Epileptic encephalopathies of the Landau-Kleffner and continuous spike and waves during slow-wave sleep types: Genomic dissection makes the link with autism

Purpose: The continuous spike and waves during slow‐wave sleep syndrome (CSWSS) and the Landau‐Kleffner (LKS) syndrome are two rare epileptic encephalopathies sharing common clinical features including seizures and regression. Both CSWSS and LKS can be associated with the electroencephalography pattern of electrical status epilepticus during slow‐wave sleep and are part of a clinical continuum that at its benign end also includes rolandic epilepsy (RE) with centrotemporal spikes. The CSWSS and LKS patients can also have behavioral manifestations that overlap the spectrum of autism disorders (ASD). An impairment of brain development and/or maturation with complex interplay between genetic predisposition and nongenetic factors has been suspected. A role for autoimmunity has been proposed but the pathophysiology of CSWSS and of LKS remains uncharacterized. Methods: In recent years, the participation of rare genomic alterations in the susceptibility to epileptic and autistic disorders has been demonstrated. The involvement of copy number variations (CNVs) in 61 CSWSS and LKS patients was questioned using comparative genomic hybridization assays coupled with validation by quantitative polymerase chain reaction (PCR). Key Findings: Whereas the patients showed highly heterogeneous in genomic architecture, several potentially pathogenic alterations were detected. A large number of these corresponded to genomic regions or genes (ATP13A4, CDH9, CDH13, CNTNAP2, CTNNA3, DIAPH3, GRIN2A, MDGA2, SHANK3) that have been either associated with ASD for most of them, or involved in speech or language impairment, or in RE. Particularly, CNVs encoding cell adhesion proteins (cadherins, protocadherins, contactins, catenins) were detected with high frequency (≈20% of the patients) and significant enrichment (cell adhesion: p = 0.027; cell adhesion molecule binding: p = 9.27 × 10^?7). Significance: Overall our data bring the first insights into the possible molecular pathophysiology of CSWSS and LKS. The overrepresentation of cell adhesion genes and the strong overlap with the genetic, genomic and molecular ASD networks, provide an exciting and unifying view on the clinical links among CSWSS, LKS, and ASD.     

Levetiracetam in continuous spike waves during slow-wave sleep syndrome

We investigated the clinical characteristics of children with continuous spike waves during slow-wave sleep syndrome and their treatment response to levetiracetam. Five boys and one girl, diagnosed with epilepsy with continuous spike waves during slow-wave sleep syndrome, were enrolled. Their clinical characteristics, including neuroimaging findings, were reviewed. The signs related to continuous spike waves during slow-wave sleep included increased seizure frequency (6/6), impaired responsiveness (3/6), and psychomotor regression (2/6). Magnetic resonance imaging disclosed lissencephaly in one patient, and porencephaly of the left hemisphere in another. The number of antiepileptic drugs before the use of levetiracetam was 0-4 (mean +/- SD, 2.3 +/- 1.5). Five of 6 children demonstrated a good response to levetiracetam, whereas 2 (40%) underwent a relapse of electrical status epilepticus during sleep pattern on electroencephalograms 4 and 5 months after clinical improvement. Both were 5 years old. The most common presenting sign in children with continuous spike waves during slow-wave sleep syndrome is increasing seizure frequency. Levetiracetam is effective in treating children with continuous spike waves during slow-wave sleep syndrome. However, the relapse rate of continuous spike waves during slow-wave sleep syndrome remains high in young children.     

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

Purpose: 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. Methods: 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. Results: 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. Conclusion: 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.     

Rett syndrome associated with continuous spikes and waves during sleep

Major speech impairment is a cardinal feature of Rett syndrome. Epilepsy, of variable presentation, is also frequently described. We report a girl who presented rapid speech regression while EEG showed continuous spikes and waves during slow sleep. The clinical picture was consistent with Rett syndrome, confirmed by MECP2 mutation R133C. We hypothesized that speech regression was partially related to nocturnal epileptic activity. Several antiepileptic drugs were used unsuccessfully but valproic acid was accompanied by improvement of verbal fluency, social interaction and manual abilities as measured by the Quebec Scale of Adaptive Behaviors and the Rett syndrome adapted Kerr scale. Continuous spikes and waves during slow sleep are unexpected in the early stages of Rett syndrome. This report suggests that it might contribute to the clinical impairment, in particular communicative capabilities, and that adequate antiepileptic treatment may be beneficial.     

SPECT and epilepsy with continuous spike waves during slow-wave sleep

Ten cases of epilepsy with continuous spike waves in slow-wave sleep (CSWS) were evaluated using single photon emission computed tomography (SPECT); in eight patients the EEG paroxysmal abnormalities showed a predominant localization. SPECT carried out using^99mTc-HMPAO allows study of cerebral blood flow (CBF); the examination was performed during phases of drowsiness and the results compared to the EEG data. In four cases SPECT revealed areas of low CBF in sites corresponding to those of the prevalent EEG discharges; in two cases the areas of hypoperfusion did not correspond to those indicated by the EEG; lastly, in four cases SPECT results were negative. The areas of hypoperfusion were predominantly located in the frontal, temporal, and parietal regions. Furthermore, the percentage of positive SPECT results was significantly higher (five cases out of six) in the group in which the CSWS phase was prolonged for at least 1 year, compared to the group in which this phase lasted less than 1 year. Thus, in this type of epilepsy, SPECT reveals focal cortical areas of decreased CBF which correlated generally to the predominant sites of EEG abnormalities. A longer duration of the CSWS phase seems to be associated with a more significant cortical disorder, documented by the presence of areas of hypoperfusion.     

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.     

The pathophysiological mechanisms of cognitive and behavioral disturbances in children with Landau-Kleffner syndrome or epilepsy with continuous spike-and-waves during slow-wave sleep.

Epilepsy with continuous spike- and -waves during slow-wave sleep and Landau-Kleffner syndrome are two rare childhood epilepsy syndromes. The underlying pathophysiology remains unknown. The current opinions about epidemiologic risk factors, genetic predisposition, EEG and MEG findings, influence of anti-epileptic drugs, neuroradiology, positron emission tomopgraphy, evoked potentials, auto-immunity and subpial transection are summarized.     

Clinical staging and electroencephalographic evolution of continuous spikes and waves during sleep

Purpose: Currently, in continuous spikes and waves during sleep (CSWS) there is a lack of systematic assessments of the clinically relevant stages and the evolution of the electroencephalographic features. The aim of this study is to describe the evolution over time of clinical and electroencephalographic features in CSWS. Methods: We enrolled patients from our video‐electroencephalography (EEG) monitoring unit with CSWS and with overnight EEG studies with at least one overnight assessment per year over a minimum period of 3 years. We studied clinical presentation and electroencephalographic features. We calculated the (1) spike‐wave percentage (SWP) as the percentage of 1‐s bins containing at least one spike‐wave complex and (2) spike frequency (SF) as the number of spikes per 100 s. Key Findings: Nine children (six boys) met the inclusion criteria during a 15‐year period. Seven (78%) had an abnormal development prior to the epilepsy onset, and in two (22%) seizures were the only presenting symptom. Median age at epilepsy onset was 2 years (range 2 days to 4 years), at neuropsychological regression 5.1 years (4–7.7 years), and at seizure freedom 8.6 years (6.5–11.4 years). Median duration and range of clinically relevant stages were as follows: dormant stage (birth‐epilepsy onset median 2 years, range 2 days–4 years), prodromal stage (epilepsy onset‐neuropsychological regression 3.9 years, range 0.9–7.7 years), acute stage (neuropsychological regression‐seizure freedom 2.9 years, range 2.1–6.6 years), and residual stage (after seizure freedom). Seven patients (78%) had a structural lesion on neuroimaging. At last follow‐up (median 11.4 years, range 7.2–20.3 years), eight patients (89%) were receiving antiepileptic treatment, and all patients had residual neurocognitive deficits. During the acute stage, SWP was <85% in 13 (42%) of 31 assessments, and after seizure freedom, 3 of 5 patients (60%) had SWP >85%. Evolution of electroencephalographic patterns included increasing‐decreasing, continuously elevated, and fluctuating patterns (33.3% each). There was good correlation between SWP and SF (Spearman correlation‐coefficient = 0.942; p < 0.0001). SF, which can exceed 100%, reflected changes in electroencephalography pattern in more detail than SWP, which cannot exceed 100% and therefore has a ceiling effect. Significance: Our series systematically studied the age of occurrence of the significant clinical events. These may assist in defining clinical stages, which can provide a useful framework for future clinical trials in patients with CSWS. The severity of the epileptiform discharges on EEG did not always correlate with seizure frequency and severity; epileptiform discharges could be prominent after seizure freedom and fluctuated along the course of the disease. The values of SWP and SF correlated well, but SWP based on 1‐s bins has the potential disadvantage of a ceiling effect.     

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.     

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.     

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.     

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.     

Pathophysiology of encephalopathy related to continuous spike and waves during sleep: the contribution of neuroimaging

In the last three decades, studies on functional neuroimaging have helped us to understand pathophysiological mechanisms responsible for electro‐clinical patterns associated with epileptic encephalopathies with continuous spikes and waves during slow sleep (ECSWS). MEG and EEG source reconstruction have revealed sources of pathological brain activity associated with epileptiform discharges in the perisylvian region pointing to the significance of this brain area for ECSWS. PET studies have revealed areas of focal hypermetabolism in perisylvian, superior temporal and inferior parietal regions as well as central cortices which were related to epileptic activity. The widespread hypometabolism in regions that belong to the default network (prefrontal and posterior cingulate cortices, parahippocampal gyrus and precuneus) was interpreted as remote inhibition following epileptic activity, which could contribute to cognitive deficits in affected individuals. Note that the described metabolic changes were functional and disappeared after successful treatment and recovery of ECSWS and were found in both sleep and wakefulness which may account for cognitive deficits in patients during the day. EEG‐fMRI studies have revealed a functional fingerprint of epileptic encephalopathy: significant positive BOLD signal changes were identified in the perisylvian regions, prefrontal cortex and anterior cingulate as well as thalamus and negative BOLD signal changes in the regions of the default mode network. The pattern of activation represents a propagation of epileptic activity specific to encephalopathy, which is independent of etiology and type of seizure associated with ECSWS. In summary, methods of neuroimaging have shed light on pathogenic mechanisms of ECSWS which may account for a number of clinical phenomena associated with this condition.     

Focal polymicrogyria,continuous spike-and-wave discharges during slow-wave sleep and Cohen syndrome: a case report

Cohen syndrome is a rare genetic disorder consisting of truncal obesity, hypotonia, mental retardation, characteristic facial appearance and ocular anomalies. Other diagnostic clinical features include narrow hands and feet, low growth parameters, neutropenia and chorioretinal dystrophy. Here, we report an 18-year-old male with Cohen syndrome associated with focal polymicrogyria and continuous spike-and-wave discharges during slow-wave sleep.     

Epilepsy with continuous discharges during slow-wave sleep. Treatment with clobazam

The authors describe the case of a 12 years old boy suffering from an epilepsy with complex partial seizures evolving to a syndrome of epilepsy with continuous spikes-waves during sleep. A dramatic improvement follows clobazam introduction in the treatment. The originality of this case report and the possible mechanism of action of clobazam are discussed.     

Treatment with flunitrazepam of continuous spikes and waves during slow wave sleep (CSWS) in children.

We describe our treatment of two boys with continuous spikes and waves during slow wave sleep (CSWS). One of the boys was suffering from non-convulsive status epilepticus and the other from conscious disturbance with automatism. Their ictal EEG readings showed continuous diffuse spike and wave complexes, which were considered to show electrical status. The boys were diagnosed as having CSWS, and were later diagnosed with Landau-Kleffner syndrome (LKS). EEG readings returned to normal on intravenous injection of flunitazepam (FZP) at a dose of 0.02 mg/kg, suggesting that FZP is an effective treatment for CSWS.     

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.