A review of the relationships between Landau-Kleffner syndrome, electrical status epilepticus during sleep, and continuous spike-waves during sleep

The burden of epilepsy on long-term outcome of genetic developmental and epileptic encephalopathies: A single tertiary center longitudinal retrospective cohort study

BACKGROUND

This retrospective cohort analysis highlighted neurodevelopmental outcome predictors of genetic developmental and epileptic encephalopathies (DEE).

PATIENTS AND METHODS

Patients' demographic, clinical and molecular genetics data were collected. All patients underwent clinical, developmental, and neuropsychological assessments.

RESULTS

We recruited 100 participants (53 males, 47 females) with a mean follow-up lasting 10.46 ± 8.37 years. Age at epilepsy-onset was predictive of poor adaptive and cognitive functions (VABS-II score, r = 0.350, p = 0.001; BRIEF control subscale, r = -0.253; p = 0.031). Duration of epilepsy correlated negatively with IQ (r = -0.234, p = 0.019) and VABS-II score (r = -0.367, p = 0.001). Correlations were found between delayed/lacking EEG maturation/organization and IQ (r = 0.587, p = 0.001), VABS-II score (r = 0.658, p = 0.001), BRIEF-MI and BRIEF-GEC scores (r = -0.375, p = 0.001; r = -0.236, p = 0.033), ASEBA anxiety (r = -0.220, p = 0.047) and ADHD (r = -0.233, p = 0.035) scores. The number of antiseizure medications (ASMs) correlated with IQ (r = -0.414, p = 0.001), VABS-II (r = -0.496, p = 0.001), and BRIEF-MI (r = 0.294, p = 0.012) scores; while age at the beginning of therapy with ASEBA anxiety score (r = 0.272, p = 0.013). The occurrence of status epilepticus was associated with worse adaptive performances. The linear regression analysis model showed that delayed/lacking EEG maturation/organization had a significant influence on the IQ (R2 = 0.252, p < 0.001) and the BRIEF-GEC variability (R2 = 0.042, p = 0.036). The delayed/lacking EEG maturation/organization and the duration of epilepsy also had a significant influence on the VABS-II score (R2 = 0.455, p = 0.005).

CONCLUSIONS

Age at seizure-onset, EEG maturation/organization, duration of epilepsy, occurrence of status epilepticus, age at the introduction and number of ASMs used are reliable predictors of long-term outcomes in patients with genetic DEE.

Differential diagnosis between autism spectrum disorder and other developmental disorders with emphasis on the preschool period

BACKGROUND

Neurodevelopmental disorders are a heterogeneous group of conditions that manifest as delays or deviations in the acquisition of expected developmental milestones and behavioral changes. Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in communication and social interaction and by repetitive and restricted patterns of behavior, interests and activities. The aim of this review is to discuss the clinical features of the differential diagnoses of ASD that are prevalent among preschoolers, focusing on their similarities and disparities.

DATA SOURCES

The international medical literature search was conducted using PubMed and was revised regarding the subject using single and/or combined keywords as follows: differential diagnosis, preschoolers, diagnostic challenge, attention deficit hyperactivity disorder, intellectual disability, high abilities/giftedness, childhood apraxia of speech, social communication disorder, Landau-Kleffner syndrome, stereotyped movement disorder and excessive screen time.

RESULTS

We describe conditions commonly found in clinical practice, taking ASD as a reference. We addressed converging and divergent aspects of behavior, cognition, communication, language, speech, socialization, and stereotypes for the diagnosis of ASD and other disorders identified as potential differential or comorbid diagnoses.

CONCLUSIONS

The ranking and characterization of symptoms appear to be essential for better understanding the underlying common ground between children with developmental disorders and children with ASD, thus properly diagnosing and directing social, professional, or medication interventions. This detailed discussion adds to the literature since, although ASD differential diagnoses are frequently mentioned and discussed in textbooks and journal articles, they rarely occupy a prominent place as we aimed herein.

Effectiveness of perampanel in the treatment of pediatric patients with focal epilepsy and ESES: A single-center retrospective study

Objective: To investigate the therapeutic effect and influencing factors of perampanel (PER) on electrical status epilepticus during sleep (ESES).

Methods: We retrospectively analyzed the clinical data of pediatric patients with focal epilepsy and ESES who were treated at the Epilepsy Center of Shengjing Hospital of China Medical University between January 2016 and March 2022. Changes in the spike wave index (SWI) after 24 weeks of PER add-on treatment were compared. Kaplan‒Meier survival analysis, the log-rank test and multivariate Cox regression analysis were performed.

Results: A total of 54 pediatric patients met the inclusion criteria, including 33 males and 21 females. The mean age at the diagnosis of epilepsy was 6.41 ± 2.14 years and at ESES diagnosis was 7.58 ± 2.40 years. The mean ESES duration before add-on PER was 25.31 ± 15.12 months. The mean age of the patients at add-on PER initiation was 9.69 ± 2.12 years. The ESES resolved in 29 children after 6 months of PER add-on treatment, and the response rate was 53.7%. Univariate analysis with the log-rank test showed that the therapeutic effect of PER differed according to the age at ESES diagnosis and ESES duration before add-on PER treatment. Multivariate Cox regression analysis showed that only ESES duration before PER administration was a risk factor for PER treatment failure, and the other factors had no effect on the therapeutic effect.

Conclusion: PER add-on treatment has a good therapeutic effect on ESES and can be used as an alternative to corticosteroid and benzodiazepines. The therapeutic effect of PER add-on treatment was not related to the dose. A longer ESES duration results in a worse therapeutic effect. Therefore, more aggressive treatment measures should be implemented for ESES.

A case of Landau-Kleffner syndrome with SLC26A4-related hearing impairment

Background

Landau-Kleffner syndrome (LKS) is an acquired aphasia and electroencephalogram (EEG) abnormalities mainly in temporoparietal areas. SLC26A4 mutations can cause hearing loss associated with enlarged vestibular aqueduct (EVA).

Case presentations

We report a case of LKS in a 5-year-old boy with non-syndromic EVA due to homozygous mutations of c.919-2A>G (IVS7-2A>G) in SLC26A4. He had normal language development before 2 years old. At the age of 2.5 years, he was admitted to the hospital due to remarkable language delay, and diagnosed with hearing loss with EVA. The seizures started at 4.4 years of age and EEG recording showed electrical status epilepticus during sleep (ESES) with a posterior-temporal predominance. He received cochlear implantation in the right ear at 4.7 years of age, which improved his hearing and language skills. The nocturnal focal motor seizures recurred at 4.9 years of age. Then a remarkable inability to respond to calls and reduction in spontaneous speech were noticed. He was treated with methylprednisolone at 5 years old, which controlled the seizures, suppressed ESES, and remarkably improved the language ability. The absence of seizures maintained until the last follow-up at 5.3 years of age, with further improvements in EEG recording and language ability.

Conclusions

The co-existence of LKS and hearing loss caused by SLC26A4 mutations increases the difficulty of LKS diagnosis, especially in the presence of hearing loss and impaired language skills. EEG discharges predominantly in temporoparietal areas, the occurrence of ESES, and language improvement after antiepileptic medications are potential indicators for LKS diagnosis.

Sleep in Neurologic Disorders

Sleep is a complex brain state with fundamental relevance for cognitive functions, synaptic plasticity, brain resilience, and autonomic balance. Sleep pathologies may interfere with cerebral circuit organization, leading to negative consequences and favoring the development of neurologic disorders. Conversely, the latter can interfere with sleep functions. Accordingly, assessment of sleep quality is always recommended in the diagnosis of patients with neurologic disorders and during neurorehabilitation programs. This review investigates the complex interplay between sleep and brain pathologies, focusing on diseases in which the association with sleep disturbances is commonly overlooked and whereby major benefits may derive from their proper management.

GRIN2A and GRIN2B and Their Related Phenotypes

Glutamate is the most relevant excitatory neurotransmitter of the central nervous system; it binds with several receptors, including N-methyl-D-aspartate receptors (NMDARs), a subtype of ionotropic glutamate receptor that displays voltage-dependent block by Mg2+ and a high permeability to Ca2+. GRIN2A and GRIN2B genes encode the GluN2A and GluN2B subunits of the NMDARs, which play important roles in synaptogenesis, synaptic transmission, and synaptic plasticity, as well as contributing to neuronal loss and dysfunction in several neurological disorders. Recently, individuals with a range of childhood-onset drug-resistant epilepsies, such as Landau–Kleffner or Lennox–Gastaut syndrome, intellectual disability (ID), and other neurodevelopmental abnormalities have been found to carry mutations in GRIN2A and GRIN2B, with high variable expressivity in phenotype. The first one is found mainly in epilepsy-aphasia syndromes, while the second one mainly in autism, schizophrenia, and ID, such as autism spectrum disorders. Brain magnetic resonance imaging alterations are found in some patients, even if without a clear clinical correlation. At the same time, increasing data on genotype–phenotype correlation have been found, but this is still not fully demonstrated. There are no specific therapies for the treatment of correlated NMDARs epilepsy, although some evidence with memantine, an antagonist of glutamate receptor, is reported in the literature in selected cases with mutation determining a gain of function.

The Correlation of ELP4-PAX6 With Rolandic Spike Sources in Idiopathic Rolandic Epilepsy Syndromes

Objective: To study the single nucleotide polymorphism rs662702 of ELP4-PAX6 in patients with idiopathic rolandic epilepsy syndromes (IRES) in China and explore the relationship between the distribution of rolandic spike sources and the single nucleotide polymorphism rs662702 in ELP4-PAX6.

Methods: First, clinical information was obtained from patients diagnosed with IRES. Next, the single nucleotide polymorphism rs662702 of ELP4 was analyzed by using the Sanger method. Resting-state magnetoencephalography data were collected from 17 patients. We analyzed the epileptic spike sources using the single equivalent current dipole (SECD) model and determined the spike distributions across the whole brain. Finally, Fisher's test was performed to assess the correlation between the single nucleotide polymorphism rs662702 of ELP4-PAX6 and rolandic spike sources.

Results: ELP4 rs662702 T alleles were found in 10.7% of IRES patients and occurred four times more frequently in these patients than in the healthy controls. TT homozygosity was found in one IRES patient (1.3%), while no TT homozygosity was found in the healthy control group. The IRES rolandic spike sources were unilateral in sixteen patients (94.1%) and were mainly located in the anterior central gyrus (58.8%). The spike source of patients without the ELP4 rs662702 T allele was correlated with the central region (p < 0.05). The rolandic spikes sources were significant correlated with the non-central gyrus (frontal and temporal lobes) in patients with the ELP4 rs662702 T allele (p < 0.05).

Conclusion: The rolandic spike sources of the IRES patients with the ELP4 rs662702 T allele were significantly associated with the non-central gyrus, including the frontal and temporal lobes. Our study confirmed for the first time in vivo that ELP4 rs662702 T allele overexpression is correlated with the rolandic spike distribution in patients with IRES and provides important insights into how genetic abnormalities can lead to brain dysfunction and into the precise targeting of abnormal discharge sources in the brain.

Encephalopathy Associated with Electrical Status Epilepticus of Sleep (ESES): A Practical Approach

Encephalopathy associated with electrical status epilepticus of sleep (ESES) is an underdiagnosed epileptic encephalopathy syndrome. Though there is considerable controversy regarding the terminology of this condition, there is increasing acceptance of the term, 'encephalopathy associated with electrical status epilepticus of sleep,' as it implies a clinical component as well as EEG feature. Core EEG feature of sleep activation of epileptiform discharges temporarily associated with cognitive or behavioral regression in a child with epilepsy is sufficient to make a diagnosis of ESES. It is important to quantify the spike wave index (SWI) during awake state and sleep to assess for sleep activation. Since focal spikes are also included in the counting of SWI, some grading to assess the distribution of epileptiform discharges is suggested to obtain the complete sleep EEG picture. MRI of the brain does not show abnormality in a number of patients. But common structural lesions include perinatal vascular insults and cortical malformations. Response to treatment is usually variable, but highest success rate is reported with the steroids. Prognosis usually depends on the duration of ESES.

Corticosteroids versus clobazam in epileptic encephalopathy with ESES: a European multicentre randomised controlled clinical trial (RESCUE ESES*)

BACKGROUND

Epileptic encephalopathy with electrical status epilepticus in sleep (ESES) is an epilepsy syndrome occurring almost exclusively in children, usually at an age between 4 and 12 years. It is characterised by abundant sleep-induced epileptic activity in the electroencephalogram (EEG) and by acquired cognitive and behavioural deficits. The goal of treatment is to prevent further decline or even improve cognitive functioning. Based on mostly small and retrospective studies, corticosteroids and clobazam are regarded by many clinicians as the most effective pharmacological treatments. This European multicentre randomised controlled trial is designed to compare the effects of corticosteroids and clobazam on cognitive functioning after 6 months. Secondary outcomes include cognitive functioning after 18 months, EEG abnormalities in sleep, safety and tolerability, and seizure frequency. We also aimed at investigating whether treatment response in epileptic encephalopathy with ESES can be predicted by measurement of inflammatory mediators and autoantibodies in serum.

METHODS

The pragmatic study will be performed in centres with expertise in the treatment of rare paediatric epilepsy syndromes across Europe. A total of 130 patients, 2 to 12 years of age, with epileptic encephalopathy with ESES will be enrolled and randomised in a 1:1 ratio to receive either corticosteroids (monthly intravenous methylprednisolone pulses or daily oral prednisolone) or oral clobazam for 6 months according to an open-label parallel-group design. Follow-up visits with clinical assessment, EEGs, and neuropsychological testing are scheduled for up to 18 months. Blood samples for cytokine and autoantibody testing are obtained before treatment and 8 months after treatment initiation.

DISCUSSION

The treatment of epileptic encephalopathy with ESES aims at improving cognitive outcome. This randomised controlled study will compare the most frequently used treatments, i.e. corticosteroids and clobazam. If the study proves superiority of one treatment over the other or identifies biomarkers of treatment response, results will guide clinicians in the early treatment of this severe epilepsy syndrome.

TRIAL REGISTRATION

ISRCTN, ISRCTN42686094 . Registered on 24 May 2013.

Pharmacological treatment for continuous spike-wave during slow wave sleep syndrome and Landau-Kleffner Syndrome

BACKGROUND

Continuous spike-wave during slow wave sleep syndrome (CSWS) and Landau-Kleffner syndrome (LKS) are two epileptic encephalopathies that present with neurocognitive regression, aphasia, and clinical seizures, typically presenting in children around five years of age. The pathophysiology of these conditions is not completely understood. Some studies suggest a common origin for both. No systematic reviews have assessed the efficacy of pharmacological interventions for these conditions.

OBJECTIVES

To assess the benefit and adverse effects of pharmacological interventions for the treatment of CSWS and LKS.

SEARCH METHODS

On 8 September 2020, we searched the Cochrane Register of Studies (CRS Web) and MEDLINE Ovid (1946 to September 04, 2020). We applied no language restrictions. CRS Web includes randomised or quasi-randomised, controlled trials from CENTRAL, PubMed, Embase, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform.

SELECTION CRITERIA

Randomised controlled trials, quasi-randomised controlled trials, and cluster-randomised trials comparing antiepileptic drugs alone, or with steroids or intravenous immunoglobulins, or both versus other antiepileptic drugs, or placebo, or no treatment, administered to children with CSWS and LKS. We planned to compare treatments for the two conditions separately.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies identified by the search strategy for inclusion. The primary outcomes considered in this review were neuropsychological-neurolinguistic functions.

MAIN RESULTS

Our search strategy yielded 18 references. Two review authors independently assessed all references. We did not find any completed studies to include. We identified one ongoing trial, which was terminated because of lack of enrolment.

AUTHORS' CONCLUSIONS

There was no evidence from trials to support or refute the use of pharmacological treatment for continuous spike-wave during slow wave sleep syndrome or Landau-Kleffner syndrome. Well-designed randomised controlled trials are needed to inform practice.

Differential Diagnosis of Landau-Kleffner Syndrome Versus Post Encephalitis Syndrome in a 13-year-old Boy With Autism Spectrum Disorder

Landau-Kleffner syndrome (LKS) is a rare childhood neurological condition that causes developmental regression, loss of language skills and abnormal electroencephalogram (EEG) patterns. Its etiology is unknown. This report describes a case of a 13-year-old boy who at 3.5 years of age was bitten by a tick. Two months thereafter, he began losing previously acquired developmental and language skills, and developed seizures. The seizures subsided with valproic acid treatment, but the developmental delays persisted. Family history and disease progression reports obtained from the patient’s father revealed that the patient displayed repetitive behaviors prior to the age of three. Clinical observation also showed the patient having numerous repetitive vocalizations and movements along with difficulty with switching sets. His developmental age at the time of presentation was determined to be 3 to 4 years of age. During the course of diagnostic testing, we were able to rule out tick-borne encephalitis (TBE) and rule in LKS in a premorbidly autistic child. This case describes the similarities between the three conditions and the diagnostic investigations used to arrive at a final diagnosis.

Resolution of EEG findings and clinical improvement in a patient with encephalopathy and ESES with a combination of immunomodulating agents other than corticosteroids: A case report

Encephalopathy with electrical status epilepticus in sleep (ESES) syndrome is characterized by a near-continuous spike-and-wave discharges during sleep with marked developmental regression, mainly in speech, and the presence of clinical seizures. Although the etiology ofESES is generally unknown, its resistance to antiseizure medication (ASM), and favorable responses to oral corticosteroids (OCS), support a role for inflammation. However, the prolonged use of OCS results in undesirable side effects and alternative treatment measures are needed. Herein, we present a patient with ESES who revealed responsed to a combination of immunomodulating agents other than OCS. The patient revealed 30, 50, and 100%, reduction in the ESES pattern on EEG with the sequential addition of anakinra (interleukin-1ß inhibitor), intravenous immunoglobulin (IVIg), and sirolimus, an inhibitor of mammalian target of rapamycin (mTOR) respectively, after discontinuation of OCS due to side effects. This combination of immune-modulating agents, that were selected based on monocyte cytokine profiles, also resulted in a gradual improvement of speech and behavioral symptoms. This case indicates a possible use of immunomodulating agents other than OCS for ESES syndrome.

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ESES syndrome can be controlled immunomodulating agents.

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OCS was not requred for maintaing good control of ESES in the presented case.

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Monocyte cytokine profiles may be useful for the selection of immunomodulating agents for treatment of ESES.

Treatment of Epileptic Encephalopathies: Current State of the Art

Childhood epileptic encephalopathies are age-dependent disorders of the brain whose hallmarks include loss of neurologic function over time, abnormal electroencephalographic findings, and seizures. Ictal and interictal electrographic activity are conjointly thought to be at the root of the often devastating neuropsychological deterioration, which is specific to the maturing brain. The goals of treatment are not only to control seizures, but also to prevent or reverse neurologic loss of function. In general, time is of the essence in diagnosis, and experienced specialists should promptly design a treatment plan. Hormonal and immune therapies are at the forefront of treatment in many cases, with traditional antiepileptic drugs and surgery (when an identifiable lesion is present) playing a limited role. However, gold standard evidence for treatment of epileptic encephalopathies remains limited. Ongoing clinical and basic research may lead to better understanding of these catastrophic conditions and to better and more effective therapies.

Neurocognitive Comorbidities in Pediatric Epilepsy: Lessons in the Laboratory and Clinical Profile

Children with epilepsy are at risk for a variety of neurocognitive comorbidities. Animal models have increased our understanding about the neurobiological mechanisms underlying the association between seizures and these comorbidities. This article starts with an overview of the current data on animal model research, studying the influence of early-life seizures, followed by a summary of potential cellular and molecular mechanisms by which seizures can affect cognitive development. We then describe specific abnormal neuropsychological profiles that accompany specific pediatric epilepsy syndromes. Finally, we offer a potential guideline to the treatment and management of children with epilepsy and its neurocognitive comorbidities.

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.

The Clinical Spectrum of Benign Epilepsy with Centro-Temporal Spikes: a Challenge in Categorization and Predictability

Benign epilepsy with centro-temporal spikes (BECTS) is the most common type of focal epilepsy in children; it is age-dependent and presumably genetic. Traditionally, children with BECTS have a very good prognosis, even without medical treatment, and are thought to show no neurological symptoms or cognitive deficits. However, many previous studies have shown that BECTS can present with various clinical and electroencephalographic characteristics that are commonly associated with neuropsychological deficits, including linguistic, cognitive, and behavioral impairment. The degree of the neuropsychological deficits appears to depend on the sleep cycle and the localization of epileptiform discharges. Furthermore, based on neurobiological studies, a complex interplay between the processes of brain maturation and the involvement of genes that confer susceptibility may contribute to a variety of different childhood epileptic syndromes with various neuropsychological deficits. Thus, BECTS, atypical benign focal epilepsy during childhood, status epilepticus of BECTS, Landau-Kleffner syndrome, and epileptic encephalopathy with continuous spike-and-wave during sleep are all considered different entities, but are part of a single spectrum of disorders. In clinical practice, we have to consider BECTS as benign only when there are no or only mild neuropsychological deficits before medical treatment.

Epilepsy-associated GRIN2A mutations reduce NMDA receptor trafficking and agonist potency - molecular profiling and functional rescue

Mutations in the N-methyl-D-aspartate receptor (NMDAR) gene GRIN2A cause epilepsy-aphasia syndrome (EAS), a spectrum of epileptic, cognitive and language disorders. Using bioinformatic and patient data we shortlisted 10 diverse missense mutations for characterisation. We used high-throughput calcium-flux assays and patch clamp recordings of transiently transfected HEK-293 cells for electrophysiological characterization, and Western blotting and confocal imaging to assay expression and surface trafficking. Mutations P79R, C231Y, G483R and M705V caused a significant reduction in glutamate and glycine agonist potency, whilst D731N was non-responsive. These mutants, along with E714K, also showed significantly decreased total protein levels and trafficking to the cell surface, whilst C436R was not trafficked at all. Crucially this reduced surface expression did not cause the reduced agonist response. We were able to rescue the phenotype of P79R, C231Y, G483R and M705V after treatment with a GluN2A-selective positive allosteric modulator. With our methodology we were not able to identify any functional deficits in mutations I814T, D933N and N976S located between the glutamate-binding domain and C-terminus. We show GRIN2A mutations affect the expression and function of the receptor in different ways. Careful molecular profiling of patients will be essential for future effective personalised treatment options.

Epileptiform activity in the mouse visual cortex interferes with cortical processing in connected areas

Epileptiform activity is associated with impairment of brain function even in absence of seizures, as demonstrated by failures in various testing paradigm in presence of hypersynchronous interictal spikes (ISs). Clinical evidence suggests that cognitive deficits might be directly caused by the anomalous activity rather than by its underlying etiology. Indeed, we seek to understand whether ISs interfere with neuronal processing in connected areas not directly participating in the hypersynchronous activity in an acute model of epilepsy. Here we cause focal ISs in the visual cortex of anesthetized mice and we determine that, even if ISs do not invade the opposite hemisphere, the local field potential is subtly disrupted with a modulation of firing probability imposed by the contralateral IS activity. Finally, we find that visual processing is altered depending on the temporal relationship between ISs and stimulus presentation. We conclude that focal ISs interact with normal cortical dynamics far from the epileptic focus, disrupting endogenous oscillatory rhythms and affecting information processing.

Global Synchronization of Multichannel EEG in Patients With Electrical Status Epilepticus in Sleep

In the research field of epilepsy, it is a challenge to understand the transition of brain activity to electrical status epilepticus in sleep (ESES). In this study, an S-estimator method is proposed to describe the course of global synchronization in multichannel electroencephalograph (EEG) from awake to sleep in 11 patients with ESES. The study confirms that there is a significant increase in spikes and global synchronization from awake to sleep. It is also found that global synchronization is strongly correlated with spikes. The proposed method has the potential of revealing the intrinsic features of EEG signals and the underlying brain dynamics in ESES.

Unbalanced Peptidergic Inhibition in Superficial Neocortex Underlies Spike and Wave Seizure Activity

Slow spike and wave discharges (0.5-4 Hz) are a feature of many epilepsies. They are linked to pathology of the thalamocortical axis and a thalamic mechanism has been elegantly described. Here we present evidence for a separate generator in local circuits of associational areas of neocortex manifest from a background, sleep-associated delta rhythm in rat. Loss of tonic neuromodulatory excitation, mediated by nicotinic acetylcholine or serotonin (5HT3A) receptors, of 5HT3-immunopositive interneurons caused an increase in amplitude and slowing of the delta rhythm until each period became the "wave" component of the spike and wave discharge. As with the normal delta rhythm, the wave of a spike and wave discharge originated in cortical layer 5. In contrast, the "spike" component of the spike and wave discharge originated from a relative failure of fast inhibition in layers 2/3-switching pyramidal cell action potential outputs from single, sparse spiking during delta rhythms to brief, intense burst spiking, phase-locked to the field spike. The mechanisms underlying this loss of superficial layer fast inhibition, and a concomitant increase in slow inhibition, appeared to be precipitated by a loss of neuropeptide Y (NPY)-mediated local circuit inhibition and a subsequent increase in vasoactive intestinal peptide (VIP)-mediated disinhibition. Blockade of NPY Y1 receptors was sufficient to generate spike and wave discharges, whereas blockade of VIP receptors almost completely abolished this form of epileptiform activity. These data suggest that aberrant, activity-dependent neuropeptide corelease can have catastrophic effects on neocortical dynamics.

Neurobiology of continuous spike-wave in slow-wave sleep and Landau-Kleffner syndromes

BACKGROUND

Several pediatric seizure disorders have common electrophysiological features during slow-wave sleep that produce different syndromes based on which part of the developing brain is involved. These disorders, of which continuous spike-wave in slow-wave sleep and Landau-Kleffner are the most common, are characterized by continuous spike-wave activity during slow-wave sleep, developmentally regulated onset and termination of abnormal electrical activity, and loss of previously acquired skills. Over the last 20 years, a variety of basic science findings suggest how spike-wave activity during sleep can cause the observed clinical outcomes.

METHODS

Literature review and analysis.

RESULTS

The role of slow-wave sleep in normal cortical plasticity during developmental critical periods, how disruption of slow-wave sleep by electrographic seizures could affect cortical maps and development, and the organization and functional connectivity of the thalamic structures that when damaged are thought to produce these seizure disorders are reviewed.

CONCLUSIONS

Potential therapeutic directions are proposed based on the mechanisms of plasticity and anatomical structures involved in cortical plasticity during slow-wave sleep.

16p11.2 600 kb Duplications confer risk for typical and atypical Rolandic epilepsy

Rolandic epilepsy (RE) is the most common idiopathic focal childhood epilepsy. Its molecular basis is largely unknown and a complex genetic etiology is assumed in the majority of affected individuals. The present study tested whether six large recurrent copy number variants at 1q21, 15q11.2, 15q13.3, 16p11.2, 16p13.11 and 22q11.2 previously associated with neurodevelopmental disorders also increase risk of RE. Our association analyses revealed a significant excess of the 600 kb genomic duplication at the 16p11.2 locus (chr16: 29.5-30.1 Mb) in 393 unrelated patients with typical (n = 339) and atypical (ARE; n = 54) RE compared with the prevalence in 65,046 European population controls (5/393 cases versus 32/65,046 controls; Fisher's exact test P = 2.83 × 10(-6), odds ratio = 26.2, 95% confidence interval: 7.9-68.2). In contrast, the 16p11.2 duplication was not detected in 1738 European epilepsy patients with either temporal lobe epilepsy (n = 330) and genetic generalized epilepsies (n = 1408), suggesting a selective enrichment of the 16p11.2 duplication in idiopathic focal childhood epilepsies (Fisher's exact test P = 2.1 × 10(-4)). In a subsequent screen among children carrying the 16p11.2 600 kb rearrangement we identified three patients with RE-spectrum epilepsies in 117 duplication carriers (2.6%) but none in 202 carriers of the reciprocal deletion. Our results suggest that the 16p11.2 duplication represents a significant genetic risk factor for typical and atypical RE.

Landau-Kleffner syndrome: a study of 29 patients

PURPOSE

The aim of the study was to retrospectively analyze the electroclinical features, etiology, treatment, and prognosis of 29 patients with Landau-Kleffner syndrome (LKS) with a long-term follow-up.

METHODS

Inclusion criteria were a diagnosis of LKS with: (1) acquired aphasia or verbal auditory aphasia; (2) with or without focal seizures, secondarily generalized tonic-clonic seizures, absences, or atonic seizures.

RESULTS

Mean follow-up was 12 years. All cases except six had seizures. Before the onset of aphasia, developmental language and behavioral disturbances were present in 19 and 14 patients, respectively. All patients had verbal auditory agnosia. Aphasia was severe in 24 patients and moderate in five. Nonlinguistic cognitive dysfunctions were moderate in 14 patients. Behavioral disturbances were found in 16 patients. During the continuous spike-and-wave discharges during slow sleep phase, the spike-wave index was >85% in 15, 50-85% in eight, and 30-50% in four. In two patients, the EEG recording showed occasional bilateral spikes, without continuous spike-and-wave discharges during slow sleep. In this phase, the awake EEG recording showed more frequent interictal abnormalities, predominantly in the temporal regions. Eight patients recovered language completely, but the remaining patients continue to have language deficits of different degrees.

CONCLUSION

Landau-Kleffner syndrome is an epileptic encephalopathy characterized by acquired verbal auditory aphasia and seizures in most of the patients associated with continuous or almost continuous spike-and-wave discharges during slow wave sleep. The most commonly used treatments were clobazam, ethosuximide, sulthiame. High-dose steroids were also administered. Adequate and early management may avoid language and cognitive deterioration.

Mutations in GRIN2A cause idiopathic focal epilepsy with rolandic spikes

Idiopathic focal epilepsy (IFE) with rolandic spikes is the most common childhood epilepsy, comprising a phenotypic spectrum from rolandic epilepsy (also benign epilepsy with centrotemporal spikes, BECTS) to atypical benign partial epilepsy (ABPE), Landau-Kleffner syndrome (LKS) and epileptic encephalopathy with continuous spike and waves during slow-wave sleep (CSWS). The genetic basis is largely unknown. We detected new heterozygous mutations in GRIN2A in 27 of 359 affected individuals from 2 independent cohorts with IFE (7.5%; P = 4.83 × 10(-18), Fisher's exact test). Mutations occurred significantly more frequently in the more severe phenotypes, with mutation detection rates ranging from 12/245 (4.9%) in individuals with BECTS to 9/51 (17.6%) in individuals with CSWS (P = 0.009, Cochran-Armitage test for trend). In addition, exon-disrupting microdeletions were found in 3 of 286 individuals (1.0%; P = 0.004, Fisher's exact test). These results establish alterations of the gene encoding the NMDA receptor NR2A subunit as a major genetic risk factor for IFE.

Continuous Spikes and Waves during Sleep: Electroclinical Presentation and Suggestions for Management

Continuous spikes and waves during sleep (CSWS) is an epileptic encephalopathy characterized in most patients by (1) difficult to control seizures, (2) interictal epileptiform activity that becomes prominent during sleep leading to an electroencephalogram (EEG) pattern of electrical status epilepticus in sleep (ESES), and (3) neurocognitive regression. In this paper, we will summarize current epidemiological, clinical, and EEG knowledge on CSWS and will provide suggestions for treatment. CSWS typically presents with seizures around 2-4 years of age. Neurocognitive regression occurs around 5-6 years of age, and it is accompanied by subacute worsening of EEG abnormalities and seizures. At approximately 6-9 years of age, there is a gradual resolution of seizures and EEG abnormalities, but the neurocognitive deficits persist in most patients. The cause of CSWS is unknown, but early developmental lesions play a major role in approximately half of the patients, and genetic associations have recently been described. High-dose benzodiazepines and corticosteroids have been successfully used to treat clinical and electroencephalographic features. Corticosteroids are often reserved for refractory disease because of adverse events. Valproate, ethosuximide, levetiracetam, sulthiame, and lamotrigine have been also used with some success. Epilepsy surgery may be considered in a few selected patients.

Ketogenic diet in epileptic encephalopathies

The ketogenic diet is a medically supervised high-fat, low-carbohydrate diet that has been found useful in patients with refractory epilepsy. It has been shown to be effective in treating multiple seizure types and epilepsy syndromes. In this paper, we review the use of the ketogenic diet in epileptic encephalopathies such as Ohtahara syndrome, West syndrome, Dravet syndrome, epilepsy with myoclonic atonic seizures, and Lennox-Gastaut syndrome.

Subclinical epileptiform activity in children with electrical status epilepticus during sleep: effects on cognition and behavior before and after treatment with levetiracetam

We performed a double-blind placebo-controlled crossover study of the effects of spike activity during sleep and when awake on learning, long-term memory, vigilance and behavior before and after treatment with levetiracetam in children with electrical status epilepticus during sleep. At baseline, verbal learning declined with increasing spike activity, but there were no relations between spike activity and memory, vigilance or behavior. Levetiracetam was effective in reducing sleep-related spike activity, but on a group level, this had no clear effects on behavior, vigilance or learning and memory. Our results do not allow firm conclusions whether to treat nocturnal epileptiform activity or not; larger samples and longer follow-up may be needed.

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.

Electrical status epilepticus in sleep: clinical presentation and pathophysiology

Electrical status epilepticus in sleep involves an electroencephalographic pattern where interictal epileptiform activity is potentiated in the transition from wakefulness to sleep. Near-continuous spikes and waves that occupy a significant proportion of nonrapid eye movement sleep appear as a result of sleep-potentiated epileptiform activity. This electroencephalographic pattern appears in different electroclinical syndromes that present three common characteristics with different degrees of severity: seizures, sleep-potentiated epileptiform activity, and neuropsychologic regression. Continuous spikes and waves during sleep comprise the severest epileptic encephalopathy in the electroclinical spectrum. Landau-Kleffner syndrome presents with intermediate severity. Some "benign" pediatric focal epileptic syndromes represent the mildest end of this continuum. Based on published data, we provide a framework for clinical and electrical events. The underlying mechanisms leading to sleep potentiation of epileptiform activity in electrical status epilepticus in sleep are incompletely understood. A genetic basis or acquired early developmental insult may disrupt the normal maturation of neuronal networks. These factors may dynamically alter normal processes of brain development, leading to an age-related pattern of electroclinical expression of electrical status epilepticus in sleep.

Short-term response of sleep-potentiated spiking to high-dose diazepam in electric status epilepticus during sleep

We describe the short-term effects of high-dose oral diazepam on sleep-potentiated epileptiform activity in patients with electric status epilepticus during sleep. We enrolled patients treated with high-dose oral bedtime diazepam from 2001-2009. We defined spike percentage as the percentage of 1-second bins containing at least one spike, and calculated it during three randomly selected 5-minute samples of wakefulness throughout the day and during the first 5 minutes of every hour of non-rapid eye movement sleep at night. In this study, patients were considered to demonstrate sleep-potentiated epileptiform activity when their spike percentage during sleep was increased by ≥50% compared with wakefulness. Twenty-nine children (18 boys) were included (median age, 7.4 years). Twenty-four hours after receiving high-dose diazepam, epileptiform activity was significantly reduced (76.7% at baseline vs 40.8% 24 hours after high-dose diazepam; Wilcoxon signed ranks test, Z = -4.287, P < 0.0001). Seven patients (24.1%) manifested mild, reversible side effects during the first 48 hours after diazepam administration. High-dose oral diazepam effectively and safely reduced epileptiform activity in patients with electric status epilepticus during sleep.

Impact of focal interictal epileptiform discharges on behaviour and cognition in children

It is hypothesised that focal interictal epileptiform discharges (IED) may exert a deleterious effect on behaviour and cognition in children. This hypothesis is supported by the abnormally high prevalence of IED in several developmental disorders, like specific language impairment, and of cognitive and behavioural deficits in epileptic children after excluding confounding factors such as underlying structural brain lesions, drug effects, or the occurrence of frequent or prolonged epileptic seizures. Neurophysiological and functional neuroimaging evidence suggests that IED may impact cognition through either transient effects on brain processing mechanisms, or through more long-lasting effects leading to prolonged inhibition of brain areas distant from but connected with the epileptic focus (i.e. remote inhibition effect). Sustained IED may also impair sleep-related learning consolidation processes. Nowadays, the benefits of anti-epileptic treatment aimed at reducing IED are not established except in specific situations like epileptic encephalopathies with continuous spike and waves during slow-wave sleep. Well-designed pharmacological studies are still necessary to address this issue.

A de novo 3.57 Mb microdeletion in 8q12.3q13.2 in a patient with mild intellectual disability and epilepsy

A female patient, nine years of age, is reported with a history characterized by delay of psychomotor and speech development, mild to moderate intellectual disability and persistent sleep disturbances since the age of two. The patient showed facial dysmorphisms, a pectus excavatum and a sandal gap. Apart from lowered intelligence, neuropsychological functioning disclosed impaired attentional capacities and executive control as well as weak motor skills. Genome wide SNP array analysis revealed a 3.57 Mb de novo microdeletion in band q12.3 of chromosome 8. The long lasting sleep disorders turned out to originate from a rare juvenile epilepsy, continuous spike-waves during slow sleep (CSWS) syndrome, that includes the electrical status epilepticus in sleep (ESES) phenomenon. MRI-scanning of the brain showed no abnormalities. To the authors knowledge, this is the first report of a de novo 8q12.3q13.2 microdeletion syndrome that presents with ESES/CSWS.

Is sleep-related consolidation impaired in focal idiopathic epilepsies of childhood? A pilot study

We investigated sleep-related declarative memory consolidation in four children with focal idiopathic epilepsy. In a population of healthy control children, recall of learned pairs of words was increased after a night of sleep, but not after a daytime wakefulness period. In children with epilepsy (1 case of benign epilepsy with centro-temporal spikes, 1 case of benign childhood epilepsy with occipital paroxysms, and 2 cases of epileptic encephalopathy (EE) with continuous spike and waves during slow-wave sleep, CSWS), recall performance significantly decreased overnight, suggesting impairment in sleep-related declarative memory consolidation. Hydrocortisone treatment in one patient with EE with CSWS resulted in normalization of the sleep EEG together with normalization of overnight memory performance, which was not the case in the other EE/CSWS patient whose sleep EEG was only partially improved. These preliminary results suggest that interictal epileptiform discharges in idiopathic focal epilepsies may disrupt the brain processes underlying sleep-related memory consolidation.