Cognition and Paroxysmal EEG Activities: From a Single Spike to Electrical Status Epilepticus during Sleep

Summary:  Epileptic EEG paroxysms can interfere with cognitive processes producing transitory effects, such as those related to a single spike, as well as long-lasting effects, such as in electrical status epilepticus during slow-wave sleep (ESES). Focal spike-related disruption of cortical functions can produce transitory cognitive impairment, with neuroanatomical specificity between the site of the epileptic focus and the impaired cognitive tasks. ESES represents a model of the long-lasting effects of continuous spike-wave activity on higher cortical functions. The duration of ESES and the localization of interictal foci seem to play a major role in influencing the degree and type of cognitive dysfunction, suggesting that the ESES clinical picture results from a localized disruption of EEG activity caused by focal epileptic activity during sleep. Recently, Giulio Tononi's group reported that a local increase of slow-wave activity (SWA) during sleep after learning is associated with improved performance of the learned task after sleep (Huber et al., Nature 2004;430:78–81). On the basis of these findings, we can speculate that prolonged focal epileptic activity during sleep (as occurring in ESES) interferes with local SWA at the site of the epileptic focus, impairing the neural processes and, possibly, the local plastic changes associated with learning and other cognitive functions.     

Encephalopathy with status epilepticus during slow sleep: "The Penelope syndrome"

ESES (encephalopathy with status epilepticus during sleep) is an epileptic encephalopathy with heterogeneous clinical manifestations (cognitive, motor, and behavioral disturbances in different associations, and various seizure types) related to a peculiar electroencephalography (EEG) pattern characterized by paroxysmal activity significantly activated during slow sleep—that is, a condition of continuous spikes and waves, or status epilepticus, during sleep. The pathophysiologic mechanisms underlying this condition are still incompletely understood; recent data suggest that the abnormal epileptic EEG activity occurring during sleep might cause the typical clinical symptoms by interfering with sleep-related physiologic functions, and possibly neuroplasticity processes mediating higher cortical functions such as learning and memory consolidation. As in the myth of Penelope, the wife of Odysseus, what is weaved during the day will be unraveled during the night.     

Nonconvulsive status epilepticus with continuous diffuse spike-and-wave discharges during sleep in childhood

On three epileptic conditions with common characteristics of almost continuous diffuse spike-and-wave discharges during sleep in EEG, clinical and electroencephalographic studies were undertaken to elucidate their pathophysiologies and interrelationships; namely on five cases of epilepsy with electrical status epilepticus during slow sleep (ESES), seven cases of a peculiar type of nonconvulsive status epilepticus in childhood (PNSE) and three cases of atypical benign partial epilepsy (ABPE). The dominant seizure types were absences and/or GTC in ESES, whereas they were focal motor seizures in PNSE and ABPE with more focalized epileptic discharges on EEGs than those in ESES. All the three conditions showed both features of generalized and partial epilepsies, although the former features were more prominent in ESES and the latter in PNSE and ABPE.     

Functional brain connectivity in electrical status epilepticus in sleep

Aims. Electrical status epilepticus in sleep (ESES) is an age‐related, self‐limited epileptic encephalopathy. The syndrome is characterized by cognitive and behavioral abnormalities and a specific EEG pattern of continuous spikes and waves during slow‐wave sleep. While spikes and sharp waves are known to result in transient cognitive impairment during learning and memory tasks performed during the waking state, the effect of epileptiform discharges during sleep on cognition and behavior is unclear. There is increasing evidence that abnormalities of coherence, a measure of the consistency of the phase difference between two EEG signals when compared over time, is an important feature of brain oscillations and plays a role in cognition and behavior. The objective of this study was to determine whether coherence of EEG activity is altered during slow‐wave sleep in children with ESES when compared to typically developing children. Methods. We examined coherence during epochs of ESES versus epochs when ESES was not present. In addition, we compared coherence during slow‐wave sleep between typically developing children and children with ESES. Results. ESES was associated with remarkably high coherences at all bandwidths and most electrode pairs. While the high coherence was largely attributed to the spikes and spike‐and‐wave discharge, activity between spikes and spike‐and‐wave discharge also demonstrated high coherence. Conclusions. This study indicates that EEG coherence during ESES is relatively high. Whether these increases in coherence correlate with the cognitive and behavioral abnormalities seen in children with this EEG pattern remains to be determined.     

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.     

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

The goal of this report is to review the relationships between Landau-Kleffner syndrome (LKS), electrical status epilepticus during sleep (ESES), and continuous spike-waves during sleep (CSWS). LKS is a clinical syndrome involving mainly acquired aphasia and sometimes seizures. Other clinical findings include cognitive impairments and global regression of behavior. The EEG may evolve from more benign conditions into ESES (or CSWS), seen in 50% of patients with LKS, or may also show focal findings. Seizures include atypical absence, generalized tonic-clonic, atonic, and partial motor attacks. Effective medications are discussed. The EEG patterns CSWS and ESES are likely equivalent terms. CSWS is used by some authors, and ESES by others. Patients with these patterns usually show mental retardation, seizures, and global regression. More benign EEG patterns, like focal discharges, may develop into these more severe generalized patterns, which are associated with atypical absences, negative myoclonus, and cognitive disturbances. Memory disorders are common, because the nearly continuous generalized discharges in sleep do not allow for the memory consolidation that also occurs during sleep. Medications and possible etiologies are discussed.     

Electrical status epilepticus in sleep

Electrical status epilepticus in sleep (ESES) describes an electroencephalographic pattern showing significant activation of epileptiform discharges in sleep. The terms continuous spike wave in slow-wave sleep (CSWS) and Landau-Kleffner syndrome (LKS) describe the clinical epileptic syndromes seen with ESES. Although there is an overlap between these 2 syndromes, children with CSWS present with a more global regression have more problematic epilepsy and have EEG foci located predominantly in frontotemporal or frontocentral regions. In contrast, children with LKS present with an acquired auditory agnosia, fewer seizures, and EEG foci in the posterotemporal regions. ESES requires a high degree of clinical suspicion because slow-wave sleep must be recorded to confirm this diagnosis. Treatment of ESES extends beyond just control of the seizures; amelioration of the continuous epileptiform discharge must occur to improve neuropsychological outcome. Although there is little evidence to guide treatment, conventional antiepileptic drugs play only a minimal role. Steroid therapy and high-dose benzodiazepines are most commonly used, but other therapies including intravenous gamma-globulin, the ketogenic diet, and surgical therapy with multiple subpial transaction have shown efficacy in small case series. Although epilepsy resolves with time in most cases, many children are left with significant cognitive or language impairment. Longer duration of ESES appears to be the major predictor of poor outcome; markedly abnormal neuronal activity during a critical period for synaptogenesis may result in aberrant synapse formation, explaining the poorer neuropsychological outcome. Early recognition and effective therapy are necessary to improve long-term prognosis in this condition.     

Interictal epileptiform discharges in sleep and the role of the thalamus in Encephalopathy related to Status Epilepticus during slow Sleep

EEG activation of interictal epileptiform discharges (IEDs) during NREM sleep is a well‐described phenomenon that occurs in the majority of epileptic syndromes. In drug‐resistant focal epilepsy, IED activation seems to be related to slow wave activity (SWA), especially during arousal fluctuations, namely phase A of the cyclic alternating pattern (CAP). Conversely, in childhood focal epileptic syndromes, including Encephalopathy related to Status Epilepticus during slow Sleep (ESES), IED activation seems primarily modulated by sleep‐inducing and maintaining mechanisms as reflected by the dynamics of spindle frequency activity (SFA) rather than SWA. In this article, we will review the effect of sleep on IEDs with a particular attention on the activation and modulation of IEDs in ESES. Finally, we will discuss the role of the thalamus and cortico‐thalamic circuitry in this syndrome.     

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

Aim: 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. Methods: Clinical charts and EEG data were reviewed. Results: 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. Conclusion: 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.     

Electrical status epilepticus during slow sleep: one case with sensory aphasia

Electrical status epilepticus during slow sleep (ESES) is characterized by an EEG picture that justifies its name. It can be accompanied by epileptic seizures, speech and behavior disturbances and in rare cases by an acquired sensory aphasia. We describe the case of a six-year-old girl, whose EEG presented the typical ESES picture, and who in the span of one year developed a complete sensory aphasia, followed by motor aphasia. After 6 months of treatment with clobazam recovery of speech was nearly complete, but after 8 months clobazam lost its effectiveness and the girl presented a speech regression. Treatment with nitrazepam led to a complete recovery of speech for a second time, while at the same time ESES in the EEG again disappeared. This case, in addition to others described in the literature, suggests the possibility of a direct correlation between electrical abnormalities of the brain and cognitive and speech disturbances.     

Sulthiame add-on therapy in children with focal epilepsies associated with encephalopathy related to electrical status epilepticus during slow sleep (ESES)

Purpose: In children with symptomatic or idiopathic focal epilepsies, their disease may evolve into an epileptic encephalopathy related to continuous spike and wave during slow sleep (CSWS) or electrical status epilepticus during slow sleep (ESES). ESES syndrome implies serious risks of neuropsychologic impairment, and its treatment has frequently been disappointing. The aim of this study is to present our experience using sulthiame as add‐on treatment in 53 patients with ESES syndrome that was refractory to other antiepileptic drugs (AEDs). Methods: Neurologic examinations, cerebral magnetic resonance imaging (MRI), and repeated prolonged sleep electroencephalography (EEG) studies were performed in all cases. Data about school achievements and or neuropsychological evaluations were obtained repeatedly during the follow‐up of 1.5–16 years. Sulthiame was added in doses ranging between 5 and 30 mg/kg/day. Key Findings: Since add‐on of sulthiame, 10 of 28 patients in the symptomatic group became seizure free: 4 patients with normal EEG studies and 6 with residual spikes. Nine of 28 patients showed a significant reduction in number of seizures and presented spikes but no ESES on EEG. The other nine cases showed neither clinical nor EEG improvement. A striking result was that 3 of 11 children with unilateral polymicrogyria and ESES syndrome became seizure free, and in another six a significant improvement in frequency of seizures and in EEG abnormalities seemed to be related to the add‐on of sulthiame. Twenty‐one of the 25 patients in the idiopathic group became seizure free and without ESES in <3 months after add on of sulthiame. In two of the patients the changes were seen in a few days. Significance: We understand that sulthiame may be effective as add‐on treatment in children with ESES syndrome.     

A clinical and EEG study on idiopathic partial epilepsies with evolution into ESES spectrum disorders

PURPOSE: Questioning the presence of any possible prognostic predictors, this study includes a long-term follow-up of clinical and EEG characteristics of 16 patients with idiopathic partial epilepsy (IPE) who subsequently developed epilepsy with electrical status epilepticus during slow sleep (ESES) spectrum disorders. METHODS: Epilepsy, cognitive and behavioral parameters, and waking and non-rapid eye movement (NREM) EEG data were evaluated and scored for initial stage (i.e., IPE stage), preESES, ESES, and ESES remission periods, individually, on a chronologic basis. Data from 25 healthy subjects who had had IPE at the appropriate ages served for comparison with the patients' data during the IPE stage. RESULTS: Results revealed a higher incidence in seizure frequency and variability in the ESES group and a resistance to a single antiepileptic drug (AED), as compared with controls, during the IPE stage. Mean age at onset of epilepsy was younger in the ESES group versus controls (5.5 and 7.3 years, respectively). At least one of the premonitory clinical features for development of ESES [an increase in the seizure frequency and/or addition of new types of seizures (93%), appearance of cognitive and/or behavioural changes (81.2%), or a progression in EEG abnormalities (66%)] was present in all patients. Epilepsy remitted in patients within the ESES spectrum at a similar age as in controls in 81.2%, as ESES findings in the EEG disappeared by age 13 years in 94%. Seizure prognosis proved to be the most favorable among the questioned parameters. CONCLUSIONS: An increase in seizure frequency or development of new seizure types, a deviance in behavior or decrease in cognitive performance, or a spreading tendency of the previously focal abnormalities in control EEGs may be premonitory features of a developing ESES and necessitate close follow-ups with sleep EEGs in children with IPEs.     

Seizures in fetal alcohol spectrum disorders: Evaluation of clinical,electroencephalographic, and neuroradiologic features in a pediatric case series

Seizures are observed with a frequency of 3–21% in children with fetal alcohol spectrum disorders (FASD). However, clinical, neuroradiologic, and electroencephalography (EEG) features are poorly described. In this study, 13 patients with FASD and epilepsy or seizures were identified retrospectively from the databases of seven Italian pediatric neurology divisions. Eleven children were affected by epilepsy, and two had at least one documented seizure. Both generalized and focal seizures were observed. EEG showed diffuse or focal epileptic activity; two children developed electric status epilepticus during sleep (ESES). Structural brain anomalies, including polymicrogyria, nodular heterotopia, atrophy, and Arnold‐Chiari type 1 malformation, were discovered in almost 50% of patients. Control of seizures was not difficult to obtain in 11 cases; one patient showed pharmacoresistant epilepsy. EEG and clinical follow‐up are recommended in children with FASD and epilepsy, since severe conditions requiring aggressive treatment, such as in ESES, may develop. Neuroradiological evaluation is warranted because several types of brain anomalies could be associated with maternal alcohol consumption during pregnancy. A PowerPoint slide summarizing this article is available for download in the Supporting Information section here .     

抗癫癎药物对儿童临床下癎性电持续状态及认知功能的影响

目的：探讨抗癫?药物（AED）对临床发作已控制,但脑电图（EEG）上仍存在癫?性电持续状态ESES患者的认知功能的影响。方法：收集2013年3月～2015年11月本院门诊、住院治疗的儿童癫?患者,用日本光电9000型长程录像脑电图（V‐EEG）监测到的16例临床下ESES患者,临床无发作均超过半年,随访观察,调整治疗方案前后均再进行神经心理学评估和V‐EEG监测。结果：16例应用卡马西平（CBZ）、奥卡西平（OXC）临床发作均已得到控制,V‐EEG提示仍存在ESES现象,神经心理学评估均存在不同程度的认知功能障碍,治疗方案调整为丙戊酸钠／丙戊酸镁、左乙拉西坦／托吡酯,3个月后复查V‐EEG提示ESES消失,脑功能状态得到改善（P＜0．05）。结论：AED的治疗目的,不仅要控制临床发作,也要控制临床下?样放电,特别是ESES现象。     

Spatial and temporal dynamics of epileptic activity at sleep onset in the Encephalopathy with Status Epilepticus during slow sleep (ESES) after unilateral thalamic lesions

ObjectiveEncephalopathy with Status Epilepticus during slow Sleep (ESES) is a syndrome where neurocognitive impairment correlates with multifocal Electroencephalography (EEG) spikes increasing abruptly at sleep onset. Demonstration of a focal onset could provide important clues to unravel the mechanisms underlying the condition, but until know it has not been established.MethodsWe studied epileptic dynamics at sleep onset to assess its focal or diffuse features in five patients with perinatal thalamic hemorrhages lateralized to one hemisphere, using high resolution EEG.ResultsDynamical functional connectivity revealed the information flow in the epileptic network and identified primary sources of outflow, equated with cortical spike sources. We found that spikes with important activation originate in restricted cortical areas of the hemisphere with the lesion, spreading widely and quickly at onset of N2 sleep stage.ConclusionsPerinatal thalamic lesions have the potential to induce, years later, a regional onset of epileptic activity with features of ESES in a cortex without apparent structural lesion. Most widespread spike activity in the scalp results from secondary propagation.SignificancePerinatal thalamic lesions produce ESES with focal onset in a restricted cortical area of the hemisphere with the lesion, and prominent secondary propagation.     

Cognitive impairment and behavioral disorders in Encephalopathy related to Status Epilepticus during slow Sleep: diagnostic assessment and outcome

Encephalopathy related to Status Epilepticus during slow Sleep (ESES) is an age‐dependent phenomenon, with usual spontaneous resolution during teenage years. However, cognitive outcome is often more disappointing, with permanent cognitive deficits in the large majority of children seen in later life. Presuming this to be an epileptic encephalopathy, current treatment practices are almost exclusively guided by the effect of the AEDs used on the degree of EEG abnormality in sleep. However, the major goal of therapy in ESES syndrome should in fact be to prevent or reduce associated cognitive and neurodevelopmental deficits. Whether or not the EEG pattern of ESES should be completely suppressed to improve cognition is unknown. Discussions on both diagnostic assessment and outcome of cognitive impairment and behavioral disorders should systematically take into account the complexity of the disorder; not only in terms of the evolution or fluctuations of the EEG patterns but also in relation to the underlying etiologies (at least lesional versus non‐lesional) and age at diagnosis. We present a common basic assessment protocol, including the minimum technical requirements for polygraphic recording, and a treatment practice protocol that could both be applied in all centres dealing with this rare form of epilepsy. Such an approach would also allow a comprehensive collection of data prospectively, for a better understanding of the natural evolution of the disorder and an evidence‐based evaluation of our practices.     

伴有睡眠中电持续状态癫痫患儿的临床表现及脑电图特点

目的探讨伴有睡眠中癫痫性电持续状态(ESES)的不同癫痫综合征患儿的临床表现及脑电图特点。方法通过长程脑电图监测,对9例合并ESES的癫痫患儿进行神经心理测试、临床资料及脑电图资料的回顾性分析。结果 9例合并ESES的癫痫患儿中,伴中央颞区棘波的儿童良性癫痫5例,韦氏儿童智力量表测定示,无言语及精神发育倒退,药物治疗效果较好;不典型儿童良性部分性癫痫2例,韦氏量表示,认知功能轻中度受损,药物治疗效果欠佳;Lennox-Gastaut综合征2例,均有多种形式的癫痫发作,精神运动发育落后,未能配合韦氏测定,多种抗癫痫药物联合应用无效。结论 ESES不是一个独立的癫痫综合征,而是包括了一系列不同病因、不同临床表现及不同预后的多种癫痫综合征。ESES,是引起神经心理损伤的主要原因,早期识别这种特殊的脑电图现象,早期干预,是改善神经心理损伤的关键。     

Cognitive deterioration and electrical status epilepticus during slow sleep

The results of long-term follow-up of 10 children with global or specific cognitive deterioration and, on the electroencephalogram, electrical status epilepticus during sleep (ESES) are described. They were referred because of cognitive deterioration and underwent repeated neurological and neuropsychological examinations and all-night electroencephalography. A previous cognitive level was known or could be estimated in all. Seven children had a continuous spikes and waves during sleep (CSWS) syndrome, with global cognitive deterioration in four and more specific cognitive decline in three, and another three children had Landau-Kleffner syndrome (LKS). Of the last three, two children never had seizures, while the other had localization-related epilepsy. No children experienced aggravation of clinical seizures. However, therapy was disappointing. Cognitive dysfunction did not respond to valproate and/or benzodiazepines in 9 of the 10 children. A frontal epileptic focus was found in 5 of 7 children with CSWS, and a left temporal focus in 2 of 3 children with LKS. The ESES persisted in CSWS for 5-9 years and in LKS for 1-5 years, and disappeared at puberty. Good cognitive recovery after disappearance of ESES occurred in only one child, and partial recovery in four. An unfavorable prognosis of cognitive deterioration seems to be related to long-duration ESES and/or early onset epileptic activity. The authors are of the opinion that cognitive deterioration in children, with or without manifest epileptic seizures, should mandate electroencephalographic investigation during sleep.     

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.