Developmental epileptic encephalopathy in DLG4-related synaptopathy

OBJECTIVE

The postsynaptic density protein of excitatory neurons PSD-95 is encoded by discs large MAGUK scaffold protein 4 (DLG4), de novo pathogenic variants of which lead to DLG4-related synaptopathy. The major clinical features are developmental delay, intellectual disability (ID), hypotonia, sleep disturbances, movement disorders, and epilepsy. Even though epilepsy is present in 50% of the individuals, it has not been investigated in detail. We describe here the phenotypic spectrum of epilepsy and associated comorbidities in patients with DLG4-related synaptopathy.

METHODS

We included 35 individuals with a DLG4 variant and epilepsy as part of a multicenter study. The DLG4 variants were detected by the referring laboratories. The degree of ID, hypotonia, developmental delay, and motor disturbances were evaluated by the referring clinician. Data on awake and sleep electroencephalography (EEG) and/or video-polygraphy and brain magnetic resonance imaging were collected. Antiseizure medication response was retrospectively assessed by the referring clinician.

RESULTS

A large variety of seizure types was reported, although focal seizures were the most common. Encephalopathy related to status epilepticus during slow-wave sleep (ESES)/developmental epileptic encephalopathy with spike-wave activation during sleep (DEE-SWAS) was diagnosed in >25% of the individuals. All but one individual presented with neurodevelopmental delay. Regression in verbal and/or motor domains was observed in all individuals who suffered from ESES/DEE-SWAS, as well as some who did not. We could not identify a clear genotype-phenotype relationship even between individuals with the same DLG4 variants.

SIGNIFICANCE

Our study shows that a subgroup of individuals with DLG4-related synaptopathy have DEE, and approximately one fourth of them have ESES/DEE-SWAS. Our study confirms DEE as part of the DLG4-related phenotypic spectrum. Occurrence of ESES/DEE-SWAS in DLG4-related synaptopathy requires proper investigation with sleep EEG.

Continuous Spike-Waves during Slow Sleep Today: An Update

In the context of childhood epilepsy, the concept of continuous spike-waves during slow sleep (CSWS) includes several childhood-onset heterogeneous conditions that share electroencephalograms (EEGs) characterized by a high frequency of paroxysmal abnormalities during sleep, which have negative effects on the cognitive development and behavior of the child. These negative effects may have the characteristics of a clear regression or of a slowdown in development. Seizures are very often present, but not constantly. The above makes it clear why CSWS have been included in epileptic encephalopathies, in which, by definition, frequent EEG paroxysmal abnormalities have an unfavorable impact on cognitive functions, including socio-communicative skills, causing autistic features, even regardless of the presence of clinically overt seizures. Although several decades have passed since the original descriptions of the electroclinical condition of CSWS, there are still many areas that are little-known and deserve to be further studied, including the EEG diagnostic criteria, the most effective electrophysiological parameter for monitoring the role of the thalamus in CSWS pathogenesis, its long-term evolution, the nosographic location of Landau-Kleffner syndrome, standardized neuropsychological and behavioral assessments, and pharmacological and non-pharmacological therapies.

Epilepsy Surgery for Cognitive Improvement in Epileptic Encephalopathy

Epileptic encephalopathies are defined by the presence of frequent epileptiform activity that causes neurodevelopmental slowing or regression. Here, we review evidence that epilepsy surgery improves neurodevelopment in children with epileptic encephalopathies. We describe an example patient with epileptic encephalopathy without drug refractory seizures, who underwent successful diagnostic and therapeutic surgeries. In patients with epileptic encephalopathy, cognitive improvement alone is a sufficient indication to recommend surgical intervention in experienced centers.

Neurocognitive Profile and 18 F-Fluorodeoxyglucose Positron Emission Tomography Brain Imaging Correlation in Children with Electrical Status Epilepticus during Sleep

Objective  Electrical status epilepticus in sleep (ESES) is defined by near-continuous epileptiform discharges during sleep along with cognitive, behavioral, and/or imaging abnormalities. We studied the neurocognitive profile and their correlation with 18 F fluorodeoxyglucose positron emission tomography (FDG PET) brain abnormalities in children with ESES. Methods  Fourteen children with ESES with normal magnetic resonance imaging (MRI) from March to December 2019 were included. The intelligence quotient (IQ) and child behavior checklist (CBCL) scores were estimated using validated scales, and FDG PET brain was done at the same point of time to look for cerebral metabolic defects which was compared with a control group. Results  Fourteen patients with a mean age of 8.2 ± 2.7 years were analyzed. The average duration of epilepsy was 6 ± 2.8 years. The mean IQ was 72.4 ± 18.2 and mean CBCL score was 37.3 ± 11.8. There was negative correlation between IQ and CBCL ( r  = -0.55, p  < 0.001). The duration of epilepsy also showed negative correlation with IQ ( r  = -4.75, p  < 0.001). FDG PET scan showed predominant thalamic hypometabolism in 12 of 14 patients (85.7%) on visual analysis with multiple other hypometabolic cortical and subcortical regions in the brain. The quantitative analysis showed significant difference in metabolism of basal ganglion when compared with control group. The total number of hypometabolic regions seen in the brain showed moderate positive correlation with CBCL score but no significant correlation with the IQ of cases. Conclusion  This study demonstrates functional impairment of cerebral cortical, basal ganglia, and thalamic hypometabolism in a cohort of ESES patients with normal structural MRI brain study. There was a moderate correlation of extent and pattern of cerebral hypometabolism with the neuropsychological status of the child and duration of epilepsy.

Continuous Spikes and Waves During Sleep (CSWS), Severe Epileptic Encephalopathy, and Choreoathetosis due to Mutations in FRRS1L

Background. Biallelic pathogenic variants in the FRRS1L gene are now known to cause developmental and epileptic encephalopathy-37 (DEE37). It can also be associated with chorea and continuous spikes and waves during sleep (CSWS). CSWS is a rare age-related epileptic encephalopathy syndrome of childhood that is characterized by seizures, neurocognitive regression and electrical status epilepticus during sleep (ESES) on electroencephalogram (EEG) that evolves in four stages. Seizures start during the prodromal phase but the ESES on EEG appears only during acute stage and this is the stage when the diagnosis of CSWS can be made. Methods. We present two patients with FRRS1L mutation causing DEE37 with CSWS. We also review twenty-nine cases of DEE37 described in the literature before and discuss its association with CSWS in the total cohort of thirty-one cases. Results. Developmental regression was found in 80% of the patients, mean age of seizure onset was 18 months, ESES or slow spike and wave on the EEG were reported mostly in the older patients (median age of 11 years) and hypsarrhythmia was reported in younger patients (median age of 4 years). This could suggest that if the younger patients were followed longer their EEG would have evolved into ESES during the acute stage of this syndrome and a diagnosis of CSWS could be made. Conclusion. Recognizing ESES and the natural evolution of CSWS is important in diagnosis and proper management of these patients. More detailed report of EEG findings and the evolution of epilepsy and development are needed to further characterize this syndrome.

Serum Levels of Neuropeptides in Epileptic Encephalopathy With Spike-and-Wave Activation in Sleep

BACKGROUND

Epileptic encephalopathy with spike-and-wave activation in sleep (EE-SWAS) is a syndrome of childhood, characterized by diffuse or generalized spike-wave activity in electroencephalography during non-rapid eye movement sleep. Neuropeptides have been demonstrated in several studies to function in the sleep-wake cycle and display convulsant and anticonvulsant features. In this study, we aimed to investigate the relationship between EE-SWAS and neuropeptides such as dynorphin, galanin, ghrelin, leptin, melatonin, and orexin.

METHODS

This multicenter study was conducted from July 2019 to January 2021. There were three groups: Group 1 contained patients with EE-SWAS. Group 2 consisted of patients with self-limited focal epilepsy of childhood (SeLFE), and group 3 was the control group. Levels of neuropeptides were compared in the sera of these three groups.

RESULTS

There were 59 children aged between four and 15 years. Group 1 contained 14 children, group 2 contained 24 children, and group 3 contained 21 children. The level of leptin is higher and the level of melatonin is lower in group 1 than in group 3 (P = 0.01 and P = 0.005, respectively). In group 3, the level of orexin was lower than in both groups 2 and 3 (P = 0.01 and P = 0.01).

CONCLUSIONS

These data show that the level of leptin was higher and the level of melatonin was lower in patients with EE-SWAS than in the control group. Furthermore, patients with EE-SWAS had lower orexin levels than both the control group and patients with SeLFE. Further research is required to understand the potential role of these neuropeptides in the pathophysiology of EE-SWAS.

Developmental and/or epileptic encephalopathy with spike-and-wave activation in sleep in Saudi Arabia: Electroclinical, etiologic, genetic, and outcome multicenter study

OBJECTIVES

To investigate the clinical features of developmental and/or epileptic encephalopathy with spike-and-wave activation in sleep (D/EE-SWAS), its electrographic characteristics, and etiology and to compare the effects of different treatment strategies on the outcomes using a Saudi Arabian database.

METHODS

This multicenter study included children with D/EE-SWAS who were evaluated between 2010 and 2020 at 11 tertiary centers. Data were collected on their baseline clinical features, etiologies, and treatment modalities. Seizure reduction, spike-wave index, and cognitive state were examined as potential therapeutic outcomes.

RESULTS

Ninety-one children were diagnosed with D/EE-SWAS, with a median age of 7 years (IQR: 3-5) and an almost equal sex distribution. The average age at which epilepsy was diagnosed was 3 years (IQR: 5-2). A genetic/metabolic etiology was found in 35.1% of the patients, and a structural etiology was found in 27.4%. Children with underlying genetic/metabolic diseases exhibited an earlier seizure onset (P = 0.001) than children with other etiologies. Benzodiazepines (76.6%) were the most common treatment, followed by steroids (51.9%). Sodium valproate (75%) was the most frequently used antiseizure medication, followed by levetiracetam (64.9%). Children with a later seizure onset were more likely to have better clinical responses (P = 0.046), EEG responses (P = 0.012), and cognitive outcomes (P = 0.006) than children with an earlier onset. Moreover, better seizure response and electrographic response were seen in patients with bilateral interictal discharges on the EEG than otherwise. Children had a higher likelihood of both clinical and electrographic improvement with combination therapy of benzodiazepines (P = 0.001) and steroids (P = 0.001) than with other therapies.

SIGNIFICANCE

This study shows a higher prevalence of genetic/metabolic causes and suggests the superior efficacy of combination therapy with steroids and benzodiazepines in D/EE-SWAS. Prospective studies that strictly assess the treatment protocols and outcomes are needed.

PRRT2 benign familial infantile seizures (BFIS) with atypical evolution to encephalopathy related to status epilepticus during sleep (ESES)

PURPOSE

Heterozygous variants in PRRT2 are mostly associated with benign phenotypes, being the major genetic cause of benign familial infantile seizures (BFIS), as well as in paroxysmal disorders. We report two children from unrelated families with BFIS that evolved to encephalopathy related to status epilepticus during sleep (ESES).

METHODS AND RESULTS

Two probands presented with focal motor seizures at 3 months of age, with a limited course. Both children presented, at around 5 years of age, with centro-temporal interictal epileptiform discharges with a source in the frontal operculum, markedly activated by sleep, and associated with stagnation on neuropsychological development. Whole-exome sequencing and co-segregation analysis revealed a frameshift mutation c.649dupC in the proline-rich transmembrane protein 2 (PRRT2) in both probands and all affected family members.

CONCLUSION

The mechanism leading to epilepsy and the phenotypic variability of PRRT2 variants remain poorly understood. However, its wide cortical and subcortical expression, in particular in the thalamus, could partially explain both the focal EEG pattern and the evolution to ESES. No variants in the PRRT2 gene have been previously reported in patients with ESES. Due to the rarity of this phenotype, other possible causative cofactors are likely contributing to the more severe course of BFIS in our probands.

Pathophysiological insights and nosological considerations

Encephalopathy related to Status Epilepticus during slow Sleep (ESES) is a childhood epilepsy syndrome characterized by the appearance of cognitive, behavioral, and motor disturbances in conjunction with a striking activation of EEG epileptic abnormalities during non-REM sleep. After more than 50 years since the first description, the pathophysiological mechanisms underlying the appearance of encephalopathy in association with a sleep-related enhancement of epileptic discharges are incompletely elucidated. Recent experimental data support the hypothesis that the development of the ESES encephalopathic picture depends on a spike-induced impairment of the synaptic homeostasis processes occurring during normal sleep and that is particularly pronounced during the developmental age. During sleep, synaptic homeostasis is promoted by synaptic weakening/elimination after the increment of synaptic strength that occurs during wakefulness. The EEG can display modifications in synaptic strength by changes in sleep slow wave activity (SWA). Recent studies during active ESES have failed to show changes in sleep SWA, while these changes occurred again after recovery from ESES, thus supporting a spike-related interference on the normal homeostatic processes of sleep. This impairment, during the developmental period, can lead to disruption of cortical wiring and brain plastic remodeling, which lead to the, often irreversible, neuropsychological compromise typical of ESES. From the nosographic point of view, these pathophysiological data lend support to the maintenance of the term ESES, i.e., "encephalopathy related to status epilepticus during sleep". Indeed, this term conveys the concept that the extreme activation of epileptic discharges during sleep is directly responsible for the encephalopathy, hence the importance of defining this condition as an encephalopathy related to the exaggerated activation of epileptic activity during sleep. In this respect, ESES represents a genuine example of a "pure" epileptic encephalopathy in which sleep-related epileptic activity "per se" has a crucial role in determining the encephalopathic picture. This paper was presented at the 8th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in September 2022.

Does Electrical Status Epilepticus in Sleep Adversely Affect Language in Self-Limiting Focal Epilepsies of Childhood?

Introduction

The electrical status epilepticus in sleep (ESES) accompanies a wide spectrum of focal and generalized epilepsies, which manifest with cognitive-linguistic regression. Both ESES and language impairment can be seen in self-limited focal epileptic syndromes of childhood (SFEC). The association between the presence of ESES pattern on the EEG and the severity of the language impairment has not been adequately clarified.

Methods

Twenty-eight SFEC cases without intellectual and motor disabilities and 32 healthy children were recruited. Cases with active ESES (A-ESES, n=6) and without ESES pattern on EEG (non-ESES, n=22) were compared in terms of clinical features and linguistic parameters by both standard and descriptive assessment tools.

Results

The only significantly different clinical feature in the A-ESES group was the increased prevalence of polytherapy. While most of the linguistic parameters were impaired in A-ESES and non-ESES groups compared to healthy controls, A-ESES patients differed from non-ESES patients only in terms of decreased complex sentence production, which was assessed by narrative analysis. A-ESES patients also showed trends toward producing lower numbers of words, nouns, verbs, and adverbs during narrative analysis. There were no differences among patients under polytherapy and monotherapy in terms of these language parameters.

Conclusion

Our results show that ESES increases the negative effect of chronic epilepsy on complex sentence and word production. Linguistic distortions that are not reflected in objective tests can be detected by narrative tools. Complex syntactic production obtained by narrative analysis is an important parameter that extensively characterizes language skills in school-age children with epilepsy.

Evaluation of Thiol-Disulfide Homeostasis with Electrical Status Epilepticus in Slow Sleep (ESES)

Background

Electrical status epilepticus in sleep (ESES) is an epileptic syndrome specific to childhood and has a broad clinical spectrum that included seizures, behavioral/cognitive impairments, and motor neurological symptoms. Antioxidants are seen as promising neuroprotective strategies for the epileptic state by combating the harmful effects of excessive oxidant formation in mitochondria.

Objective

This study aims to evaluate the thiol-disulfide balance and to determine whether it can be used in the clinical and electrophysiological follow-up of patients with ESES, especially in addition to the electroencephalography (EEG) examination.

Methods

The study included 30 patients, aged 2-18 years and diagnosed with ESES in the Pediatric Neurology Clinic of the Training and Research Hospital and a control group of 30 healthy children. Total thiol, native thiol, disulfide, and ischemia-modified albumin (IMA) levels were measured, and disulfide-thiol ratios were calculated for both groups.

Results

Native thiol and total thiol levels were significantly lower and IMA level and disulfide-native thiol percentage ratio were significantly higher in the ESES patient group than in the control group.

Conclusion

Serum thiol-disulfide homeostasis is an accurate marker of oxidative stress in ESES, and standard and automated measures of thiol-disulfide balance as an indicator of oxidative stress showed a shift toward oxidation in ESES patients in this study. The negative correlation between spike-wave index (SWI) and thiol levels, and serum thiol-disulfide levels suggest that they can be used as biomarkers for follow-up of patients with ESES in addition to EEG. IMA can also be used for long-term response to monitoring purposes at ESES.

High incidence of early thalamic lesions in the Continuous Spike-Wave related with slow Sleep (CSWS)

OBJECTIVE

Continuous Spike-Wave during slow Sleep (CSWS) syndrome associates a clinically important neurocognitive regression with strong activation of non-REM sleep spikes. Its mechanisms remain unknown, but a contribution of rare perinatal thalamic injuries has been highlighted. We determine the incidence of such lesions in a cohort of CSWS patients.

METHODS

N = 65 patients with CSWS and a control group (N = 51) were studied. Spikes were quantified in long-term ambulatory EEGs, brain Magnetic Ressonance Imaging (MRI) structural lesions were assessed and thalamic volumetry was performed. A neurocognitive scale was used to assess dysfunction.

RESULTS

The most common etiologies in the control patients were not represented in the CSWS group. Structural lesions were detected in a minority of CSWS patients (25/53) but included a thalamic injury in the large majority (24/25). This ratio was 4/40 in controls. Lesions belonged to one of five types: 1. Circumscribed to the thalamus (N = 11); 2. Extending beyond the thalamus (N = 3); 3. Hypothalamic-Hamartomas (N = 4); 4. Periventricular-Leukomalacia (N = 4); 5. Hypoplasia-Polymicrogyria (N = 1). Most lesions were lateralized to one hemisphere, which in all cases corresponded to the lateralization of the CSWS.

SIGNIFICANCE

Thalamic lesions are present in most CSWS patients with abnormal MRIs, supporting an important role in its genesis.

Classification of electrical status epilepticus in sleep based on EEG patterns and spatiotemporal mapping of spikes

Objective

We firstly aimed to describe and classify EEG patterns in electrical status epilepticus in sleep (ESES), and secondly subclassify EEG patterns based on analysis of spikes using spatio-temporal mapping and electrical source analysis.

Methods

Overnight EEGs (minimum: eight hours) of 30 children, aged 2-12 years, with ESES (spike-wave index: at least 50%) were selected. Average reference montage was used for dipole analysis and mapping. The location and orientation of the dipoles were determined by mapping positive and negative poles and applying the rules of mapping. The onset and propagation of the spikes and the latency between the two hemispheres (for bisynchronous spikes) were determined (based on source analysis using BESA research 7.1).

Results

(1) ESES was classified as “generalised” (80%) and focal (20%) patterns; (2) the bisynchronous subtype in the “generalised” pattern was due to apparently synchronous bilateral activation of spikes (with lead-in of 20-60 ms from one hemisphere) with a tangential/oblique dipole (source analysis localised these spikes to around the peri-rolandic cortex); (3) the classic description of ESES spikes as “diffuse” spikes with bifrontal maxima is a misinterpretation using the 10-20 EEG system .Using voltage mapping and source analysis, cortical activation in the rolandic cortex was identified which imparts diffuse frontal negativity and parieto-occipital positivity; (4) ESES spikes showed intraspike and interspike dipole instability and the orientation of dipoles changed due to local spike propagation around the source and into the depth of the sulcus (which we refer to herein as “dancing dipoles”); and (5) focal ESES were classified as parietal, occipital and temporo-occipital patterns;a frontal ESES pattern was not seen.

Significance

Based on detailed mapping and source analysis of ESES, we have successfully reinterpreted various misconceptions in the literature. We have simplified the interpretation of complicated EEG patterns by extracting the primary and propagated sources which aid the classification of ESES. As the dipole is always stable in self-limited childhood epilepsy with centrotemporal spikes, we believe that the phenomenon of an intrinsically unstable dipole is a reliable qualitative EEG marker of ESES.

Neurobehavioral deterioration associated with sleep-augmented epileptiform abnormalities: A steroid responsive state in children

OBJECTIVE

Retrospective case record analysis of children with Neurobehavioral Deterioration associated with Sleep-augmented Epileptiform abnormalities (NDSE).

METHODS

Hospital records of children with NDSE (July, 2015 through December, 2016) were analyzed. Children were categorized as: Encephalopathy with electrical status epilepticus in sleep (ESES) if sleep EEG Spike-wave-Index (SWI) was ≥50% and sleep-induced epileptiform activity (SIEA)-related cognitive dysfunction if SWI ≥25% but <50%. Demography, neurobehavior profile (IQ/SQ and behavior using validated psychometric tools), etiology, investigations and treatment details were documented. Outcome assessment was based on three-month follow-up records.

RESULTS

Eighteen children with NDSE {12 boys; median age at diagnosis: 7.5 years (IQR: 6-10 years); SIEA (7); ESES (11)} were included. Etiology was structural (23%) and presumed genetic (77%). All children received intravenous-methylprednisolone pulse followed by oral steroids for eight weeks. Electroencephalography of children with SIEA was partly organized with median SWI of 40% (IQR 35, 42), with anterior-predominant epileptiform abnormalities and less apparent secondary synchronization. Children with ESES had a disorganized EEG background with median SWI of 80% (IQR 66, 95). Both SIEA and ESES groups had a similar neurobehavior profile. Behavior scores improved in 6/8 children with ESES and 5/7 in SIEA post steroids. In both the groups, median SWI improved (to <5% in SIEA, 45% in ESES). Mild improvement in IQ/SQ was also noted {SIEA [Median (IQR): 3 (1.6, 4.3)]; ESES [Median (IQR): 3.8 (2.8, 7)]}.

CONCLUSION

The study supports the fact that SWI >50% in the nap EEG is not mandatory for the diagnosis of ESES, thus it should not be a constraint for steroid treatment.

Electrical status epilepticus in sleep: The role of thalamus in etiopathogenesis

PURPOSE

In patients diagnosed with epilepsy, decreased ratio of N-acetyl aspartate to creatine (NAA/Cr) measured in magnetic resonance spectroscopy (MRS) has been accepted as a sign of neuronal cell loss or dysfunction. In this study, we aimed to determine whether a similar neuronal cell loss is present in a group of encephalopathy with electrical status epilepticus in sleep (ESES) patients METHODS: We performed this case-control study at a tertiary pediatric neurology center with patients with ESES. Inclusion criteria for the patient group were as follows: 1) a spike-wave index of at least 50%, 2) acquired neuropsychological regression, 3) normal cranial MRI. Eventually, a total of 21 patients with ESES and 17 control subjects were enrolled in the study. MRI of all control subjects was also within normal limits. 3D Slicer program was used for the analysis of thalamic and brain volumes. LCModel spectral fitting software was used to analyze single-voxel MRS data from the right and left thalamus of the subjects.

RESULTS

The mean age was 8.0 ± 1.88 years and 8.3 ± 1.70 years in ESES patients and the control subjects. After correcting for the main potential confounders (age and gender) with a linear regression model, NAA/Creatine ratio of the right thalamus was significantly lower in the ESES patient group compared to the healthy control group (p = 0.026). Likewise, the left thalamus NAA/Cr ratio was significantly lower in the ESES patient group than the healthy control group (p = 0.007). After correcting for age and gender, right thalamic volume was not statistically significantly smaller in ESES patients than in healthy controls (p = 0.337), but left thalamic volume was smaller in ESES patients than in healthy controls (p = 0.024).

CONCLUSION

In ESES patients, the NAA/Creatine ratio, which is an indicator of neuronal cell loss or dysfunction in the right and left thalamus, which appears regular on MRI, was found to be significantly lower than the healthy control group. This metabolic-induced thalamic dysfunction, which was reported for the first time up to date, may play a role in ESES epileptogenesis.

Acquired visual agnosia as an uncommon presentation of epileptic encephalopathy in a 6-year-old boy with CSWS

•

Acquired visual agnosia is an underrecognized and rare manifestation of CSWS.

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Highly specific spared and affected areas of visual performance may be seen.

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Methylprednisolone was found most effective to treat cognitive symptoms.

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Recovery on EEG (SWI) and neuropsychological results showed partial synchronicity.

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SWI is likely not the only neurophysiological marker of epileptic encephalopathy.

Background

Acquired visual agnosia in the context of continuous spikes and waves during slow sleep (CSWS) is rarely described. We present a case of an almost 7-year-old boy who lost his ability to name pictures and recognize familiar faces. Initial encephalography (EEG) revealed sleep induced epileptiform activity with a spike-wave index (SWI) of 100%, predominanting in the left posterior head region.

Methods

Serial neuropsychological testing with concomitant EEG was done during the first 18 months of treatment with intravenous methylprednisolone. We administered intelligence scales, verbal tasks (memory, fluency), visual tasks (drawings, search, face recognition), and tasks requiring visual-verbal integration (picture naming, visual closure).

Analyses

Neuropsychological recovery studied with reliable cognitive change cut-offs and 95% confidence intervals.

Results

With treatment, there was an improvement of the EEG pattern (SWI reduction to 45%), followed by a relapse (SWI 82%). Neuropsychological measures in part synchronized with improvement, stability, and fluctuating values. Significant increases were seen on Verbal Comprehension Index and semantic memory. Visual Spatial Index remained unchanged (67 to 73). Naming pictures showed only limited change. Interpreting degraded pictures remained extremely difficult.

Discussion

Acquired visual agnosia may be seen in children with CSWS. Early recognition, prompt accurate treatment and tailored neuropsychological assessment remain crucial.

CNKSR2-related neurodevelopmental and epilepsy disorder: a cohort of 13 new families and literature review indicating a predominance of loss of function pathogenic variants

Background

Pathogenic variants in connector enhancer of kinase suppressor of Ras-2 (CNKSR2) located on the X chromosome (Xp22.12) lead to a disorder characterized by developmental delay and a characteristic seizure phenotype. To date, 20 affected males representing 13 different pathogenic variants have been published.

Case presentation

We identified an 8-year-old male with seizures, abnormal electroencephalogram (EEG) with epileptiform abnormalities in the right hemisphere, and developmental delay with notable loss of speech following seizure onset. Additional concerns include multiple nighttime awakenings, hyperactivity, and autism spectrum disorder. Genetic testing identified a de novo pathogenic nonsense variant in CNKSR2.

Through an active family support group, an additional 12 males are described, each harboring a different CNKSR2 variant. The clinical presentation and natural history consistently show early developmental delay, sleep disturbances, and seizure onset in childhood that is initially intractable but later becomes better controlled. Virtually all of the pathogenic variants are predicted to be loss of function, including genomic deletions, nonsense variants, splice site mutations, and small insertions or deletions.

Conclusions

This expanded knowledge, combined with functional studies and work with animal models currently underway, will enable a better understanding and improved ability to care for individuals with CNKSR2-related neurodevelopmental and epilepsy disorder.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-021-01033-7.

Treatment Practices and Outcomes in Continuous Spike and Wave during Slow Wave Sleep: A Multicenter Collaboration

OBJECTIVES

To determine how continuous spike and wave during slow wave sleep (CSWS) is currently managed and to compare the effectiveness of current treatment strategies using a database from 11 pediatric epilepsy centers in the US.

STUDY DESIGN

This retrospective study gathered information on baseline clinical characteristics, CSWS etiology, and treatment(s) in consecutive patients seen between 2014 and 2016 at 11 epilepsy referral centers. Treatments were categorized as benzodiazepines, steroids, other antiseizure medications (ASMs), or other therapies. Two measures of treatment response (clinical improvement as noted by the treating physician; and electroencephalography improvement) were compared across therapies, controlling for baseline variables.

RESULTS

Eighty-one children underwent 153 treatment trials during the study period (68 trials of benzodiazepines, 25 of steroids, 45 of ASMs, 14 of other therapies). Children most frequently received benzodiazepines (62%) or ASMs (27%) as first line therapy. Treatment choice did not differ based on baseline clinical variables, nor did these variables correlate with outcome. After adjusting for baseline variables, children had a greater odds of clinical improvement with benzodiazepines (OR 3.32, 95%CI 1.57-7.04, P = .002) or steroids (OR 4.04, 95%CI 1.41-11.59, P = .01) than with ASMs and a greater odds of electroencephalography improvement after steroids (OR 3.36, 95% CI 1.09-10.33, P = .03) than after ASMs.

CONCLUSIONS

Benzodiazepines and ASMs are the most frequent initial therapy prescribed for CSWS in the US. Our data suggests that ASMs are inferior to benzodiazepines and steroids and support earlier use of these therapies. Multicenter prospective studies that rigorously assess treatment protocols and outcomes are needed.

Electrical Status Epilepticus During Slow-wave Sleep (ESES): Current Perspectives

Electrical status epilepticus during slow-wave sleep (ESES) is an epilepsy syndrome with sleep-induced epileptic discharges and acquired impairment of cognition or behavior. Since the disease’s original description in 1971, no clear consensus has emerged on diagnostic criteria or optimal treatment. The treatment of ESES can be challenging, often including numerous antiepileptic drugs, immunomodulatory agents, and even surgical interventions. There is little evidence to guide treatment because only retrospective studies and case reports on the efficacy of treatment of ESES are present in literature. In this paper, we aim to analyze the etiopathogenesis of ESES in the new genetic era and to evaluate the treatment modalities in accordance with the genetic data and electroclinic spectrum of ESES.

Reduced thalamic volume is strongly associated with electrical status epilepticus in sleep

To identify the relationship between thalamic volume and electrical status epilepticus in sleep (ESES). We analyzed subcortical gray matter volumes in patients with an ESES pattern on their electroencephalographs. All magnetic resonance imaging scans were considered within normal limits. The patients were not receiving antiepileptic drug at the time of the MRI study. High resolution T1-weighted 3-dimensional MPRAGE scans were assessed for segmentation and quantitative volumetric analysis of the brain by using the "volBrain" method. After correcting for total brain volume, volumes were compared with a group of healthy controls (HCs) and patients with benign childhood epilepsy with centrotemporal spikes (BECTS). Fifteen patients with ESES, 15 patients with BECTS, and 30 HCs were included. The median age of the patients with ESES was 8.5 (range, 5.8-13) years, 8 (range, 5-14) years for the HCs, and 7.8 (range, 4-13.5) years for the patients with BECTS. The total relative thalamic volume was significantly lower in patients with ESES than in the healthy controls (0.87 ± 0.07 vs. 0.93 ± 0.03, p = 0.002), and in patients with ESES than in those with BECTS (0.87 ± 0.07 vs. 0.93 ± 0.03, p = 0.006). There was no significant difference the HCs and patients with BECTS (0.93 ± 0.03 vs. 0.93 ± 0.03, p = 0.999). Both right and left relative thalamic volumes were lower in patients with ESES than in HCs (right thalamus: 0.43 ± 0.04 vs. 0.46 ± 0.02, p = 0.003, left thalamus: 0.44 ± 0.03 vs. 0.47 ± 0.02, p = 0.002), in patients with ESES than in patients with BECTS (right thalamus: 0.43 ± 0.04 vs. 0.46 ± 0.01, p = 0.01, left thalamus: 0.43 ± 0.04 vs. 0.47 ± 0.01, p = 0.007); however, there was no significant difference between the HCs and patients with BECTS (right thalamus: 0.46 ± 0.02 vs. 0.46 ± 0.01, p = 0.999, left thalamus: 0.47 ± 0.02 vs. 0.47 ± 0.01, p = 0.999). This study highlights the association between thalamic involvement and ESES, even when not severe enough to cause a detectable lesion on visual interpretation of MRI.

Clinical spectrum and treatment outcome of 95 children with continuous spikes and waves during sleep (CSWS)

OBJECTIVE

Continuous spikes and waves during sleep (CSWS) is an epileptic encephalopathy characterized by generalised epileptiform activity and neurocognitive dysfunction. Causes and outcome are diverse and treatment is mainly empirical.

METHODS

Retrospective descriptive analysis of clinical and EEG data of children with CSWS diagnosed between 1998 and 2018 at the University Hospital Heidelberg.

RESULTS

Ninety-five children were included with a median age at diagnosis of 5.4 years. A structural/metabolic aetiology was found in 43.2%, genetic alterations in 17.9%, while it remained unknown in 38.9%. The proportion of patients with genetic aetiology increased from 10.3% (1998-2007) to 22.8% (2008-2018). On average, each patient received 5 different treatments. CSWS was refractory in >70% of cases, steroids and neurosurgery were most effective. No difference was observed between children with CSWS or Near-CSWS (Spike-Wave-Index 40-85%).

CONCLUSIONS

Our cohort confirms CSWS as an age-dependent epileptic encephalopathy. Structural brain abnormalities were most frequent, but genetic causes are increasingly identified. More specific criteria for the diagnosis and treatment goals should be elaborated and implemented based on evidence.

SIGNIFICANCE

This study is the largest monocentric observational study on treatment effects in children with CSWS, providing data for diagnostic and therapeutic decisions.

Automated quantification of spike-wave activity may be used to predict the development of electrical status epilepticus in sleep (ESES) in children with perinatal stroke

OBJECTIVE

Continuous spike and wave in slow-wave sleep (CSWS), an epileptic encephalopathy, occurs after perinatal stroke where it is associated with cognitive decline. CSWS features a distinct EEG pattern, electrical status epilepticus in sleep (ESES). Biomarkers for the prediction of ESES have not been identified but will facilitate earlier diagnosis and treatment. We hypothesized that spike-frequency and differences in power spectra would be predictive of subsequent ESES.

METHODS

A cross-sectional study comparing EEG spike-frequency and Power before the development of ESES in patients with perinatal stroke, patients with focal epilepsy, and appropriate controls.

RESULTS

43 patients met the inclusion criteria; 11 stroke-ESES, 10 stroke controls, 14 epilepsy-ESES, 8 epilepsy controls. ESES patients had higher pre-diagnosis mean spike-frequency (24.0 ± 24 versus 6.6 ± 9.1 SW/min, p = 0.002) than patients that did not develop ESES; these differences present ~ 3 years before ESES diagnosis. Pre-diagnosis, normalized delta power (1-4 Hz) was higher in the stroke-ESES group (105.7 ± 58 dB/Hz) compared to stroke controls (57.4 ± 45 dB/Hz, p = 0.036).

CONCLUSION

Spike-frequency and delta power may represent EEG biomarkers of the risk of developing ESES in children with perinatal stroke.

SIGNIFICANCE

EEG biomarkers may be used by clinicians to assess which patients are more at-risk for ESES. Using spike-frequency, clinicians may be able to identify patients at risk of developing ESES.

Wearable EEG Device for Continuous Spike-Wave in Sleep

Investigators from the Hospital Dona Estefânia, Escola Superior de Tecnologias e Saúde de Lisboa and Centro Hospitalar Psiquiátrico de Lisboa investigated 38 patients with continuous spike-wave of sleep (CSWS) syndrome.

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.

Encephalopathy related to status epilepticus during sleep due to a de novo KCNA1 variant in the Kv-specific Pro-Val-Pro motif: phenotypic description and remarkable electroclinical response to ACTH

Although the classic phenotype of episodic ataxia type 1 (EA1) caused by variants in KCNA1 includes episodic ataxia and myokymia, further genotype-phenotype correlations are difficult to establish due to highly heterogeneous clinical presentations associated with KCNA1 pathogenic variants. De novo variants in the paralogous Pro-Val-Pro motif (PVP) of KCNA2, an essential region for channel gating, have been reported to be associated with severe epilepsy phenotypes, including developmental and epileptic encephalopathies (DEE). Here, we describe the first patient with a DEE who developed an encephalopathy related to status epilepticus during sleep (ESES) and cerebellar signs, harbouring a variant in the Kv-specific PVP motif of the KCNA1 gene. Interestingly, he showed a remarkable long-term electroclinical response to IM ACTH therapy. This report extends the range of phenotypes associated with KCNA1 variants to include that of ESES, and suggests that ACTH therapy is likely to have a positive effect in patients with these variants.

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.

Sleep slow-wave homeostasis and cognitive functioning in children with electrical status epilepticus in sleep

STUDY OBJECTIVES

Encephalopathy with electrical status epilepticus in sleep (ESES) is characterized by non-rapid eye movement (non-REM)-sleep-induced epileptiform activity and acquired cognitive deficits. The synaptic homeostasis hypothesis describes the process of daytime synaptic potentiation balanced by synaptic downscaling in non-REM-sleep and is considered crucial to retain an efficient cortical network. We aimed to study the overnight decline of slow waves, an indirect marker of synaptic downscaling, in patients with ESES and explore whether altered downscaling relates to neurodevelopmental and behavioral problems.

METHODS

Retrospective study of patients with ESES with at least one whole-night electroencephalogram (EEG) and neuropsychological assessment (NPA) within 4 months. Slow waves in the first and last hour of non-REM-sleep were analyzed. Differences in slow-wave slope (SWS) and overnight slope course between the epileptic focus and non-focus electrodes and relations to neurodevelopment and behavior were analyzed.

RESULTS

A total of 29 patients with 44 EEG ~ NPA combinations were included. Mean SWS decreased from 357 to 327 µV/s (-8%, p < 0.001) across the night and the overnight decrease was less pronounced in epileptic focus than in non-focus electrodes (-5.6% vs. -8.7%, p = 0.003). We found no relation between SWS and neurodevelopmental test results in cross-sectional and longitudinal analyses. Patients with behavioral problems showed less SWS decline than patients without and the difference was most striking in the epileptic focus (-0.9% vs. -8.8%, p = 0.006).

CONCLUSIONS

Slow-wave homeostasis-a marker of synaptic homeostasis-is disturbed by epileptiform activity in ESES. Behavioral problems, but not neurodevelopmental test results, were related to severity of this disturbance.

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.

Sulthiame add-on treatment in children with epileptic encephalopathy with status epilepticus: an efficacy analysis in etiologic subgroups

PURPOSE

Sulthiame (STM) has been recommended as an effective antiepileptic drug (AED) in children with epileptic encephalopathy with status epilepticus in sleep (ESES). The aim of this study is to evaluate the efficacy of STM add-on treatment in children with pattern of ESES with respect to the etiologic subgroup.

METHODS

Twenty-nine children with ESES pattern with three different etiologic subgroups (epileptic syndromes: 14, structural/infectious: 9, unknown: 6) who were given STM as add-on treatment were included into the study. The efficacy of STM was evaluated in terms of seizure control, electroencephalography (EEG) findings, need of the new AEDs after add-on STM, and behavioral and cognitive improvement.

RESULTS

The range of the follow-up duration after add-on STM treatment was between 5 and 51 months. At the end of 1 year of STM treatment, the most successful electrophysiologic improvement was identified in the well-defined epileptic syndrome group; epileptic syndrome, 71.4% (10/14); structural/infectious, 33.3% (3/9); and unknown, 0% (0/6). Patients who had complete response or persistent ESES pattern at the 3rd month were still in the same condition at the 6th and 12th months. However, the ESES pattern reappeared in 35.2% of the patients who had partial electrophysiological improvement at the 3rd month. In the epilepsy syndrome group, eight out of ten patients who had either complete or partial EEG response after 1 year of STM treatment displayed behavioral and cognitive improvement.

CONCLUSION

Sulthiame might be a valid add-on treatment of ESES especially in children with epilepsy syndromes.

Electrical status epilepticus in sleep (ESES) - Treatment pattern and EEG outcome in children with very high spike-wave index

OBJECTIVE

The objective of the study was to determine electrical status epilepticus in sleep (ESES) outcome in children with very high spike-wave index (SWI; ≥85%), and assess treatment pattern.

METHODS

Medical records of children 1-17 years old with ESES were reviewed. In this study, ESES is defined as SWI in non-rapid eye movement (non-REM) sleep of ≥85%. Electrical status epilepticus in sleep resolution is defined as reduction of SWI to <50%.

RESULTS

Complete data were available in 33 children. Age at ESES diagnosis ranged from 32 to 165 months, median 76 months. The median duration of follow-up was 33 months. Two-thirds of the children were on one or more antiepileptic drugs (AED) at ESES diagnosis. Antiepileptic drugs were used as first treatment for ESES in 24/33 (73%). Electrical status epilepticus in sleep initially resolved in 76%, but 56% had subsequent relapse. The relapse rate was higher for steroids (89%) and benzodiazepines (60%) as compared with nonbenzodiazepine AEDs (29%). At last follow-up, ESES resolved in 21 children (64%). Electrical status epilepticus in sleep resolution was associated with seizure freedom (Fisher's exact, p < 0.05).

SIGNIFICANCE

Using electroencephalogram (EEG) criteria, ESES resolved in 64%. We found high failure rate of first-line AEDs in preventing ESES, and high relapse rate. Standardization of ESES management is urgently needed.

A Novel WAC Loss of Function Mutation in an Individual Presenting with Encephalopathy Related to Status Epilepticus during Sleep (ESES)

WAC (WW Domain Containing Adaptor With Coiled-Coil) mutations have been reported in only 20 individuals presenting a neurodevelopmental disorder characterized by intellectual disability, neonatal hypotonia, behavioral problems, and mildly dysmorphic features. Using targeted deep sequencing, we screened a cohort of 630 individuals with variable degrees of intellectual disability and identified five WAC rare variants: two variants were inherited from healthy parents; two previously reported de novo mutations, c.1661_1664del (p.Ser554*) and c.374C>A (p.Ser125*); and a novel c.381+2T>C variant causing the skipping of exon 4 of the gene, inherited from a reportedly asymptomatic father with somatic mosaicism. A phenotypic evaluation of this individual evidenced areas of cognitive and behavioral deficits. The patient carrying the novel splicing mutation had a clinical history of encephalopathy related to status epilepticus during slow sleep (ESES), recently reported in another WAC individual. This first report of a WAC somatic mosaic remarks the contribution of mosaicism in the etiology of neurodevelopmental and neuropsychiatric disorders. We summarized the clinical data of reported individuals with WAC pathogenic mutations, which together with our findings, allowed for the expansion of the phenotypic spectrum of WAC-related disorders.

Perinatal thalamic injury: MRI predictors of electrical status epilepticus in sleep and long-term neurodevelopment

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The majority of patients with perinatal thalamic injury, will develop epilepsy with ESES after the age of two years.

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ESES is associated with neurodevelopmental deficits.

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Larger residual thalamic volume at the three months MRI correlates to higher total IQ/DQ during follow-up.

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MRI at three months appears to be useful to predict neurodevelopmental outcome in this population.

Objective

Perinatal thalamic injury is associated with epilepsy with electrical status epilepticus in sleep (ESES). The aim of this study was to prospectively quantify the risk of ESES and to assess neuroimaging predictors of neurodevelopment.

Methods

We included patients with perinatal thalamic injury. MRI scans were obtained in the neonatal period, around three months of age and during childhood. Thalamic and total brain volumes were obtained from the three months MRI. Diffusion characteristics were assessed. Sleep EEGs distinguished patients into ESES (spike-wave index (SWI) >85%), ESES-spectrum (SWI 50–85%) or no ESES (SWI < 50%). Serial Intelligence Quotient (IQ)/Developmental Quotient (DQ) scores were obtained during follow-up. Imaging and EEG findings were correlated to neurodevelopmental outcome.

Results

Thirty patients were included. Mean thalamic volume at three months was 8.11 (±1.67) ml and mean total brain volume 526.45 (±88.99) ml. In the prospective cohort (n = 23) 19 patients (83%) developed ESES (-spectrum) abnormalities after a mean follow-up of 96 months. In the univariate analysis, larger thalamic volume, larger total brain volume and lower SWI correlated with higher mean IQ/DQ after 2 years (Pearson's r = 0.74, p = 0.001; Pearson's r = 0.64, p = 0.005; and Spearman's rho -0.44, p = 0.03). In a multivariable mixed model analysis, thalamic volume was a significant predictor of IQ/DQ (coefficient 9.60 [p < 0.001], i.e., corrected for total brain volume and SWI and accounting for repeated measures within patients, a 1 ml higher thalamic volume was associated with a 9.6 points higher IQ). Diffusion characteristics during childhood correlated with IQ/DQ after 2 years.

Significance

Perinatal thalamic injury is followed by electrical status epilepticus in sleep in the majority of patients. Thalamic volume and diffusion characteristics correlate to neurodevelopmental outcome.

Expanding the clinical and EEG spectrum of CNKSR2-related encephalopathy with status epilepticus during slow sleep (ESES)

OBJECTIVE

To investigate the clinical and EEG features of Encephalopathy with Status Epilepticus during slow Sleep (ESES) related to CNKSR2 pathogenic variants.

METHODS

Detailed clinical history, repeated wakefulness/overnight sleep EEGs, brain MRI were collected in five patients, including one female, with CNKSR2-related ESES.

RESULTS

Neurodevelopment in infancy was normal in two patients, delayed in three. Epilepsy onset (age range: 2-6 years) was associated with appearance or aggravation of cognitive impairment, language regression and/or behavioral disorders. Worsening of epilepsy and of cognitive/behavioral disturbances paralleled by enhancement of non-rapid eye movement (NREM) sleep-related, frontally predominant, EEG epileptic discharges [spike-wave-index (SWI): range 60-96%] was consistent with ESES. In three patients, episodes of absence status epilepticus or aggravation of atypical absences occurred, in this latter case associated with striking increment of awake SWI. Speech/oro-motor dyspraxia was diagnosed in four patients. In two patients, long-term follow-up showed epilepsy remission and persistence of mild/moderate cognitive disorders and behavioral disturbances into adulthood.

CONCLUSIONS

Novel findings of our study are occurrence also in females, normal neurodevelopment before epilepsy onset, epilepsy aggravation associated with enhanced awake SWI, mild/moderate evolution in adulthood and language disorder due to speech/oro-motor dyspraxia.

SIGNIFICANCE

Our findings expand the phenotypic spectrum of CNKSR2-related ESES.

Encephalopathy related to status epilepticus during slow sleep (ESES) as atypical evolution of Panayiotopoulos syndrome: an EEG and neuropsychological study

We report two patients with Panayiotopoulos syndrome (PS) who developed encephalopathy related to status epilepticus during slow sleep (ESES) at the peak of their clinical course. Clinical charts and EEG data were reviewed. The patients exhibited nocturnal autonomic seizures and occipital EEG foci, the latter of which later evolved into multifocal EEG foci with synchronous frontopolar and occipital spikes (Fp-O EEG foci), and finally into continuous spikes-waves during sleep (CSWS; spike-wave index >85% based on whole-night sleep recording) at eight years and seven years of age, respectively. The occipital spikes always preceded frontopolar spikes by 30∼50 mseconds based on the analysis of CSWS. Neuropsychological ability, including IQ, deteriorated during the CSWS period in both patients. The autonomic seizures and focal to bilateral tonic-clonic seizures were initially resistant to antiepileptic drugs (AEDs), and occurred more than 10 times in both patients. However, the seizures and EEG findings gradually resolved, and AEDs were successfully terminated in both patients. PS can progress to ESES if the clinical course exhibits atypical evolution. The initial autonomic symptom of the seizures and interictal Fp-O EEG foci should be carefully monitored in patients with CSWS or ESES.

Progressive intellectual impairment in children with Encephalopathy related to Status Epilepticus during slow Sleep

We investigated whether Encephalopathy related to Status Epilepticus during slow Sleep (ESES) in childhood was associated with progressive intellectual decline. Participants were identified from the caseload of a single paediatric neurosciences centre and EEG department. A retrospective review of overnight sleep EEG reports (n=2200) over a five-year period identified twenty-two children as having the neurophysiological characteristics of ESES. All had repeat neuropsychological assessment using the WISC-III (UK) and/or WPPSI-R (UK). There was a statistically significant reduction in Full-Scale IQ and Performance IQ across a mean and median time interval of two years. Around a third of the participants showed a clinically significant regression in intellectual functioning evidenced by =>12-point reduction in IQ. These patients were not distinguishable from the rest of the cohort in terms of clinical history, imaging or duration of ESES. The reduction in IQ reflected reduced processing speed, working memory and overall cognitive efficiency. Children with a history of ESES require close monitoring in order to support educational planning and provide families with accurate information about prognosis.

Encephalopathy related to Status Epilepticus during slow Sleep: a link with sleep homeostasis?

Encephalopathy related to Status Epilepticus during slow Sleep (ESES) is a childhood epilepsy syndrome characterized by appearance of cognitive and behavioural disturbances in conjunction with a striking activation of EEG epileptic abnormalities during sleep. The link between the extreme amount of epileptic discharges during sleep and the deterioration of cognitive functions and behavior is poorly understood. We hypothesize that the negative effects of ESES may depend on the impairment of the synaptic homeostasis processes occurring during normal sleep and that are particularly important in the developmental age. Sleep ensures synaptic homeostasis by promoting synaptic weakening/elimination after the increase of synaptic strength that occurs during wakefulness. Changes in synaptic strength are reflected in the EEG by changes of sleep slow wave activity (SWA). Recent studies in ESES have failed to show changes of sleep SWA, particularly at the site of the epileptic focus, suggesting a spike-related impairment of the homeostatic recovery of sleep. This impaired synaptic homeostasis in the critical period of development may alter cortical wiring and thereby disrupt, often irreversibly, cognitive functions and behavior, leading to the neuropsychological compromise typical of ESES.

Generalized quasiperiodic epileptiform activity in sleep is associated with cognitive impairment in children with drug-resistant focal lesional epilepsy

OBJECTIVE

To evaluate the impact of generalized quasiperiodic epileptiform discharges ("hurdles") observed in non-rapid eye movement (NREM) sleep on cognitive function in children with intractable focal epilepsy. "Hurdles" pattern does not meet the criteria of the electrical status epilepticus in slow-wave sleep (ESES).

METHODS

In a retrospective analysis, 24 patients with "hurdles" and their 24 peers matched for demographic and epilepsy-related variables were compared in terms of neuropsychological domains and electroencephalography (EEG)-derived quantifiers. Both "hurdles" and controls were children between 2 and 19 years of age who had intractable focal epilepsy evaluated as candidates of resective epilepsy surgery.

RESULTS

Full-scale intelligence quotient/developmental quotient (FSIQ/DQ) (P = .002) and visuoconstructional skills (P = .004) were significantly lower in children with "hurdles" compared to controls. Patients with "hurdles" presented with higher interictal spike indexes in sleep (P < .001, median difference -0.9, 95% confidence interval [CI] -1.4, -0.6) and wakefulness (P < .001, median difference -0.3, 95% CI -0.5, -1). Relative time of sleep spindles in NREM sleep was significantly reduced (P < .001, median difference 0.1, 95% CI 0.0, 0.1) in the "hurdles" group. The time proportion of sleep spindles represented a significant positive (P = .008) and spike index of generalized spikes in sleep a significant negative explanatory variable (P = .004) of FSIQ/DQ scores. The proportion of seizure-free patients 2 years after epilepsy surgery did not differ significantly between the two groups (P = .19).

SIGNIFICANCE

Although the "hurdles" pattern does not fulfill the criteria of ESES, it is associated with a pronounced cognitive dysfunction. Disturbed sleep structure marked by reduced sleep spindles and generalized spiking in sleep is associated with worse cognitive performance. Despite having a generalized nature, we did not find a lower probability of postsurgical seizure freedom in patients with "hurdles" pattern.

Scalp EEG high frequency oscillations as a biomarker of treatment response in epileptic encephalopathy with continuous spike-and-wave during sleep (CSWS)

PURPOSE

We investigated whether the presence of interictal scalp EEG high frequency oscillations (HFOs) in children with epileptic encephalopathy with continuous spike-and-wave during sleep (CSWS) can predict seizure and cognitive outcome after steroid therapy.

METHODS

Twenty-two children with CSWS were prospectively enrolled and received methylprednisolone therapy. Interictal scalp HFOs, spike wave index (SWI) and intelligence quotient (IQ) were assessed before and after the treatment. The children were divided into two groups based on the early seizure reduction ratio at 2 weeks (≥50%, "response group"; otherwise "non-response group"). The "response group" was further divided into two subgroups ("relapse" and "non-relapse" subgroups) according to the late seizure outcome (after 3 months).

RESULTS

Interictal HFOs and electrical status epilepticus in sleep (ESES) (defined as SWI ≥ 85%) were detected in all children at the baseline. In the response with relapse group (n = 11), the detection ratio of HFOs was significantly higher than that of ESES at 2 weeks (81.2 vs. 27.3%), 3 months (90.9 vs. 36.4%), and 6 months (100 vs. 54.5%) post-therapy. In the non-response group (n = 4), both HFOs and ESES persisted in all children. The average IQ improved significantly only in the response with non-relapse group. The persistence of HFOs negatively correlated with both the average IQ, yet the persistence of ESES did not.

CONCLUSION

Interictal scalp HFOs may be a favorable non-invasive biomarker of predicting seizure and cognitive outcome in CSWS.

An electroclinical, genetic, and follow-up study

OBJECTIVE

The objective of the study was to investigate electroclinical and neuropsychological features, genetic background, and evolution of children with idiopathic encephalopathy with status epilepticus during slow sleep (ESES), including Landau-Kleffner syndrome (LKS).

MATERIAL AND METHODS

All children diagnosed with idiopathic ESES at the Danish Epilepsy Centre between March 2003 and December 2014 were retrospectively reviewed. Repeated 24-hour electroencephalography (24-h EEG) recordings, neuropsychological assessments, and clinical-neurological evaluation were performed throughout the follow-up in all patients. In 13 children, genetic investigations were performed.

RESULTS

We collected 24 children (14 males and 10 females). Mean age at ESES diagnosis was 6 years, and mean ESES duration was 2 years and 7 months. Twenty-one children had epileptic seizures. Three children had LKS. Topography of sleep-related EEG epileptic abnormalities was diffuse in 3 subjects, hemispheric in 6, multifocal in 9, and focal in 6. During the active phase of ESES, all children presented with a heterogeneous combination of behavioral and cognitive disturbances. In 14 children, a parallel between severity of the clinical picture and spike-wave index (SWI) was observed. We could not find a strict correlation between the type and severity of neurobehavioral impairment and the side/topography of sleep-related EEG discharges during the active phase of ESES. At the last follow-up, 21 children were in remission from ESES. Complete recovery from neurobehavioral disorders was observed in 5 children. Genetic assessment, performed in 13 children, showed GRIN2A variant in two (15.4%).

SIGNIFICANCE

Our patients with idiopathic ESES showed a heterogeneous pattern of epileptic seizures, neurobehavioral disorders, and sleep EEG features. Only one-fourth of children completely recovered from the neuropsychological disturbances after ESES remission. Lack of correlation between severity/type of cognitive derangement and SWI and/or topography of sleep EEG epileptic abnormalities may suggest the contribution of additional factors (including impaired sleep homeostasis due to epileptic activity) in the neurobehavioral derangement that characterize ESES.

EEG features in Encephalopathy related to Status Epilepticus during slow Sleep

Encephalopathy related to Status Epilepticus during slow Sleep (ESES) is a peculiar electro-clinical condition, with variable etiologies, characterized by an age-dependent phenomenon of extreme activation of epileptic activity during sleep, i.e. "status epilepticus during sleep", that is strictly associated with the appearance of cognitive and behavioral disturbances. Even though the peculiar EEG picture is fundamental for the diagnosis of ESES, clear-cut and shared diagnostic criteria for defining the EEG boundaries of this syndrome are still lacking. The diagnosis of ESES can be further complicated by the variability of the EEG findings, that during the course of the disease can change from diffuse to more or less focal and viceversa, depending both on the spontaneous clinical evolution of this condition and/or on the effects of medications. Given the complexity and the heterogeneity of EEG parameters during the ESES course, it is important to correlate the EEG findings with the concomitant cognitive and behavioral status, possibly taking into account not only the spike-wave index, but also other parameters, such as for instance the topography of the epileptic abnormalities, their patterns of spread, and their fluctuations over time. Moreover, the epileptiform activity not only during sleep, but also during wakefulness, the presence of focal slowing, the organization of the EEG background and a derangement of the sleep architecture may play a role in determining the clinical picture.

Pathophysiology of encephalopathy related to continuous spike and waves during sleep: the contribution of neuroimaging

In the last three decades, studies on functional neuroimaging have helped us to understand pathophysiological mechanisms responsible for electro-clinical patterns associated with epileptic encephalopathies with continuous spikes and waves during slow sleep (ECSWS). MEG and EEG source reconstruction have revealed sources of pathological brain activity associated with epileptiform discharges in the perisylvian region pointing to the significance of this brain area for ECSWS. PET studies have revealed areas of focal hypermetabolism in perisylvian, superior temporal and inferior parietal regions as well as central cortices which were related to epileptic activity. The widespread hypometabolism in regions that belong to the default network (prefrontal and posterior cingulate cortices, parahippocampal gyrus and precuneus) was interpreted as remote inhibition following epileptic activity, which could contribute to cognitive deficits in affected individuals. Note that the described metabolic changes were functional and disappeared after successful treatment and recovery of ECSWS and were found in both sleep and wakefulness which may account for cognitive deficits in patients during the day. EEG-fMRI studies have revealed a functional fingerprint of epileptic encephalopathy: significant positive BOLD signal changes were identified in the perisylvian regions, prefrontal cortex and anterior cingulate as well as thalamus and negative BOLD signal changes in the regions of the default mode network. The pattern of activation represents a propagation of epileptic activity specific to encephalopathy, which is independent of etiology and type of seizure associated with ECSWS. In summary, methods of neuroimaging have shed light on pathogenic mechanisms of ECSWS which may account for a number of clinical phenomena associated with this condition.

Quantitative EEG analysis in Encephalopathy related to Status Epilepticus during slow Sleep

Since its first description, quantifying the burden of epileptiform abnormalities in sleep EEG has played a fundamental role in the diagnosis of Encephalopathy related to Status Epilepticus during slow Sleep (ESES). In fact, in the 1971 seminal paper by Tassinari's group and in the following studies on this syndrome, the amount of epileptiform discharges (EDs) was calculated as the percentage of slow sleep occupied by spike-and-waves and referred to as "spike and wave index" (SWI). However, nowadays it is becoming increasingly clear that the SWI alone does not explain the whole clinical course of patients affected by ESES. In this paper, we aim to provide a state-of-the-art summary of the quantitative EEG methods currently used in the ESES/CSWS literature, highlighting the possible pitfalls and discrepancies explaining the unsatisfactory correlation between SWI and clinical course. Furthermore; we illustrate a number of methodological refinements - taking into account inter-individual, intra-individual, and temporal variability of EDs - alongside "new" quantitative variables -including ED-related and sleep-related features - potentially useful to reach a reliable electro-clinical correlation in patients with ESES.

Sleep in Mowat-Wilson Syndrome: a clinical and video-polysomnographic study

OBJECTIVE

Sleep disturbances are frequently reported in Mowat-Wilson Syndrome (MWS). The current study aimed to evaluate clinical and video-polysomnographic (VPSG) characteristics of the sleep architecture and abnormal electroencephalogram (EEG) patterns during sleep in MWS.

METHODS

Sixteen individuals with MWS (range 16 months-25 years), attending the Department of Child Neurology and Psychiatry of the University of Bologna, were included. The "Sleep Disturbances Scale for Children (SDSC)" questionnaire was administered to all parents of MWS patients, and all patients underwent a VPSG recording.

RESULTS

The analysis of the SDSC questionnaire revealed disturbances mainly at the sleep-wake transition and in initiating and maintaining sleep. Evaluation of sleep structure in MWS patients showed a significant reduction of total sleep time, an increase of wake after sleep onset and arousal index as compared to normal controls. An EEG pattern characterized by slowing of background activity and poverty of physiological sleep characterisitcs was observed in all patients. Moreover, in patients aged >7 years, anteriorly predominant spike and waves were observed, markedly activated by sleep configuring a sub-continuous or continuous activity.

CONCLUSION

Our data (both clinical and VPSG) documented the presence of significant and clinically relevant sleep disturbances in MWS patients. Moreover, we identified a characteristic age-dependent sleep EEG pattern that could provide a new element to assist in the management of MWS.

Amantadine: A new treatment for refractory electrical status epilepticus in sleep

PURPOSE

Electrical status epilepticus in sleep (ESES) is an electrographic abnormality linked to language abnormalities and cognitive dysfunction and specifically associated with Landau-Kleffner syndrome (LKS), the syndrome of continuous spike and wave in slow-wave sleep (CSWS), and autistic regression with epileptiform EEG (AREE). As first-line therapies for treatment of ESES display inadequate efficacy and confer substantial risk, we set out to describe our center's experience with amantadine in the treatment of ESES.

METHODS

Patients with video-EEG-confirmed ESES who received amantadine were retrospectively identified in a clinical EEG database. Spike-wave index, before and after amantadine exposure, was compared in a pairwise fashion. In an exploratory analysis, we cataloged reported changes in language functioning, cognition, and autistic features, which accompanied treatment.

RESULTS

We identified 20 patients with ESES-associated syndromes. Median cumulative weighted average amantadine dosage was 2.1 mg/kg/d (interquartile range (IQR): 1.1, 4.5), and median duration of therapy was 11.5 months (IQR: 7.8, 26.6). In comparison with median baseline spike-wave index (76%), post-amantadine spike-wave index (53%) was reduced, with P = 0.01. Six (30%) patients exhibited complete (or nearly complete) resolution of ESES. A majority of patients exhibited subjective cognitive, linguistic, or behavioral benefit. Amantadine was generally well-tolerated despite substantial dosage and duration of therapy.

CONCLUSIONS

This study suggests that amantadine may be effective in the treatment of ESES-associated syndromes but warrants replication in a more rigorous study.

Ketogenic diet use in children with intractable epilepsy secondary to malformations of cortical development: A two- centre experience

PURPOSE

To evaluate the efficacy and tolerability of the ketogenic diet (KD) as a treatment for drug-resistant epilepsy secondary to malformations of cortical development.

METHODS

A two-centre retrospective analysis of 45 paediatric patients with refractory epilepsy due to malformation of cortical development was carried out. Patients were divided into three groups based on malformation type: abnormal neural proliferation (Group 1); abnormal neural migration (Group 2) and abnormal post-migrational development (Group 3). The efficacy of the KD was assessed in terms of seizure frequency reduction. We identified the proportion of patients achieving > 50% seizure frequency reduction overall and in the three subgroups.

RESULTS

The adherence to KD was variable. KD was pursued from a minimum of 4 months to a maximum of 96 months. 20 patients (44%) obtained a seizure reduction of > 50% and 2 patients became seizure free. >50% seizure reduction was most commonly achieved by patients in group 3 (64.7%) than in groups 2 (31.8%) and 1 (33.3%).

CONCLUSIONS

The best response was observed in patients with malformations of post migrational development. Considering its tolerability, the use of KD should be considered in patients with drug-resistant epilepsy secondary to malformations of cortical development when surgery is not a viable option.

Treatment of electrical status epilepticus in sleep: Clinical and EEG characteristics and response to 147 treatments in 47 patients

OBJECTIVE

Electrical status epilepticus in sleep (ESES) syndrome is characterized by near-continuous sleep-induced epileptiform activity and acquired cognitive deficits. Treatment is assumed mandatory to improve cognitive outcome. We aimed to compare EEG characteristics, subjective evaluation and objective neuropsychological assessment as measures to evaluate treatment efficacy, and to analyze possible predictors.

METHODS

We retrospectively included patients with ESES syndrome treated in our center. Treatment effect was analyzed on sleep EEG spike wave index (SWI) and cognitive functioning.

RESULTS

47 patients had 147 (43 steroid and 104 non-steroid) treatments. Cognitive improvement was reported after 36% of treatments at first follow-up and 45% of treatments at last follow-up. The median SWI change for treatments resulting in subjective cognitive improvement was -44%, and 0% for those not resulting in subjective cognitive improvement at first follow-up (p = 0.008) and -50% vs. +5% at last follow-up (p = 0.002). No clear association between subjective cognitive improvement and IQ change, and between SWI and IQ change was found. By means of logistic regression we found that steroid treatment, as compared to non-steroid treatment, was associated with cognitive improvement at first follow-up (multivariate OR after multiple imputation 2.5, 95% CI 1.1-5.7), while at last follow-up, higher age at diagnosis was related to cognitive improvement only in univariate analysis (OR 1.02, 95% CI 1.01-1.04).

CONCLUSIONS

We found that in children with ESES, cognitive improvement after treatment was strongly associated with SWI decrease, while it was not reflected by a significant IQ increase. Steroid treatment was most successful in improving cognitive performance.

Electrical status epilepticus during sleep in Mowat-Wilson syndrome

AIM

Mowat-Wilson Syndrome (MWS) is a genetic rare disease. Epilepsy is present in 70-75% of Patients and an age-dependent electroclinical pattern has been described. Up to date, there are studies with overnight sleep EEGs, probably because of the severe intellectual disability (ID) and hyperactivity of these Patients. Our purpose was to verify the hypothesis that MWS Patients might have electrical status epilepticus in slow wave sleep (ESES pattern).

METHODS

A retrospective analysis of anamnestic and electrographic data was performed on 7 consecutive MWS Patients followed between 2007 and 2016. Only Patients with at least one overnight sleep EEG were included in the study.

RESULTS

Five out of 7 Patients had overnight sleep EEG studies and were included in this study. All of them had an anterior ESES pattern with spike-and-wave index>85%. The architecture of sleep was abnormal. An ESES related regression of cognitive and motor functions with impact on daily activities (ESES-related syndrome) was demonstrated in 3 out of 5 (60%) Patients. In two Patients marked improvement of cognitive and motor performances was observed when the epileptiform activity during sleep was successfully controlled or it was spontaneously reduced.

CONCLUSIONS

The clinical significance of the ESES pattern is hard to assess in MWS Patients due to severe ID, but changing in behaviour or in motor and cognitive functions should mandate sleep EEG investigation and, if ESES is present, an appropriate treatment should be tried. Furthermore, overnight sleep EEG recordings, if regularly performed in the follow up, might help to understand if ESES pattern hampers the cognitive and communicative profile in MWS.

Neurobehavioral consequences of continuous spike and waves during slow sleep (CSWS) in a pediatric population: A pattern of developmental hindrance

INTRODUCTION

Continuous spike and waves during slow sleep (CSWS) is a typical EEG pattern defined as diffuse, bilateral and recently also unilateral or focal localization spike-wave occurring in slow sleep or non-rapid eye movement sleep. Literature results so far point out a progressive deterioration and decline of intellectual functioning in CSWS patients, i.e. a loss of previously normally acquired skills, as well as persistent neurobehavioral disorders, beyond seizure and EEG control. The objective of this study was to shed light on the neurobehavioral impact of CSWS and to identify the potential clinical risk factors for development.

METHODS

We conducted a retrospective study involving a series of 16 CSWS idiopathic patients age 3-16years, considering the entire duration of epilepsy from the onset to the outcome, i.e. remission of CSWS pattern. All patients were longitudinally assessed taking into account clinical (sex, age at onset, lateralization and localization of epileptiform abnormalities, spike wave index, number of antiepileptic drugs) and behavioral features. Intelligent Quotient (IQ) was measured in the whole sample, whereas visuo-spatial attention, visuo-motor skills, short term memory and academic abilities (reading and writing) were tested in 6 out of 16 patients.

RESULTS

Our results showed that the most vulnerable from an intellectual point of view were those children who had an early-onset of CSWS whereas those with later onset resulted less affected (p=0.004). Neuropsychological outcome was better than the behavioral one and the lexical-semantic route in reading and writing resulted more severely affected compared to the phonological route.

CONCLUSIONS

Cognitive deterioration is one but not the only consequence of CSWS. Especially with respect to verbal skills, CSWS is responsible of a pattern of consequences in terms of developmental hindrance, including slowing of development and stagnation, whereas deterioration is rare. Behavioral and academic problems tend to persist beyond epilepsy resolution.

Epilepsy surgery for epileptic encephalopathy as a sequela of herpes simplex encephalitis: case report

Herpes simplex virus (HSV) encephalitis can manifest with different clinical presentations, including acute monophasic illness and biphasic chronic granulomatous HSV encephalitis. Chronic encephalitis is much less common, and very rare late relapses are associated with intractable epilepsy and progressive neurological deficits with or without evidence of HSV in the cerebrospinal fluid. The authors report on an 8-year-old girl with a history of treated HSV-1 encephalitis when she was 13 months of age and focal epilepsy when she was 2 years old. Although free of clinical seizures, when she was 5, she experienced behavioral and academic dysfunction, which was later attributed to electrographic focal seizures and worsening electroencephalography (EEG) findings with electrical status epilepticus during slow-wave sleep (ESES). Following a right temporal lobectomy, chronic granulomatous encephalitis was diagnosed. The patient's clinical course improved with the resolution of seizures and EEG abnormalities.

Topiramate in childhood epileptic encephalopathy with continuous spike-waves during sleep: A retrospective study of 21 cases

OBJECTIVE

Encephalopathy with continuous spike-wave during sleep (CSWS) is a particularly difficult-to-treat childhood epileptic syndrome. This study sought to present the EEG improvement and clinical efficacy of topiramate (TPM), a broad spectrum antiepileptic drug (AED), in a series of 21 children with CSWS encephalopathy.

METHODS

We retrospectively reviewed the EEG results and clinical data of children with CSWS followed-up in our institution and treated with TPM. Sleep EEGs were performed 0-3 months prior to TPM introduction and then at 3 and 12 months. The exclusion criteria were (1) introduction of another AED and (2) withdrawal of a potentially aggravating AED during the first 3 months of treatment. In addition to spike index (SI), the severity of EEG abnormalities was rated using an original scale that also considered the spatial extent of interictal epileptiform discharges.

RESULTS

21 patients were included (18 males, 4-14y, three symptomatic cases). At 3 months, sleep EEG was improved in 14 and normalized in four (TPM doses: 2-5.5 mg/kg/day). Among these 18 patients, 16 manifested cognitive or behavioural improvement. In a subgroup of seven patients with frequent seizures, five became seizure-free and one had over 75% decrease in seizure frequency. At the one-year follow-up, 20 children were still on TPM and 10 exhibited persistent EEG improvement without any other AED being introduced, most of them with clinical benefits.

CONCLUSION

TPM can decrease EEG abnormalities in epileptic encephalopathy with CSWS, achieving clinical improvement in the majority of patients. However, relapse may occur in the long-term in nearly half of cases. Otherwise, TPM has proven particularly useful in reducing seizure frequency in refractory cases.