Continuous Spikes And Waves During Slow Sleep Research Articles

DYNC1H1-related epilepsy: Genotype-phenotype correlation.

To explore the phenotypic spectrum and refine the genotype-phenotype correlation of DYNC1H1-related epilepsy. The clinical data of 15 patients with epilepsy in our cohort and 50 patients with epilepsy from 24 published studies with the DYNC1H1 variants were evaluated. In our cohort, 13 variants were identified from 15 patients (seven males, eight females). Twelve variants were de novo and seven were new. Age at seizure onset ranged from 3 months to 4 years 5 months (median age 1 year). Common seizure types were epileptic spasms, focal seizures, tonic seizures, and myoclonic seizures. Mild-to-severe developmental delay was present in all patients. Six patients were diagnosed with West syndrome and one was diagnosed with epileptic encephalopathy with continuous spikes and waves during slow sleep (CSWS). Collectively, in our cohort and published studies, 17% had ophthalmic diseases, 31% of variants were located in the stalk domain, and 92% patients with epilepsy had a malformation of cortical development (MCD). The phenotypes of DYNC1H1-related epilepsy included multiple seizure types; the most common epileptic syndrome was West syndrome. CSWS is a new phenotype of DYNC1H1-related epilepsy. One-third of the variants in patients with epilepsy were located in the stalk domain. Most patients had a MCD and developmental delay. Nearly 40% of patients with DYNC1H1 variants had epilepsy. Ninety-two percent of patients with DYNC1H1-related epilepsy had malformation of cortical development. More than 10% of patients with DYNC1H1-related epilepsy were diagnosed with West syndrome. Continuous spikes and waves during slow sleep could be a new phenotype of DYNC1H1 variants. One-third of the variants in patients with epilepsy were located in the stalk domain.

Methylprednisolone pulse therapy in 31 patients with refractory epilepsy: A single-center retrospective analysis

PurposeWe investigated the efficacy of methylprednisolone pulse therapy (MP) and responder characteristics in patients with refractory epilepsy. MethodsWe reviewed medical records of our center to identify patients with refractory epilepsy treated with MP other than continuous spikes and waves during slow sleep (CSWS), Landau–Kleffner syndrome (LKS), or Rasmussen's syndrome (RS) between 2004 and 2015. A course of MP consisted of intravenous methylprednisolone (30 mg/kg/day) on three consecutive days. Patients received multiple courses at intervals of four weeks. We examined seizure outcome, developmental outcome, antibodies to N-methyl-d-aspartate (NMDA)-type glutamate receptors (GluRs), cerebral spinal fluid (CSF)-albumin/serum–albumin ratio, and interictal electroencephalograms (EEGs). Responder to MP was defined as maintaining seizure reduction rate (SRR) ≥50% for three months after the first course of MP. ResultsThirty-one consecutive patients treated with MP at our center were studied. Seizure types were focal onset impaired awareness seizure (FIAS) only (n = 23), FIAS with epileptic spasms (ES) (n = 7), and ES only (n = 1). Responder rate was 32.2% (10/31 patients), and seizure-free rate was 9.7% (3/31). Responders constituted 43.5% of patients without ES. No patient with ES was responder. Behavior and cognition also improved in 6 of 10 responders. History of seizure aggravation after inactivated vaccine before MP was found significantly higher rate in responder patients, comparing with nonresponder patients (p = 0.01). ConclusionMethylprednisolone pulse therapy may be considered for possible treatment in patients with focal epilepsy with drug-resistant seizures without ES, and it may improve cognitive function and behavioral comorbidities.

Continuous Spike and Waves During Slow Sleep in the Neurological Department of Fann National University Hospital of Dakar: Topographic Aspects and Age

Continuous spikes and waves during slow sleep (CSWS), are characterized by marked activation of epileptic activity on electroencephalographic (EEG) recording during slow sleep [1], acom panied by the occurrence of or increase of pre-existing spikes and waves, these becoming bilateral and continuous/subcontinuous [2]. The anomalies can occur during awakness, realizing isolated spikes and waves or bursts of spikes and waves [1-3].

Continuous spike-waves during slow-wave sleep: Experience during 20 years

Continuous spikes and waves during slow sleep (CSWS) is an EEG pattern that appears during childhood, and is often associated with cognitive impairment. It can appear in the course of epileptic syndromes, as well as in benign epilepsy. The aim of this study is to analyse epidemiological and clinical characteristic of patients with CSWS, in order to describe possible predictive factors in their outcome. A retrospective study was conducted on paediatric patients with CSWS treated in a third-level hospital from November 1997 to November 2017. The study included 25 patients (68% male), of whom 76% had abnormalities in the neuroimaging or suffered from psychomotor development disorder (secondary CSWS). The rest were healthy, or diagnosed with idiopathic epilepsy. The mean age of onset of CSWS was 6.7 years, but earlier in the secondary CSWS cases. Symptoms were present during the CSWS episode in 72% of cases. All of them were treated with antiepileptic drugs, which were effective in 36%. CSWS stopped in 72%, and remission was longer if the CSWS onset occurred at an older age. One-third (33%) presented with sequelae, mostly cognitive and behavioural alterations. Outcome was poorer in those with secondary CSWS and, in those whose CSWS started at an earlier age and lasted longer. The CSWS pattern, although rare, is still a therapeutic challenge. A close follow-up of the patients with epilepsy is important, especially if associated with cognitive impairment, in order to establish an early diagnosis and treatment.

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.

The 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. Clinical 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)). Symptomatic 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. This 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.

Neuronal networks in epileptic encephalopathies with CSWS.

The aim of our study was to investigate the neuronal networks underlying background oscillations of epileptic encephalopathy with continuous spikes and waves during slow sleep (CSWS). Sleep electroencephalography (EEG) studies before and after the treatment were investigated in 15 patients with CSWS. To investigate functional and effective connectivity within the network generating the delta activity in the background sleep EEG, the methods of dynamic imaging of coherent sources (DICS) and renormalized partial directed coherence (RPDC) were applied. Independent of etiology and severity of epilepsy, background EEG pattern in patients with CSWS before treatment is associated with the complex network of coherent sources in medial prefrontal cortex, somatosensory association cortex/posterior cingulate cortex, medial prefrontal cortex, middle temporal gyrus/parahippocampal gyrus/insular cortex, thalamus, and cerebellum. The analysis of information flow within this network revealed that the medial parietal cortex, the precuneus, and the thalamus act as central hubs, driving the information flow to other areas, especially to the temporal and frontal cortex. The described CSWS-specific pattern was no longer observed in patients with normalized sleep EEG. In addition, frequency of spiking showed a strong linear correlations with absolute source power, source coherence strength, and source RPDC strength at both time points: (1) Spike and wave index (SWI) versus absolute source power at EEG1 (r = 0.56; p = 0.008) and at EEG2 (r = 0.45; p = 0.009); (2) SWI versus source coherence strength at EEG1 (r = 0.71; p = 0.005) and at EEG2 (r = 0.52; p = 0.006); and (3) SWI versus source RPDC strength at EEG1 (r = 0.65; p = 0.003) and at EEG2 (r = 0.47; p = 0.009). The leading role of the precuneus and thalamus in the hierarchical organization of the network underlying the background EEG points toward the significance of fluctuations of vigilance in the generation of CSWS. This hierarchical network organization appears to be specific for CSWS as it is resolved after successful treatment.

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

ObjectiveTo determine the etiology of epilepsy with continuous spikes and waves during slow sleep (CSWS)/electrical status epilepticus during sleep (ESES) in an 8-year old boy with a history of neuroblastoma and opsoclonus-myoclonus. Material & methodsA combination of clinical characterization and follow-up, video EEG and laboratory investigations. ResultsWe report the case of an 8-year old boy with a history of neuroblastoma and opsoclonus-myoclonus, who presented with intellectual disability, pharmacotherapy-resistant epilepsy and CSWS/ESES. Although the patient's neuroblastoma had been successfully treated 8 years prior to presentation and an extensive workup did not show a tumor reoccurrence, testing for onconeuronal antibodies was positive for anti-Ma2 and anti-CV2/CRMP5 antibodies. High-dose intravenous methylprednisolone and a taper of oral methylprednisolone were given, leading to a significant clinical improvement. During the taper the patient's condition and EEG manifestations deteriorated again necessitating another cycle of steroid therapy, which lead to a stable improvement. During a 6-month follow-up no CSWS/ESES was seen on EEG and anti-Ma2 and anti-CV2/CRMP5 antibodies remained undetectable. ConclusionThis case suggests that onconeuronal antibodies may be involved in the pathogenesis of CSWS/ESES.

Congenital hemiparesis, unilateral polymicrogyria and epilepsy with or without status epilepticus during sleep: a study of 66 patients with long‐term follow‐up

We retrospectively analysed the electroclinical features, treatment, and outcome in patients with unilateral polymicrogyria (PMG), focussing on epileptic syndrome with or without encephalopathy, with status epilepticus during sleep (ESES) or continuous spikes and waves during slow sleep (CSWS) syndrome. From June 1990 to December 2012, 39 males and 27 females, aged 5-26 years, were studied. We did not include patients with bilateral PMG or cases with unilateral PMG associated with other cerebral lesions. The mean follow-up period was 12 years (range: 3-22 years). Mean age at epilepsy onset was 6.5 years. Focal motor seizures occurred in all cases and 25 had secondary generalised seizures. Six patients also had complex focal seizures. Interictal EEG recordings showed focal spikes in all cases. For 43 of 53 patients with epilepsy, aged 2-9.5 years, the electroclinical features changed. An increase in frequency of focal motor seizures was reported in 20 patients, negative myoclonus occurred in 32 patients, atypical absences in 25 patients, and positive myoclonus in 19 patients. All patients had a continuous symmetric or asymmetric pattern of spike-wave activity during slow-wave sleep. For patients presenting with congenital hemiparesis, negative or positive myoclonus, and absences and focal motor seizures with ESES/CSWS, unilateral PMG should be considered. Brain MRI is mandatory to confirm this cortical malformation. The most commonly used treatments were clobazam, ethosuximide, and sulthiame, alone or in combination. For refractory cases, high-dose steroids were administered and surgery was performed in two patients. Outcome was relatively benign.

EEG‐fMRI in atypical benign partial epilepsy

Atypical benign partial epilepsy (ABPE) is a subgroup among the idiopathic focal epilepsies of childhood. Aim of this study was to investigate neuronal networks underlying ABPE and compare the results with previous electroencephalography (EEG)-functional magnetic resonance imaging (fMRI) studies of related epilepsy syndromes. Ten patients with ABPE underwent simultaneous EEG-fMRI recording. In all 10 patients several types of interictal epileptiform discharges (IEDs) were recorded. Individual IED-associated blood oxygen level-dependent (BOLD) signal changes were analyzed in a single subject analysis for each IED type (33 studies). A group analysis was also performed to determine common BOLD signal changes across the patients. IED-associated BOLD signal changes were found in 31 studies. Focal BOLD signal changes concordant with the spike field (21 studies) and distant cortical and subcortical BOLD signal changes (31 studies) were detected. The group analysis revealed a thalamic activation. This study demonstrated that ABPE is characterized by patterns similar to studies in rolandic epilepsy (focal BOLD signal changes in the spike field) as well as patterns observed in continuous spikes and waves during slow sleep (CSWS) (distant BOLD signal changes in cortical and subcortical structures), thereby underscoring that idiopathic focal epilepsies of childhood form a spectrum of overlapping syndromes.

Neuropsychiatric impairment in children with Continuous Spikes and Waves during slow Sleep: A long‐term follow-up study

A long‐term follow‐up study was conducted in patients affected by Continuous Spikes and Waves during slow Sleep (CSWS) to evaluate the long-term outcomes. Twenty-five patients (19 males, 6 females), from 2 to 16years of age (mean age 6years±3 SD), affected by CSWS syndrome, as defined by the International League Against Epilepsy (ILAE, 1989), were enrolled and followed for 11years (mean duration of follow‐up: 3.9years). At the time of the appearance of CSWS, one or more neuropsychiatric disorders were present in 96% of the patients, such as behavioral problems in 54%, mental retardation in 37.5%, learning disabilities in 33%, developmental coordination disorder in 17%, language disorder in 12.5%, and pervasive developmental disorder in 8%. During the follow-up, neuropsychiatric dysfunctions remained unaltered in 52% of the patients, worsened in 24%, and improved in only 24%. Our data confirm that CSWS may be associated with a broad spectrum of neuropsychiatric disorders and may promote their worsening over time. Moreover, the findings cannot be generalized to all cases of children with CSWS because most of the children in the subgroups with no change in outcome and worse outcome had symptomatic CSWS.

Effects of levetiracetam on seizure frequency and neuropsychological impairments in children with refractory epilepsy with secondary bilateral synchrony

PurposeIn epilepsy with continuous spikes and waves during slow sleep (CSWS), which is a representative epileptic syndrome of secondary bilateral synchrony (SBS), the urgent suppression of this electroencephalographic (EEG) abnormality may be necessary to prevent the progression of neuropsychological impairments. The purpose of this study was to determine the efficacy of levetiracetam (LEV) on SBS, seizure frequency, and neuropsychological impairments in children with refractory epilepsy. MethodsEleven (seven male and four female) patients with refractory epilepsy with SBS on EEG, aged between 4.7 years and 11.3 years, were included in this study. After a 3-month baseline period, the patients were given LEV at an initial dose of 10mg/kg/day for the first week, followed at increments of 5mg/kg/day every week, up to 20mg/kg/day. The LEV dose was then adjusted up to a maximum of 60mg/kg/day, according to the clinician's judgment. EEG recordings and clinical evaluations were performed every 3 months, focusing on SBS. The occurrence of SBS was then scored, and the relationship between the score and the response to LEV treatment was evaluated. In comparison with the baseline SBS frequency, the EEG response to LEV treatment was classified, and responders were identified as having a ≥50% reduction in SBS frequency. In addition, in comparison with the baseline seizure frequency, response to LEV treatment was classified. Responders were identified as patients with complete cessation (100% seizure control) and a response of ≥50% reduction in seizures. Furthermore, neuropsychological impairments such as hyperactivity, impulsiveness, and inattention were evaluated before and after LEV treatment. ResultsEight patients (72.7%) were considered responders. In addition, all eight patients were also considered responders for clinical seizures. Furthermore, 7 of 8 (87.5%) patients with response showed decreased hyperactivity and impulsivity after LEV administration. ConclusionsThe present data clearly indicate the usefulness of LEV in reducing both SBS on EEG and seizure frequency. LEV represents an important addition to the treatments available for refractory childhood epilepsies with SBS on EEG.

Evolution of Ohtahara Syndrome to Continuous Spikes and Waves during Slow Sleep in an Infant

ABSTRACT.Encephalopathy with electrical status epilepticus in sleep (ESES) is defined as an age-related and self-limited electroclinical syndrome whose etiology is unknown and characterized by continuous spikes and waves during slow sleep (CSWS). Typical CSWS starts at an age of 4 to 5 years and ends by an average of 11 years. We report on an unexpected finding of CSWS in an 18-month-old male whose previous EEC at age 45 days was grossly abnormal with the presence of a burst suppression pattern during wakefulness and sleep. The patient had clinical seizures beginning day 1 of life leading to the suspicion of Ohtahara syndrome (the earliest form of epileptic encephalopathy). Patients with ESES usually have normal EEGs and functional development prior to the onset of CSWS pattern. To our knowledge, this presentation of a neonate with a history of neonatal seizures and developmental delay with an evolution to CSWS has not been described. A sleep record is strongly advised in children with epilepsy (despite the recording of awake EEG abnormalities), especially in patients with behavior or cognitive regression, to rule out the presence of CSWS.

Therapy of Encephalopathy with ESES/CSWS

Researchers at University of Pavia, Italy review treatment options for electrical status epilepticus in sleep (ESES)/continuous spikes and waves during slow sleep (CSWS) and their comparative value.

Electroclinical overlap of two types of epileptic encephalopathy occurring in the same children in a certain age period?

In this study, we describe three patients who each had an electroclinical overlap of two different epileptic encephalopathies (EE), with onset in a certain age period. Patient 1 had electroclinical features compatible with continuous spikes and waves during slow sleep (CSWSS) syndrome that changed into Lennox-Gastaut syndrome (LGS) (symptomatic, cause porencephalic cyst) at the age of 8.5 years. Patient 2 had LGS which evolved into CSWSS at the age of 6 years (symptomatic, cause polymicrogyria). The third patient had cryptogenic CSWSS syndrome at age the age of 7 years which evolved into LGS at the age of 7.5 years. All three patients could be considered to have two EE: CSWSS syndrome and LGS or to have had overlapping features of these epileptic syndromes.

Therapy of encephalopathy with status epilepticus during sleep (ESES/CSWS syndrome): an update

Electrical status epilepticus in sleep (ESES)/continuous spikes and waves during slow sleep (CSWS) is an age-related, self-limiting disorder characterised by epilepsy with different seizure types, global or selective neuropsychological regression, motor impairment, and a typical EEG pattern of continuous epileptiform activity for more than 85% of non-rapid eye movement (NREM) sleep. Although the first description of ESES/CSWS dates back to 1971, an agreement about the optimal treatment for this condition is still lacking. ESES/CSWS is rare (incidence is 0.2-0.5% of all childhood epilepsies) and no controlled clinical trials have been conducted to establish the efficacy of different antiepileptic drugs; only uncontrolled studies and case reports are reported in the literature. Treatment options for ESES/CSWS include some antiepileptic drugs (valproic acid, ethosuximide, levetiracetam, and benzodiazepines), steroids, immunoglobulins, the ketogenic diet, and surgery (multiple subpial transections). In this study, the comparative value of each of these treatments is reviewed and a personal therapeutic approach is proposed.

Benign childhood seizure susceptibility syndrome: three case reports

In this study, we describe three patients who each had two different forms of idiopathic focal epilepsiy. Two of these patients had electroclinical features compatible with Panayiotopoulos syndrome and benign childhood epilepsy with centro-temporal spikes (BCECTS), one of whom developed a particular electroclinical picture of atypical benign focal epilepsy and the other an atypical evolution characterized by verbal auditory agnosia and aphasia. The third patient had clinical and electroencephalographic features of BCECTS and of idiopathic childhood occipital epilepsy (Gastaut type) which evolved into electroclinical features of continuous spikes and waves during slow sleep (CSWS). All three patients presented with two focal idiopathic epilepsies with a particular evolution associated with CSWS, supporting the concept of benign childhood seizure susceptibility syndrome as described by Panayiotopoulos (1993).

Insights into the pathophysiology of psychomotor regression in CSWS syndromes from FDG‐PET and EEG‐fMRI

Epilepsy syndromes with continuous spikes-and-waves during slow sleep (CSWS) are age-related epileptic encephalopathies characterized by the development of various types of psychomotor regression in close temporal concordance with the appearance of the electroencephalography (EEG) pattern of CSWS. Functional cerebral imaging studies performed in children with CSWS have shown evidence for the existence of increase in metabolism or perfusion at the site of the epileptic focus, associated with decrease in metabolism or perfusion in distant and connected brain areas. Longitudinal [18F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) studies and effective connectivity analyses have suggested the existence of a pathophysiologic link between increases and decreases in metabolism/perfusion that could be explained by the theory of remote inhibition. These findings highlight that the psychomotor regression observed in CSWS syndromes is not only related to the neurophysiologic impairment at the site of the epileptic foci but also to epilepsy-induced neurophysiologic changes in distant connected brain areas.

Guidelines for EEG in encephalopathy related to ESES/CSWS in children

Electrical status epilepticus during slow sleep (ESES) or continuous spikes and waves during slow sleep (CSWS) is a phenomenon characterized by strong activation of epileptiform activity in the electroencephalogram (EEG) during sleep. The literature contains several small series of patients and many case reports. Large prospective studies are lacking. Definitions of the syndromes and EEG criteria and methods vary, as does their classification. The fluctuating clinical course and EEG findings complicate the diagnostic process and evaluation of effect of therapy. Studies describing quantitative aspects of the epileptiform abnormalities in EEG are overrepresented in literature, whereas qualitative aspects are relatively undervalued. Guidelines for evaluation of the EEG in these syndromes, which focus on both aspects, are presented.

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

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). 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. 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. 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.

Epileptic encephalopathy with continuous spikes and waves during sleep in children with shunted hydrocephalus: A study of nine cases

We present a series of nine patients with early-onset hydrocephalus who had seizures and continuous spikes and waves during slow sleep (CSWS) associated with neurocognitive and motor deterioration. Six boys and three girls aged 9-16 years (mean 11.3 years) were studied. [Correction added after online publication 12-Apr-2008: Number of girls and boys has been updated.] All patients underwent clinical examinations, electroencephalographic evaluations, neuroradiological imaging and neuropsychological assessment at first examination. Antiepileptic drugs (AEDs) were given in all cases and changed according to clinical and EEG evolution. Onset of epilepsy occurred from age 8 to 60 months (mean 19.6 months and median 14 months) with focal seizures with or without secondary generalized tonic-clonic seizures. Between ages 6 and 13 years (mean 10.4 years and median 8 years), hyperkinesia, aggressiveness, and poor socialization appeared in all nine cases. Reduced attention span, deterioration of language, and temporospatial disorientation were found in three of them. Negative myoclonus was found in two patients. The EEG showed CSWS. Response to change in treatment was good in all patients. None of the patients had relapses, seven of them have remained seizure free, and two continued having sporadic focal motor seizures during 2-5 years (mean 3 years) of follow-up. In children with early-onset hydrocephalus, particularly with behavioral and language disturbances and/or motor deterioration, CSWS should be considered. Periodic EEG recordings during sleep should be done in these children. The early identification of this particular electroclinical picture is crucial to start adequate treatment to avoid progressive cognitive deterioration.