Age-Dependency of Location of Epileptic Foci in "Continuous Spike-and-Waves during Sleep": A Parallel to the Posterior-Anterior Trajectory of Slow Wave Activity

BACKGROUND

Epileptic encephalopathy with continuous spike-and-waves during sleep (CSWS) occurs during childhood and is characterized by an activation of spike wave complexes during slow wave sleep. The location of epileptic foci is variable, as is etiology. A relationship between the epileptic focus and age has been shown in various focal epilepsies following a posterior-anterior trajectory, and a link to brain maturation has been proposed. We hypothesize that in CSWS, maximal spike wave activity, corresponding to the epileptic focus, is related to age and shows a posterior-anterior evolution.

FINDINGS

In a retrospective cross-sectional study on CSWS (22 EEGs of 22 patients aged 3.1–13.5 years), the location of the epileptic focus is related to age and follows a posterior-anterior course. Younger patients are more likely to have posterior foci than older ones.

CONCLUSIONS

We propose that the posterior-anterior trajectory of maximal spike waves in CSWS might reflect maturational changes of maximal expression of sleep slow waves, which follow a comparable course. Epileptic spike waves, that is, “hyper-synchronized slow waves” may occur at the place where the highest and therefore most synchronized slow waves meet brain tissue with an increased susceptibility to synchronization.

Hemispherotomy in children with electrical status epilepticus of sleep

OBJECTIVE Electrical status epilepticus of sleep (ESES) is a rare electrographic pattern associated with global regression, which is often poorly responsive to traditional epilepsy treatments and can have a devastating and permanent neurocognitive outcome. The authors analyzed clinical, electroencephalographic, and neuropsychological outcomes in 9 patients with refractory ESES treated with functional hemispherotomy to illustrate the wide clinical spectrum associated with the disease and explore the role of hemispherotomy in its treatment. METHODS During the period between 2003 and 2015, 80 patients underwent hemispherotomy at the authors' institution. Video electroencephalography (EEG) reports were reviewed for ESES or continuous spikes and waves during sleep (CSWS). Patients with preoperative ESES (> 85% slow-wave sleep occupied by spike waves), a unilateral structural lesion amenable to surgery, and more than 6 months of follow-up data were included in the analysis. Clinical data, EEG recordings, neuropsychological testing, and parental and clinician reports were retrospectively reviewed. RESULTS Nine patients were eligible for study inclusion. Age at seizure onset ranged from birth to 4.2 years (mean 1.9 years), age at ESES diagnosis ranged from 3.5 to 8.8 years (mean 6.0 years), and age at hemispherotomy ranged from 3.7 to 11.5 years (mean 6.8 years). All patients had drug-resistant epilepsy. The duration of epilepsy prior to hemispherotomy ranged from 2.7 to 8.9 years (mean ± SD, 5.0 ± 2.2 years). Engel Class I seizure outcome was observed in all 9 children, with a mean follow-up of 3.0 years (range 0.5-6.1 years). Hemispherotomy terminated ESES in 6 of 6 patients with available postoperative sleep EEG. All children had preoperative neuropsychological impairments. Developmental regression was halted postoperatively, but none of the children returned to their original pre-ESES baseline. Four children demonstrated academic gains, 2 of whom transitioned to mainstream classes. CONCLUSIONS Children with drug-resistant ESES and a unilateral structural lesion should be evaluated for hemispherotomy as they may experience the cessation of seizures, termination of ESES, and improvement in neuropsychological status.

The yield of video-EEG telemetry evaluation for non-surgical candidate children

BACKGROUND

Video EEG (VEEG) is performed for most pediatric patients in order to evaluate unclear paroxysmal events and improve our understanding of difficult to control epileptic patients.

PURPOSE

To characterize the video EEG studies on children who are not candidates for surgery in order to identify the parameters that affect results in level of improving the rate of acquisition, as well as improving the ability to expect the likelihood of epilepsy and of gathering new information as a result of the VEEG.

METHODS

Retrospective chart analysis of all consecutive patients who underwent VEEG in two VEEG monitoring units.

RESULTS

323 children of a mean age of 7 years (STD 4.73, range 0-17 years) were monitored for a mean duration of 2 days (STD 1.65, range 1-10 days). The main reasons for monitoring were: evaluation of unclear events (n = 234), evaluation of previously diagnosed epilepsy (n = 36) and confirmation of Electrical Status Epilepticus in Sleep (ESES) (n = 34). The main event types for evaluation were: staring episodes (n = 67), myoclonic jerks (n = 35) and abnormal eye movement (n = 22). Suspected events were captured in 70% of the patients. There was a positive correlation between acquisition of suspected events and each of the following: duration of the monitoring, the frequency of investigated events per history, the type of investigated events. A prior interictal epileptic activity on routine EEG was a positive predictor of an event to be epileptic (p = 0.003). Amongst the group of known epileptic patients, VEEG had role in changing diagnosis in 53% of patients. Many of them had focal interictal epileptiform activity in their routine EEG.

CONCLUSIONS

Selecting patients with frequent events and longer monitoring periods increase the yield of VEEG. Looking carefully into clinical characteristics of the patient prior to VEEG can clarify diagnosis therefore render the VEEG test superfluous to subgroups of patients. Prior routine epileptic EEG, coexistence of other seizure types, behaviors accompanying the investigated habitual behavior and abnormalities in other investigations (MRI, cognitive function and EEG) are the parameters that can predict diagnosis of epilepsy. Precise diagnosis in known epileptic patients as a result of VEEG is more likely for those with focal interictal epileptiform discharges in routine EEG.

Seizures and electroencephalography findings in 61 patients with fetal alcohol spectrum disorders

Fetal alcohol spectrum disorders (FASD) cause neurodevelopmental abnormalities. However, publications about epilepsy and electroencephalographic features are scarce. In this study, we prospectively performed electroencephalography (EEG) and brain magnetic resonance (MR) imaging in 61 patients with diagnosis of FASD. One patient had multiple febrile seizures with normal EEGs. Fourteen children showed EEG anomalies, including slow background activity and interictal epileptiform discharges, focal and/or generalized, and 3 of them had epilepsy. In one patient, seizures were first detected during the EEG recording and one case had an encephalopathy with electrical status epilepticus during slow sleep (ESES). Focal interictal discharges in our patients did not imply the presence of underlying visible focal brain lesions in the neuroimaging studies, such as cortical dysplasia or polymicrogyria. However, they had nonspecific brain MR abnormalities, including corpus callosum hypoplasia, vermis hypoplasia or cavum septum pellucidum. The latter was significantly more frequent in the group with EEG abnormal findings (p < 0.01).

Psychiatric and Behavioural Disorders in Children with Epilepsy (ILAE Task Force Report): Epilepsy and autism

A high proportion of children with epilepsy have autism spectrum disorder. Although estimates vary, depending both on the population studied and the definitions used, a figure of around 20% has typically been reported. Autism can have a major impact on the life of the child and family. Despite the importance of this comorbidity and although many studies have been performed, a full understanding of the possible links between epilepsy and autism remains elusive. In a minority of cases, for example in the Landau-Kleffner syndrome, the autistic features can be the result of the epilepsy itself. However, there has been a failure to demonstrate that the epilepsy itself plays a major role in most cases. The current evidence seems to point to a common underlying predisposing factor. The discovery of a growing number of genetic defects leading to both conditions would support this explanation of the link.

Psychiatric and Behavioural Disorders in Children with Epilepsy (ILAE Task Force Report): Subtle behavioural and cognitive manifestations of epilepsy in children

A subtle behavioural or cognitive manifestation of epilepsy can be defined in two ways. First, epileptiform discharges not presenting as obvious seizures may nevertheless affect cognition and/or behaviour. Second, the actual seizures may be obvious but the way they affect cognition or behaviour may not be. There is a growing body of evidence indicating that the epileptiform discharges in benign epilepsy with centrotemporal spikes can affect behaviour and cognition. The focal discharges in other forms of epilepsy can also be associated with behavioural change. The Landau-Kleffner syndrome, the CSWS syndrome, transitory cognitive impairment and transient epileptic amnesia provide further examples of cognitive and behavioural manifestations resulting from subtle manifestations of the epilepsy. Prompt, effective antiepileptic treatment with medication or surgery can improve behaviour and cognition in at least some cases.

Atypical benign partial epilepsy of childhood with acquired neurocognitive, lexical semantic, and autistic spectrum disorder

Atypical benign partial epilepsy (ABPE) of childhood or pseudo-Lennox syndrome is a form of idiopathic focal epilepsy characterized by multiple seizure types, focal and/or generalized epileptiform discharges, continuous spike–wave during sleep (CSWS), and sometimes reversible neurocognitive deficits. There are few reported cases of ABPE describing detailed correlative longitudinal follow-up of the various associated neurocognitive, language, social communicative, or motor deficits, in parallel with the epilepsy. Furthermore, the molecular inheritance pattern for ABPE and the wider spectrum of epilepsy aphasia disorders have yet to be fully elucidated. We describe the phenotype–genotype study of a boy with ABPE with follow-up from ages 5 to 13 years showing acquired oromotor and, later, a specific lexical semantic and pervasive developmental disorder. Exome sequencing identified variants in SCN9A, CPA6, and SCNM1. A direct role of the epilepsy in the pathogenesis of the oromotor and neurocognitive deficits is apparent.

Serum inflammatory mediators correlate with disease activity in electrical status epilepticus in sleep (ESES) syndrome

We aimed to study serum cytokine levels in 11 electrical status epilepticus in sleep (ESES) patients and 20 healthy control children. Patients showed significantly higher levels of interleukin (IL)-1α, IL-6, IL-10, chemokine (C-C motif) ligand (CCL)2 and chemokine (C-X-C motif) ligand (CXCL)8/IL-8 than controls, while macrophage migration inhibitory factor (MIF) and CCL3 were significantly lower. Follow-up analyses in five patients revealed a significant decrease of IL-6 levels after immunomodulating treatment. IL-6 changes were accompanied by clear improvement of electroencephalography (EEG) patterns and neuropsychological evaluation. We hypothesize that IL-6 correlates with disease activity and immunomodulating treatment efficacy.

Successful Treatment of Electrographic Status Epilepticus of Sleep With Felbamate in a Patient With SLC9A6 Mutation

BACKGROUND

Mutations of SLC9A6 may cause an X-linked clinical syndrome first described by Christianson in 1999 in which affected males exhibited profound intellectual disability, autism, drug-resistant epilepsy, ophthalmoplegia, mild craniofacial dysmorphism, microcephaly, and ataxia.

METHODS

We describe a child with an SLC9A6 mutation and an electroencephalographic pattern consistent with electrographic status epilepticus of sleep.

RESULTS

Our patient's electrographic status epilepticus of sleep resolved after treatment with felbamate. Following treatment, he remained seizure-free but did not make significant or lasting gains in language.

CONCLUSION

Our report extends the clinical epilepsy phenotype in children with SLC9A6 mutations to include electrographic status epilepticus of sleep. In addition, felbamate was an effective treatment for electrographic status epilepticus of sleep in our patient.

Lack of Prominent Cognitive Regression in the Long-term Outcome of Patients Having Electrical Status Epilepticus During Sleep With Different Types of Epilepsy Syndromes

The purpose was to document 4 patients with different epilepsy syndromes, showing electrical status epilepticus during sleep (ESES), without marked cognitive and behavioral regression in the long-term follow-up. The mean age at onset of seizures was 8 years. Absences, myoclonic, focal motor, or generalized tonic - clonic seizures and drop attacks were the prominent seizure types. The neurological examination and neuroimaging findings revealed no abnormality. Focal epileptiform electroencephalographic (EEG) activity was seen in 3 cases, whereas generalized photosensitive epileptic discharges were detected in 1 patient with juvenile myoclonic epilepsy. Neuropsychological evaluations of all cases were within the normal range, and deterioration in mental status was not observed during their mean follow-up duration of 14 years. Our data support the view that ESES can emerge along with different types of childhood epilepsy syndromes, including idiopathic generalized epilepsies, and may not always be a poor prognostic factor.

An 8-year old boy with continuous spikes and waves during slow sleep presenting with positive onconeuronal antibodies

OBJECTIVE

To determine the etiology of epilepsy with continuous spikes and waves during slow sleep (CSWS)/electrical status epilepticus during sleep (ESES) in an 8-year old boy with a history of neuroblastoma and opsoclonus-myoclonus.

MATERIAL & METHODS

A combination of clinical characterization and follow-up, video EEG and laboratory investigations.

RESULTS

We report the case of an 8-year old boy with a history of neuroblastoma and opsoclonus-myoclonus, who presented with intellectual disability, pharmacotherapy-resistant epilepsy and CSWS/ESES. Although the patient's neuroblastoma had been successfully treated 8 years prior to presentation and an extensive workup did not show a tumor reoccurrence, testing for onconeuronal antibodies was positive for anti-Ma2 and anti-CV2/CRMP5 antibodies. High-dose intravenous methylprednisolone and a taper of oral methylprednisolone were given, leading to a significant clinical improvement. During the taper the patient's condition and EEG manifestations deteriorated again necessitating another cycle of steroid therapy, which lead to a stable improvement. During a 6-month follow-up no CSWS/ESES was seen on EEG and anti-Ma2 and anti-CV2/CRMP5 antibodies remained undetectable.

CONCLUSION

This case suggests that onconeuronal antibodies may be involved in the pathogenesis of CSWS/ESES.

Benign childhood epilepsy with Centro-Temporal spikes (BCECTSs), electrical status epilepticus in sleep (ESES), and academic decline--how aggressive should we be?

Since many of the children with BCECTSs display electrical status epilepticus during sleep and many present with different comorbidities, mainly ADHD and behavioral disturbances, clinicians are often confronted with the dilemma of how aggressive they should be with their efforts of normalizing the EEG. We conducted a retrospective study by screening medical records of all consecutive patients with BCECTSs, spike-wave index (SWI) >30%, and ADHD/ADD that were evaluated in our pediatric epilepsy service and were followed up for at least two years. Patients with neurocognitive deterioration detected by formal testing were excluded. A total of 17 patients with mean age of 6.9years at BCECTS diagnosis were identified. The patients' mean SWI was 60% and that dense electrical activity lasted 1.5years on average (range: 1-4.5years). Six children were formally diagnosed with learning disabilities in addition to ADD/ADHD. All of them were treated with an average of three antiepileptic medications, mainly for the purpose of normalizing the EEG, but none of them was treated with steroids or high-dose diazepam. The mean duration of follow-up was 5.5years. A cognitive or behavioral deterioration was not detected in any of them. Our data suggest that when treating a child with BCECTSs, high SWI, and school difficulties, the most critical parameter that determines the necessity of using second-line antiepileptic agents such as steroids or high-dose diazepam is a formal psychological evaluation that proves cognitive (I.Q.) decline. Otherwise, these agents may be avoided.

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

BACKGROUND

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

METHODS

Literature review and analysis.

RESULTS

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

CONCLUSIONS

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

A novel mutation in the endosomal Na+/H+ exchanger NHE6 (SLC9A6) causes Christianson syndrome with electrical status epilepticus during slow-wave sleep (ESES)

Mutations in the solute carrier family 9, subfamily A member 6 (SLC9A6) gene, encoding the endosomal Na+/H+ exchanger 6 (NHE6) are associated with Christianson syndrome, a syndromic form of X-linked intellectual disability characterized by microcephaly, severe global developmental delay, autistic behavior, early onset seizures and ataxia. In a 7-year-old boy with characteristic clinical and neuroimaging features of Christianson syndrome and epileptic encephalopathy with continuous spikes and waves during sleep, we identified a novel splice site mutation (IVS10-1G>A) in SLC9A6. These findings expand the clinical spectrum of the syndrome and indicate NHE6 dysfunction as a new cause of electrical status epilepticus during slow-wave sleep (ESES).

Measuring spike strength in patients with continuous spikes and waves during sleep: comparison of methods for prospective use as a clinical index

OBJECTIVE

To compare methods of estimating spike strength as a potential index in the assessment of continuous spikes and waves during sleep (CSWS).

METHODS

Spikes were searched and averaged automatically from pre- and postoperative EEGs of ten patients with CSWS who underwent corpus callosotomy (eight) or resective epilepsy surgery (two). From the most prominent spike, we measured peak amplitude and root mean square (RMS) over ±150ms window around the peak. In order to compensate for spatiotemporal instability of spikes, the cumulative amplitude and RMS were computed from the highest quartile of electrodes (Ampl-Q and RMS-Q, respectively). The stability of parameters was studied by comparing two ten minute epochs during the first hour of NREM sleep, as well as by analyzing overnight variation of indices in further ten patients with CSWS. The Ampl-Q and RMS-Q were compared between pre- and postoperative recordings.

RESULTS

All four measures, amplitude, RMS, Ampl-Q and RMS-Q, were correlated with each other and highly dependent on NREM/REM-sleep stage and arousals. Expectedly, Ampl-Q and RMS-Q had the greatest intra-individual stability. The amplitude had up to 71% intra-individual variation making it unhelpful for clinical use. Ampl-Q and RMS-Q were comparable in assessing change following surgical treatment.

CONCLUSIONS

Computing an integrated RMS over multiple electrodes during steady NREM sleep offers a stable and reliable parameter for evaluating the strength of spikes in CSWS.

SIGNIFICANCE

Analyzing spike strength with RMS-Q may offer a clinically useful, supplementary index for EEG monitoring of CSWS where spike index has been of limited value.

Centrotemporal spikes during NREM sleep: The promoting action of thalamus revealed by simultaneous EEG and fMRI coregistration

Benign childhood epilepsy with centrotemporal spikes (BECTS) has been investigated through EEG-fMRI with the aim of localizing the generators of the epileptic activity, revealing, in most cases, the activation of the sensory-motor cortex ipsilateral to the centrotemporal spikes (CTS). In this case report, we investigated the brain circuits hemodynamically involved by CTS recorded during wakefulness and sleep in one boy with CTS and a language disorder but without epilepsy. For this purpose, the patient underwent EEG-fMRI coregistration. During the "awake session", fMRI analysis of right-sided CTS showed increments of BOLD signal in the bilateral sensory-motor cortex. During the "sleep session", BOLD increments related to right-sided CTS were observed in a widespread bilateral cortical-subcortical network involving the thalamus, basal ganglia, sensory-motor cortex, perisylvian cortex, and cerebellum. In this patient, who fulfilled neither the diagnostic criteria for BECTS nor that for electrical status epilepticus in sleep (ESES), the transition from wakefulness to sleep was related to the involvement of a widespread cortical-subcortical network related to CTS. In particular, the involvement of a thalamic-perisylvian neural network similar to the one previously observed in patients with ESES suggests a common sleep-related network dysfunction even in cases with milder phenotypes without seizures. This finding, if confirmed in a larger cohort of patients, could have relevant therapeutic implication.