the following two groups: BZD effective group and BZD non-effective group. The choice of treatment was dependent on physicians' discretion according to the protocol for SE in our institution.

RESULTS

Sixty-eight SE episodes in 10 patients were assessed. The median age at SE was 31 months. Of 68 episodes, 42 episodes (61.8%) were in the BZD effective group and 26 (38.2%) in the BZD non-effective group. There were no significant differences in clinical features. In the BZD non-effective group, the effective rates of continuous midazolam, phenobarbital, phenytoin/fosphenytoin were 9/9 episodes (100%), 14/17 (82.4%), and 2/5 (40.0%), respectively. Adverse effects were identified in 19/68 episodes (27.9%), including 11/42 episodes in the BZD effective group and 8/26 in the BZD non-effective group, which was no statistical difference between the two groups. Respiratory suppression was found in all 19 episodes and the incidence of endotracheal intubation in the BZD non-effective group (15.4%) was higher than that in the BZD effective group (2.4%) (p = 0.046).

CONCLUSION

BZD may be used as first choice, and phenobarbital prior to continuous midazolam as second choice for SE with Dravet syndrome. There might be no predictable clinical features showing that BZD will be effective.

The clinical, economic, and humanistic burden of Dravet syndrome - A systematic literature review

Dravet syndrome (DS) is a developmental and epileptic encephalopathy with evolving disease course as individuals age. In recent years, the treatment landscape of DS has changed considerably, and a comprehensive systematic review of the contemporary literature is lacking. Here we synthesized published evidence on the occurrence of clinical impacts by age, the economic and humanistic (health-related quality-of-life [HRQoL]) burden, and health state utility. We provide an evidence-based, contemporary visualization of the clinical manifestations, highlighting that DS is not limited to seizures; non-seizure manifestations appear early in life and increase over time, contributing significantly to the economic and humanistic burden of disease. The primary drivers of HRQoL in DS include seizure severity, cognition, and motor and behavioral problems; in turn, these directly affect caregivers through the extent of assistance required and consequent impact on activities of daily living. Unsurprisingly, costs are driven by seizure-related events, hospitalizations, and in-home medical care visits. This systematic review highlights a paucity of longitudinal data; most studies meeting inclusion criteria were cross-sectional or had short follow-up. Nonetheless, available data illustrate the substantial impact on individuals, their families, and healthcare systems and establish the need for novel therapies to address the complex spectrum of DS manifestations.

Progressive Worsening of Gait and Motor Abnormalities in Older Adults With Dravet Syndrome

BACKGROUND AND OBJECTIVES

Relative to the pediatric population, there is very limited information about Dravet Syndrome (DS) in adults. In addition to some of the gait abnormalities reported in children with DS (such as crouch gait and ataxia), adults with this condition have other gait and motor disturbances. Our primary objective was to examine gait and motor manifestations in older adults with DS.

METHODS

This study has a prospective arm where 6 patients (mean age 32-years-old) were examined through a modified version of the Unified Parkinson's Disease Rating Scale (mUPDRS) in 2014 and again in 2019. mUPDRS scores were assigned to gait, resting tremors, facial expression, arising from a chair, posture, and body bradykinesia. The cross-sectional arm includes mUPDRS testing in patients that were not evaluated in 2014, and an instrumental gait analysis (IGA). These cross-sectional tests were done in the 2019-2020 period. The IGA was performed using the ProtoKinetics software with a gait mat built with sensors and two cameras capturing the sagittal and coronal planes. The IGA was performed in a group of 17 patients with DS (mean age: 31-years-old), the control group consisted of 81 healthy individuals, whose mean age was 62-years-old. Regression analyses were performed for the IGA and mUPDRS data.

RESULTS

Five out of six participants evaluated prospectively over 5 years experienced worsening of their parkinsonian manifestations, including gait. Two patients (47 and 51 years old) who were initially ambulatory, could no longer walk 5 years later. The cross-sectional analysis of mUPDRS in a larger group of adults showed that worse scores for arising from a chair (p= 0.04), body bradykinesia (p= 0.01), and gait (p= 0.0003) were positively associated with age. The IGA cross-sectional arm revealed that all 17 adults with DS had abnormal gait parameters in all domains tested. This group of patients performed worse than the healthy and older control group.

DISCUSSION

Although seizures may decrease in older adults with DS, this prospective and cross-sectional study showed that their motor symptoms and gait become progressively worse as they age.

Motor and behavioral phenotype of Dravet syndrome in adulthood

In a comparative cross-sectional study, 26 adult individuals with clinically typical, genetically confirmed Dravet syndrome (DS) and an equal number of individuals with early onset, problematic epilepsy, and intellectual disability (ID) of comparable severity were included. The aim of the study was to find out whether patients with DS could be clearly distinguished from the comparison group with regard to neurological and behavioral symptoms. Significant differences were found in that individuals with DS clearly more frequently exhibited a symptom cluster characterized by bradykinesia, hypomimia, hypophonia, (spastic) increased muscle tone, ataxia, sthenic perseveration, and a special interest in colors. To these symptoms must be added, according to the findings of previous examinations, mastication, camptocormia/antecollis on the one hand, and the tendency to visual hallucinations on the other hand, in order to define one neuropsychiatric phenotype of DS in adulthood. To these symptoms must be added, according to the findings of previous investigations, crouch gait with camptocormia/antecollis on the one hand, and the tendency to visual hallucinations on the other hand, in order to define one outlined neuropsychiatric phenotype of DS in adulthood.

Guidance on Dravet syndrome from infant to adult care: Road map for treatment planning in Europe

Dravet syndrome (DS) is a severe, rare, and complex developmental and epileptic encephalopathy affecting 1 in 16 000 live births and characterized by a drug‐resistant epilepsy, cognitive, psychomotor, and language impairment, and behavioral disorders. Evidence suggests that optimal treatment of seizures in DS may improve outcomes, even though neurodevelopmental impairments are the likely result of both the underlying genetic variant and the epilepsy. We present an updated guideline for DS diagnosis and treatment, taking into consideration care of the adult patient and nonpharmaceutical therapeutic options for this disease. This up‐to‐date guideline, which is based on an extensive review of the literature and culminates with a new treatment algorithm for DS, is a European consensus developed through a survey involving 29 European clinical experts in DS. This guideline will serve professionals in their clinical practice and, as a consequence, will benefit DS patients and their families.

Rare and Complex Epilepsies from Childhood to Adulthood: Requirements for Separate Management or Scope for a Lifespan Holistic Approach?

PURPOSE

In this descriptive review, we describe current models of transition in rare and complex epilepsy syndromes and propose alternative approaches for more holistic management based on disease biology.

RECENT FINDINGS

Previously published guidance and recommendations on transition strategies in individuals with epilepsy have not been systematically and uniformly applied. There is significant heterogeneity in models of transition/transfer of care across countries and even within the same country. We provide examples of the most severe epilepsy and related syndromes and emphasise the limited data on their outcome in adulthood. Rare and complex epilepsy syndromes have unique presentations and require high levels of expertise and multidisciplinary approach. Lifespan clinics, with no transition, but instead continuity of care from childhood to adulthood with highly specialised input from healthcare providers, may represent an alternative effective approach. Effectiveness should be measured by evaluation of quality of life for both patients and their families/caregivers.

Impact of fenfluramine on the expected SUDEP mortality rates in patients with Dravet syndrome

PURPOSE

To assess the impact of fenfluramine (FFA) on the expected mortality incidence, including sudden unexpected death in epilepsy (SUDEP), in persons with Dravet syndrome (DS).

METHODS

In this pooled analysis, total time of exposure for persons with DS who were treated with FFA in phase 3 clinical trials, in United States and European Early Access Programs, and in two long-term open-label observational studies in Belgium was calculated. Literature was searched for reports of SUDEP mortality in DS, which were utilized as a comparison. Mortality rates were expressed per 1000 person-years.

RESULTS

A total of 732 persons with DS were treated with FFA, representing a total of 1185.3 person-years of exposure. Three deaths occurred, all in the phase 3 program: one during placebo treatment (probable SUDEP) and two during treatment with FFA (one probable SUDEP and one definite SUDEP). The all-cause and SUDEP mortality rates during treatment with FFA was 1.7 per 1000 person-years (95% CI, 0.4 to 6.7), a value lower than the all-cause estimate of 15.8 per 1000 person-years (95% CI, 9.9 to 25.4) and SUDEP estimate of 9.3 (95% CI, 5.0 to 17.3) reported by Cooper et al. (Epilepsy Res 2016;128:43-7) for persons with DS receiving standard-of-care.

CONCLUSION

All-cause and SUDEP mortality rates in DS patients treated with FFA were substantially lower than in literature reports. Further studies are warranted to confirm that FFA reduces SUDEP risk in DS patients and to better understand the potential mechanism(s) by which FFA lowers SUDEP risk.

CLINICAL TRIAL REGISTRATION

NCT02926898, NCT02682927, NCT02826863, NCT02823145, NCT03780127.

Inherited Developmental and Epileptic Encephalopathies

Epileptic encephalopathies often have a genetic etiology. The epileptic activity itself exerts a direct detrimental effect on neurodevelopment, which may add to the cognitive impairment induced by the underlying mutation (“developmental and epileptic encephalopathy”). The focus of this review is on inherited syndromes. The phenotypes of genetic disorders affecting ion channels, metabolic signalling, membrane trafficking and exocytosis, cell adhesion, cell growth and proliferation are discussed. Red flags suggesting family of genes or even specific genes are highlighted. The knowledge of the phenotypical spectrum can indeed prompt the clinician to suspect specific etiologies, expediting the diagnosis.

Clinical spectrum and the comorbidities of Dravet syndrome in Taiwan and the possible molecular mechanisms

Dravet syndrome (DS) is an uncommon epilepsy syndrome that may negatively affect the patients and their caregivers. However, reliable and valid measures of its impact on caregivers and the characteristics of patients with DS in Taiwan are lacking. This study aimed to describe the characteristics of patients with DS and concerns of their caregivers and establish a baseline frequency of disease characteristics using a cross-sectional survey in Taiwan. We assessed the caregivers of patients with DS using an online anonymous questionnaire. The seizure frequency decreased with age, although lacking statistical significance. Vaccines show no influence on the condition of patients with DS. Our findings revealed the highest impact on the domains affecting the caregivers’ daily life, including additional household tasks, symptom observation, further medical plan, and financial issues. Caregivers also expressed concerns regarding the lack of independence/constant care, seizure control, speech/communication, and impacts on siblings because of long-term care of the patients in parents’ absence. Our findings highlight the significant effects of caring for a child with DS on the lives of their caregivers in Taiwan; these findings will help raise awareness regarding the needs of these families. Furthermore, we discussed the possible pathophysiological mechanisms of associated comorbidities.

Dravet syndrome: A quick transition guide for the adult neurologist

INTRODUCTION

Dravet syndrome (DS) is still seen as a "pediatric disease", where patients receive excellent care in pediatric centers, but care is less than optimal in adult health care systems (HCS). This creates a barrier when young adults need to leave the family-centered pediatric system and enter the adult, patient-centered HCS. Here we create a guide to help with the transition from pediatric to adult for patients with DS.

METHODS

Experts in Dravet syndrome flagged the main barriers in caring for adults with DS and created a 2-page transition summary guide based on their expertise and a literature review.

RESULTS

The 2-page guide addresses: DS diagnosis in children and adults; clinical manifestations, including the differences in seizures types and frequencies between children and adults with DS; the natural history of intellectual disability, behavior, gait, motor disorders and dysautonomia; a review of optimal treatments (including medications not commonly used in adult epilepsy settings such as stiripentol and fenfluramine), as well as emergency seizure management; avoidance of triggers, preventive measures, and vaccine administration in adults with DS.

CONCLUSION

Several young adults with DS are still followed by their child neurologist. This 2-page transition guide should help facilitate the transition of patients with DS to the adult HCS and should be given to families as well as adult health care providers that may not be familiar with DS.

Genetics and clinical correlation of Dravet syndrome and its mimics - experience of a tertiary center in Taiwan

BACKGROUND

Dravet syndrome is a severe developmental and epileptic encephalopathy characterized by the onset of prolonged febrile and afebrile seizures in infancy and SCN1A gene mutations. In some cases, non-SCN1A gene mutations can present with a phenotype very similar to that of Dravet syndrome. The aim of this study was to compare phenotypes of patients with SCN1A and non-SCN1A gene mutation-related Dravet syndrome.

METHODS

Thirty-six patients with Dravet syndrome-like phenotypes were followed from July 2017 to December 2019. We retrospectively analyzed their clinical profiles and genetic surveys.

RESULTS

Of the 36 enrolled patients, 15 (41.7%) had SCN1A mutations, one (2.8%) had an SCN8A mutation, one (2.8%) had an STX1B mutation, and five females (13.9%) had PCDH 19 mutations. The median age at first seizure onset was 7 months in those with SCN1A mutations, 1.3 years in those with PCDH19 mutations, and 10 months for the remaining patients. The majority of the patients with SCN1A mutations had status epilepticus (80% vs. 20%) and fever-sensitive seizures (76% vs. 31%) compared to those with PCDH19 mutations. The patients with SCN1A-related seizures had a higher rate of focal seizures as first seizure type than those without SCN1A mutations. Three of five (60%) patients with PCDH19 mutations had brain magnetic resonance imaging abnormalities. The three most commonly used antiseizure medications were sodium valproate, levetiracetam, and clobazam. Seven of the 15 patients with SCN1A mutations used stiripentol. The median time from seizure onset to genetic diagnosis was 6.6 years (range 4 months-22.3 years).

CONCLUSION

The patients with SCN1A mutations in this study had high rates of fever-sensitive seizures, status epilepticus, seizure onset with focal seizure type, and relatively young age at seizure onset. The patients with PCDH19 mutations had a relatively high rate of abnormal brain magnetic resonance imaging findings.

Transcription factors in neurodevelopmental and associated psychiatric disorders: A potential convergence for genetic and environmental risk factors

Neurodevelopmental disorders (NDDs) are a heterogeneous and highly prevalent group of psychiatric conditions marked by impairments in the nervous system. Their onset occurs during gestation, and the alterations are observed throughout the postnatal life. Although many genetic and environmental risk factors have been described in this context, the interactions between them challenge the understanding of the pathways associated with NDDs. Transcription factors (TFs)-a group of over 1,600 proteins that can interact with DNA, regulating gene expression through modulation of RNA synthesis-represent a point of convergence for different risk factors. In addition, TFs organize critical processes like angiogenesis, blood-brain barrier formation, myelination, neuronal migration, immune activation, and many others in a time and location-dependent way. In this review, we summarize important TF alterations in NDD and associated disorders, along with specific impairments observed in animal models, and, finally, establish hypotheses to explain how these proteins may be critical mediators in the context of genome-environment interactions.

[Self-induced epileptic seizures: Prevalence, Causes and Treatment]

Self-induced seizures were first described in 1827. A majority of authors found that in unselected patients with epilepsy, the prevalence rate of these seizures was 1%. In patients with photosensitive epilepsy, there was roughly a 25% prevalence. Apart from visual stimulation, many other mechanisms of self-induction have been described. A feeling of pleasure or relaxation during seizures may be a reason for self-inductive behaviour. But often the procedure of self-induction is experienced as involuntary. Treatment is always difficult. Behavioral therapy has been proven effective in some patients. In patients with photosensitive epilepsy, sunglasses are recommended. Fenfluramine, clonazepam and valproate seem to be a bit more effective than other drugs. After all, the treatment effect depends on the motivation of the patient to change the condition.

Dravet Syndrome: Novel Approaches for the Most Common Genetic Epilepsy

Dravet syndrome (DS) is a severe developmental and epileptic encephalopathy that is mainly associated with variants in SCN1A. While drug-resistant epilepsy is the most notable feature of this syndrome, numerous symptoms are present that have significant impact on patients' quality of life. In spite of novel, third-generation anti-seizure treatment options becoming available over the last several years, seizure freedom is often not attained and non-seizure symptoms remain. Precision medicine now offers realistic hope for seizure freedom in DS patients, with several approaches demonstrating preclinical success. Therapeutic approaches such as antisense oligonucleotides (ASO) and adeno-associated virus (AAV)-delivered gene modulation have expanded the potential treatment options for DS, with some of these approaches now transitioning to clinical trials. Several of these treatments may risk the exacerbation of gain-of-function variants and may not be reversible, therefore emphasizing the need for functional testing of new pathogenic variants. The current absence of treatments that address the overall disease, in addition to seizures, exposes the urgent need for reliable, valid measures of the entire complement of symptoms as outcome measures to truly know the impact of treatments on DS. Additionally, with so many treatment options on the horizon, there will be a need to understand how to select appropriate patients for each treatment, whether treatments are complementary or adverse to each other, and long-term risks of the treatment. Nevertheless, precision therapeutics hold tremendous potential to provide long-lasting seizure freedom and even complete cures for this devastating disease.

Comparative short-term efficacy and safety of add-on anti-seizure medications in Dravet syndrome: An indirect treatment comparison

PURPOSE

Although cannabidiol and fenfluramine have been recently approved by the US Food and Drug Administration (FDA) for seizures in children with Dravet syndrome (DS), the comparative efficacy and safety of these and stiripentol as an add-on therapy for DS has not been evaluated in head-to-head trials. The current study aimed to assess the comparative efficacy and safety of add-on anti-seizure medications in DS.

METHODS

PubMed and EMBASE database search and a manual search was done using keywords; "antiepileptic", "Dravet syndrome" and "antiseizure". The primary efficacy outcome was ≥50% reduction in convulsive seizure frequency from baseline while the safety outcome was treatment-emergent adverse events (TEAEs). Frequentist approach were used for combining direct and indirect evidence and network plots prepared. The drugs were ranked based on p-scores obtained using the surface under the cumulative ranking (SUCRA). Heterogeneity across studies was calculated by I² statistic and Q test.

RESULTS

Five randomized controlled trials (RCTs) with 565 patients with DS (2-20 years) who received placebo or any of the three active interventions (stiripentol, cannabidiol, and fenfluramine) were included. Compared with placebo, all the three drugs were associated with a significant reduction in convulsive seizure frequency from baseline. Stiripentol had the highest probability ranking for ≥50% reduction in convulsive seizure frequency from baseline [OR: 20.2; 95% CI: 2.1-198.0] and for occurrence of any treatment emergent adverse events (TEAEs) [OR:53.9; 95% CI: 1.4 to 2079.8] followed by fenfluramine and cannabidiol. However, for serious TEAEs, the ranking order was stiripentol followed by cannabidiol and fenfluramine. The trial on stiripentol had limited sample size explaining the wide confidence intervals for the comparative outcomes.

CONCLUSION

In this indirect comparison, fenfluramine and stiripentol hadd comparable efficacy but fenfluramine appeareded to be safer in terms of less frequent serious TEAEs. Cannabidiol had relatively lower efficacy and was associated with serious TEAEs. A head-to-head trial between stiripentol, cannabidiol and fenfluramine is the need of the hour.

Age-related evolution of EEG in Dravet syndrome: Meta-analysis of 155 patients

PURPOSE

Dravet syndrome is an early-onset developmental and epileptic encephalopathy caused by pathogenic SCN1A variants in 80-90% of patients. EEG is initially normal, but abnormalities, both generalized and focal, may develop later. There is a limited understanding of typical EEG evolution in Dravet syndrome.

METHODS

We searched Pubmed in July 2020 for studies including: ≥ 1 patient with Dravet syndrome clinical diagnosis and SCN1A pathogenic variant, and for each such patient, a description of ≥ 1 EEG and age at the time of the EEG. For each study, we evaluated for bias in patient selection. We also reviewed our research database for Dravet patients with available EEG reports. We extracted demographic data and EEG abnormalities reported (generalized/focal epileptiform abnormalities, focal/diffuse slowing). We determined the earliest ages at which different abnormalities were seen, as well as the percentage of reported abnormalities for different age ranges.

RESULTS

We included 247 EEGs from 155 patients (from 31 studies and our research database). The earliest reported ages of generalized epileptiform discharges, focal epileptiform discharges, diffuse background slowing, and focal slowing, were six months, four months, four months, and four months, respectively. In patients 0-12 months, EEG was abnormal in 43%, but this rose to 90% for the 1-2 year-old group, and remained at approximately the same level for the remainder of the age groups.

CONCLUSION

Our results help clarify the relationship between age and EEG in Dravet syndrome; however, findings should be interpreted with caution given the inherent potential biases in the study design.

SCN1A and Its Related Epileptic Phenotypes

Epilepsy is one of the most common neurological disorders, with a lifetime incidence of 1 in 26. Approximately two-thirds of epilepsy has a substantial genetic component in its etiology. As a result, simultaneous screening for mutations in multiple genes and performing whole exome sequencing (WES) are becoming very frequent in the clinical evaluation of children with epilepsy. In this setting, mutations in voltage-gated sodium channel (SCN) α-subunit genes are the most commonly identified cause of epilepsy, with sodium channel genes (i.e., SCN1A, SCN2A, SCN8A) being the most frequently identified causative genes. SCN1A mutations result in a wide spectrum of epilepsy phenotypes ranging from simple febrile seizures to Dravet syndrome, a severe epileptic encephalopathy. In case of mutation of SCN1A, it is also possible to observe behavioral alterations, such as impulsivity, inattentiveness, and distractibility, which can be framed in an attention deficit hyperactivity disorder (ADHD) like phenotype. Despite more than 1,200 SCN1A mutations being reported, it is not possible to assess a clear phenotype–genotype correlations. Treatment remains a challenge and seizure control is often partial and transitory.

Bad Timing for Epileptic Networks: Role of Temporal Dynamics in Seizures and Cognitive Deficits

The precise coordination of neuronal activity is critical for optimal brain function. When such coordination fails, this can lead to dire consequences. In this review, I will present evidence that in epilepsy, failed coordination leads not only to seizures but also to alterations of the rhythmical patterns observed in the electroencephalogram and cognitive deficits. Restoring the dynamic coordination of epileptic networks could therefore both improve seizures and cognitive outcomes.

Multicenter prospective longitudinal study in 34 patients with Dravet syndrome: Neuropsychological development in the first six years of life

The objective of this study was to identify developmental trajectories of developmental/behavioral phenotypes and possibly their relationship to epilepsy and genotype by analyzing developmental and behavioral features collected prospectively and longitudinally in a cohort of patients with Dravet syndrome (DS). Thirty-four patients from seven Italian tertiary pediatric neurology centers were enrolled in the study. All patients were examined for the SCN1A gene mutation and prospectively assessed from the first years of life with repeated full clinical observations including neurological and developmental examinations. Subjects were found to follow three neurodevelopmental trajectories. In the first group (16 patients), an initial and usually mild decline was observed between the second and the third year of life, specifically concerning visuomotor abilities, later progressing towards global involvement of all abilities. The second group (12 patients) showed an earlier onset of global developmental impairment, progressing towards a generally worse outcome. The third group of only two patients ended up with a normal neurodevelopmental quotient, but with behavioral and linguistic problems. The remaining four patients were not classifiable due to a lack of critical assessments just before developmental decline. The neurodevelopmental trajectories described in this study suggest a differential contribution of neurobiological and genetic factors. The profile of the first group, which included the largest fraction of patients, suggests that in the initial phase of the disease, visuomotor defects might play a major role in determining developmental decline. Early diagnosis of milder cases with initial visuomotor impairment may therefore provide new tools for a more accurate habilitation strategy.

Dose-Ranging Effect of Adjunctive Oral Cannabidiol vs Placebo on Convulsive Seizure Frequency in Dravet Syndrome: A Randomized Clinical Trial

Importance

Clinical evidence supports effectiveness of cannabidiol for treatment-resistant seizures in Dravet syndrome, but this trial is the first to evaluate the 10-mg/kg/d dose.

Objective

To evaluate the efficacy and safety of a pharmaceutical formulation of cannabidiol, 10 and 20 mg/kg/d, vs placebo for adjunctive treatment of convulsive seizures in patients with Dravet syndrome.

Design, Setting, and Participants

This double-blind, placebo-controlled, randomized clinical trial (GWPCARE2) recruited patients from April 13, 2015, to November 10, 2017, with follow-up completed on April 9, 2018. Of 285 patients screened from 38 centers in the United States, Spain, Poland, the Netherlands, Australia, and Israel, 86 were excluded, and 199 were randomized. Patients were aged 2 to 18 years with a confirmed diagnosis of Dravet syndrome and at least 4 convulsive seizures during the 4-week baseline period while receiving at least 1 antiepileptic drug. Data were analyzed from November 16 (date of unblinding) to December 13 (date of final outputs), 2018, based on intention to treat and per protocol.

Interventions

Patients received cannabidiol oral solution at a dose of 10 or 20 mg/kg per day (CBD10 and CBD20 groups, respectively) or matched placebo in 2 equally divided doses for 14 weeks. All patients, caregivers, investigators, and individuals assessing data were blinded to group assignment.

Main Outcomes and Measures

The primary outcome was change from baseline in convulsive seizure frequency during the treatment period. Secondary outcomes included change in all seizure frequency, proportion with at least a 50% reduction in convulsive seizure activity, and change in Caregiver Global Impression of Change score.

Results

Of 198 eligible patients (mean [SD] age, 9.3 [4.4] years; 104 female [52.5%]), 66 were randomized to the CBD10 group, 67 to the CBD20 group, and 65 to the placebo group, and 190 completed treatment. The percentage reduction from baseline in convulsive seizure frequency was 48.7% for CBD10 group and 45.7% for the CBD20 group vs 26.9% for the placebo group; the percentage reduction from placebo was 29.8% (95% CI, 8.4%-46.2%; P = .01) for CBD10 group and 25.7% (95% CI, 2.9%-43.2%; P = .03) for the CBD20 group. The most common adverse events were decreased appetite, diarrhea, somnolence, pyrexia, and fatigue. Five patients in the CBD20 group discontinued owing to adverse events. Elevated liver transaminase levels occurred more frequently in the CBD20 (n = 13) than the CBD10 (n = 3) group, with all affected patients given concomitant valproate sodium.

Conclusions and Relevance

Adjunctive cannabidiol at doses of 10 and 20 mg/kg/d led to similar clinically relevant reductions in convulsive seizure frequency with a better safety and tolerability profile for the 10-mg/kg/d dose in children with treatment-resistant Dravet syndrome. Dose increases of cannabidiol to greater than 10 mg/kg/d should be tailored to individual efficacy and safety.

Trial Registration

ClinicalTrials.gov Identifier: NCT02224703.

Alterations of Neuronal Dynamics as a Mechanism for Cognitive Impairment in Epilepsy

Epilepsy is commonly associated with cognitive and behavioral deficits that dramatically affect the quality of life of patients. In order to identify novel therapeutic strategies aimed at reducing these deficits, it is critical first to understand the mechanisms leading to cognitive impairments in epilepsy. Traditionally, seizures and epileptiform activity in addition to neuronal injury have been considered to be the most significant contributors to cognitive dysfunction. In this review we however highlight the role of a new mechanism: alterations of neuronal dynamics, i.e. the timing at which neurons and networks receive and process neural information. These alterations, caused by the underlying etiologies of epilepsy syndromes, are observed in both animal models and patients in the form of abnormal oscillation patterns in unit firing, local field potentials, and electroencephalogram (EEG). Evidence suggests that such mechanisms significantly contribute to cognitive impairment in epilepsy, independently of seizures and interictal epileptiform activity. Therefore, therapeutic strategies directly targeting neuronal dynamics rather than seizure reduction may significantly benefit the quality of life of patients.

Fatal Status Epilepticus in Dravet Syndrome

Dravet Syndrome (DS) is burdened by high epilepsy-related premature mortality due to status epilepticus (SE). We surveyed centres within Europe through the Dravet Italia Onlus and EpiCARE network (European Reference Network for Rare and Complex Epilepsies). We collated responses on seven DS SCN1A+ patients who died following refractory SE (mean age 6.9 year, range 1.3–23.4 year); six were on valproate, clobazam, and stiripentol. All patients had previous SE. Fatal SE was always triggered by fever: either respiratory infection or one case of hexavalent vaccination. SE lasted between 80 min and 9 h and all patients received IV benzodiazepines. Four patients died during or within hours of SE; in three patients, SE was followed by coma with death occurring after 13–60 days. Our survey supports the hypothesis that unresponsive fever is a core characteristic feature of acute encephalopathy. We highlight the need for management protocols for prolonged seizures and SE in DS.

Fenfluramine HCl (Fintepla® ) provides long-term clinically meaningful reduction in seizure frequency: Analysis of an ongoing open-label extension study

OBJECTIVE

Fenfluramine has been shown to provide clinically meaningful and statistically significant reductions in convulsive seizure frequency in children and adolescents (aged 2-18 years) with Dravet syndrome in two randomized, placebo-controlled clinical trials. The objective of this analysis was to assess longer-term safety and efficacy of fenfluramine in patients who completed one of the double-blind studies and entered an open-label extension (OLE) study.

METHODS

Patients enrolling in the OLE study initiated fenfluramine at 0.2 mg/kg/d regardless of their treatment assignment in the double-blind study. After 4 weeks, the fenfluramine dose could be titrated based on efficacy and tolerability to maximum of 0.7 mg/kg/d (absolute maximum 27 mg/d) or maximum of 0.4 mg/kg/d (absolute maximum 17 mg/d) in patients receiving concomitant stiripentol. The number and type of seizures were recorded daily in an electronic diary, and safety, including echocardiography, was assessed at Months 1, 2, and 3, and at 3-month intervals thereafter.

RESULTS

A total of 232 patients were enrolled as of March 13, 2018. During this analysis period, patients were treated for a median 256 days (range = 46-634 days). Over the entire OLE analysis period, the median decrease in convulsive seizure frequency compared to baseline in the double-blind studies was -66.8% (range = -100% to 234.9%; P < .001). The median reduction in seizure frequency was similar in patients <6 (-75.7%) and ≥6 years old (-64.7%). The most commonly reported adverse events included pyrexia (21.6%), nasopharyngitis (19.4%), and decreased appetite (-15.9%). No valvular heart disease (VHD) or pulmonary arterial hypertension (PAH) was observed.

SIGNIFICANCE

Study results demonstrate that fenfluramine provides clinically meaningful (≥50%) seizure frequency reduction over an extended period in patients with Dravet syndrome. No patient developed VHD or PAH, and fenfluramine was generally well tolerated.

A retrospective review of changes and challenges in the use of antiseizure medicines in Dravet syndrome in Norway

OBJECTIVE

Dravet syndrome is a developmental and epileptic encephalopathy characterized by severe and drug-resistant seizures in early childhood, followed by developmental delay. The purpose of this study was to investigate aspects of pharmacological treatment of Norwegian patients with Dravet syndrome, focusing on the use of antiseizure medicines (ASMs) and identifying treatment challenges.

METHODS

Patients were identified through medical registries at the National Center for Epilepsy in Norway and National Center for Rare Epilepsy Related Disorders during 2008-2018. Additional clinical data were obtained from medical records and laboratory request forms.

RESULTS

We identified 53 patients with Dravet syndrome, 30/23 males/females, aged 2-50 years. The majority of patients with known seizure frequency experienced frequent seizures, 80% (n = 35/44). Only two patients were seizure-free. Valproate (n = 48), clobazam (n = 45), levetiracetam (n = 30), and stiripentol (n = 38) were most commonly used, previous or current use. More than one-third (n = 20) had tried sodium channel blockers (including lamotrigine), but these drugs were used less during the last decade. Polytherapy was common, 81% (n = 43) used two or more ASMs, and eight of these patients used 4-5 drugs (15%). Several challenges were identified: high seizure frequency, comorbidities, treatment changes with a wide range of ASMs, common use of oral gastro-tubes, extensive polypharmacy, and drug interactions.

SIGNIFICANCE

The use of ASMs has changed over the last decade, in accordance with updated international recommendations. Various treatment challenges were identified. This vulnerable group of patients needs close follow-up for an optimal treatment outcome.

Disruption of hippocampal rhythms via optogenetic stimulation during the critical period for memory development impairs spatial cognition

BACKGROUND

Hippocampal oscillations play a critical role in the ontogeny of allocentric memory in rodents. During the critical period for memory development, hippocampal theta is the driving force behind the temporal coordination of neuronal ensembles underpinning spatial memory. While known that hippocampal oscillations are necessary for normal spatial cognition, whether disrupted hippocampal oscillatory activity during the critical period impairs long-term spatial memory is unknown. Here we investigated whether disruption of normal hippocampal rhythms during the critical period have enduring effects on allocentric memory in rodents.

OBJECTIVE/HYPOTHESIS

We hypothesized that disruption of hippocampal oscillations via artificial regulation of the medial septum during the critical period for memory development results in long-standing deficits in spatial cognition.

METHODS

After demonstrating that pan-neuronal medial septum (MS) optogenetic stimulation (465 nm activated) regulated hippocampal oscillations in weanling rats we used a random pattern of stimulation frequencies to disrupt hippocampal theta rhythms for either 1Hr or 5hr a day between postnatal (P) days 21-25. Non-stimulated and yellow light-stimulated (590 nm) rats served as controls. At P50-60 all rats were tested for spatial cognition in the active avoidance task. Rats were then sacrificed, and the MS and hippocampus assessed for cell loss. Power spectrum density of the MS and hippocampus, coherences and voltage correlations between MS and hippocampus were evaluated at baseline for a range of stimulation frequencies from 0.5 to 110 Hz and during disruptive hippocampal stimulation. Unpaired t-tests and ANOVA were used to compare oscillatory parameters, behavior and cell density in all animals.

RESULTS

Non-selective optogenetic stimulation of the MS in P21 rats resulted in precise regulation of hippocampal oscillations with 1:1 entrainment between stimulation frequency (0.5-110 Hz) and hippocampal local field potentials. Across bandwidths MS stimulation increased power, coherence and voltage correlation at all frequencies whereas the disruptive stimulation increased power and reduced coherence and voltage correlations with most statistical measures highly significant (p < 0.001, following correction for false detection). Rats receiving disruptive hippocampal stimulation during the critical period for memory development for either 1Hr or 5hr had marked impairment in spatial learning as measured in active avoidance test compared to non-stimulated or yellow light-control rats (p < 0.001). No cell loss was measured between the blue-stimulated and non-stimulated or yellow light-stimulated controls in either the MS or hippocampus.

CONCLUSION

The results demonstrated that robust regulation of hippocampal oscillations can be achieved with non-selective optogenetic stimulation of the MS in rat pups. A disruptive hippocampal stimulation protocol, which markedly increases power and reduces coherence and voltage correlations between the MS and hippocampus during the critical period of memory development, results in long-standing spatial cognitive deficits. This spatial cognitive impairment is not a result of optogenetic stimulation-induced cell loss.

Dravet Syndrome: A Review of Current Management

Dravet syndrome is a debilitating epileptic encephalopathy of childhood with few treatment options available in the United States before 2018. In the modern era, new genetic testing options will allow diagnosis closer to disease onset. Three new medicines-stiripentol, cannabidiol, and fenfluramine-have documented efficacy and safety as adjunctive therapies for treating pharmacoresistant Dravet syndrome. Early diagnosis resulting in earlier treatment with these and other medications may improve prognosis of long-term outcomes, including less severity of cognitive, motor, and behavioral impairments. New rescue medication formulations can now manage acute seizures and help prevent status epilepticus via intranasal, buccal, and intramuscular routes as opposed to rectal administration. Preventing status epilepticus and generalized tonic-clonic seizures could potentially lower the risk of sudden unexpected death in epilepsy. With this changing landscape in diagnostic and treatment options comes questions and controversies for the practicing clinician, especially as diagnostic techniques outpace clinical treatment strategies. Critical decision points include when to start treatment, what pharmacotherapy combinations to try first, which rescue medication to recommend, and how to advise parents on controversial topics (e.g., immunizations). Given that most patients require polypharmacy, clinicians must be cognizant of drug-drug interactions between new medicines, existing anti-epileptic drugs, and other medications to manage comorbidities and must have an understanding of available therapeutic drug monitoring strategies and pharmacokinetic parameters. This review places new diagnostic, treatment and acute care options into the modern era and provides an overview of the challenges and opportunities facing the pediatric epileptologist in this rapidly changing landscape.

Dravet syndrome: Early electroclinical findings and long-term outcome in adolescents and adults

To describe the outcome of Dravet syndrome (DS) in adolescents and adults we conducted a longitudinal retrospective study of two independent cohorts of 34 adolescents (group 1) and 50 adults (group 2). In both cohorts, we collected information about genetic mutation, and semiology of seizures at onset and during disease course. At the last evaluation, we considered the following features: epilepsy (distinguishing myoclonic/complete and nonmyoclonic/incomplete phenotype), neurologic signs, intellectual disability (ID), and behavioral disorders. Moreover, in both cohorts, we performed a correlation analysis between early characteristics of the disease and the outcome of DS with regard to seizure persistence, ID, behavioral disorder, and neurologic impairment at last evaluation. Group 1 includes 22 adolescents with complete form of DS and 12 with incomplete form; group 2 includes 35 adults with complete form and 15 with incomplete form. The seizures persisted in 73.6% of adolescents and in 80% of adults, but epilepsy severity progressively decreased through age. Seizure persistence correlated with the complete phenotype and with the occurrence of reflex seizures. At last evaluation, ID was moderate or severe in 70.5% of adolescents and in 80% of adults. The most severe cognitive and motor impairment was observed in patients with persisting seizures. The severity of cognition, language, and neurologic impairment at last evaluation correlated statistically with the complete phenotype. The study confirms that the global outcome of DS is poor in most cases, albeit epilepsy severity decreases throughout adulthood. The improvement of epilepsy throughout ages is not associated with improvement in intellectual abilities and motor skills; this confirms that the unfavorable outcome is not a pure consequence of epilepsy.

Cannabidiol improves survival and behavioural co-morbidities of Dravet syndrome in mice

Background and Purpose

Dravet syndrome is a severe, genetic form of paediatric epilepsy associated with premature mortality and co‐morbidities such as anxiety, depression, autism, motor dysfunction and memory deficits. Cannabidiol is an approved anticonvulsive drug in the United States and Europe for seizures associated with Dravet syndrome in patients 2 years of age and older. We investigated its potential to prevent premature mortality and improve associated co‐morbidities.

Experimental Approach

The efficacy of sub‐chronic cannabidiol administration in two mouse models of Dravet syndrome was investigated. The effect of cannabidiol on neonatal welfare and survival was studied using Scn1a^−/− mice. We then used a hybrid, heterozygote Scn1a^+/− mouse model to study the effect of cannabidiol on survival and behavioural co‐morbidities: motor deficits (rotarod and static‐beam test), gait abnormality (gait test), social anxiety (social interaction test), anxiety‐like (elevated plus maze) and depressive‐like behaviours (sucrose preference test) and cognitive impairment (radial arm maze test).

Key Results

In Scn1a^−/− mice, cannabidiol increased survival and delayed worsening of neonatal welfare. In Scn1a^+/− mice, chronic cannabidiol administration did not show any adverse effect on motor function and gait, reduced premature mortality, improved social behaviour and memory function, and reduced anxiety‐like and depressive‐like behaviours.

Conclusion and Implications

We are the first to demonstrate a potential disease‐modifying effect of cannabidiol in animal models of Dravet syndrome. Cannabidiol treatment reduced premature mortality and improved several behavioural co‐morbidities in Dravet syndrome mice. These crucial findings may be translated into human therapy to address behavioural co‐morbidities associated with Dravet syndrome.

Seizures in Mouse Models of Rare Neurodevelopmental Disorders

Genetic neurodevelopmental disorders - that often include epilepsy as part of their phenotype - are a heterogeneous and clinically challenging spectrum of disorders in children. Although seizures often contribute significantly to morbidity in these affected populations, the mechanisms of epileptogenesis in these conditions remain poorly understood. Different model systems have been developed to aid in unraveling these mechanisms, which include a number of specific mutant mouse lines which genocopy specific general types of mutations present in patients. These mouse models have not only allowed for assessments of behavioral and electrographic seizure phenotypes to be ascertained, but also have allowed effects on the neurodevelopmental alterations and cognitive impairments associated with these disorders to be examined. In addition, these models play a role in advancing our understanding of these epileptic processes and developing preclinical therapeutics. The concordance of seizure phenotypes - in a select group of rare, genetic, neurodevelopmental disorders and epileptic encephalopathies - found between human patients and their model counterparts will be summarized. This review aims to assess whether models of Rett syndrome, CDKL5 deficiency disorder, Fragile-X syndrome, Dravet syndrome, and Ohtahara syndrome phenocopy the seizures seen in human patients.

Modifier genes in SCN1A-related epilepsy syndromes

Background

SCN1A is one of the most important epilepsy‐related genes, with pathogenic variants leading to a range of phenotypes with varying disease severity. Different modifying factors have been hypothesized to influence SCN1A‐related phenotypes. We investigate the presence of rare and more common variants in epilepsy‐related genes as potential modifiers of SCN1A‐related disease severity.

Methods

87 patients with SCN1A‐related epilepsy were investigated. Whole‐exome sequencing was performed by the Beijing Genomics Institute (BGI). Functional variants in 422 genes associated with epilepsy and/or neuronal excitability were investigated. Differences in proportions of variants between the epilepsy genes and four control gene sets were calculated, and compared to the proportions of variants in the same genes in the ExAC database.

Results

Statistically significant excesses of variants in epilepsy genes were observed in the complete cohort and in the combined group of mildly and severely affected patients, particularly for variants with minor allele frequencies of <0.05. Patients with extreme phenotypes showed much greater excesses of epilepsy gene variants than patients with intermediate phenotypes.

Conclusion

Our results indicate that relatively common variants in epilepsy genes, which would not necessarily be classified as pathogenic, may play a large role in modulating SCN1A phenotypes. They may modify the phenotypes of both severely and mildly affected patients. Our results may be a first step toward meaningful testing of modifier gene variants in regular diagnostics for individual patients, to provide a better estimation of disease severity for newly diagnosed patients.

Epilepsy and brain channelopathies from infancy to adulthood

Genetic brain channelopathies result from inherited or de novo mutations of genes encoding ion channel subunits within the central nervous system. Most neurological channelopathies arise in childhood with paroxysmal or episodic symptoms, likely because of a transient impairment of homeostatic mechanisms regulating membrane excitability, and the prototypical expression of this impairment is epilepsy. Migraine, episodic ataxia and alternating hemiplegia can also occur, as well as chronic phenotypes, such as spinocerebellar ataxias, intellectual disability and autism spectrum disorder. Voltage-gated and ligand-gated channels may be involved. In most cases, a single gene may be associated with a phenotypical spectrum that shows variable expressivity. Different clinical features may arise at different ages and the adult phenotype may be remarkably modified from the syndrome onset in childhood or adolescence. Recognizing the prominent phenotypical traits of brain channelopathies is essential to perform appropriate diagnostic investigations and to provide the better care not only in the paediatric setting but also for adult patients and their caregivers. Herein, we provide an overview of genetic brain channelopathies associated with epilepsy, highlight the different molecular mechanisms and describe the different clinical characteristics which may prompt the clinician to suspect specific syndromes and to possibly establish tailored treatments.

Seizure management and prescription patterns of anticonvulsants in Dravet syndrome: A multicenter cohort study from Germany and review of literature

OBJECTIVE

The aim of this study was to describe the treatment pattern of patients with Dravet syndrome (DS) in Germany with routine antiepileptic drugs (AEDs) and emergency medication, and to review the literature of real-world evidence on medicine utilization of patients with DS in Europe.

METHODS

Patient use of routine AEDs and emergency medications over 3-6 months was analyzed from a 2018 multicenter survey of 93 caregivers of patients with DS throughout Germany. Results were contextualized in a review of real-world evidence on medicine utilization of patients with DS in Europe.

RESULTS

The variety of medications and the most frequent combinations routinely used by patients with DS (AEDs and others) are described. Patients use a large number of pharmaceutical treatments to manage seizures. The five most commonly used AEDs were sodium valproate (66% of the patients; mean daily dose: 660 mg; 24.5 mg per kg bodyweight), bromide (44%; 1462 mg; 51.2 mg per kg), clobazam (41%; 10.4 mg; 0.32 mg per kg), stiripentol (35%; 797 mg; 27.6 mg per kg), and topiramate (24%; 107 mg; 3.5 mg per kg). Ninety percent had reported using emergency medications in the last 3 months;, with the most common medications being Buccolam (40%, an oromucosal form of midazolam) and diazepam (20%, mostly rectal application). No discernable relationships between current medication and age or seizure frequency were observed.

SIGNIFICANCE

This is the first comprehensive report of routine AEDs and emergency medication use in a large sample of patients with DS in Germany over a period of 3-6 months and shows that despite the most common AED combinations being in line with clinical guidelines/best practice, there is no discernable impact of best treatment on seizure frequency. We find a higher use of bromide in Germany compared with other real-world evidence in Europe.

Transcriptomes of Dravet syndrome iPSC derived GABAergic cells reveal dysregulated pathways for chromatin remodeling and neurodevelopment

Dravet syndrome (DS) is an early onset refractory epilepsy typically caused by de novo heterozygous variants in SCN1A encoding the α-subunit of the neuronal sodium channel Na_v1.1. The syndrome is characterized by age-related progression of seizures, cognitive decline and movement disorders. We hypothesized that the distinct neurodevelopmental features in DS are caused by the disruption of molecular pathways in Na_v1.1 haploinsufficient cells resulting in perturbed neural differentiation and maturation. Here, we established DS-patient and control induced pluripotent stem cell derived neural progenitor cells (iPSC NPC) and GABAergic inter-neuronal (iPSC GABA) cells. The DS-patient iPSC GABA cells showed a shift in sodium current activation and a perturbed response to induced oxidative stress. Transcriptome analysis revealed specific dysregulations of genes for chromatin structure, mitotic progression, neural plasticity and excitability in DS-patient iPSC NPCs and DS-patient iPSC GABA cells versus controls. The transcription factors FOXM1 and E2F1, positive regulators of the disrupted pathways for histone modification and cell cycle regulation, were markedly up-regulated in DS-iPSC GABA lines. Our study highlights transcriptional changes and disrupted pathways of chromatin remodeling in Na_v1.1 haploinsufficient GABAergic cells, providing a molecular framework that overlaps with that of neurodevelopmental disorders and other epilepsies.

Dravet Syndrome: An Overview

Dravet syndrome (DS), also known as severe myoclonic epilepsy of infancy (SMEI), is one of the rare early childhood intractable epileptic encephalopathies associated with pleomorphic seizure activity, cognitive decline, motor, and behavioral abnormalities. The convulsive seizure is the most common type seen in DS. After the first episode of seizure-like activity, behavioral disorders and cognitive decline are progressive and long-lasting. The most common etiology identified in patients with DS is a de-novo genetic mutation alpha-1 subunit of voltage-gated calcium channel gene (SCN1A). DS is diagnosed clinically and if unclear, genetic testing is recommended. DS treatment options include anti-epileptic drugs and cannabinoids; ketogenic diet therapy and surgical options such as the deep brain and vagal nerve stimulation. Due to drug-refractory epilepsy in DS, many more therapies are being investigated to increase the longevity of patients.