Early-infantile epileptic encephalopathy with suppression-bursts, Ohtahara syndrome; its overview referring to our 16 cases

Disease-linked mutations in Munc18-1 deplete synaptic Doc2

Heterozygous de novo mutations in the neuronal protein Munc18-1/STXBP1 cause syndromic neurological symptoms, including severe epilepsy, intellectual disability, developmental delay, ataxia and tremor, summarized as STXBP1 encephalopathies. Although haploinsufficiency is the prevailing disease mechanism, it remains unclear how the reduction in Munc18-1 levels causes synaptic dysfunction in disease as well as how haploinsufficiency alone can account for the significant heterogeneity among patients in terms of the presence, onset and severity of different symptoms. Using biochemical and cell biological readouts on mouse brains, cultured mouse neurons and heterologous cells, we found that the synaptic Munc18-1 interactors Doc2A and Doc2B are unstable in the absence of Munc18-1 and aggregate in the presence of disease-causing Munc18-1 mutants. In haploinsufficiency-mimicking heterozygous knockout neurons, we found a reduction in Doc2A/B levels that is further aggravated by the presence of the disease-causing Munc18-1 mutation G544D as well as an impairment in Doc2A/B synaptic targeting in both genotypes. We also demonstrated that overexpression of Doc2A/B partially rescues synaptic dysfunction in heterozygous knockout neurons but not heterozygous knockout neurons expressing G544D Munc18-1. Our data demonstrate that STXBP1 encephalopathies are not only characterized by the dysfunction of Munc18-1 but also by the dysfunction of the Munc18-1 binding partners Doc2A and Doc2B, and that this dysfunction is exacerbated by the presence of a Munc18-1 missense mutant. These findings may offer a novel explanation for the significant heterogeneity in symptoms observed among STXBP1 encephalopathy patients.

Type 1 early infantile epileptic encephalopathy: A case report and literature review

BACKGROUND

Variants in the Aristaless-related homeobox (ARX) gene lead to a variety of phenotypes, with intellectual disability being a steady feature. Other features can include severe epilepsy, spasticity, movement disorders, hydranencephaly, and ambiguous genitalia in males. X-linked Ohtahara syndrome or Type 1 early infantile epileptic encephalopathy (EIEE1) is a severe early-onset epileptic encephalopathy with arrested psychomotor development caused by hemizygous mutations in the ARX gene, which encodes a transcription factor in fundamental brain developmental processes.

METHODS

We presented a case report of a 2-year-old boy who exhibited symptoms such as microcephaly, seizures, and severe multifocal epileptic abnormalities, and genetic techniques such as autozygosity mapping, Sanger sequencing, and whole-exome sequencing.

RESULTS

We confirmed that the patient had the NM_139058.3:c.84C>A; p.(Cys28Ter) mutation in the ARX gene.

CONCLUSION

The patient with EIEE1 had physical symptoms and hypsarrhythmia on electroencephalogram. Genetic testing identified a causative mutation in the ARX gene, emphasizing the role of genetic testing in EIEE diagnosis.

A Retrospective Study of the Patient State Index During General Anesthesia in Infants and Young Children

This study described electroencephalogram (EEG) parameters in children under general anesthesia, which could monitor patient-specific brain responses to anesthetics and assess the effects of anesthesia. The objective was to detect the patient state index (PSI) and associated factors. We analyzed EEG parameters in patients in the age range 1 to 36 months. Patients were stratified into 2 groups as those aged 1 to 12 months and 13 to 36 months. Sixty-two patients were involved. Spectral edge frequency (SEF), PSI, and blood pressure were lower, and burst suppression rate (BSR) and heart rate were higher in the 1 to 12 months group. The SEF was associated with PSI in both groups. Age and blood pressure were positively associated with PSI, and BSR was negatively related to PSI in children under 1 year of age. Blood pressure was not associated with PSI in the 13 to 36 months age group. We found that the PSI levels did not accurately assess the depth of anesthesia in children under 1 year of age.

Respiratory Dysfunction in Epileptic Encephalopathies: Insights and Challenges

Epileptic encephalopathies constitute a group of severe epileptic disorders characterized by intractable seizures and cognitive regression. Beyond the hallmark neurological manifestations, these disorders frequently exhibit associated respiratory dysfunction, which is increasingly recognized as a critical aspect of their pathophysiology. Respiratory abnormalities in epileptic encephalopathies encompass a spectrum of manifestations, ranging from subtle alterations in breathing patterns to life-threatening events such as apneas and hypoventilation. These respiratory disturbances often occur during seizures, the interictal period, or even persist chronically, leading to significant morbidity and mortality. We explore the varied clinical presentations and their implications on patient outcomes, emphasizing the need for heightened awareness among clinicians. This review unravels the intricate mechanisms linking epilepsy and respiratory dysfunction. GABAergic and glutamatergic imbalances, alterations in central respiratory centers, and abnormal autonomic control are among the key factors contributing to respiratory disturbances in these patients. We elucidate the neurobiological intricacies that underlie these processes and their relevance to therapeutic interventions. Accurate diagnosis of respiratory dysfunction in epileptic encephalopathies is often hindered by its diverse clinical phenotypes and the absence of routine screening protocols. We scrutinize the diagnostic hurdles, highlighting the necessity of comprehensive respiratory assessments in managing these patients. Timely recognition of respiratory issues may guide treatment decisions and mitigate complications. Management of respiratory dysfunction in epileptic encephalopathies is complex and necessitates a multidisciplinary approach. We explore various therapeutic modalities, including antiepileptic drugs (AEDs), ventilatory support, and novel interventions like neuromodulation techniques. The review emphasizes the individualized nature of treatment strategies tailored to each patient's specific needs. In conclusion, this narrative review offers a comprehensive overview of respiratory dysfunction in epileptic encephalopathies, shedding light on its clinical importance, underlying mechanisms, diagnostic challenges, and therapeutic considerations. By addressing these insights and challenges, we hope to inspire further research and innovation to enhance the care and outcomes of patients with epileptic encephalopathies.

Alternating hemiplegia of childhood: a distinct clinical entity and ATP1A3-related disorders: A narrative review

Alternating Hemiplegia of Childhood (AHC) is a rare disorder with onset in the first 18 months of life characterized by stereotyped paroxysmal manifestations of tonic and dystonic attacks, nystagmus with other oculomotor abnormalities, respiratory and autonomic dysfunctions. AHC is often associated with epileptic seizures and developmental delay. Hemiplegic paroxysm is the most remarkable symptom, although AHC includes a large series of clinical manifestations that interfere with the disease course. No cure is available and the treatment involves many specialists and therapies. Flunarizine is the most commonly used drug for reducing the frequency and intensity of paroxysmal events. Mutations in ATP1A2, particularly in ATP1A3, are the main genes responsible for AHC. Some disorders caused by ATP1A3 variants have been defined as ATP1A3-related disorders, including rapid-onset dystonia-parkinsonism, cerebellar ataxia, pes cavus, optic atrophy, sensorineural hearing loss, early infant epileptic encephalopathy, child rapid-onset ataxia, and relapsing encephalopathy with cerebellar ataxia. Recently, the term ATP1A3 syndrome has been identified as a fever-induced paroxysmal weakness and encephalopathy, slowly progressive cerebellar ataxia, childhood-onset schizophrenia/autistic spectrum disorder, paroxysmal dyskinesia, cerebral palsy/spastic paraparesis, dystonia, dysmorphism, encephalopathy, MRI abnormalities without hemiplegia, and congenital hydrocephalus. Herewith, we discussed about historical annotations of AHC, symptoms, signs and associated morbidities, diagnosis and differential diagnosis, treatment, prognosis, and genetics. We also reported on the ATP1A3-related disorders and ATP1A3 syndrome, as 2 recently established and expanded genetic clinical entities.

The relationship between the characteristics of burst suppression pattern and different etiologies in epilepsy

To analyze the relationship between the characteristics of burst suppression (BS) pattern and different etiologies in epilepsy. Patients with a BS pattern who were younger than 6 months old were screened from our electroencephalogram (EEG) database. The synchronized and symmetric BS patterns under different etiologies in epilepsy were analyzed. A total of 32 patients had a BS pattern on EEG. The etiologies included genetic disorders (37.5%), cortical malformations (28.1%), inborn errors of metabolism (12.5%), and unknown (21.9%). Twenty-five patients were diagnosed with Ohtahara syndrome, one as early myoclonic encephalopathy, and one as epilepsy of infancy with migrating focal seizure. Five cases could not be classified into any epileptic syndrome. Asynchronous BS pattern was identified in 18 cases, of which 13 (72%) patients had genetic and/or metabolic etiologies. Synchronous BS pattern was identified in 14 cases, of which 8 (57%) patients had structural etiologies. Twenty-three patients had symmetric BS patterns, of which 15 (65%) patients had genetic etiologies. Nine patients had asymmetric BS patterns, of which 8 (89%) patients had structural etiologies. Patients with genetic epilepsies tended to have asynchronous and symmetric BS patterns, whereas those with structural epilepsies were more likely to have synchronous and asymmetric BS patterns.

Epilepsy Syndromes in the First Year of Life and Usefulness of Genetic Testing for Precision Therapy

The high pace of gene discovery has resulted in thrilling advances in the field of epilepsy genetics. Clinical testing with comprehensive gene panels, exomes, or genomes are now increasingly available and have led to a significant higher diagnostic yield in early-onset epilepsies and enabled precision medicine approaches. These have been instrumental in providing insights into the pathophysiology of both early-onset benign and self-limited syndromes and devastating developmental and epileptic encephalopathies (DEEs). Genetic heterogeneity is seen in many epilepsy syndromes such as West syndrome and epilepsy of infancy with migrating focal seizures (EIMFS), indicating that two or more genetic loci produce the same or similar phenotypes. At the same time, some genes such as SCN2A can be associated with a wide range of epilepsy syndromes ranging from self-limited familial neonatal epilepsy at the mild end to Ohtahara syndrome, EIFMS, West syndrome, Lennox–Gastaut syndrome, or unclassifiable DEEs at the severe end of the spectrum. The aim of this study was to review the clinical and genetic heterogeneity associated with epilepsy syndromes starting in the first year of life including: Self-limited familial neonatal, neonatal-infantile or infantile epilepsies, genetic epilepsy with febrile seizures plus spectrum, myoclonic epilepsy in infancy, Ohtahara syndrome, early myoclonic encephalopathy, West syndrome, Dravet syndrome, EIMFS, and unclassifiable DEEs. We also elaborate on the advantages and pitfalls of genetic testing in such conditions. Finally, we describe how a genetic diagnosis can potentially enable precision therapy in monogenic epilepsies and emphasize that early genetic testing is a cornerstone for such therapeutic strategies.

Current Pharmacologic Strategies for Treatment of Intractable Epilepsy in Children

Epileptic encephalopathy (EE) is a devastating pediatric disease that features medically resistant seizures, which can contribute to global developmental delays. Despite technological advancements in genetics, the neurobiological mechanisms of EEs are not fully understood, leaving few therapeutic options for affected patients. In this review, we introduce the most common EEs in pediatrics (i.e., Ohtahara syndrome, Dravet syndrome, and Lennox-Gastaut syndrome) and their molecular mechanisms that cause excitation/inhibition imbalances. We then discuss some of the essential molecules that are frequently dysregulated in EEs. Specifically, we explore voltage-gated ion channels, synaptic transmission-related proteins, and ligand-gated ion channels in association with the pathophysiology of Ohtahara syndrome, Dravet syndrome, and Lennox-Gastaut syndrome. Finally, we review currently available antiepileptic drugs used to treat seizures in patients with EEs. Since these patients often fail to achieve seizure relief even with the combination therapy, further extensive research efforts to explore the involved molecular mechanisms will be required to develop new drugs for patients with intractable epilepsy.

SLC25A22 and Its Related Epileptic Encephalopathies

Epileptic encephalopathy is a condition in which seizures, electroencephalographic epileptiform abnormalities lead to a progressive deterioration of brain functions causing a significant psychomotor delay. One of the typical features of this heterogeneous and large group of severe disorders is the extremely early onset of seizures. The main causes of the epileptic encephalopathies include structural brain defects, inherited metabolic disorders; in this aspect, more than 100 genetic defects, including mutations in the solute carrier family 25 (SLC25A22) gene which encodes a mitochondrial glutamate carrier. To date, the main clinical phenotypes related to mutations of this gene are Ohtahara syndrome (or early infantile epileptic encephalopathy), early myoclonic encephalopathy and migrating partial seizures in infancy. In all the cases, prognosis is poor and no disease-modifying treatment is available in the present days.

Adult phenotype of KCNQ2 encephalopathy

BACKGROUND

Pathogenic KCNQ2 variants are a frequent cause of developmental and epileptic encephalopathy.

METHODS

We recruited 13 adults (between 18 years and 45 years of age) with KCNQ2 encephalopathy and reviewed their clinical, EEG, neuroimaging and treatment history.

RESULTS

While most patients had daily seizures at seizure onset, seizure frequency declined or remitted during childhood and adulthood. The most common seizure type was tonic seizures (early) infancy, and tonic-clonic and focal impaired awareness seizures later in life. Ten individuals (77%) were seizure-free at last follow-up. In 38% of the individuals, earlier periods of seizure freedom lasting a minimum of 2 years followed by seizure recurrence had occurred. Of the 10 seizure-free patients, 4 were receiving a single antiseizure medication (ASM, carbamazepine, lamotrigine or levetiracetam), and 2 had stopped taking ASM. Intellectual disability (ID) ranged from mild to profound, with the majority (54%) of individuals in the severe category. At last contact, six individuals (46%) remained unable to walk independently, six (46%) had limb spasticity and four (31%) tetraparesis/tetraplegia. Six (46%) remained non-verbal, 10 (77%) had autistic features/autism, 4 (31%) exhibited aggressive behaviour and 4 (31%) destructive behaviour with self-injury. Four patients had visual problems, thought to be related to prematurity in one. Sleep problems were seen in six (46%) individuals.

CONCLUSION

Seizure frequency declines over the years and most patients are seizure-free in adulthood. Longer seizure-free periods followed by seizure recurrence are common during childhood and adolescence. Most adult patients have severe ID. Motor, language and behavioural problems are an issue of continuous concern.

STXBP1 encephalopathies: Clinical spectrum, disease mechanisms, and therapeutic strategies

Mutations in Munc18-1/STXBP1 (syntaxin-binding protein 1) are linked to various severe early epileptic encephalopathies and neurodevelopmental disorders. Heterozygous mutations in the STXBP1 gene include missense, nonsense, frameshift, and splice site mutations, as well as intragenic deletions and duplications and whole-gene deletions. No genotype-phenotype correlation has been identified so far, and patients are treated by anti-epileptic drugs because of the lack of a specific disease-modifying therapy. The molecular disease mechanisms underlying STXBP1-linked disorders are yet to be fully understood, but both haploinsufficiency and dominant-negative mechanisms have been proposed. This review focuses on the current understanding of the phenotypic spectrum of STXBP1-linked disorders, as well as discusses disease mechanisms in the context of the numerous pathways in which STXBP1 functions in the brain. We additionally evaluate the available animal models to study these disorders and highlight potential therapeutic approaches for treating these devastating diseases.

Seizures in the neonate: A review of etiologies and outcomes

Neonatal seizures occur in their majority in close temporal relation to an acute brain injury or systemic insult, and are accordingly defined as acute symptomatic or provoked seizures. However less frequently, unprovoked seizures may also present in the neonatal period as secondary to structural brain abnormalities, thus corresponding to structural epilepsies, or to genetic conditions, thus corresponding to genetic epilepsies. Unprovoked neonatal seizures should be thus considered as the clinical manifestation of early onset structural or genetic epilepsies that often have the characteristics of early onset epileptic encephalopathies. In this review, we address the conundrum of neonatal seizures including acute symptomatic, remote symptomatic, provoked, and unprovoked seizures, evolving to post-neonatal epilepsies, and neonatal onset epilepsies. The different clinical scenarios involving neonatal seizures, each with their distinct post-neonatal evolution are presented. The structural and functional impact of neonatal seizures on brain development and the concept of secondary epileptogenesis, with or without a following latent period after the acute seizures, are addressed. Finally, we underline the need for an early differential diagnosis between an acute symptomatic seizure and an unprovoked seizure, since it is associated with fundamental differences in clinical evolution. These are crucial aspects for neonatal management, counselling and prognostication. In view of the above aspects, we provide an outlook on future strategies and potential lines of research in this field.

Does electroencephalographic burst suppression still play a role in the perioperative setting?

With the widespread use of electroencephalogram [EEG] monitoring during surgery or in the Intensive Care Unit [ICU], clinicians can sometimes face the pattern of burst suppression [BS]. The BS pattern corresponds to the continuous quasi-periodic alternation between high-voltage slow waves [the bursts] and periods of low voltage or even isoelectricity of the EEG signal [the suppression] and is extremely rare outside ICU and the operative room. BS can be secondary to increased anesthetic depth or a marker of cerebral damage, as a therapeutic endpoint [i.e., refractory status epilepticus or refractory intracranial hypertension]. In this review, we report the neurophysiological features of BS to better define its role during intraoperative and critical care settings.

Neonatal SCN2A encephalopathy: A peculiar recognizable electroclinical sequence

INTRODUCTION

Sodium voltage-gated channel alpha subunit 2 (SCN2A) gene encodes the Nav1.2 subunit of voltage-gated sodium channel in pyramidal neurons. SCN2A gain-of-function mutations are identified more and more often with gene panels and whole exome sequencing. Phenotype ranges from benign neonatal or infantile seizures to severe epileptic encephalopathy. Although large series of patients targeting genetic background point out two main phenotypes with SCN2A encephalopathy, Ohtahara syndrome and malignant migrating partial seizures in infancy (EMPSI), we noticed that in fact, a peculiar clinical and electroencephalogram (EEG) sequence distinct from these syndromes should suggest the diagnosis early.

PATIENTS AND METHODS

We report three new cases with de novo SCN2A mutations - 166237617C>A p.(Asp1487Glu), c.407T>G p.(Met136Arg), and c.4633A>G p.(Met1545Val) - diagnosed by direct sequencing or genes panel, their follow-up ranging from 4 to 5 years.

RESULTS

For all three patients, seizures started at two days of life and consisted of apnea and cyanosis with partial clonic or tonic, alternating on both sides with, up to 100/day, evolving to generalized tonic-clonic seizures (GTCS) and epileptic spasms by three months. First EEG showed a discontinuous pattern, evolving to multifocal spikes, by 3 (two patients) and 6 months (one). Seizure frequency decreased progressively by the middle or end of the first year of life. Only less frequent GTCS persisted during the second year of life for two patients. Improvement was observed in two patients with sodium channel blocker (phenytoin) used at age of 1 month for one patient and at 2 years for another one. All patients remained with severe psychomotor delay.

DISCUSSION

All three infants share a condition different from Ohtahara syndrome in which tonic spasms predominate and suppression-burst pattern is obvious, and from EMPSI, in which partial migrating discharges involve successively the various parts of the brain including occipital regions with oculoclonic seizures, but there is neither discontinuous pattern nor therapeutic response to sodium channel blockers.

CONCLUSION

Neonatal SCN2A encephalopathy has a recognizable phenotype starting soon after birth with alternating partial motor seizures evolving to infantile spasms and a discontinuous EEG pattern. Seizures improve spontaneously in the first year of life. This electroclinical sequence should indicate the search of SCN2A mutation and suggest the administration of sodium channel blockers.

Modeling epileptic spasms during infancy: Are we heading for the treatment yet?

Infantile spasms (IS or epileptic spasms during infancy) were first described by Dr. William James West (aka West syndrome) in his own son in 1841. While rare by definition (occurring in 1 per 3200-3400 live births), IS represent a major social and treatment burden. The etiology of IS varies - there are many (>200) different known pathologies resulting in IS and still in about one third of cases there is no obvious reason. With the advancement of genetic analysis, role of certain genes (such as ARX or CDKL5 and others) in IS appears to be important. Current treatment strategies with incomplete efficacy and serious potential adverse effects include adrenocorticotropin (ACTH), corticosteroids (prednisone, prednisolone) and vigabatrin, more recently also a combination of hormones and vigabatrin. Second line treatments include pyridoxine (vitamin B6) and ketogenic diet. Additional treatment approaches use rapamycin, cannabidiol, valproic acid and other anti-seizure medications. Efficacy of these second line medications is variable but usually inferior to hormonal treatments and vigabatrin. Thus, new and effective models of this devastating condition are required for the search of additional treatment options as well as for better understanding the mechanisms of IS. Currently, eight models of IS are reviewed along with the ideas and mechanisms behind these models, drugs tested using the models and their efficacy and usefulness. Etiological variety of IS is somewhat reflected in the variety of the models. However, it seems that for finding precise personalized approaches, this variety is necessary as there is no "one-size-fits-all" approach possible for both IS in particular and epilepsy in general.

A knock-in mouse model for KCNQ2-related epileptic encephalopathy displays spontaneous generalized seizures and cognitive impairment

Objective

Early onset epileptic encephalopathy with suppression‐burst is one of the most severe epilepsy phenotypes in human patients. A significant proportion of cases have a genetic origin, and the most frequently mutated gene is KCNQ2, encoding Kv7.2, a voltage‐dependent potassium channel subunit, leading to so‐called KCNQ2‐related epileptic encephalopathy (KCNQ2‐REE). To study the pathophysiology of KCNQ2‐REE in detail and to provide a relevant preclinical model, we generated and described a knock‐in mouse model carrying the recurrent p.(Thr274Met) variant.

Methods

We introduced the p.(Thr274Met) variant by homologous recombination in embryonic stem cells, injected into C57Bl/6N blastocysts and implanted in pseudopregnant mice. Mice were then bred with 129Sv Cre‐deleter to generate heterozygous mice carrying the p.(Thr274Met), and animals were maintained on the 129Sv genetic background. We studied the development of this new model and performed in vivo electroencephalographic (EEG) recordings, neuroanatomical studies at different time points, and multiple behavioral tests.

Results

The Kcnq2^Thr274Met/+ mice are viable and display generalized spontaneous seizures first observed between postnatal day 20 (P20) and P30. In vivo EEG recordings show that the paroxysmal events observed macroscopically are epileptic seizures. The brain of the Kcnq2^Thr274Met/+ animals does not display major structural defects, similar to humans, and their body weight is normal. Kcnq2^Thr274Met/+ mice have a reduced life span, with a peak of unexpected death occurring for 25% of the animals by 3 months of age. Epileptic seizures were generally not observed when animals grew older. Behavioral characterization reveals important deficits in spatial learning and memory in adults but no gross abnormality during early neurosensory development.

Significance

Taken together, our results indicate that we have generated a relevant model to study the pathophysiology of KCNQ2‐related epileptic encephalopathy and perform preclinical research for that devastating and currently intractable disease.

Genetic diagnosis and clinical characteristics by etiological classification in early-onset epileptic encephalopathy with burst suppression pattern

BACKGROUND

Early-onset epileptic encephalopathies with burst suppression (EOEE-BS) are a group of neonatal epileptic syndromes characterized by intractable epilepsy and severe psychomotor delay with structural and metabolic factors accounting for major etiologies. However, recent advances in gene sequencing have identified that genetic factors might also play a significant role in the development of EOEE-BS. Herein, we used various genetic tests to identify pathogenic genetic variants in EOEE-BS irrespective of structural malformations and analyzed the clinical features associated with each different etiology.

METHODS

A total of 48 patients with EOEE-BS were included. Except for patients with severe hypoxic damage, patients with structural malformations were included in our patient cohort. Clinical features of the patients were reviewed, and etiological diagnoses were made based on several genetic tests, metabolic studies, and radiological findings.

RESULT

A genetic diagnosis was made in 31 (64.6 %) patients, with the most commonly diagnosed gene being STXBP1 (n = 13, 27.1 %), followed by KCNQ2 (n = 5, 10.4 %), SCN2A (n = 5, 10.4 %), DEPDC5 (n = 3, 6.3 %), CASK (n = 1, 2.1 %), CDKL5 (n = 1, 2.1 %), GNAO1 (n = 1, 2.1 %), SLC6A8 (n = 1, 2.1 %), and LIS1 deletion (n = 1, 2.1 %). Other than the classification of epilepsy syndrome, no clinical features were associated with the genetically diagnosed group. Among eight patients with structural malformations, genetic diagnosis was achieved in five (62.5 %), and those patients had pathogenic mutations in DEPDC5 and CASK or LIS1 deletion, indicating the significance of gene sequencing irrespective of structural abnormalities. Treatment responses to a variety of medications and the ketogenic diet differed by etiology, and surgical resection proved to be effective in patients with cortical dysplasia.

CONCLUSION

Genetic etiologies are an important factor in EOEE-BS irrespective of structural malformations and the treatment options may differ by etiology.

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.

Status Epilepticus Manifested as Continuous Epileptic Spasms

Objective: The etiology and outcome of status epilepticus with continuous epileptic spasms have not been fully understood; and only rare cases have been reported in the literature. Here, we described 11 children, who manifested continuous epileptic spasms with various etiologies and different outcomes. Methods: This is a case series study designed to systematically review the charts, video-electroencephalography (video-EEG), magnetic resonance images, and longitudinal follow-up of patients who presented continuous epileptic spasms lasting more than 30 min. Results: Median age at onset was 2 years old, ranging from 2 months to 5.6 years. The etiology of continuous epileptic spasms for these 11 cases consisted of not only some known electro-clinical epilepsy syndromes like West Syndrome and Ohtahara Syndrome, but also secondary symptomatic continuous epileptic spasms, caused by acute encephalitis or encephalopathy, which extends the etiological spectrum of continuous epileptic spasms. The most characteristic feature of these 11 cases was prolonged epileptic spasms, lasting for a median of 13.00 days (95% CI: 7.26-128.22 days). The interictal EEG findings typically manifested as hypsarrhythmia or its variants, including burst suppression. Hospital stays were much longer in acute symptomatic cases than in primary epileptic syndromic cases (59.67 ± 50.82 vs. 15.00 ± 1.41 days). However, the long-term outcomes were extremely poor in the patients with defined electro-clinical epilepsy syndromes, including severe motor and intellectual developmental deficits (follow-up of 4.94 ± 1.56 years), despite early diagnosis and treatment. Continuous epileptic spasms were refractory to corticosteroids, immuno-modulation or immunosuppressive therapies, and ketogenic diet. Conclusion: Continuous epileptic spasms were associated with severe brain impairments in patients with electro-clinical syndromes; and required long hospital stays in patients with acute symptomatic causes. We suggest to include continuous epileptic spasms in the international classification of status epilepticus, as a special form. Further investigations are required to better recognize this condition, better understand the etiology, as well as to explore more effective treatments to improve outcomes.

Different types of suppression-burst patterns in patients with epilepsy of infancy with migrating focal seizures (EIMFS)

PURPOSE

In rare cases, patients with epilepsy of infancy withmigrating focal seizures (EIMFS) exhibit suppression-burst (SB) patterns on electroencephalography (EEG), similar to the findings observed in patients with Ohtahara syndrome and early myoclonic encephalopathy. In this report, we discuss six cases of EIMFS in which patients exhibited two types of SB patterns.

METHODS

We evaluated six patients with EIMFS who had been admitted to the NHO Shizuoka Institute of Epilepsy and Neurological Disorders between 2011 and 2018. We retrospectively examined clinical characteristics and EEG findings for each patient. In all patients, the first EEG was performed within 1 month after seizure onset. Afterwards, EEG examinations were performed at irregular intervals (ranging from 1 to 5 months).

RESULTS

Age at seizure onset ranged from 2 days to 3 months. SB was first detected within 1 month of age in two patients, and within the range of 3-14 months in the remaining four patients. Among the latter four patients, SB patterns persisted at the final EEG recording in three patients (34-54 months). In all patients, SB patterns were observed during sleep only. Interhemispheric asynchrony in SB was observed in the two patients who exhibited SB within 1 month of age, while synchronous SB patterns were observed in the remaining four patients.

CONCLUSIONS

Our findings indicate that EIMFS may be associated with two types of SB patterns (early-onset and late-onset), which can be distinguished based on the stage of emergence and level of synchrony.

Benign and severe early-life seizures: a round in the first year of life

BACKGROUND

At the onset, differentiation between abnormal non-epileptic movements, and epileptic seizures presenting in early life is difficult as is clinical diagnosis and prognostic evaluation of the various seizure disorders presenting at this age. Seizures starting in the first year of life including the neonatal period might have a favorable course, such as in infants presenting with benign familial neonatal epilepsy, febrile seizures simplex or acute symptomatic seizures. However, in some cases, the onset of seizures at birth or in the first months of life have a dramatic evolution with severe cerebral impairment. Seizure disorders starting in early life include the "epileptic encephalopathies", a group of conditions characterized by drug resistant seizures, delayed developmental skills, and intellective disability. This group of disorders includes early infantile epileptic encephalopathy also known as Ohtahara syndrome, early myoclonic encephalopathy, epilepsy of infancy with migrating focal seizures, infantile spasms syndrome (also known as West syndrome), severe myoclonic epilepsy in infancy (also known as Dravet syndrome) and, myoclonic encephalopathies in non-progressive disorder. Here we report on seizures manifesting in the first year of life including the neonatal period. Conditions with a benign course, and those with severe evolution are presented. At this early age, clinical identification of seizures, distinction of each of these disorders, type of treatment and prognosis is particularly challenging. The aim of this report is to present the clinical manifestations of each of these disorders and provide an updated review of the conditions associated with seizures in the first year of life.

Targeting the Mammalian Target of Rapamycin for Epileptic Encephalopathies and Malformations of Cortical Development

Malformations of cortical development represent a common cause of epileptic encephalopathies and drug-resistant epilepsy in children. As current treatments are often ineffective, new therapeutic targets are needed for epileptic encephalopathies associated with cortical malformations. The mechanistic/mammalian target of rapamycin (mTOR) pathway constitutes a signaling pathway that drives cellular and molecular mechanisms of epileptogenesis in a variety of focal cortical malformations. mTOR inhibitors prevent epilepsy and associated pathogenic mechanisms of epileptogenesis in mouse models of tuberous sclerosis complex and are currently in clinical trials for drug-resistant seizures in these patients. A recent explosion of genetic studies has linked mutations in various genes regulating the mTOR pathway to other cortical malformations, such as focal cortical dysplasia and hemimegalencephaly. Thus, mTOR inhibitors represent promising candidates as novel antiseizure and antiepileptogenic therapies for epilepsy associated with a spectrum of cortical malformations.

Munc18-1 haploinsufficiency impairs learning and memory by reduced synaptic vesicular release in a model of Ohtahara syndrome

Ohtahara syndrome, also known as type 4 of Early Infantile Epileptic Encephalopathy with suppression bursts (EIEE-4) is currently an untreatable disorder that presents with seizures and impaired cognition. EIEE-4 patients have mutations most frequently in the STXBP1 gene encoding a Sec protein, munc18-1. The exact molecular mechanism of how these munc18-1 mutations cause impaired cognition, remains elusive. The leading haploinsufficiency hypothesis posits that mutations in munc18-1 render the protein unstable leading to its degradation. Expression driven by the healthy allele is not sufficient to maintain the physiological function resulting in haploinsufficiency. The aim of this study has been to understand how munc18-1 haploinsufficiency causes cognitive impairment seen in EIEE-4. Here we present results from behavioral to cellular effects from a mouse model of munc18-1 haploinsufficiency. Munc18-1 heterozygous knock-out mice showed impaired spatial learning and memory in behavior tests as well as reduced synaptic plasticity in hippocampal CA1 long-term potentiation. Cultured munc18-1 heterozygous hippocampal neurons had significantly slower rate of synaptic vesicle release and decreased readily releasable vesicle pool compared to wild-type control neurons in fluorescent FM dye assays. These results demonstrate that reduced munc18-1 levels are sufficient to impair learning and memory by reducing neurotransmitter release. Therefore, our study implicates munc18-1 haploinsufficiency as a primary cause of cognitive impairment seen in EIEE-4 patients.

Cognitive and Social Outcomes of Epileptic Encephalopathies

The term "epileptic encephalopathy" denotes a disorder in which seizures or frequent interictal discharges exacerbate neurocognitive dysfunction beyond what would be expected on the basis of underlying etiology. However, many underlying causes of epileptic encephalopathy also result in neurocognitive deficits, and it can be challenging to discern to what extent these deficits can be improved with better seizure control. Additionally, as seizures in these conditions are typically refractory, children are often exposed to high doses of multiple antiepileptic drugs which further exacerbate these comorbidities. This review will summarize the neurocognitive and social outcomes in children with various epileptic encephalopathies. Prompt, accurate diagnosis of epilepsy syndrome and etiology allows selection of optimal therapy to maximize seizure control, limiting the impact of ongoing seizures and frequent epileptiform abnormalities on the developing brain. Furthermore, mandatory screening for comorbidities allows early recognition and focused therapy for these commonly associated conditions to maximize neurocognitive outcome.

Epileptic Encephalopathies-Clinical Syndromes and Pathophysiological Concepts

Epileptic encephalopathies account for a large proportion of the intractable early-onset epilepsies and are characterized by frequent seizures and poor developmental outcome. The epileptic encephalopathies can be loosely divided into two related groups of named syndromes. The first comprises epilepsies where continuous EEG changes directly result in cognitive and developmental dysfunction. The second includes patients where cognitive impairment is present at seizure onset and is due to the underlying etiology but the epileptic activity may then worsen the cognitive abilities over time. Recent, large-scale exome studies have begun to establish the genetic architecture of the epileptic encephalopathies, resulting in a re-consideration of the boundaries of these named syndromes. The emergence of this genetic architecture has lead to three main pathophysiological concepts to provide a mechanistic framework for these disorders. In this article, we will review the classic syndromes, the most significant genetic findings, and relate both to the pathophysiological understanding of epileptic encephalopathies.

Genetics and genotype-phenotype correlations in early onset epileptic encephalopathy with burst suppression

OBJECTIVE

We sought to identify genetic causes of early onset epileptic encephalopathies with burst suppression (Ohtahara syndrome and early myoclonic encephalopathy) and evaluate genotype-phenotype correlations.

METHODS

We enrolled 33 patients with a referral diagnosis of Ohtahara syndrome or early myoclonic encephalopathy without malformations of cortical development. We performed detailed phenotypic assessment including seizure presentation, electroencephalography, and magnetic resonance imaging. We confirmed burst suppression in 28 of 33 patients. Research-based exome sequencing was performed for patients without a previously identified molecular diagnosis from clinical evaluation or a research-based epilepsy gene panel.

RESULTS

In 17 of 28 (61%) patients with confirmed early burst suppression, we identified variants predicted to be pathogenic in KCNQ2 (n = 10), STXBP1 (n = 2), SCN2A (n = 2), PNPO (n = 1), PIGA (n = 1), and SEPSECS (n = 1). In 3 of 5 (60%) patients without confirmed early burst suppression, we identified variants predicted to be pathogenic in STXBP1 (n = 2) and SCN2A (n = 1). The patient with the homozygous PNPO variant had a low cerebrospinal fluid pyridoxal-5-phosphate level. Otherwise, no early laboratory or clinical features distinguished the cases associated with pathogenic variants in specific genes from each other or from those with no prior genetic cause identified.

INTERPRETATION

We characterize the genetic landscape of epileptic encephalopathy with burst suppression, without brain malformations, and demonstrate feasibility of genetic diagnosis with clinically available testing in >60% of our cohort, with KCNQ2 implicated in one-third. This electroclinical syndrome is associated with pathogenic variation in SEPSECS. Ann Neurol 2017;81:419-429.

[Genetics and treatment of early infantile epileptic encephalopathies]

Epileptic encephalopathies (EE) are the group of progressive conditions with various etiologies that can produce neurocognitive deficit both per se and due to constant epileptiform discharges. Epileptic encephalopathies constitute about 15% of epilepsy in childhood and 40% of all seizures occurring in the first 3 years of life. Ten syndrome forms of EE are identified. Genetic factors contribute to 70-80% of all epileptic diseases and approximately 40% of idiopathic epilepsies have a monogenic mode of inheritance. Thirty-five genes of EE have been identified and the search is still continuing. The marked genetic heterogeneity of early EE, including 16 with autosomal-dominant-, 13 with autosomal-recessive-, 4 with X-linked recessive- and 2 with X-linked autosomal inheritance, was shown. The article describes differentiated approaches to the treatment of certain EE syndromes. Recent publications record the effectiveness of targeted therapy for certain forms of monogenic early EE (stiripentol in SCN1A mutations, diphenine in SCN8A mutations, levetiracetam in STXBP1 mutations). These results indicate the necessity for accurate diagnosis of genetic variants in early infantile EE for preventive actions in burdened families and for increasing the effectiveness of treatment.

Diagnostic Approach to Genetic Causes of Early-Onset Epileptic Encephalopathy

Epileptic encephalopathies are characterized by recurrent clinical seizures and prominent interictal epileptiform discharges seen during the early infantile period. Although epileptic encephalopathies are mostly associated with structural brain defects and inherited metabolic disorders, pathogenic gene mutations may also be involved in the development of epileptic encephalopathies even when no clear genetic inheritance patterns or consanguinity exist. The most common epileptic encephalopathies are Ohtahara syndrome, early myoclonic encephalopathy, epilepsy of infancy with migrating focal seizures, West syndrome and Dravet syndrome, which are usually unresponsive to traditional antiepileptic medication. Many of the diagnoses describe the phenotype of these electroclinical syndromes, but not the underlying causes. To date, approximately 265 genes have been defined in epilepsy and several genes including STXBP1, ARX, SLC25A22, KCNQ2, CDKL5, SCN1A, and PCDH19 have been found to be associated with early-onset epileptic encephalopathies. In this review, we aimed to present a diagnostic approach to primary genetic causes of early-onset epileptic encephalopathies.

Clinical Electroencephalography for Anesthesiologists: Part I: Background and Basic Signatures

The widely used electroencephalogram-based indices for depth-of-anesthesia monitoring assume that the same index value defines the same level of unconsciousness for all anesthetics. In contrast, we show that different anesthetics act at different molecular targets and neural circuits to produce distinct brain states that are readily visible in the electroencephalogram. We present a two-part review to educate anesthesiologists on use of the unprocessed electroencephalogram and its spectrogram to track the brain states of patients receiving anesthesia care. Here in part I, we review the biophysics of the electroencephalogram and the neurophysiology of the electroencephalogram signatures of three intravenous anesthetics: propofol, dexmedetomidine, and ketamine, and four inhaled anesthetics: sevoflurane, isoflurane, desflurane, and nitrous oxide. Later in part II, we discuss patient management using these electroencephalogram signatures. Use of these electroencephalogram signatures suggests a neurophysiologically based paradigm for brain state monitoring of patients receiving anesthesia care.

Relationship of Lennox-Gastaut syndrome with perinatal event: A cross-sectional study

Introduction:

About one-half of children with Lennox–Gastaut syndrome (LGS) have history of birth hypoxia or other perinatal event but the knowledge about clinical, radiological profile and severity of epilepsy in these children as compared to those without a perinatal event is not known.

Materials and Methods:

Thirty-one children with LGS were enrolled in this study and divided into two groups: One group with the perinatal event and other group without evidence of the perinatal event. We hypothesized that LGS with the perinatal event will have an early age of onset of LGS, more motor deficits and abnormal brain magnetic resonance imaging (MRI) and more severe epilepsy.

Results:

There were 17 children in the perinatal event group and 14 in the other group. The mean age of onset of illness was significantly earlier in the perinatal event group (P < 0.05). More children in the perinatal event group had delayed milestones (P < 0.05), had higher seizure frequency (P < 0.05) however; there was no significant difference in number of anti-epileptic drugs consumed, motor deficits or MRI abnormalities.

Conclusion:

LGS children with the perinatal event have more severe epilepsy with early onset of disease and delayed milestones. History of perinatal insult in these children may help in predicting prognosis in LGS.

De novo mutations in SIK1 cause a spectrum of developmental epilepsies

Developmental epilepsies are age-dependent seizure disorders for which genetic causes have been increasingly identified. Here we report six unrelated individuals with mutations in salt-inducible kinase 1 (SIK1) in a series of 101 persons with early myoclonic encephalopathy, Ohtahara syndrome, and infantile spasms. Individuals with SIK1 mutations had short survival in cases with neonatal epilepsy onset, and an autism plus developmental syndrome after infantile spasms in others. All six mutations occurred outside the kinase domain of SIK1 and each of the mutants displayed autophosphorylation and kinase activity toward HDAC5. Three mutations generated truncated forms of SIK1 that were resistant to degradation and also showed changes in sub-cellular localization compared to wild-type SIK1. We also report the human neuropathologic examination of SIK1-related developmental epilepsy, with normal neuronal morphology and lamination but abnormal SIK1 protein cellular localization. Therefore, these results expand the genetic etiologies of developmental epilepsies by demonstrating SIK1 mutations as a cause of severe developmental epilepsy.

Epileptic encephalopathies: new genes and new pathways

Epileptic encephalopathies represent a group of devastating epileptic disorders that occur early in life and are often characterized by pharmaco-resistant epilepsy, persistent severe electroencephalographic abnormalities, and cognitive dysfunction or decline. Next generation sequencing technologies have increased the speed of gene discovery tremendously. Whereas ion channel genes were long considered to be the only significant group of genes implicated in the genetic epilepsies, a growing number of non-ion-channel genes are now being identified. As a subgroup of the genetically mediated epilepsies, epileptic encephalopathies are complex and heterogeneous disorders, making diagnosis and treatment decisions difficult. Recent exome sequencing data suggest that mutations causing epileptic encephalopathies are often sporadic, typically resulting from de novo dominant mutations in a single autosomal gene, although inherited autosomal recessive and X-linked forms also exist. In this review we provide a summary of the key features of several early- and mid-childhood onset epileptic encephalopathies including Ohtahara syndrome, Dravet syndrome, Infantile spasms and Lennox Gastaut syndrome. We review the recent next generation sequencing findings that may impact treatment choices. We also describe the use of conventional and newer anti-epileptic and hormonal medications in the various syndromes based on their genetic profile. At a biological level, developments in cellular reprogramming and genome editing represent a new direction in modeling these pediatric epilepsies and could be used in the development of novel and repurposed therapies.

Emerging role of the KCNT1 Slack channel in intellectual disability

The sodium-activated potassium KNa channels Slack and Slick are encoded by KCNT1 and KCNT2, respectively. These channels are found in neurons throughout the brain, and are responsible for a delayed outward current termed I KNa. These currents integrate into shaping neuronal excitability, as well as adaptation in response to maintained stimulation. Abnormal Slack channel activity may play a role in Fragile X syndrome, the most common cause for intellectual disability and inherited autism. Slack channels interact directly with the fragile X mental retardation protein (FMRP) and I KNa is reduced in animal models of Fragile X syndrome that lack FMRP. Human Slack mutations that alter channel activity can also lead to intellectual disability, as has been found for several childhood epileptic disorders. Ongoing research is elucidating the relationship between mutant Slack channel activity, development of early onset epilepsies and intellectual impairment. This review describes the emerging role of Slack channels in intellectual disability, coupled with an overview of the physiological role of neuronal I KNa currents.

A novel method for detecting uniparental disomy from trio genotypes identifies a significant excess in children with developmental disorders

Exome sequencing of parent-offspring trios is a popular strategy for identifying causative genetic variants in children with rare diseases. This method owes its strength to the leveraging of inheritance information, which facilitates de novo variant calling, inference of compound heterozygosity, and the identification of inheritance anomalies. Uniparental disomy describes the inheritance of a homologous chromosome pair from only one parent. This aberration is important to detect in genetic disease studies because it can result in imprinting disorders and recessive diseases. We have developed a software tool to detect uniparental disomy from child-mother-father genotype data that uses a binomial test to identify chromosomes with a significant burden of uniparentally inherited genotypes. This tool is the first to read VCF-formatted genotypes, to perform integrated copy number filtering, and to use a statistical test inherently robust for use in platforms of varying genotyping density and noise characteristics. Simulations demonstrated superior accuracy compared with previously developed approaches. We implemented the method on 1057 trios from the Deciphering Developmental Disorders project, a trio-based rare disease study, and detected six validated events, a significant enrichment compared with the population prevalence of UPD (1 in 3500), suggesting that most of these events are pathogenic. One of these events represents a known imprinting disorder, and exome analyses have identified rare homozygous candidate variants, mainly in the isodisomic regions of UPD chromosomes, which, among other variants, provide targets for further genetic and functional evaluation.

Burst suppression in sleep in a routine outpatient EEG

Burst suppression (BS) is an electroencephalogram (EEG) pattern that is characterized by brief bursts of spikes, sharp waves, or slow waves of relatively high amplitude alternating with periods of relatively flat EEG or isoelectric periods. The pattern is usually associated with coma, severe encephalopathy of various etiologies, or general anesthesia. We describe an unusual case of anoxic brain injury in which a BS pattern was seen during behaviorally defined sleep during a routine outpatient EEG study.

Electroencephalogram of age-dependent epileptic encephalopathies in infancy and early childhood

Epileptic encephalopathy syndromes are disorders in which the epileptiform abnormalities are thought to contribute to a progressive cerebral dysfunction. Characteristic electroencephalogram findings have an important diagnostic value in classification of epileptic encephalopathy syndromes. In this paper, we focus on electroencephalogram findings of childhood epileptic encephalopathy syndromes and provide sample illustrations.

Epidemiology and aetiology of neonatal seizures

Neonatal seizures constitute the most frequent and distinctive neurological symptom in the neonatal period. Seizures in the neonatal period differ considerably from those observed later in life with respect to their aetiological profile and clinical presentation. In addition, the aetiological profile in preterm infants is different from that seen in term infants. Hypoxic-ischaemic encephalopathy is the most frequent cause of neonatal seizures in term babies followed by focal ischaemia (stroke), cerebral malformations and metabolic disturbances. In preterm neonates, intraventricular haemorrhage and infections cause most of the seizures reported in this group. Better neuroimaging techniques have reduced the number of undiagnosed cases, and the institution of newer neuroprotective strategies has influenced the outcome.

Diagnosis and management of epileptic encephalopathies in children

Epileptic encephalopathies refer to a group of disorders in which the unremitting epileptic activity contributes to severe cognitive and behavioral impairments above and beyond what might be expected from the underlying pathology alone, and these can worsen over time leading to progressive cerebral dysfunction. Several syndromes have been described based on their electroclinical features (age of onset, seizure type, and EEG pattern). This review briefly describes the clinical evaluation and management of commonly encountered epileptic encephalopathies in children.

Genetic testing of epileptic encephalopathies of infancy: an approach

The epileptic encephalopathies of infancy are a group of disorders characterized by intractable seizures, persistent abnormality of cortical function documented on EEG, and consequently impaired neuro-developmental outcomes. The etiologies vary and include; structural brain malformations, acquired brain insults, and inborn errors of metabolism in the majority of the affected patients. In a proportion of these cases no obvious etiology is identifiable on investigation. Recent advances in molecular diagnostics have led to the discovery of a number of gene defects that may be causal in many epileptic encephalopathies. Identification of the causative mutation is important for prognostic and genetic counseling, and may also carry treatment implications. The recently described genes include; Cyclin-Dependent Kinase-Like 5 gene (CDKL5), Protocadherin 19 (PCDH19), Sodium channel neuronal type 1a subunit gene (SCN1A), Aristaless-Related Homeobox Gene (ARX), and Syntaxin binding protein 1 gene (STXBP1), amongst others. Distinct electro-clinical syndromes are increasingly being identified amongst patients carrying the various mutations. In this review, we outline the approach to clinical evaluation and genetic testing of epileptic encephalopathies in infancy.

Treatment of epileptic encephalopathies

Epileptic encephalopathy is defined as a condition where the epileptic activity itself may contribute to the severe neurological and cognitive impairment seen, over and above that which would be expected from the underlying pathology alone. The epilepsy syndromes at high risk of this are a disparate group of conditions characterized by epileptic seizures that are difficult to treat and developmental delay. In this review, we discuss the ongoing debate regarding the significance of inter-ictal discharges and the impact of the seizures themselves on the cognitive delay or regression that is a common feature of these syndromes. The syndromes also differ in many ways and we provide a summary of the key features of the early-onset epileptic encephalopathies including Ohtahara and West syndromes in addition to later childhood-onset syndromes such as Lennox Gastaut and Doose syndromes. An understanding of the various severe epilepsy syndromes is vital to understanding the rationale for treatment. For example, the resolution of hypsarrhythmia in West syndrome is associated with an improvement in cognitive outcome and drives treatment choice, but the same cannot be applied to frequent inter-ictal discharges in Lennox Gastaut syndrome. We discuss the evidence base for treatment where it is available and describe current practice where it is not. For example, in West syndrome there is some evidence for preference of hormonal treatments over vigabatrin, although the choice and duration of hormonal treatment remains unclear. We describe the use of conventional and newer anti-epileptic medications in the various syndromes and discuss which medications should be avoided. Older possibly forgotten treatments such as sulthiame and potassium bromide also have a role in the severe epilepsies of childhood. We discuss hormonal treatment with particular focus on the treatment of West syndrome, continuous spike wave in slow wave sleep (CSWS)/electrical status epilepticus in slow wave sleep (ESES) and Landau Kleffner syndrome. The role of the ketogenic diet has in recent years come to the fore of the management of these severe epilepsies and we describe successful use in myoclonic astatic epilepsy, Lennox Gastaut syndrome and Dravet syndrome. It is important that resective epilepsy surgery is not ignored in the management of these children, particularly those with hemi-pathology who may present with ESES and respond well to hemispheric disconnection. Adjunctive and symptomatic surgical treatments such as vagal nerve stimulation and corpus callosotomy may improve seizure burden. Finally, it is vital that the identification and treatment of developmental, behavioural and psychiatric co-morbidities are not neglected and that a rational, holistic approach is taken to the management of epileptic encephalopathies.

Ohtahara syndrome or early-onset West syndrome? A case with overlapping features and favorable response to vigabatrin

BACKGROUND

The so called "severe neonatal epilepsies with suppression-burst pattern" include early infantile epileptic encephalopathy, and early myoclonic encephalopathy. Both syndromes are characterized by pharmacoresistant seizures that appear in the first weeks (up to the third month) of life, an electroencephalographic suppression-burst pattern, and a grim prognosis. Many patients later present with other forms of epileptic encephalopathies with difficult-to-treat seizures, such as West syndrome, and those who survive usually suffer from severe neurodevelopmental troubles. We here report the case of a patient who presented at our center with features consistent with a mixed form of these epileptic encephalopathies, and favorable neurodevelopmental evolution.

AIMS

To draw attention on the potentially favorable effect of vigabatrin in early-onset epileptic encephalopathies.

METHODS

Case study.

RESULTS

In our patient, seizures immediately stopped upon initiation of vigabatrin treatment, and his development and neurological examination at one year are normal.

CONCLUSIONS

Vigabatrin should be considered as an early treatment option in early-onset epileptic encephalopathies.

Early-onset epileptic encephalopathies: Ohtahara syndrome and early myoclonic encephalopathy

Ohtahara syndrome and early myoclonic encephalopathy are the earliest presenting of the epileptic encephalopathies. They are typically distinguished from each other according to specific clinical and etiologic criteria. Nonetheless, considerable overlap exists between the two syndromes in terms of clinical presentation, prognosis, and electroencephalographic signature. Newer understandings of underlying etiologies of these conditions may support the previously suggested concept that they represent a single spectrum of disease rather than two distinct disorders. We review both syndromes, with particular focus on the underlying genetics and pathophysiology and implications regarding the classification of these conditions.

Epileptic encephalopathies in adults and childhood

Epileptic encephalopathies are motor-mental retardations or cognitive disorders secondary to epileptic seizures or epileptiform activities. Encephalopaties due to brain damage, medications, or systemic diseases are generally not in the scope of this definition, but they may rarely accompany the condition. Appropriate differential diagnosis of epileptic seizures as well as subclinical electroencephalographic discharges are crucial for management of seizures and epileptiform discharges and relative regression of cognitive deterioration in long-term followup. Proper antiepileptic drug, hormonal treatment, or i.v. immunoglobulin choice play major role in prognosis. In this paper, we evaluated the current treatment approaches by reviewing clinical electrophysiological characteristics of epileptic encephalopathies.

CASK aberrations in male patients with Ohtahara syndrome and cerebellar hypoplasia

PURPOSE

Ohtahara syndrome (OS) is one of the most severe and earliest forms of epilepsy. STXBP1 and ARX mutations have been reported in patients with OS. In this study, we aimed to identify new genes involved in OS by copy number analysis and whole exome sequencing.

METHODS

Copy number analysis and whole exome sequencing were performed in 34 and 12 patients with OS, respectively. Fluorescence in situ hybridization, quantitative polymerase chain reaction (PCR), and breakpoint-specific and reverse-transcriptase PCR analyses were performed to characterize a deletion. Immunoblotting using lymphoblastoid cells was done to examine expression of CASK protein.

KEY FINDINGS

Genomic microarray analysis revealed a 111-kb deletion involving exon 2 of CASK at Xp11.4 in a male patient. The deletion was inherited from his mother, who was somatic mosaic for the deletion. Sequencing of the mutant transcript expressed in lymphoblastoid cell lines derived from the patient confirmed the deletion of exon 2 in the mutant transcript with a premature stop codon. Whole exome sequencing identified another male patient who was harboring a c.1A>G mutation in CASK, which occurred de novo. Both patients showed severe cerebellar hypoplasia along with other congenital anomalies such as micrognathia, a high arched palate, and finger anomalies. No CASK protein was detected by immunoblotting in lymphoblastoid cells derived from two patients.

SIGNIFICANCE

The detected mutations are highly likely to cause the loss of function of the CASK protein in male individuals. CASK mutations have been reported in patients with intellectual disability with microcephaly and pontocerebellar hypoplasia or congenital nystagmus, and those with FG syndrome. Our data expand the clinical spectrum of CASK mutations to include OS with cerebellar hypoplasia and congenital anomalies at the most severe end.

Ohtahara syndrome with emphasis on recent genetic discovery

Ohtahara syndrome or Early Infantile Epileptic Encephalopathy (EIEE) with Suppression-Burst, is the most severe and the earliest developing age-related epileptic encephalopathy. Clinically, the syndrome is characterized by early onset tonic spasms associated with a severe and continuous pattern of burst activity. It is a debilitating and early progressive neurological disorder, resulting in intractable seizures and severe mental retardation. Specific mutations in at least four genes (whose protein products are essential in lower brain's neuronal and interneuronal functions, including mitochondrial respiratory chains have been identified in unrelated individuals with EIEE and include: (a) the ARX (aristaless-related) homeobox gene at Xp22.13 (EIEE-1 variant); (b) the CDKL5 (SYK9) gene at Xp22 (EIEE-2 variant); (c) the SLC25A22 (GC1) gene at 11p15.5 (EIEE-3 variant); and (d) the Stxbp1 (MUNC18-1) gene at 9q34-1 (EIEE-4 variant). A yet unresolved issue involves the relationship between early myoclonic encephalopathy (EME-ErbB4 mutations) versus the EIEE spectrum of disorders.