Copy number variations in patients with electrical status epilepticus in sleep

The genetic landscape of developmental and epileptic encephalopathy with spike-and-wave activation in sleep

OBJECTIVE

Epileptic Encephalopathy / Developmental Epileptic Encephalopathy with spike-and-wave activation in sleep (EE/DEE-SWAS) is defined as an epilepsy syndrome characterized by neurodevelopmental regression temporally related to the emergence of significant activation of spike-wave discharges in EEG during sleep. The availability of genetic testing has made it evident that monogenic and chromosomal abnormalities play an aetiological role in the development of EE/DEE-SWAS. We sought to review the literature to better understand the genetic landscape of EE/DEE-SWAS.

METHODS

In this systematic review, we reviewed cases of EE/DEE-SWAS associated with a genetic aetiology, collecting information related to the underlying aetiology, onset, management, and EEG patterns.

RESULTS

One hundred and seventy-two cases of EE/DEE-SWAS were identified. Genetic causes of note included pathogenic variants in GRIN2A, ZEB2, CNKSR2 and chromosome 17q21.31 deletions, each of which demonstrated unique clinical characteristics, EEG patterns, and age of onset. Factors identified to raise suspicion of a potential genetic aetiology included the presentation of DEE-SWAS and onset of SWAS under the age of five years. Treatment of EE/DEE-SWAS due to genetic causes was diverse, including a combination of anti-seizure medications, steroids, and other clinical strategies, with no clear consensus on a preferred or superior treatment. Data collected was significantly heterogeneous, with a lack of consistent use of neuropsychology testing, EEG patterns, or use of established clinical definitions.

CONCLUSIONS

Uniformity concerning the new definition of EE/DEE-SWAS, guidelines for management and more frequent genetic screening will be needed to guide best practices for the treatment of patients with EE/DEE-SWAS.

Status Epilepticus in Chromosomal Disorders Associated with Epilepsy: A Systematic Review

Status Epilepticus (SE) is a neurological emergency resulting from the failure of mechanisms of seizure termination or from the initiation of mechanisms that lead to prolonged seizures. The International League Against Epilepsy (ILAE) identified 13 chromosomal disorders associated with epilepsy (CDAE); data regarding SE occurrence in these patients is lacking. A systematic scoping review was conducted to outline current literature evidence about clinical features, treatments, and outcomes of SE in pediatric and adult patients with CDAE. A total of 373 studies were identified with the initial search; 65 of these were selected and regarded as SE in Angelman Syndrome (AS, n = 20), Ring 20 Syndrome (R20, n = 24), and other syndromes (n = 21). Non-convulsive status epilepticus (NCSE) is frequently observed in AS and R20. No specific, targeted therapies for SE in CDAE are available to date; anecdotal reports about SE treatment are described in the text, as well as various brief- and long-term outcomes. Further evidence is needed to precisely portray the clinical features, treatment options, and outcomes of SE in these patients.

Relationship between brain activity, cognitive function, and sleep spiking activation in new-onset self-limited epilepsy with centrotemporal spikes

Objective

This study aimed to investigate the relationship between cognitive function sleep spiking activation and brain activity in self-limited epilepsy with centrotemporal spikes (SeLECTS).

Methods

We used spike-wave index (SWI), which means the percentage of the spike and slow wave duration to the total non-REM (NREM) sleep time, as the grouping standard. A total of 14 children with SeLECTS (SWI ≥ 50%), 21 children with SeLECTS (SWI < 50%), and 20 healthy control children were recruited for this study. Cognitive function was evaluated using the Wechsler Intelligence Scale for Children, Fourth Edition (Chinese version) (WISC-IV). Magnetic source activity was assessed using magnetoencephalography calculated for each frequency band using the accumulated source imaging (ASI) technique.

Results

Children with SeLECTS (SWI ≥ 50%) had the lowest cognitive function scores, followed by those with SeLECTS (SWI < 50%) and then healthy controls. There were significant differences in the localization of magnetic source activity between the three groups: in the alpha (8–12 Hz) frequency band, children with SeLECTS (SWI ≥ 50%) showed deactivation of the medial frontal cortex (MFC) region; in the beta (12–30 Hz) frequency band, children with SeLECTS (SWI ≥ 50%) showed deactivation of the posterior cingulate cortex (PCC) segment; and in the gamma (30–80 Hz) frequency band, children in the healthy group showed activation of the PCC region.

Conclusion

This study revealed significant decreases in cognitive function in children with SeLECTS (SWI ≥ 50%) compared to children with SeLECTS (SWI < 50%) and healthy children, as well as significant differences in magnetic source activity between the three groups. The findings suggest that deactivation of magnetic source activity in the PCC and MFC regions is the main cause of cognitive function decline in SeLECTS patients with some frequency dependence.

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.

The spectrum of epilepsy in children with 15q13.3 microdeletion syndrome

PURPOSE

To further define the epilepsy phenotype in a cohort of children with 15q13.3 microdeletion syndrome.

METHODS

We retrospectively reviewed the phenotypic spectrum of all children aged < 18 years with epilepsy and 15q13.3 microdeletion syndrome.

RESULTS

Thirteen children were included, 69% were female. The median age of children in the cohort was 12 years (age range: 3 years-15 years). Median age at seizure onset was 4 years. Eleven children (85%) had intellectual disability. Nine of 13 children (69%) had a history of typical absence seizures with median age of onset at 5 years (2 had absence status epilepticus). Thirty-one percent (4/13) had focal with impaired awareness non-motor onset seizures. ILAE recognized absence epilepsy syndromes were diagnosed in 6/13 (46%). The remainder were classified as having genetic generalized epilepsies with overlap clinical features, combined or focal epilepsies. Electroencephalogram in the cohort showed generalized (85%) and focal epileptiform discharges (62%) and posterior dominant rhythm slowing (33%). One child had electrical status epilepticus of sleep. Neuroimaging was performed in 5 children (38%) and revealed abnormal findings in 3. Seizures were drug resistant in a third of the cohort. Valproate resulted in seizure freedom in 5 (42%). Oxcarbazepine caused clinical worsening in one child with combined seizure types. Two children tried cannabidiol and one tried the ketogenic diet; neither was effective.

CONCLUSIONS

The epilepsy phenotype in children with 15q13.3 microdeletion syndrome is defined by childhood onset absence seizures, and may have atypical features such as, early onset absences, persistence into adolescence, status epilepticus, intellectual disability and treatment resistance. Focal seizures and focal EEG findings may be observed and should be treated cautiously, given the possibility of combined seizure types. Valproate appeared effective, although other treatments must be explored further.

[Epileptiform activity index for the evaluation of treatment efficacy in patients with epileptic encephalopathy]

Continuous spike and waves during sleep (CSWS) may lead to different cognitive, motor and behavioral symptoms. CSWS is characterized by an electroencephalography (EEG) pattern of electrical status epilepticus during sleep (ESES). The article reviews the main criteria of ESES, localization of EEG-changes and main EEG-patterns. An analysis of abnormal neuroimaging findings in patients with ESES was performed. The main pathophysiologic theories of ESES pattern formation are reviewed. ESES diagnosis is usually based on rough visual assessment of the number of spikes and waves, but other methods of assessment are also utilized, including spike-wave index (SWI), which is widely used in clinical practice. SWI reflects the percentage of sleep covered with spikes and waves. Two different strategies of SWI calculation are used, but none of them is officially validated. Moreover, there is no consensus on the period of sleep to be used for the calculation of SWI. The article presents a detailed review of calculation and utilization of SWI. It is concluded that further research is needed to develop an optimal algorithm of SWI calculation.

Genetic etiologies of the electrical status epilepticus during slow wave sleep: systematic review

Background

Electrical status epilepticus during slow-wave sleep (ESESS) which is also known as continuous spike-wave of slow sleep (CSWSS) is type of electroencephalographic (EEG) pattern which is seen in ESESS/CSWSS/epilepsy aphasia spectrum. This EEG pattern can occur alone or with other syndromes. Its etiology is not clear, however, brain malformations, immune disorders, and genetic etiologies are suspected to contribute. We aimed to perform a systematic review of all genetic etiologies which have been reported to associate with ESESS/CSWSS/epilepsy-aphasia spectrum. We further aimed to identify the common underlying pathway which can explain it. To our knowledge, there is no available systematic review of genetic etiologies of ESESS/CSWSS/epilepsy-aphasia spectrum. MEDLINE, EMBASE, PubMed and Cochrane review database were searched, using terms specific to electrical status epilepticus during sleep or continuous spike–wave discharges during slow sleep or epilepsy-aphasia spectrum and of studies of genetic etiologies. These included monogenic mutations and copy number variations (CNVs). For each suspected dosage-sensitive gene, further studies were performed through OMIM and PubMed database.

Results

Twenty-six studies out of the 136 identified studies satisfied our inclusion criteria. I51 cases were identified among those 26 studies. 16 studies reported 11 monogenic mutations: SCN2A (N = 6), NHE6/SLC9A6 (N = 1), DRPLA/ ATN1 (N = 1), Neuroserpin/SRPX2 (N = 1), OPA3 (N = 1), KCNQ2 (N = 2), KCNA2 (N = 5), GRIN2A (N = 34), CNKSR2 (N = 2), SLC6A1 (N = 2) and KCNB1 (N = 5). 10 studies reported 89 CNVs including 9 recurrent ones: Xp22.12 deletion encompassing CNKSR2 (N = 6), 16p13 deletion encompassing GRIN2A (N = 4), 15q11.2–13.1 duplication (N = 15), 3q29 duplication (N = 11), 11p13 duplication (N = 2), 10q21.3 deletion (N = 2), 3q25 deletion (N = 2), 8p23.3 deletion (N = 2) and 9p24.2 (N = 2). 68 of the reported genetic etiologies including monogenic mutations and CNVs were detected in patients with ESESS/CSWSS/epilepsy aphasia spectrum solely. The most common underlying pathway was channelopathy (N = 56).

Conclusions

Our review suggests that genetic etiologies have a role to play in the occurrence of ESESS/CSWSS/epilepsy-aphasia spectrum. The common underlying pathway is channelopathy. Therefore we propose more genetic studies to be done for more discoveries which can pave a way for proper drug identification. We also suggest development of common cut-off value for spike-wave index to ensure common language among clinicians and researchers.

Electronic supplementary material

The online version of this article (10.1186/s12863-018-0628-5) contains supplementary material, which is available to authorized users.

The relevance of inter- and intrastrain differences in mice and rats and their implications for models of seizures and epilepsy

It is becoming increasingly clear that the genetic background of mice and rats, even in inbred strains, can have a profound influence on measures of seizure susceptibility and epilepsy. These differences can be capitalized upon through genetic mapping studies to reveal genes important for seizures and epilepsy. However, strain background and particularly mixed genetic backgrounds of transgenic animals need careful consideration in both the selection of strains and in the interpretation of results and conclusions. For instance, mice with targeted deletions of genes involved in epilepsy can have profoundly disparate phenotypes depending on the background strain. In this review, we discuss findings related to how this genetic heterogeneity has and can be utilized in the epilepsy field to reveal novel insights into seizures and epilepsy. Moreover, we discuss how caution is needed in regards to rodent strain or even animal vendor choice, and how this can significantly influence seizure and epilepsy parameters in unexpected ways. This is particularly critical in decisions regarding the strain of choice used in generating mice with targeted deletions of genes. Finally, we discuss the role of environment (at vendor and/or laboratory) and epigenetic factors for inter- and intrastrain differences and how such differences can affect the expression of seizures and the animals' performance in behavioral tests that often accompany acute and chronic seizure testing.

New genes for focal epilepsies with speech and language disorders

The last 2 years have seen exciting advances in the genetics of Landau-Kleffner syndrome and related disorders, encompassed within the epilepsy-aphasia spectrum (EAS). The striking finding of mutations in the N-methyl-D-aspartate (NMDA) receptor subunit gene GRIN2A as the first monogenic cause in up to 20% of patients with EAS suggests that excitatory glutamate receptors play a key role in these disorders. Patients with GRIN2A mutations have a recognizable speech and language phenotype that may assist with diagnosis. Other molecules involved in RNA binding and cell adhesion have been implicated in EAS; copy number variations are also found. The emerging picture highlights the overlap between the genetic determinants of EAS with speech and language disorders, intellectual disability, autism spectrum disorders and more complex developmental phenotypes.

Recent developments in the genetics of childhood epileptic encephalopathies: impact in clinical practice

Recent advances in molecular genetics led to the discovery of several genes for childhood epileptic encephalopathies (CEEs). As the knowledge about the genes associated with this group of disorders develops, it becomes evident that CEEs present a number of specific genetic characteristics, which will influence the use of molecular testing for clinical purposes. Among these, there are the presence of marked genetic heterogeneity and the high frequency of de novo mutations. Therefore, the main objectives of this review paper are to present and discuss current knowledge regarding i) new genetic findings in CEEs, ii) phenotype-genotype correlations in different forms of CEEs; and, most importantly, iii) the impact of these new findings in clinical practice. Accompanying this text we have included a comprehensive table, containing the list of genes currently known to be involved in the etiology of CEEs.

The human clinical phenotypes of altered CHRNA7 copy number

Copy number variants (CNVs) have been implicated in multiple neuropsychiatric conditions, including autism spectrum disorder (ASD), schizophrenia, and intellectual disability (ID). Chromosome 15q13 is a hotspot for such CNVs due to the presence of low copy repeat (LCR) elements, which facilitate non-allelic homologous recombination (NAHR). Several of these CNVs have been overrepresented in individuals with neuropsychiatric disorders; yet variable expressivity and incomplete penetrance are commonly seen. Dosage sensitivity of the CHRNA7 gene, which encodes for the α7 nicotinic acetylcholine receptor in the human brain, has been proposed to have a major contribution to the observed cognitive and behavioral phenotypes, as it represents the smallest region of overlap to all the 15q13.3 deletions and duplications. Individuals with zero to four copies of CHRNA7 have been reported in the literature, and represent a range of clinical severity, with deletions causing generally more severe and more highly penetrant phenotypes. Potential mechanisms to account for the variable expressivity within each group of 15q13.3 CNVs will be discussed.

Encephalopathy with Electrical Status Epilepticus in Slow Wave Sleep – a review with an emphasis on regional (perisylvian) aspects

Aim.The aim of this article is to review criticaly the Electrical Status Epilepticus in Slow Sleep (ESES) phenomenon from a neurophysiological mechanisms aspect as well as terminological and classification issues.

Methods.The review includes all the relevant papers published during the last 43 years on the subject of ESES and Continous Spike – Wave in Sleep (CSWS).These papers were identified in various large databases via the internet.

Rewiev and remarks.ESES/CSWS phenomena can be held as a common final pathway originating from different etiologies, including patients with early brain damage (probably involving thalamic structures), but also patients without structural pathology as in atypical evolution of idiopathic regional childhood hyperexcitability syndromes (with Rolandic epilepsy as a prototype). There are hints that genetic predisposition might be an important factor in the development of this process. The two large patient groups (lesional and non-lesional) show the same EEG evolution and encephalopathic cognitive consequences. The sleep EEG activation can be held as a common endophenotype. ESES represents an extreme sleep activation/potentiation of the local/regional interictal discharges, enhancing them in frequency, territorial extension, intra and trans-hemispherial propagation, synchrony and continuity. This process is most probably not identical with the development of bilateral spike-wave pattern in „generalized” epilepsies which involves primarily or secondarily the thalamocortical system as it had been explored by Gloor (1979) for idiopathic generalized rpilepsy and Steriade and Amzica (2003) for different types of generalized spike and wave discharges.

Conclusions and syndromological embedding of ESES.In an overwhelming majority of the investigated cases, the maps of the single discharges constituting sleep activation are identical; with focal/regional interictal spikes followed by slow closing wave, as it is seen in childhood regional age dependent hyperexcitability syndromes (prototype of the centro-temporal spikes of Rolandic epilepsy). The main mechanism of the developing cognitive impairment is most probably the consequence of interference with plastic function of slow wave sleep by obliterating synaptic decline during sleep. Presently, the consensus and co-operative research is highly obstacled by the terminological chaos, the controversial definitions and views around this still striking and enigmatic phenomenon.

Chromosomal microaberrations in patients with epilepsy, intellectual disability, and congenital anomalies

Epilepsy is a common finding in patients with chromosomal macro- and micro-rearrangements but only few aberrations show a constant pattern of seizures. DNA array-based studies have reported causative copy number variations (CNVs) in 5-30% of patients with epilepsy with or without co-morbidities. The interpretation of many of the detected CNVs remains challenging. In order to identify CNVs carrying epilepsy-related genes we investigated 43 children with various patterns of epileptic seizures, intellectual disability (ID), and minor dysmorphism, using the Illumina® Infinium Human1M-DuoV1 array. In three patients we found likely causative de novo CNVs, i.e. deletions in 1q41q42.12 (3.4 Mb) and 19p13.2 (834 kb), and a mosaic two-segment duplication in 17p13.2 (218 kb) and 17p13.1 (422 kb). In six additional patients there were aberrations (a deletion in one and duplications in five patients) with uncertain clinical consequences. In total, the finding of causative chromosomal micro-rearrangements in 3 out of 43 patients (7%) and potentially causative CNVs in 6 additional patients (14%) with epilepsy and ID but without major malformations confirms the power of DNA arrays for the detection of new disease-related genetic regions.

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.

The tower of Babel: survey on concepts and terminology in electrical status epilepticus in sleep and continuous spikes and waves during sleep in North America

PURPOSE

The terms "electrical status epilepticus during sleep (ESES)" and "continuous spikes and waves during sleep (CSWS)" have been used interchangeably when referring to related but different concepts. In addition, the quantification of epileptiform activity has not been standardized, and different approaches to quantification have been used. The aim of this study was to evaluate the extent to which pediatric neurologists and epileptologists use a homogeneous terminology and conceptualization in CSWS and ESES and to characterize the current understanding of these conditions.

METHODS

A survey addressing the use of terminology in "ESES" and "CSWS" and the understanding of related concepts was distributed online to all members of the Child Neurology Society and the American Epilepsy Society mailing lists. Surveys were self-administered and collected using an online survey website (http://www.surveymonkey.com).

KEY FINDINGS

  Two hundred nineteen surveys were completed, 137 from the Child Neurology Society mailing list and 82 from the American Epilepsy Society mailing list. ESES and CSWS were considered synonymous by 117 respondents, not synonymous by 61, 21 respondents did not know, and 20 did not respond. Most respondents (63.1%) considered CSWS as a devastating epileptic encephalopathy with severe sequelae even if treated correctly, but 25.1% of respondents indicated that it does not leave sequelae if epilepsy was treated early and another 11.8% noted that cognitive difficulties resolved with age. Cognitive and/or language regression were considered mandatory for the diagnosis of CSWS by only 27% of the respondents. The diagnosis of CSWS was based on electroencephalography (EEG) assessment alone by 31% of respondents. Respondents used different methods for calculation of the epileptiform activity, different EEG samples for calculation, and considered differently the lateralized epileptiform activity. The cut-off values for percentage of the sleep record occupied by spike-waves were variable depending on the respondent. There was no agreement on whether these cutoff values were mandatory for the diagnosis of ESES and CSWS.

SIGNIFICANCE

  Our data show that the professionals caring for children with ESES and CSWS in North America use the terms, concepts, and defining features heterogeneously. The lack of a common language may complicate communication among clinicians and jeopardize research in this field. We anticipate that our data will fuel the development of much needed common terminology and conceptualization of ESES and CSWS.

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.

Epileptic Encephalopathies with Status Epilepticus during Sleep: New Techniques for Understanding Pathophysiology and Therapeutic Options

Encephalopathy with status epilepticus during sleep (ESES) is an epileptic encephalopathy, as defined by the International League Against Epilepsy (ILAE) Task Force on Classification and Terminology, that is, a condition in which the epileptic processes themselves are believed to contribute to the disturbance in cerebral function. Clinical manifestations of ESES are heterogeneous: apart from different seizure types, they consist in combinations of cognitive, motor, and behavioural disturbances associated with a peculiar electroencephalographic pattern of paroxysmal activity significantly activated during slow sleep, which culminates in a picture of continuous spikes and waves during sleep (CSWS). The pathophysiological mechanisms underlying this condition are still incompletely understood. Establishing a clear-cut correlation between EEG abnormalities and clinical data, though interesting, is very complex. Computer-assisted EEG analyses especially if combined with functional magnetic resonance imaging (EEG-fMRI) and metabolic neuroimaging have recently emerged as useful approaches to better understand the pathophysiological processes underlying ESES. Treatment of ESES is not just limited to seizures control but it should be focused on controlling neuropsychological outcome through an improvement of the continuous epileptiform activity. General agreement on treatment guidelines is still lacking. Implementation of new techniques might allow a better understanding of the pathophysiology of ESES and could enhance therapeutics options.

Epileptic encephalopathies of the Landau-Kleffner and continuous spike and waves during slow-wave sleep types: genomic dissection makes the link with autism

PURPOSE

The continuous spike and waves during slow-wave sleep syndrome (CSWSS) and the Landau-Kleffner (LKS) syndrome are two rare epileptic encephalopathies sharing common clinical features including seizures and regression. Both CSWSS and LKS can be associated with the electroencephalography pattern of electrical status epilepticus during slow-wave sleep and are part of a clinical continuum that at its benign end also includes rolandic epilepsy (RE) with centrotemporal spikes. The CSWSS and LKS patients can also have behavioral manifestations that overlap the spectrum of autism disorders (ASD). An impairment of brain development and/or maturation with complex interplay between genetic predisposition and nongenetic factors has been suspected. A role for autoimmunity has been proposed but the pathophysiology of CSWSS and of LKS remains uncharacterized.

METHODS

In recent years, the participation of rare genomic alterations in the susceptibility to epileptic and autistic disorders has been demonstrated. The involvement of copy number variations (CNVs) in 61 CSWSS and LKS patients was questioned using comparative genomic hybridization assays coupled with validation by quantitative polymerase chain reaction (PCR).

KEY FINDINGS

Whereas the patients showed highly heterogeneous in genomic architecture, several potentially pathogenic alterations were detected. A large number of these corresponded to genomic regions or genes (ATP13A4, CDH9, CDH13, CNTNAP2, CTNNA3, DIAPH3, GRIN2A, MDGA2, SHANK3) that have been either associated with ASD for most of them, or involved in speech or language impairment, or in RE. Particularly, CNVs encoding cell adhesion proteins (cadherins, protocadherins, contactins, catenins) were detected with high frequency (≈20% of the patients) and significant enrichment (cell adhesion: p = 0.027; cell adhesion molecule binding: p = 9.27 × 10(-7)).

SIGNIFICANCE

Overall our data bring the first insights into the possible molecular pathophysiology of CSWSS and LKS. The overrepresentation of cell adhesion genes and the strong overlap with the genetic, genomic and molecular ASD networks, provide an exciting and unifying view on the clinical links among CSWSS, LKS, and ASD.

Clinical staging and electroencephalographic evolution of continuous spikes and waves during sleep

PURPOSE

Currently, in continuous spikes and waves during sleep (CSWS) there is a lack of systematic assessments of the clinically relevant stages and the evolution of the electroencephalographic features. The aim of this study is to describe the evolution over time of clinical and electroencephalographic features in CSWS.

METHODS

We enrolled patients from our video-electroencephalography (EEG) monitoring unit with CSWS and with overnight EEG studies with at least one overnight assessment per year over a minimum period of 3 years. We studied clinical presentation and electroencephalographic features. We calculated the (1) spike-wave percentage (SWP) as the percentage of 1-s bins containing at least one spike-wave complex and (2) spike frequency (SF) as the number of spikes per 100 s.

KEY FINDINGS

Nine children (six boys) met the inclusion criteria during a 15-year period. Seven (78%) had an abnormal development prior to the epilepsy onset, and in two (22%) seizures were the only presenting symptom. Median age at epilepsy onset was 2 years (range 2 days to 4 years), at neuropsychological regression 5.1 years (4-7.7 years), and at seizure freedom 8.6 years (6.5-11.4 years). Median duration and range of clinically relevant stages were as follows: dormant stage (birth-epilepsy onset median 2 years, range 2 days-4 years), prodromal stage (epilepsy onset-neuropsychological regression 3.9 years, range 0.9-7.7 years), acute stage (neuropsychological regression-seizure freedom 2.9 years, range 2.1-6.6 years), and residual stage (after seizure freedom). Seven patients (78%) had a structural lesion on neuroimaging. At last follow-up (median 11.4 years, range 7.2-20.3 years), eight patients (89%) were receiving antiepileptic treatment, and all patients had residual neurocognitive deficits. During the acute stage, SWP was <85% in 13 (42%) of 31 assessments, and after seizure freedom, 3 of 5 patients (60%) had SWP >85%. Evolution of electroencephalographic patterns included increasing-decreasing, continuously elevated, and fluctuating patterns (33.3% each). There was good correlation between SWP and SF (Spearman correlation-coefficient = 0.942; p < 0.0001). SF, which can exceed 100%, reflected changes in electroencephalography pattern in more detail than SWP, which cannot exceed 100% and therefore has a ceiling effect.

SIGNIFICANCE

Our series systematically studied the age of occurrence of the significant clinical events. These may assist in defining clinical stages, which can provide a useful framework for future clinical trials in patients with CSWS. The severity of the epileptiform discharges on EEG did not always correlate with seizure frequency and severity; epileptiform discharges could be prominent after seizure freedom and fluctuated along the course of the disease. The values of SWP and SF correlated well, but SWP based on 1-s bins has the potential disadvantage of a ceiling effect.

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.