Deconstructing Dravet syndrome neurocognitive development: A scoping review.

Dravet syndrome (DS) is a rare severe epilepsy syndrome associated with slowed psychomotor development and behavioral disorders from the second year onward in a previously seemingly normal child. Among cognitive impairments, visuospatial, sensorimotor integration, and expressive language deficits are consistently reported. There have been independent hypotheses to deconstruct the typical cognitive development in DS (dorsal stream vulnerability, cerebellar-like pattern, sensorimotor integration deficit), but an encompassing framework is still lacking. We performed a scoping review of existing evidence to map the current understanding of DS cognitive and behavioral developmental profiles and to summarize the evidence on suggested frameworks. We searched PubMed, Scopus, PsycInfo, and MEDLINE to identify reports focusing on cognitive deficits and/or behavioral abnormalities in DS published between 1978 and March 15, 2020. We followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. Twenty-one reports were selected and tabulated by three independent reviewers based on predefined data extraction and eligibility forms. Eighteen reports provided assessments of global intelligence quotients with variable degrees of cognitive impairment. Eleven reports analyzed single subitems contribution to global cognitive scores: these reports showed consistently larger impairment in performance scales compared to verbal ones. Studies assessing specific cognitive functions demonstrated deterioration of early visual processing, fine and gross motor abilities, visuomotor and auditory-motor integration, spatial processing, visuo-attentive abilities, executive functions, and expressive language. Behavioral abnormalities, reported from 14 studies, highlighted autistic-like traits and attention and hyperactivity disorders, slightly improving with age. The cognitive profile in DS and some behavioral and motor abnormalities may be enclosed within a unified theoretical framework of the three main hypotheses advanced: a pervasive sensorimotor integration deficit, encompassing an occipito-parietofrontal circuit (dorsal stream) dysfunction and a coexistent cerebellar deficit.

Application of induced pluripotent stem cells in epilepsy.

Epilepsy is among the most common neurological disorders, affecting approximately 50 million people worldwide. Importantly, epilepsy is genetically and etiologically heterogenous, but several epilepsy types exhibit similar clinical presentations. Epilepsy-associated genes are being identified. However, the molecular pathomechanisms remain largely unknown. Approximately one-third of epilepsy is refractory to multiple conventional anti-epileptic drugs (AEDs). Induced pluripotent stem cells (iPSCs) provide an excellent tool to study the pathomechanisms underlying epilepsy and to develop novel treatments. Indeed, disease-specific iPSCs have been established for several genetic epilepsies. In particular, the molecular mechanisms underlying certain developmental and epileptic encephalopathies, such as Dravet syndrome, have been revealed. Modeling epilepsy with iPSCs enables new drug development based on the elucidated pathomechanisms. This can also be used to evaluate conventional AEDs and drug repurposing. Furthermore, transplanting neuronal cells derived from iPSCs into the brain has great potential to treat refractory epilepsies. Recent advances in iPSC technology have enabled the generation of neuronal organoids, or "mini brains." These organoids demonstrate electrophysiological activities similar to those of the brain and have the potential for extensive epilepsy research opportunities. Thus, the application of iPSCs in epilepsy provides insight into novel treatments based on the molecular pathomechanisms of epilepsy. In this review, we comprehensively discuss the studies conducted on iPSCs established for genetic epilepsy or epilepsies without major structural dysmorphic features.

Low-dose fenfluramine significantly reduces seizure frequency in Dravet syndrome: a prospective study of a new cohort of patients.

BACKGROUND AND PURPOSE: Dravet syndrome (DS) is a severe, drug-resistant epilepsy. Fenfluramine has been reported to have a long-term clinically meaningful anticonvulsive effect in patients with DS. METHODS: This prospective, open-label study assessed the safety and effectiveness of low-dose fenfluramine in a new cohort of patients with DS. Following a 3-month baseline period, fenfluramine was added to each patient's current antiepileptic drug regimen at a dose of 0.25-1.0 mg/kg/day (max. 20 mg/day). The incidence of major motor seizures (tonic, clonic, tonic-clonic, atonic and myoclonic seizures lasting >30 s) in both the baseline and treatment periods was assessed via a seizure diary. Periodic echocardiographic examinations during the treatment period were used to assess cardiovascular safety. RESULTS: Nine patients (aged 1.2-29.8 years) enrolled in the study and were treated with fenfluramine for a median duration of 1.5 (range, 0.3-5.1) years. Median frequency of major motor seizures was 15.0/month in the baseline period. All patients demonstrated a reduction in seizure frequency during the treatment period with a median reduction of 75% (range, 28-100%). Seven patients (78%) experienced a ≥50% reduction in major motor seizure frequency. The most common adverse events were somnolence (n = 5) and anorexia (n = 4). No evidence of cardiac valvulopathy or pulmonary hypertension was observed. CONCLUSIONS: The effectiveness and safety of low-dose fenfluramine as an add-on therapy for DS in this new prospective cohort supports previous findings.

The humanistic and economic burden of Dravet syndrome on caregivers and families: Implications for future research.

We reviewed the current literature with respect to the humanistic and financial burdens of Dravet Syndrome (DS) on the caregivers of children with DS, in order to (1) identify key unanswered questions or gaps in knowledge that need to be addressed and then, based on these knowledge gaps, (2) propose a research agenda for the scientific community to address in the coming decade. The findings support the conclusion that caring for a child with DS is associated with significant humanistic burden and direct costs. However, due in part to the paucity of studies, as well as the lack of measures of specific burden domains, there remains much that is not known regarding the burden of caregiving for children with DS. To address the significant knowledge gaps in this area, research is needed that will: (1) identify the specific domains of caregivers' lives that are impacted by caring for a child with DS; (2) identify or, if needed, develop measures of caregiving impact in this area; (3) identify the factors that influence DS caregiving burden; (4) develop and evaluate the efficacy of treatments for reducing the negative impact of DS and its comorbidities on DS caregivers; (5) quantify the direct medical costs associated with DS and DS comorbidities and identify the factors that influence these costs; and (6) quantify and fully explore the indirect costs of DS. Research that addresses these goals will provide the empirical foundation needed for improving the quality of life of children with DS and their families.

Life impact of caregiving for severe childhood epilepsy: Results of expert panels and caregiver focus groups.

Severe epilepsy in children and young adults can significantly affect the lives of their caregivers. However, the lack of a reliable and valid measure of caregiver impact has limited our understanding of the scope and correlates of this impact, as well as our ability to measure the effects of treatments that could lessen it. The purpose of this study was to facilitate focus groups and interviews with an international group of clinician experts and caregivers to identify the most important domains that should be assessed in a measure of caregiver impact. Ten specific subdomains emerged from the panel discussions, which could be classified into the four overarching categories of physical health, mental health, social function, and financial resources. The caregivers highlighted the impact on the subdomains of sleep and fatigue as most critical. A review of existing caregiver impact measures confirmed that there is no measure currently available that assesses all of these relevant domains, indicating the need for the development of such a measure. The current findings highlight the significant life effects of caring for a child with severe epilepsy and can be used to inform the development of such a tool.

The incidence of SCN1A-related Dravet syndrome in Denmark is 1:22,000: a population-based study from 2004 to 2009.

Dravet syndrome is a severe infantile-onset epileptic encephalopathy associated with mutations in the sodium channel alpha-1 subunit gene SCN1A. We aimed to describe the incidence of Dravet syndrome in the Danish population. Based on a 6-year birth cohort from 2004 to 2009, we propose an incidence of 1:22,000, which is higher than what has been established earlier. We identified 17 cases with SCN1A mutation-positive Dravet syndrome. Fifteen patients were found, by conventional Sanger sequencing. Two additional patients with clinical Dravet syndrome, but without a detectable SCN1A mutation by Sanger sequencing, were diagnosed with a SCN1A mutation after using a targeted next-generation sequencing gene panel.

Autism and behavior in adult patients with Dravet syndrome (DS).

INTRODUCTION: Autism and behavioral characteristics in adults with Dravet syndrome (DS) have rarely been systematically studied. METHOD: Three scales were used to assess the outcomes of DS in adulthood in terms of autism and behavior. All the adult patients with DS, nine male and four female, aged between 18 and 60 years, living at the Epilepsy Center Kempenhaeghe in The Netherlands were included in the study. In addition, the past medical history of each patient was systematically screened for diagnoses like autism, Pervasive Development Disorder-Not Otherwise Specified (PDD-NOS), autism spectrum disorder (ASD), hyperactivity, Attention Deficit Hyperactivity Disorder (ADHD), and self-mutilation. Information concerning past and current use of psychoactive drugs was also evaluated. RESULTS: Eight patients (61.5%) were classified as having autism spectrum disorder (ASD) according to the AVZ-R or according to the medical record. Self-mutilation was seen in four patients (30.8%), hyperactivity in none. Three patients (23.1%) currently used psychoactive drugs. CONCLUSION: Autism spectrum disorders persist in adult patients with DS, while certain characteristics associated with behavioral problems, such as hyperactivity or use of psychoactive medication, seem to be less prominent than in childhood.

Long-term course of Dravet syndrome: a study from an epilepsy center in Japan.

OBJECTIVE: This study attempted to clarify the long-term course of Dravet syndrome (DS). METHODS: Sixty-four patients diagnosed with DS (44 with typical DS, and 20 with atypical DS) were studied. The long-term outcomes of clinical seizures, electroencephalographic findings, neuropsychological findings, and social situation were analyzed. The follow-up period ranged from 11 to 34 years 5 months (median 24 years). RESULTS: At the last visit, the ages ranged from 19 years to 45 years (median 30 years). Fifty-nine patients continued to have generalized tonic-clonic seizures (GTCS). Status epilepticus and unilateral seizures were not observed and myoclonic seizures, atypical absence seizures, and photosensitive seizures were resolved in most patients. The frequency of complex partial seizures was equally low, with five patients at presentation and six patients at the last visit, respectively. Five patients achieved seizure remission (seizure-free for 1 year or longer). Only 1 of 44 patients with typical DS had seizure remission, whereas 4 of 20 patients with atypical DS remitted, with a statistically significant difference between the two phenotypes (p = 0.03). Intellectual disability was found in all patients; especially, severe intellectual disability was prevalent. Patients with atypical DS tended to have milder intellectual disability compared to those with typical DS (p = 0.0283). Occipital alpha rhythm in the basic activity was associated with milder intellectual disability (p = 0.0085). The freedom from seizures correlated with appearance of occipital alpha rhythms (p = 0.0008) and disappearance of epileptic discharges (p = 0.0004). Two patients with GTCS died. Mutations of the neuronal voltage-gated sodium channel alpha subunit type 1 gene were detected at a high frequency (33 of 36 patients examined). Seizure remission was found only in the missense mutation group. SIGNIFICANCE: The long-term seizure and intellectual outcomes are extremely poor in patients with typical DS compared to those with atypical DS. Epilepsy phenotype may influence long-term course of DS.

Reflex myoclonic epilepsy in infancy: a critical review.

Benign myoclonic epilepsy in infancy, classified among the generalised idiopathic epilepsies, is characterised by the occurrence of myoclonic seizures in the first three years of life in otherwise normal infants. Some authors have described cases of myoclonic seizures as a reflex response to sudden unexpected tactile or acoustic stimuli and this clinical entity has been proposed as a separate nosographic syndrome, referred to as "reflex myoclonic epilepsy in infancy" (RMEI). We reviewed all published articles and case reports on RMEI in order to clarify clinical and electroencephalographic findings, with particular attention to outcome and treatment. RMEI appears to be a benign variant of idiopathic myoclonic epilepsy in infancy with specific features that occur in neurologically and developmentally normal children. This rare clinical entity is often under-described and under-diagnosed, and for this reason should be brought to the attention of paediatricians in order to avoid extensive investigations and reassure parents of the lack of long-term complications.

Do All Roads Lead to Rome? Genes Causing Dravet Syndrome and Dravet Syndrome-Like Phenotypes.

Background: Dravet syndrome (DS) is a severe epileptic encephalopathy mainly caused by haploinsufficiency of the gene SCN1A, which encodes the voltage-gated sodium channel NaV1. 1 in the brain. While SCN1A mutations are known to be the primary cause of DS, other genes that may cause DS are poorly understood. Several genes with pathogenic mutations result in DS or DS-like phenotypes, which may require different drug treatment approaches. Therefore, it is urgent for clinicians, especially epilepsy specialists to fully understand these genes involved in DS in addition to SCN1A. Particularly for healthcare providers, a deep understanding of these pathogenic genes is useful in properly selecting and adjusting drugs in a more effective and timely manner. Objective: The purpose of this study was to identify genes other than SCN1A that may also cause DS or DS-like phenotypes. Methods: A comprehensive search of relevant Dravet syndrome and severe myoclonic epilepsy in infancy was performed in PubMed, until December 1, 2021. Two independent authors performed the screening for potentially eligible studies. Disagreements were decided by a third, more professional researcher or by all three. The results reported by each study were narratively summarized. Results: A PubMed search yielded 5,064 items, and other sources search 12 records. A total of 29 studies published between 2009 and 2021 met the inclusion criteria. Regarding the included articles, seven studies on PCDH19, three on SCN2A, two on SCN8A, five on SCN1B, two on GABRA1, three on GABRB3, three on GABRG2, and three on STXBP1 were included. Only one study was recorded for CHD2, CPLX1, HCN1 and KCNA2, respectively. It is worth noting that a few articles reported on more than one epilepsy gene. Conclusion: DS is not only identified in variants of SCN1A, but other genes such as PCDH19, SCN2A, SCN8A, SCN1B, GABRA1, GABRB3, GABRG2, KCNA2, CHD2, CPLX1, HCN1A, STXBP1 can also be involved in DS or DS-like phenotypes. As genetic testing becomes more widely available, more genes associated with DS and DS-like phenotypes may be identified and gene-based diagnosis of subtypes of phenotypes in this spectrum may improve the management of these diseases in the future.

Follow-up study of idiopathic generalized epilepsy with associated absence seizure and myoclonic epilepsy of infancy.

We evaluated the long-term prognosis of patients featuring the association of absences and myoclonic epilepsy of infancy. Our cohort consisted of 10 male subjects with mean age at seizure onset of 29 months. Follow-up data included seizure outcome and EEG findings. All individuals received antiepileptic drugs (AEDs) as monotherapy (6 patients) or polytherapy (4 patients) for a mean period of 24 months. Over a 30-60 month evaluation period (mean: 43 months), all patients were seizure-free. Follow-up data after withdrawal of antiepileptic therapy were obtained for a mean period of 22 months. None of the children did develop other age-related epileptic syndrome after AEDs discontinuation. Furthermore, follow-up EEG data after drugs withdrawal were normal and none of the patients showed cognitive impairment. In conclusion, we confirm that absence seizures may occur in association with myoclonic epilepsy of infancy. This condition shows excellent prognosis with either favourable neurologic development and seizure outcome in these children.

Myoclonic epilepsy in infancy with preceding or concurrent afebrile generalized tonic-clonic seizures in Chinese children.

OBJECTIVE: To investigate the general characteristics and the category of myoclonic epilepsy in infancy (MEI) with or without afebrile generalized tonic-clonic seizures (GTCS). METHODS: Thirty-three children were retrospectively recruited from approximately 42,814 video-electroencephalogram (VEEG) recordings monitored in our department over last nearly 10years. Myoclonic seizures (MS) must be identified by VEEG in all patients. The clinical, EEG features and outcome were analyzed among these patients. RESULTS: The 33 patients (25 boys and 8 girls) were divided into three groups: 11 patients with typical MEI; 16 patients with MEI experienced afebrile GTCS before MS onset; and 6 patients with MEI presented afebrile GTCS occurring concurrently with MS. No significant differences were found among the three groups, including gender distribution, family history, personal history of febrile seizures, the age at seizure onset and control, the duration of MS, the interval between age at onset and seizure control, the age at EEG normalization, the interval between seizure onset age and EEG normalization age and normal psychomotor development at the end of follow-up. More patients in group two and group three were controlled by two or three kinds of antiepileptic drugs compared with those in group one. CONCLUSIONS: In this study, three groups of patients had similar clinical, EEG features and outcome. Afebrile GTCS was associated with a stronger cortical hyperexcitability. It was worth considering whether MEI with preceding or concurrent afebrile GTCS should be recognized as subgroups or different epileptic syndromes independent of MEI.

Do pure absence seizures occur in myoclonic epilepsy of infancy? A case series.

PURPOSE: To assess if absence seizures (ASs) occur in patients with myoclonic epilepsy of infancy (MEI). METHODS: A retrospective chart review was conducted in 37 patients with MEI followed at seven different paediatric epilepsy centres in Italy, between 2002 and 2014. To assess the possible occurrence of pure ASs or absences associated with myoclonias, ASs were defined according to the following criteria: (i) a sudden onset and interruption of ongoing activities; (ii) bilateral polyspikes or spike-and-wave (SW) complexes; spike SW complexes at 2-4Hz; (iii) duration of AS: 3-30seconds. RESULTS: Thirty-seven MEI patients (25 boys and 12 girls) were identified. Nine patients (24.3%) had a history of simple FS during the first year of life. Ten patients (27%) had a family history of epilepsy, and six patients (16.2%) had a family history of FS. In 7/37 (18.9%) patients, during the occurrence of MSs, a total of nineteen brief ASs were captured by video-EEG recordings. ASs occurred both during a brief cluster of rhythmic MSs than after single myoclonic jerks. The ictal EEG abnormalities observed in patients with ASs were similar to the ictal EEG patterns associated with only myoclonias. No differences in relation to gender, family history, ictal EEG discharge were found between patients with myoclonic seizures with ASs and myoclonias without ASs. CONCLUSIONS: Absence seizures can occur in approximately 20% of MEI patients and the occurrence of ASs, though not essential to formulate the diagnosis, do not automatically exclude the diagnosis of MEI.

Long-term safety and efficacy of stiripentol for the treatment of Dravet syndrome: A multicenter, open-label study in Japan.

BACKGROUND: We have previously shown the benefits of short-term add-on stiripentol therapy for Dravet syndrome inadequately controlled by clobazam and valproate in Japanese patients. We report here the outcomes of long-term stiripentol use. METHODS: Patients with Dravet syndrome having ≥4 clonic/tonic-clonic seizures per 30 days while on clobazam and valproate (with or without bromide) received add-on stiripentol for 16 weeks. Those benefiting from stiripentol (50mg/kg/day; up to 2500mg/day) continued the therapy for additional up to 40 weeks. Responders were defined as those whose clonic/tonic-clonic seizures became ≤50% frequent as compared to baseline. RESULTS: Of 24 patients starting stiripentol, 21 received the drug for >16 weeks and 19 completed the study. At the endpoint, the responder rate was 54%, with 2 patients remaining clonic/tonic-clonic seizure-free. Twenty-two patients experienced stiripentol-related adverse events, with two having severe ones. They included somnolence (79%), loss of appetite (67%), ataxia (58%), and elevated gamma-glutamyltransferase (38%). No adverse events led to study discontinuation, but 19 patients required dose reduction for stiripentol and/or either antiepileptic drug combined. Stiripentol dose reduction was done in 9 patients, mostly due to somnolence or loss of appetite. CONCLUSIONS: During adjunctive stiripentol use with clobazam and valproate, careful monitoring for adverse events such as somnolence and loss of appetite is recommended, and dose reduction may become needed for any of the antiepileptics. Despite the need for safety precautions, the durable responses to stiripentol for up to 56 weeks suggest that the drug is effective as an adjunct to clobazam and valproate for the treatment of Dravet syndrome.

Mutant GABA(A) receptor subunits in genetic (idiopathic) epilepsy.

The γ-aminobutyric acid receptor type A (GABAA receptor) is a ligand-gated chloride channel that mediates major inhibitory functions in the central nervous system. GABAA receptors function mainly as pentamers containing α, ß, and either γ or δ subunits. A number of antiepileptic drugs have agonistic effects on GABAA receptors. Hence, dysfunctions of GABAA receptors have been postulated to play important roles in the etiology of epilepsy. In fact, mutations or genetic variations of the genes encoding the α1, α6, ß2, ß3, γ2, or δ subunits (GABRA1, GABRA6, GABRB2, GABRB3, GABRG2, and GABRD, respectively) have been associated with human epilepsy, both with and without febrile seizures. Epilepsy resulting from mutations is commonly one of following, genetic (idiopathic) generalized epilepsy (e.g., juvenile myoclonic epilepsy), childhood absence epilepsy, genetic epilepsy with febrile seizures, or Dravet syndrome. Recently, mutations of GABRA1, GABRB2, and GABRB3 were associated with infantile spasms and Lennox-Gastaut syndrome. These mutations compromise hyperpolarization through GABAA receptors, which is believed to cause seizures. Interestingly, most of the insufficiencies are not caused by receptor gating abnormalities, but by complex mechanisms, including endoplasmic reticulum (ER)-associated degradation, nonsense-mediated mRNA decay, intracellular trafficking defects, and ER stress. Thus, GABAA receptor subunit mutations are now thought to participate in the pathomechanisms of epilepsy, and an improved understanding of these mutations should facilitate our understanding of epilepsy and the development of new therapies.

The ketogenic diet in Dravet syndrome.

Dravet syndrome is an infantile epilepsy syndrome with intractable pleomorphic seizures, cognitive impairment, and a number of comorbidities including ataxia/gait abnormalities and behavioral issues. Antiseizure medications are only partially effective in controlling seizures. Secondary to the intractable epilepsy, patients are often on multiple antiseizure medications with significant accumulative neurotoxic side effects. Specifically for Dravet syndrome, the medical literature includes both laboratory and clinical research that supports the use of the ketogenic diet. In addition, a review of the children with Dravet syndrome who were treated with the ketogenic diet at our center was undertaken. Thirteen of the 20 children (65%) with Dravet syndrome treated with the ketogenic diet experienced a greater than 50% reduction in seizure frequency. The ketogenic diet is a good alternative to medication for seizure management in children with Dravet syndrome.

¿Crisis febriles complejas o síndrome de Dravet?: Descripción de 3 casos clínicos / Complex febrile Seizures or Dravet syndrome?: Description of 3 case reports

Introduction: Dravet syndrome (DS) is one of the most intractable forms of epilepsy that begins in infancy. This syndrome is characterized by beginning with complex febrile seizures (FS) in a healthy infant and progresses to refractory epilepsy with psychomotor regression. The detection of a SCN1A mutation encoding the sodium channel can confirm the diagnosis. Objective: To report 3 confirmed cases of genetically DS. Case reports: We describe 3 girls diagnosed with complex FS that started when they were between 2 and 7 months old. FS were frequent, hemi generalized and myoclonic associated with recurrent febrile status epilepticus (SE). Despite FS and SE recurrence, the psychomotor development, electrophysiological studies and magnetic resonance imaging (MRI) of the brain were normal. After a year, they developed afebrile seizures progressing to refractory epilepsy with developmental regression. A molecular study detected SCN1A mutation confirming DS. The specific antiepileptic treatment and prevention of febrile episodes allowed partial control of epilepsy with some recovery of psychomotor skills. Conclusions: The high frequency complex FS associated with recurrent SE in a previously healthy infant should alert about the possibility of DS. Molecular diagnostics helps us to establish a drugs and non-drug therapies treatment, as well as long-term prognosis and genetic counseling.

Introducción: El Síndrome de Dravet (SD) es una de las formas más intratables de epilepsia que debuta en lactantes con convulsiones febriles (CF) complejas recurrentes que evolucionan posteriormente a epilepsia refractaria con regresión psicomotora. La detección de una mutación del canal de Sodio (SCN1A) permite certificar el diagnóstico. Objetivo: Reportar 3 casos de SD confirmados genéticamente. Casos clínicos: Se describen 3 niñas con diagnóstico de CF complejas iniciadas entre los 2 y 7 meses de edad. Las CF eran frecuentes, hemigeneralizadas, mioclónicas asociadas a status epilepticus (SE) febriles recurrentes. A pesar de la recurrencia de CF y SE, tanto el desarrollo psicomotor como los estudios electrofisiológicos y la resonancia magnética (RM) cerebral, fueron normales. Posterior al año iniciaron crisis afebriles que evolucionaron a epilepsia refractaria con regresión del desarrollo. El estudio molecular detectó la mutación SCN1A confirmando SD. El tratamiento antiepiléptico específico y la prevención de cuadros febriles permitieron un control parcial de la epilepsia con recuperación de algunas habilidades psicomotoras. Conclusiones: La alta frecuencia de CF complejas asociadas a SE recurrentes en un lactante previamente sano, debe alertar sobre la posibilidad de un SD. El diagnóstico molecular nos permite instaurar un tratamiento antiepiléptico y terapias no farmacológicas además de un pronóstico a largo plazo y consejería genética.