The effect of surgery in encephalopathy with electrical status epilepticus during sleep

Surgical treatment of epileptic encephalopathy with spike-and-wave activation in sleep: A systematic review and meta-analysis

OBJECTIVE

Epileptic Encephalopathy / Developmental Epileptic Encephalopathy with spike-and-wave activation during sleep (EE/DEE-SWAS) is a self-limiting childhood epilepsy syndrome but may cause permanent neurocognitive impairment. Surgical interventions have been controversial in the treatment of EE/DEE-SWAS. This systematic review aims to evaluate the efficacy of various surgical procedures on the outcomes of EE/DEE-SWAS.

METHODS

A systematic review was performed per the PRISMA guidelines. A total of 14 retrospective studies were identified, comprising 131 cases of EE/DEE-SWAS treated with epilepsy surgery. The review analyzed presurgical data, surgical interventions, as well as outcomes related to seizures, EEG, and neuropsychological assessments.

RESULTS

Epilepsy surgery was successfully performed in 131 cases with minor complications. The average age was 2.6 years at seizure onset and 5.0 years at diagnosis of SWAS. Excellent seizure control (Engel I and II) was achieved in 80.6 %, 78.6 %, 77.4 % and 27.2 % of patients receiving hemispherectomies, focal resections, multiple subpial transections (MSTs), and corpus callosotomies (CCTs), respectively. EEG SWAS resolution was seen in 79.7 % of hemispherectomy cases, 78.6 % in focal resections, 63.9 % in MSTs, and 8.3 % in CCTs. Neurocognitive and behavioral improvement was noted in 58.0 %, 71.4 %, 58.3 % and 16.7 % for patients receiving hemispherectomies, focal resections, MSTs, and CCTs, respectively. A correlation between improved seizure control and SWAS resolution was observed with improved neuropsychological outcomes.

CONCLUSION

Epilepsy surgery is a safe and effective treatment for carefully selected children with drug-resistant EE/DEE-SWAS. Patients who underwent epilepsy surgery had reduction of seizure burden, SWAS resolution and improvements in neurocognitive and behavioral function.

Successful Hemispherotomy in a Patient With 22q11.2 Deletion Syndrome Who Had Developmental and Epileptic Encephalopathy With Spike-and-Wave Activation During Sleep

We report a case of developmental and epileptic encephalopathy with spike-and-wave activation during sleep with 22q11.2 deletion syndrome in a patient who had undergone hemispherotomy and achieved developmental improvement. A four-year-old male child with paralysis on the left side of his body since birth had a mild developmental delay. An MRI of the brain revealed polymicrogyria diffusely throughout the right hemisphere. He was diagnosed with the 22q11.2 deletion syndrome at one year of age. Focal impaired awareness seizure in the right hemisphere origin and focal to bilateral tonic-clonic seizure appeared by two years of age. At three years of age, myoclonic seizures occurred, which induced frequent falls. Simultaneously, developmental and epileptic encephalopathy with spike-and-wave activation during sleep were observed. At four years and seven months of age, the patient underwent a right hemispherotomy. Epileptic seizures and spike-and-wave activation during sleep disappeared, and cognitive improvement was observed one year after surgery. In spite of chromosomal abnormalities being present, drug-resistant epilepsy with localized regions on MRI should be evaluated to determine surgical options to improve cognitive function and development.

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.

Long-term outcome of developmental and epileptic encephalopathies

Developmental and epileptic encephalopathies are conditions where there is developmental impairment related to both the underlying etiology independent of epileptiform activity and the epileptic encephalopathy. Usually they have multiple etiologies. Therefore, long-term outcome is related to both etiology-related factors and epilepsy-related factors-age at onset of epilepsy, type(s) of seizure(s), type of electroencephalographic abnormalities, duration of the epileptic disorder. This paper focuses on long-term outcome of six developmental and epileptic encephalopathies with onset from the neonatal period to childhood: early epileptic encephalopathy with suppression bursts, West syndrome, Dravet syndrome, Lennox-Gastaut syndrome, epilepsy with myoclonic atonic seizures and epileptic encephalopathy with continuous spike and waves during slow-wave sleep including Landau-Kleffner syndrome. For each syndrome, definition, main etiologies if multiple, and long-term outcome are discussed.

Epilepsy Surgery: Special Circumstances

Epilepsy surgery has proven to be very effective in treating refractory focal epilepsies in children, producing seizure freedom or partial seizure control well beyond any other medical or dietary therapies. While surgery is mostly utilized in certain clinical phenotypes, either based on the location such as temporal lobe epilepsy, or based on the presence of known epileptogenic lesions such as focal cortical dysplasia, tumors or hemimegalencephaly, there is a growing body of evidence to support the role of surgery in other patients' cohorts that were classically not thought of as surgical candidates. These include patients with rare genetic disorders, electrical status epilepticus in sleep, status epilepticus and the very young patients. Furthermore, epilepsy surgery is not considered as a "last resort" as seizure and cognitive outcomes of surgery are considerably better when done earlier rather than later in relation to the time of onset of epilepsy and age of surgery especially in the context of known focal cortical dysplasia. This article examines the accumulating evidence of the utility of epilepsy surgery in these special circumstances.

Successful Hemispherotomy in a Patient with Encephalopathy with Continuous Spikes and Waves during Sleep Related to Neonatal Thalamic Hemorrhage: A Case Report with Intracranial Electroencephalogram Findings

Neonatal thalamic hemorrhage is a strong risk factor for developing encephalopathy with continuous spikes and waves during sleep (ECSWS), even when not accompanied by widespread cortical destruction. The efficacy and indication of resective epilepsy surgery in such patients has not yet been reported. A 4-year-old boy was diagnosed with ECSWS based on strong epileptiform activation during sleep and neurocognitive deterioration. He had a history of left thalamic hemorrhage related to a straight sinus thrombosis during the newborn period. He presented with daily absence seizures that were refractory to medical treatment. At age 5, he underwent intracranial electroencephalogram (EEG) recording using depth and subdural strip electrodes placed in the left thalamus and over bilateral cortex, respectively. Interictal and ictal epileptiform discharges were observed in the thalamus, always preceded by discharges in the left or right parietal lobe. Left hemispherotomy successfully normalized the EEG of his unaffected hemisphere and extinguished his seizures. This is the first case report documenting resective epilepsy surgery in a patient with ECSWS due to neonatal thalamic injury without widespread cerebral destruction. Based on intracranial EEG findings, his injured thalamus did not directly generate the EEG abnormalities or absence seizures on its own. Patients with ipsilateral neonatal thalamic injury and even mild lateralized cortical changes may be candidates for resective or disconnective surgery for ECSWS.

Corpus callosotomy in pediatric patients with non-lesional epileptic encephalopathy with electrical status epilepticus during sleep

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Corpus callosotomy (CC) was performed in 3 pediatric patients with refractory epileptic encephalopathy with ESES.

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IQ was improved after CC with complete resolution of ESES in one patient.

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Developmental regression ceased after CC with worthwhile seizure reduction and temporary improvement of ESES in 2 patients.

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Epileptiform discharges disappeared or became lateralized after CC.

Epileptic encephalopathy with electrical status epilepticus during sleep (ESES) is often refractory to medical treatment and leads to poor cognitive outcomes. Corpus callosotomy may be an effective treatment option for drug-resistant ESES with no focal etiology. We retrospectively identified three patients who underwent corpus callosotomy for drug-resistant ESES in our institution. Electroencephalography (EEG) findings and cognitive functions were evaluated before surgery, at 3 months, 6 months, 1 year, and 2 years after surgery. Age at surgery was 6 years 10 months, 7 years 9 months, and 8 years 4 months, respectively. Period between the diagnosis of ESES and surgery ranged from 7 to 25 months. All patients had no obvious structural abnormalities and presented with cognitive decline despite multiple antiseizure medications and steroid therapies. One patient showed complete resolution of ESES and an improvement of intelligence quotient after surgery. Epileptiform EEG was lateralized to one hemisphere after surgery and spike wave index (SWI) was decreased with moderate improvement in development and seizures in the other 2 patients. SWI re-exacerbated from 6 months after surgery, but without subsequent developmental regression in these 2 patients. Corpus callosotomy may become an important treatment option for drug-resistant ESES in patients with no structural abnormalities.

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.

Four-dimensional tractography animates propagations of neural activation via distinct interhemispheric pathways

OBJECTIVE

To visualize and validate the dynamics of interhemispheric neural propagations induced by single-pulse electrical stimulation (SPES).

METHODS

This methodological study included three patients with drug-resistant focal epilepsy who underwent measurement of cortico-cortical spectral responses (CCSRs) during bilateral stereo-electroencephalography recording. We delivered SPES to 83 electrode pairs and analyzed CCSRs recorded at 268 nonepileptic electrode sites. Diffusion-weighted imaging (DWI) tractography localized the interhemispheric white matter pathways as streamlines directly connecting two electrode sites. We localized and visualized the putative SPES-related fiber activation, at each 1-ms time window, based on the propagation velocity defined as the DWI-based streamline length divided by the early CCSR peak latency.

RESULTS

The resulting movie, herein referred to as four-dimensional tractography, delineated the spatiotemporal dynamics of fiber activation via the corpus callosum and anterior commissure. Longer streamline length was associated with delayed peak latency and smaller amplitude of CCSRs. The cortical regions adjacent to each fiber activation site indeed exhibited CCSRs at the same time window.

CONCLUSIONS

Our four-dimensional tractography successfully animated neural propagations via distinct interhemispheric pathways.

SIGNIFICANCE

Our novel animation method has the potential to help investigators in addressing the mechanistic significance of the interhemispheric network dynamics supporting physiological function.

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.

Treatment strategies for encephalopathy related to status epilepticus during slow sleep, a narrative review of the literature

Encephalopathy related to Status Epilepticus during slow Sleep (ESES) is an age-dependent syndrome characterized by the appearance of neuropsychological and behavioral disorders associated with extreme activation of epileptic activity during sleep. The major goal of therapy in ESES is to prevent neuropsychological deficits. Effective therapy to reduce seizures and resolve the EEG pattern of status epilepticus during sleep (SES) may be crucial to improve long-term prognosis. However, whether to improve neurodevelopmental deficits by suppressing or eliminating SES remains unknown. The purpose of this article is to review current therapeutic options in ESES, in order to provide better alternatives. Treatment options consist of antiepileptic drugs, steroids, immunoglobulins, the ketogenic diet, and surgery. Maybe therapy targeted mechanisms can be developed with deep insight into the etiology of ESES.

Changes in Physiological and Pathological Behaviours Produced by Deep Microelectrode Implantation Surgery in Rats: A Temporal Analysis

Physiological behaviours such as the sleep-wake cycle and exploratory behaviours are important parameters in intact and sham-operated animals and are usually thought to be unaffected by experimental protocols in which neurosurgery is performed. However, there is insufficient evidence in the literature on the behavioural and cognitive effects observed after deep microelectrode implantation surgery in animal models of neurological diseases. Similarly, in studies that utilize animal models of neurological diseases, the impact of surgery on the pathological phenomena being studied is often minimized. Based on these considerations, we performed a temporal analysis of the effects of deep microelectrode implantation surgery in the hippocampus of rats on quiet wakefulness, sleep, and exploratory activity and the pathological behaviours such as convulsive seizures according to the Racine scale. Male Wistar rats (210-300 g) were used and grouped in sham and epileptic animals. Single doses of pilocarpine hydrochloride (2.4 mg/2 μl; i.c.v.) were administered to the animals to generate spontaneous and recurrent seizures. Deep microelectrode implantation surgeries in both groups and analysis of Fast ripples were performed. Physiological and pathological behaviours were recorded through direct video monitoring of animals (24/7). Our principal findings showed that in epileptic animals, one of the main behaviours affected by surgery is sleep; as a consequence of this behavioural change, a decrease in exploratory activity was also found as well as the mean time spent daily in seizures of scale 4 and the number of seizure events of scales 4 and 5 was increased after surgery. No significant correlations between the occurrence of FR and seizure events of scale 4 (rho 0.63, p value 0.25) or 5 (rho -0.7, p value 0.18) were observed. In conclusion, microelectrode implantation surgeries modified some physiological and pathological behaviours; therefore, it is important to consider this fact when it is working with animal models.

Examining the Utility of Resective Epilepsy Surgery in Children With Electrical Status Epilepticus in Sleep: Long Term Clinical and Electrophysiological Outcomes

Background: Electrical Status Epilepticus in Sleep (ESES) is an epileptic encephalopathy syndrome characterized by infrequent clinical seizures and prominent interictal burden during slow wave sleep associated with cognitive deficits and behavioral dysfunction. Medical treatment with anti-epileptic drugs is often unsuccessful. Resective surgery may be a valuable option in carefully selected patients. This case series aims to describe the indications, long term results and utility of resective surgery for ESES.

Methods: Information on 14 patients who underwent surgery for epilepsy and ESES at the Children's Hospital of Wisconsin between 2007 and 2017 is included. Clinical, electrographic and neuropsychological features and outcomes are described in detail.

Results: The most common pathology was encephalomalacia due to perinatal middle cerebral artery stoke (5/14). Twelve patients had imaging findings of perinatal pathologies; however, two patients had normal magnetic resonance imaging. Surgery was performed to control refractory epilepsy in eight patients. Six patients had no clinical seizures for 1–6 years prior to surgery, one of which had no known clinical seizures at all. All showed cognitive declines (6/14) or impairment (8/14) on neuropsychological assessments, and surgery was suggested to minimize further cognitive declines. The most common surgical procedure was hemispherotomy (10/14). Temporo-parieto-occipital disconnection, frontal lobectomy, parieto-occipital resection, and limited corticectomy were also used, with good outcomes for the first three procedures. Clinical follow up mean was 4.4 years and 12 patients had excellent seizure outcome. Electroencephalography (EEG) follow up mean was 3 years and ESES resolved in 12/14 patients. All patients completed post-surgical neuropsychological evaluation with mean follow-up of 17.46 months.

Conclusions: Resective surgery is an effective treatment for selected cases of ESES, producing long term seizure freedom, resolution of ESES and stabilization of cognitive and behavioral functioning in most patients. Our case series is the largest single center cohort description addressing resective surgery for ESES. Outcomes in this sample suggest that good long-term seizure, EEG and cognitive/behavioral outcomes can be achieved in patients with normal brain imaging and in limited lobar or multi-lobar resections. Moreover, patients with ESES and very infrequent clinical seizures can benefit from surgery with stabilization of cognitive and behavioral functioning.

Clinical features and surgical treatment of epilepsy after viral encephalitis

Encephalitis is an acute inflammatory process of the brain parenchyma, which is often caused by viral infection. It is an vital cause of acute symptomatic seizures and subsequent epilepsy. The incidence of unprovoked and recurrent seizures after previous infections of the central nervous system is high and accounts for 1%~5% of the cases of epilepsy. Viral encephalitis (VE) is directly caused by viral infection. The occurrence of seizures after VE is associated with poor prognosis. In survivors of VE, among other neurological sequelae, the risk of developing epilepsy is increased 10-fold. The risk of severe neurological sequelae after VE is particularly high in very young children. Studies on seizure occurrence, possible underlying mechanisms, clinical characteristics, and clinical treatment (especially surgical treatment) of VE have yielded only limited detailed data. We reviewed the most recent literature on the clinical features and surgical treatment of post-VE epilepsy.

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.

Response to clobazam in continuous spike-wave during sleep

AIM

To evaluate the efficacy of clobazam treatment in reducing epileptiform discharges and modifying neuropsychological function in continuous spike-wave during slow wave sleep.

METHOD

We performed a prospective clinical trial in patients with continuous spike-wave during sleep aged 4 to 10 years. Patients underwent neuropsychological assessment and overnight electroencephalographic monitoring before treatment, and subsequent repeat assessment and overnight electroencephalographic monitoring 3 months after treatment. Treatment consisted of 1mg/kg clobazam up to a maximum dose of 30mg during the first night, followed by 0.5mg/kg nightly for 3 months.

RESULTS

Nine patients completed the study and had pre- and post-neuropsychological evaluation. There was a qualitative reduction in median (p₂₅ -p₇₅ ) spike percentage after 3 months (72.2 [68.0-75.8] vs 32.7 [4.7-81.7]). There were no marked changes in median (p₂₅ -p₇₅ ) IQ comparing pre- and post-clobazam treatment (80.0 [74.0-88.0] vs 80.0 [67.0-89.0]). There was a qualitative increase in Verbal IQ (83.0 [69.0-92.0] vs 95.0 [83.0-99.0]) and a qualitative decrease in Non-verbal IQ (84.0 [74.0-87.0] vs 71.0 [60.0-84.0]).

INTERPRETATION

Qualitative improvements in epileptiform activity and cognition occurred in patients treated with clobazam for 3 months and the relationship between epileptiform activity and cognitive outcome should be studied in larger studies.

WHAT THIS PAPER ADDS

Verbal IQ in patients with continuous spike-wave during sleep improved following short-term treatment with clobazam. Other neuropsychological improvements were observed, but varied by patient. Cognitive improvement was observed despite some worsening of epileptiform discharges.

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.

Genetic basis of pediatric epilepsy syndromes

Childhood epilepsy affects ~0.5-1% in the general population worldwide. Early-onset epileptic encephalopathies are considered to be severe neurological disorders, which lead to impaired motor, cognitive, and sensory development due to recurrence of seizures. Many of the observed epilepsy phenotypes are associated with specific chromosomal imbalances and thus display gene dosage effects, and also specific mutations of a variety of genes ranging from ion channels to transcription factors. High throughput sequencing technologies and whole exome sequencing have led to the recognition of several new candidate genes with a possible role in the pathogenesis of epileptic encephalopathies. The mutations causing channelopathies can be either a gain or a loss of ion channel function and contribute to the pathogenesis of epilepsy syndrome. Nearly 300 mutations of SCN1A gene coding for the Nav1.1 channel protein have been identified that contribute to the pathology of epilepsy. Besides Na, potassium and calcium channels are also implicated in epileptic encephalopathies. Therapeutic management of epileptic encephalopathies has been challenging as the majority of the medications are not efficient and often have many undesirable side effects. A better understanding of the molecular nature of epilepsy in an individual is important to design a personalized medication, considering the number of possible genetic mutations that can contribute to epileptic encephalopathies.

Immediate termination of electrical status epilepticus in sleep after hemispherotomy is associated with significant progress in language development

AIM

To study the effect of hemispherotomy on electrical status epilepticus in sleep (ESES) and language development.

METHOD

Children with a confirmed diagnosis of ESES prior to surgery and a minimum of 24 months of developmental follow-up data were compared with age-matched controls without ESES. Language quotients (LQs) were calculated before and after surgery.

RESULTS

Eleven patients (five females, six males) and 21 controls (11 females, 10 males) were included. Before surgery a significantly higher number of children in the study group (n=9) demonstrated severe developmental delay compared with children in the control group (n=13; p=0.015). In the study group ESES remitted immediately after surgery in 10 children, and a significant catch-up in LQs was observed in this group (preoperative mean 40.0 [standard deviation (SD) 22.2, interquartile range (IQR) 30.0-62.0]; postoperative mean 73.0 [SD 33.5, IQR 41.0-97.0]; p=0.037). There was no significant difference compared with controls at last follow-up after surgery (study group: five with severe impairment; control group: eight with severe impairment [p=0.971]). Overall, a favourable developmental outcome was associated with freedom from seizures (seizure-free group: median preoperative LQ 61.5, median postoperative LQ 78.0 [p=0.017]; seizure group: median preoperative LQ 35.5, median postoperative LQ 56.5 [p=0.273]) and antiepileptic drug withdrawal (off medication: median preoperative LQ 49.5, median postoperative LQ 78.0 [p=0.011]; on medication: median preoperative LQ 78.0, median postoperative LQ 83.5 [p=0.889]).

INTERPRETATION

Children with ESES showed significantly lower preoperative language abilities than children without ESES. In cases with remission of ESES after surgery, marked improvement in LQs was noticed. This improvement cannot be fully explained by seizure-freedom alone as seizure-free children without preoperative ESES showed less improvement.

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.

Vagus Nerve Stimulation for Electrographic Status Epilepticus in Slow-Wave Sleep

BACKGROUND

Electrographic status epilepticus in slow sleep or continuous spike and waves during slow-wave sleep is an epileptic encephalopathy characterized by seizures, neurocognitive regression, and significant activation of epileptiform discharges during nonrapid eye movement sleep. There is no consensus on the diagnostic criteria and evidence-based optimal treatment algorithm for children with electrographic status epilepticus in slow sleep.

PATIENT DESCRIPTION

We describe a 12-year-old girl with drug-resistant electrographic status epilepticus in slow wave sleep that was successfully treated with vagus nerve stimulation. Her clinical presentation, presurgical evaluation, decision-making, and course after vagus nerve stimulator implantation are described in detail.

FINDINGS

After vagus nerve stimulator implantation, the girl remained seizure free for more than a year, resolved the electrographic status epilepticus in slow sleep pattern on electroencephalography, and exhibited significant cognitive improvement.

CONCLUSION

Vagus nerve stimulation may be considered for electrographic status epilepticus in slow sleep.

Current and Emerging Therapies of Severe Epileptic Encephalopathies

In this article, we review the treatment options for the pediatric epileptic encephalopathies and provide an update on the new and emerging therapies targeted at the underlying pathophysiology of many of these syndromes. We illustrate how the identification of the specific genetic and autoimmune causes has made possible the evaluation and development of novel, better targeted therapies, as and at times, avoidance of potentially offending agents.

Epileptic encephalopathies: Optimizing seizure control and developmental outcome

Cognitive and developmental outcomes in patients with epileptic encephalopathy are hypothesized to result from an interplay between the underlying epileptic pathologic substrate and the acquired consequences of frequent and repetitive seizures and epileptiform discharges that often straddle the interictal and ictal boundaries. This article briefly reviews the evidence related to this assumption, presents critical questions that need to be answered to clarify this relationship, and advances a set of concrete steps that may help improve developmental patient outcomes.

Should epileptiform discharges be treated?

To evaluate the impact of epileptiform discharges (EDs) that do not occur within seizure patterns--such as spikes, sharp waves or spike waves--on cognitive function and to discuss the circumstances under which treatment of EDs might be considered. Methods used in this article is "Review of the literature". EDs may disrupt short-term cognition in humans. Frequent EDs for a prolonged period can potentially impair long-term cognitive function in humans. However, there is conflicting evidence on the impact of EDs on long-term cognitive outcome because this relationship may be confounded by multiple factors such as underlying etiology, seizures, and medication effects. Limitations of existing studies include the lack of standardized ED quantification methods and of widely accepted automated spike quantification methods. Although there is no solid evidence for or against treatment of EDs, a non-evidence-based practical approach is suggested. EDs in otherwise asymptomatic individuals should not be treated because the risks of treatment probably outweigh its dubious benefits. A treatment trial for EDs may be considered when there is cognitive dysfunction or regression or neurologic symptoms that are unexplained by the underlying etiology, comorbid conditions, or seizure severity. In patients with cognitive or neurologic dysfunction with epilepsy or EDs, treatment may be warranted to control the underlying epileptic syndrome. EDs may cause cognitive or neurologic dysfunction in humans in the short term. There is conflicting evidence on the impact of EDs on long-term cognitive outcome. There is no evidence for or against treatment of asymptomatic ED.

Clinical management of epileptic encephalopathies of childhood and infancy

Epileptic encephalopathies represent a group of devastating epileptic disorders that appear early in life and are characterized by pharmacoresistant generalized or focal seizures, persistent severe EEG abnormalities, and cognitive dysfunction or decline. The ictal and interictal epileptic discharges are age-specific and are either the main cause or contribute to cognitive deterioration in the idiopathic or symptomatic group respectively. Despite choosing the most appropriate anti-seizure drugs for the seizure-type and syndrome the results are often disappointing and polytherapy and/or alternative therapy becomes unavoidable. In those cases, consideration should be given to the quality of life of the child and carers. In this review we will discuss the clinical and EEG characteristics, evolution and management of age-related epileptic encephalopathies, recognized by the International League Against Epilepsy.

Epileptic encephalopathies: new genes and new pathways

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

Efficacy of levetiracetam in electrical status epilepticus during sleep of children: a multicenter experience

BACKGROUND

Electrical status epilepticus during sleep is characterized by epilepsy, a specific electroencephalographic pattern, and neuropsychological impairment. This study aims to evaluate the efficacy and safety of levetiracetam in treating children with electrical status epilepticus during sleep.

METHODS

A multicenter, retrospective, open-label study enrolled 73 children (mean age: 8 years) affected by electrical status epilepticus during sleep. The efficacy was rated according to the seizure frequency and electroencephalography response.

RESULTS

After a mean treatment period of 19 months (range: 6 to 24 months), 33 (63.5%) of 52 patients became seizure-free or had experienced remarkable reduction in seizures. The electrical status epilepticus of 41 (56.2%) of 73 patients disappeared off their electroencephalography. The electroencephalography efficacy of levetiracetam treatment was noted in the monotherapy (61.9%) and add-on (53.9%) groups. The clinical (67.7%) and electroencephalography (64.3%) response rates of the idiopathic group were better than those of the symptomatic group (57.1% and 45.2%, respectively). No patient discontinued the trial because of intolerability of side effects.

CONCLUSIONS

Levetiracetam is effective in individuals with electrical status epilepticus during sleep with tolerable side effects.

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.

Surgical treatment of pediatric epileptic encephalopathies

Pediatric epileptiform encephalopathies are a group of neurologically devastating disorders related to uncontrolled ictal and interictal epileptic activity, with a poor prognosis. Despite the number of pharmacological options for treatment of epilepsy, many of these patients are drug resistant. For these patients with uncontrolled epilepsy, motor and/or neuropsychological deterioration is common. To prevent these secondary consequences, surgery is often considered as either a curative or a palliative option. Magnetic resonance imaging to look for epileptic lesions that may be surgically treated is an essential part of the workup for these patients. Many surgical procedures for the treatment of epileptiform encephalopathies have been reported in the literature. In this paper the evidence for these procedures for the treatment of pediatric epileptiform encephalopathies is reviewed.

Long-term response to high-dose diazepam treatment in continuous spikes and waves during sleep

BACKGROUND

This study evaluated whether the reduction in epileptiform activity after treatment with high-dose diazepam in continuous spikes and waves during sleep persists over time.

PATIENTS

Patients aged 1 to 21 years with continuous spikes and waves during sleep who received high-dose nocturnal diazepam and who had electroencephalogram follow-up were included. Twenty-nine patients met the inclusion criteria and underwent a total of 48 high-dose diazepam treatment cycles.

RESULTS

An overnight reduction of the spike wave percentage of at least 25% (i.e., 75-50%) occurred in 29 cycles (20 patients), and persisted within 6 months in 16 of 29 cycles (12 patients), but returned to baseline in three of 29 cycles (three patients). An overnight reduction of at least 50% (i.e., 75-25%) occurred in 15 cycles (13 patients), and persisted within 6 months in eight of 15 cycles (eight patients), but returned to baseline in three cycles (three patients). Twenty of 29 cycles that responded in the short term had persistent response on follow-up. Thirteen cycles of treatment were associated with mild side effects that did not recur with repeated treatment cycles.

CONCLUSIONS

Treatment with high-dose diazepam reduced epileptiform activity in continuous spikes and waves during sleep in the short term, and improvement persisted for several months in most cycles. Short-term response predicted persistence of this effect on subsequent follow-up.

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

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

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

PURPOSE

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

METHODS

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

KEY FINDINGS

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

SIGNIFICANCE

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

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

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

Treatment of epileptic encephalopathies

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

Seizure and developmental outcomes after hemispherectomy in children and adolescents with intractable epilepsy

PURPOSE

The aim of this study is to describe a series of pediatric hemispherectomies, reviewing pathologic substrate, epilepsy characteristics and seizure outcome as well as developmental profiles, before and after surgery, in different domains.

METHODS

Seventeen patients with full pre-surgical work-up, minimum follow-up of 12 months, and at least one post-surgical neuropsychological evaluation were selected. Three had Rasmussen encephalitis (RE), five hemispheric malformations of cortical development (MCD), and nine hemispheric vascular lesions.

RESULTS

At latest follow-up, all patients with RE and 66.7 % of those with vascular lesions are in Engel's class I; in the latter group, pre-surgical independent contralateral EEG discharges statistically correlated with a worse seizure outcome. Patients with MCD showed the worst seizure outcome. Pre-surgical language transfer to the right hemisphere was confirmed in a boy with left RE, operated on at 6 years of age. Patients with MCD and vascular lesions already showed severe global developmental delay before surgery, which persists afterwards. A linear correlation was found between earlier age at surgery and better outcome in personal-social, gross motor, and adaptive domains, in the vascular lesions group. The case with highest cognitive improvement had continuous spike and wave during sleep on pre-surgical EEG.

CONCLUSIONS

Pathologic substrate was the main factor related with seizure outcome. In children with MCD and vascular lesions, although developmental progression is apparent, significant post-surgical improvements are restricted by the severity of pre-surgical neuropsychological disturbances and a slow maturation. Early surgery assessment is recommended to enhance the possibilities for a better quality of life in terms of seizure control, as well as better autonomy and socialization.

Electrical status epilepticus in sleep: clinical presentation and pathophysiology

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