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.     

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.     

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.     

Continuous spikes and waves during slow sleep in a child with karyotype 47, XYY

The XYY syndrome is a sex chromosome aneuploidy occurring in one of 1,000 live male births. Only few data exist regarding the correlation between this syndrome and epilepsy. An EEG pattern suggestive of benign focal epilepsy with centro‐temporal spikes has recently been described in four XYY patients. We report the first patient with XYY trisomy, rolandic spikes, and atypical evolution with continuous spikes and waves during slow sleep (CSWSS). The present report suggests that the association between an EEG pattern similar to that of BECTS and 47, XYY karyotype may not be coincidental. Moreover, we show that an atypical evolution with CSWSS may occur in this chromosomal disorder.     

Clinical characteristics of 10 patients with continuous spikes and waves during slow sleep syndrome

Continuous spikes and waves during slow sleep syndrome is characterized by the presence of spike-and-wave discharges in at least 85% of non-rapid eye movement sleep. Associated clinical features vary. Here, features of 10 patients with this syndrome are compared to those in the literature. Patients ranged in age from 4 to 11 years. All patients had predominantly nocturnal partial motor or generalized tonic-clonic seizures; four patients also had daily atonic seizures. All 10 patients had different degrees of neuropsychologic disturbances: 9 patients had low intelligence quotient scores (the 10th, diagnosed attention deficit and hyperactivity disorder, had normal intelligence quotient score); 4 patients had autistic-like features. Apart from mental retardation (7 of 10), physical and neurologic findings were normal. Significant pyramidal signs and microcephaly were detected in two patients, and hypotonia, ataxia, and bilateral pyramidal signs were found in one other. Cranial magnetic resonance imaging findings were normal for 6 patients; the other 4 had some abnormal findings. Continuous spikes and waves during slow sleep syndrome is a rare epileptic syndrome in childhood. A variety of clinical and neurocognitive features were found in patients with continuous spikes and waves during slow sleep syndrome.     

Levetiracetam efficacy in epileptic syndromes with continuous spikes and waves during slow sleep: experience in 12 cases

PURPOSE: To assess the add-on efficacy of levetiracetam on the EEG, behavior, and cognition of children with continuous spikes and waves during slow sleep (CSWS). METHODS: Charts of children with behavioral and/or cognitive deterioration associated with CSWS who received levetiracetam at 50 mg/kg/day as add-on treatment were retrospectively reviewed. Awake and sleep EEG recordings and detailed neuropsychological and behavioral assessments were available at baseline and 2 months after levetiracetam initiation. In children showing clinical and/or electrophysiological improvement after 2 months, levetiracetam was continued with a new evaluation at 1 year. RESULTS: Twelve patients were included (9 cryptogenic and 3 symptomatic cases). Seven patients (58.3%) showed improvement of EEG record. Among these seven patients, neuropsychological evaluation was improved in three, and in the other four patients, not testable because of severe cognitive impairment, behavior was improved. Two patients improved in neuropsychological evaluation despite the lack of EEG improvement. Eight patients (66.6%) continued levetiracetam treatment after 2 months. After 1 year, four patients were still on levetiracetam, two because sustained effect on EEG and behavior and the two others because improvement in neuropsychological testing despite unchanged EEG. Levetiracetam was discontinued in the other four patients because of neuropsychological or behavioral deterioration associated with CSWS pattern, between 9 and 11 months after treatment initiation. CONCLUSIONS: This retrospective study suggests that levetiracetam has a positive effect on the EEG, the behavior, and the cognition of patients with epilepsy and CSWS. Additional studies are warranted in order to assess the place of this drug in these epileptic conditions.     

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

ObjectiveTo compare methods of estimating spike strength as a potential index in the assessment of continuous spikes and waves during sleep (CSWS).MethodsSpikes 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 ±150 ms 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.ResultsAll 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.ConclusionsComputing an integrated RMS over multiple electrodes during steady NREM sleep offers a stable and reliable parameter for evaluating the strength of spikes in CSWS.SignificanceAnalyzing 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.     

Transient psychosis in a girl with epilepsy and continuous spikes and waves during slow sleep (CSWS)

A normally developed and healthy 6-year-old girl suffered the onset of epilepsy with generalized tonic-clonic seizures and atypical absences. Initially the EEG showed epileptiform activity over the temporal and parietal regions, later there were episodes of bilateral synchronous spike-wave activity with a frequency of 1.5–2.5 Hz. After a few months, deterioration of cognitive and behavioural functions appeared and gradually increased with the development of a fullblown disintegrative psychosis that went on for several months. Sleep EEG recordings showed the characteristic abnormality described as continuous spikes and waves during slow sleep. Later there was a remarkable improvement of neuropsy chiatric functions but a second outbreak of psychosis seems to have left the girl, who is now 9 years of age, with severe mental impairment.     

Ketogenic diet in the treatment of refractory continuous spikes and waves during slow sleep

Purpose: To evaluate the effect of the ketogenic diet on electroclinical characteristics and cognitive function in children with continuous spikes and waves during slow sleep (CSWS). Methods: Five children (four boys, one girl) aged between 8 and 13 years with CSWS refractory to conventional antiepileptic drugs (AEDs), including levetiracetam, and steroids were included. The prospective electroclinical assessment was performed prior to the ketogenic diet and once every 6 months post initiation during the 2‐year period. All children underwent neuropsychological testing prior to the ketogenic diet and four of the children again 12 months after the diet’s introduction. In case 4 the testing has been performed after 7 months and the diet was withdrawn after 9 months because of the lack of efficacy and the parent’s wishes. In two patients the cognitive functions were also evaluated after 24 months since the diet’s initiation. During the period on the ketogenic diet the concomitant AED treatment was unchanged. Results: Electrographic evaluation after 24 months on the ketogenic diet showed CSWS resolution in one patient, mild decrease of the spike–wave index in one, and lack of response in three patients. The ketogenic diet did not influence the neuropsychological outcome, and intelligence quotient (IQ) scores remained low at the end of the follow‐up period. However, in two patients an improvement in attention and behavior was demonstrated. Discussion: This is the first study evaluating the efficacy of the ketogenic diet in children with CSWS. Five presented cases were refractory to AEDs and steroids. Only one case responded with complete CSWS disappearance; in one the effect of the ketogenic diet was partial and intermittent, whereas in three patients no response has been observed. These results show that the ketogenic diet did not appear to influence the neuropsychological outcome; however, the absence of a control group makes it impossible to conclude with certainty.     

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.     

The epileptic syndromes with continuous spikes and waves during slow sleep: definition and management guidelines

The authors propose to define the epileptic syndromes with continuous spikes and waves during slow sleep (CSWS) as a cognitive or behavioral impairment acquired during childhood, associated with a strong activation of the interictal epileptiform discharges during NREM sleep--whatever focal or generalized--and not related to another factor than the presence of CSWS. The type of syndrome will be defined according to the neurological and neuropsychological deficit. These syndromes have to be classified among the localization-related epileptic syndromes. Some cases are idiopathic and others are symptomatic. Guidelines for work-up and treatment are proposed.     

Transcranial direct current stimulation in refractory continuous spikes and waves during slow sleep: a controlled study

Cathodal transcranial direct current stimulation (tDCS) decreases cortical excitability. The purpose of the study was to investigate whether cathodal tDCS could interrupt the continuous epileptiform activity. Five patients with focal, refractory continuous spikes and waves during slow sleep were recruited. Cathodal tDCS and sham stimulation were applied to the epileptic focus, before sleep (1 mA; 20 min). Cathodal tDCS did not reduce the spike-index in any of the patients.     

Epileptic encephalopathy with continuous spikes and waves in the occipito‐temporal region during slow‐wave sleep in two patients with acquired Kanji dysgraphia

We encountered two patients with acquired Kanji dysgraphia in whom continuous spikes and waves, dominant in the occipito‐temporal region, were recorded during slow‐wave sleep. Electrical status epileptics during sleep (ESES) was demonstrated on overnight electroencephalography, and dipoles clustered in and around the posterior inferior temporal cortex on magnetoencephalography. Functional neuroimaging suggested dysfunction in the left posterior temporal lobe, including the posterior inferior temporal cortex. The patients had normal intelligence with no problems in reading and writing Kana, as well as copying, reading aloud, and identifying Kanjis, but showed Kanji dysgraphia (morphological, phonemic, and semantic error) accompanied by impaired visual processing. ESES was resolved by sodium valproate, clonazepam, and acetazolamide in Patient 1, and by adrenocorticotropic hormone, sodium valproate, and clorazepate in Patient 2. The present cases had the unique cognitive dysfunction of Kanji dysgraphia, which is distinct from that of Landau‐Kleffner syndrome and continuous spikes and waves during slow‐wave sleep. However, the present cases also share common features with these two encephalopathies in terms of the clinical course, pathophysiology, neuroimaging, and response to steroids and antiepileptic drugs. In the context of the Japanese language, acquired Kanji dysgraphia may occur due to electrical dysfunction of left posterior inferior temporal cortex in patients with ESES.     

Electrical status epilepticus in sleep (ESES)/continuous spikes and waves during slow sleep (CSWS) syndrome in children: An electroclinical evaluation according to the EEG patterns

ObjectiveThe aim of this study was to describe the electroclinical spectrum in children with electrical status epilepticus in sleep (ESES)/continuous spikes and waves during slow sleep (CSWS) syndrome according to the EEG patterns.MethodsClinical data of 44 patients with ESES/CSWS syndrome who were treated and followed at least two years were analyzed. Records of EEGs of patients were reevaluated to determine two aspects of the ESES pattern: (1) the spike–wave index (SWI) on the NREM sleep EEG (Group I: typical vs. atypical ESES pattern (33/11 patients)) and (2) the area of maximum amplitude of continuous epileptic activity (Group II: anterior vs. posterior ESES pattern (33/11 patients)).ResultsSymptomatic etiology was more defined in patients with the typical ESES pattern (40%) than the group with the atypical ESES pattern (9%) by a factor of four. All patients were receiving at least two antiepileptic drug (AED) treatments. Eighteen patients (41%) received AEDs plus ACTH therapy. Complete disappearance of the ESES pattern on the EEG was observed in 18 patients (41%), more than 50% reduction was observed in five patients (11%), less than 50% reduction was observed in eight patients (18%), and no response was observed in five patients (11%). No significant difference was found when comparing the groups in terms of reduction of seizures and the SWI. Seizure outcome at the two-year follow-up was similar between the group with ESES treated with AEDs plus ACTH and the group with ESES treated with AEDs without ACTH therapy.SignificanceThis study demonstrated that the rate of the SWI (typical vs. atypical ESES) and the maximum amplitude of the ESES pattern (anterior vs. posterior) have no significant correlation with seizure control and reduction of the SWI on the EEG in children with ESES syndrome.     

Continuous spikes and waves during slow sleep: a 30 months follow-up study of neuropsychological recovery and EEG findings

An eight-year-old boy is reported who presented with a progressive mental deterioration in the years following a nocturnal asymmetrical generalized tonic-clonic seizure. The diagnosis of continuous spikes and waves during slow sleep (CSWS) was made. Once a month a sleep recording was made during twenty-two consecutive months and detailed neuropsychological studies were made over a period of 30 months. Intensive antiepileptic treatment resulted in the disappearance of the CSWS and in a recovery from intellectual-, language- and behavioural disturbances. The good results were still present at a follow-up examination 30 months later.     

Atypical language impairment in two siblings: relationship with electrical status epilepticus during slow wave sleep

We report the case of a young girl who presented severe learning disabilities in oral and written language related to a continuous spike-waves during slow sleep (CSWS) syndrome. A sleep EEG recording obtained in her younger brother, who presented a clinical pattern suggesting developmental dysphasia, also showed a CSWS syndrome. These two clinical cases underscore the need to look for this syndrome in the siblings of an affected child when learning difficulties appear in a child who previously had normal psychomotor development.