Unmet needs in epileptic encephalopathy with spike-and-wave activation in sleep: A systematic review.

INTRODUCTION: Developmental and/or epileptic encephalopathy with spike-and-wave activation in sleep (D/EE-SWAS), also referred to as electrical status epilepticus during sleep (ESES) or epileptic encephalopathy with continuous spike-and-wave during sleep (CSWS or EE-CSWS), is a spectrum of rare childhood epileptic encephalopathies that can lead to long-term cognitive impairment. Despite the importance of early diagnosis and intervention for D/EE-SWAS, there is a paucity of well-controlled clinical trial data to inform treatment, and no approved treatments are available. To assess correlations between diagnosis, treatment, and outcomes in D/EE-SWAS, we carried out a systematic review of the literature. METHODS: In August 2020, we conducted comprehensive database searches using search terms including "electrical status epilepticus," "ESES," "CSWS," and "Landau-Kleffner syndrome." Two or more independent reviewers screened titles, abstracts, and full-text articles for those that met the following criteria: prospective studies (randomized controlled trials [RCTs] or open-label trials), retrospective studies (drug evaluations or observational studies/chart reviews), and case series with ≥ 10 participants. Both interventional and non-interventional studies were included (i.e., drug intervention was not an inclusion criterion). Articles published before 2012, review articles, animal studies, and studies of surgical or dietary interventions were excluded. Standardized data extraction templates were used to capture data on study design, patient characteristics, interventions, and outcomes from each of the selected publications. Study quality was assessed using the Cochrane Risk of Bias Tool for RCTs and the Newcastle-Ottawa Scale (NOS) or the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for retrospective, observational studies. RESULTS: A total of 34 studies were included for full data extraction, most of which were uncontrolled and observational. Interpretation of study outcomes was limited by small study populations, variability in inclusion criteria, and inconsistency in methods of assessment and reporting of outcomes, which resulted in large heterogeneity in patients and their presenting symptoms. Despite these limitations, some patterns could be discerned. Several studies found that longer duration of ESES and younger age at onset were correlated with more severe language and cognitive deficits. In addition, several studies reported an association between improvement in cognitive outcomes and reduction in electroencephalogram (EEG) abnormalities and/or seizure frequency. In the 16 prospective or retrospective studies that evaluated drug treatments (e.g., antiseizure medications, corticosteroids, and high-dose diazepam), there was some improvement in EEG, seizure, and/or cognitive outcomes, although the specific outcomes and rates of improvement reported varied from study to study. CONCLUSION: Long-term cognitive deficits remain common in D/EE-SWAS, and data gaps exist in the literature that preclude an evidence-based approach to managing this complex epilepsy indication. Early intervention with more effective medications is needed to optimize long-term outcomes. Sufficiently powered, randomized, double-blind, controlled trials with standardized methods and predefined primary and secondary outcomes are needed.

[Epileptic syndromes associated with focal clonic seizures]. / Epilepticheskie sindromy, assotsiirovannye s fokal'nymi klonicheskimi pristupami.

OBJECTIVE: To study clinical, electroencephalographic and neuroimaging features in children with epileptic syndromes associated with focal clonic seizures (FCS). MATERIAL AND METHODS: We examined 1258 patients with various forms of epilepsy with the onset of seizures from the first day of life to 18 years. RESULTS: FCS was identified in 263 patients (20.9%). FCS were included in the structure of 13 different epileptic syndromes: Rolandic epilepsy (28.1%), structural focal epilepsy (27.5%), structural focal epilepsy associated with benign epileptiform discharges of childhood (SFE-BEDC) (20.6%), focal epilepsy of unknown etiology (7.5%), epilepsia partialis continua (4.6%), pseudo-Lennox syndrome (3.4%), ESES syndrome (2.7%), Landau-Kleffner syndrome (1.5%), Dravet syndrome (1.1%), benign occipital epilepsy (1.1%), benign focal epilepsy in infancy (0.8%), MISF syndrome (0.8%), cognitive epileptiform disintegration (0.8%). In 50% of cases, epilepsy associated with FCS debuts before the age of 5 years (from 1 month to 18 years, average age 4.26±3.9). CONCLUSION: The groups of syndromes associated with FCS have different prognosis for remission of seizures. Prognostic predictors of seizure remission are: epileptic syndromes associated with BEDC, the presence of periventricular leukomalacia. A severe prognosis for the course of epilepsy is associated with local structural changes in the neocortex. Despite a favorable prognosis for seizures, continued diffuse interictal epileptiform activity with BEDC on the electroencephalogram is a predictor of the onset of cognitive impairment in children.

Aphasia and a Dual-Stream Language Model in a 4-Year-Old Female with Landau-Kleffner Syndrome.

Landau-Kleffner syndrome (LKS) is a rare neurological disorder characterized by acquired aphasia. LKS presents with distinctive electroencephalography (EEG) findings, including diffuse continuous spike and wave complexes (CSW), particularly during sleep. There has been little research on the mechanisms of aphasia and its origin within the brain and how it recovers. We diagnosed LKS in a 4-year-old female with an epileptogenic zone located primarily in the right superior temporal gyrus or STG (nondominant side). In the course of her illness, she had early signs of motor aphasia recovery but was slow to regain language comprehension and recover from hearing loss. We suggest that the findings from our patient's brain imaging and the disparity between her recovery from expressive and receptive aphasias are consistent with the dual-stream model of speech processing in which the nondominant hemisphere also plays a significant role in language comprehension. Unlike aphasia in adults, the right-hemisphere disorder has been reported to cause delays in language comprehension and gestures in early childhood. In the period of language acquisition, it requires a process of understanding what the words mean by integrating and understanding the visual, auditory, and contextual information. It is thought that the right hemisphere works predominantly with respect to its integrating role.

Idiopathic encephalopathy related to status epilepticus during slow sleep (ESES) as a "pure" model of epileptic encephalopathy. An electroclinical, genetic, and follow-up study.

OBJECTIVE: The objective of the study was to investigate electroclinical and neuropsychological features, genetic background, and evolution of children with idiopathic encephalopathy with status epilepticus during slow sleep (ESES), including Landau-Kleffner syndrome (LKS). MATERIAL AND METHODS: All children diagnosed with idiopathic ESES at the Danish Epilepsy Centre between March 2003 and December 2014 were retrospectively reviewed. Repeated 24-hour electroencephalography (24-h EEG) recordings, neuropsychological assessments, and clinical-neurological evaluation were performed throughout the follow-up in all patients. In 13 children, genetic investigations were performed. RESULTS: We collected 24 children (14 males and 10 females). Mean age at ESES diagnosis was 6 years, and mean ESES duration was 2 years and 7 months. Twenty-one children had epileptic seizures. Three children had LKS. Topography of sleep-related EEG epileptic abnormalities was diffuse in 3 subjects, hemispheric in 6, multifocal in 9, and focal in 6. During the active phase of ESES, all children presented with a heterogeneous combination of behavioral and cognitive disturbances. In 14 children, a parallel between severity of the clinical picture and spike-wave index (SWI) was observed. We could not find a strict correlation between the type and severity of neurobehavioral impairment and the side/topography of sleep-related EEG discharges during the active phase of ESES. At the last follow-up, 21 children were in remission from ESES. Complete recovery from neurobehavioral disorders was observed in 5 children. Genetic assessment, performed in 13 children, showed GRIN2A variant in two (15.4%). SIGNIFICANCE: Our patients with idiopathic ESES showed a heterogeneous pattern of epileptic seizures, neurobehavioral disorders, and sleep EEG features. Only one-fourth of children completely recovered from the neuropsychological disturbances after ESES remission. Lack of correlation between severity/type of cognitive derangement and SWI and/or topography of sleep EEG epileptic abnormalities may suggest the contribution of additional factors (including impaired sleep homeostasis due to epileptic activity) in the neurobehavioral derangement that characterize ESES.

Amantadine: A new treatment for refractory electrical status epilepticus in sleep.

PURPOSE: Electrical status epilepticus in sleep (ESES) is an electrographic abnormality linked to language abnormalities and cognitive dysfunction and specifically associated with Landau-Kleffner syndrome (LKS), the syndrome of continuous spike and wave in slow-wave sleep (CSWS), and autistic regression with epileptiform EEG (AREE). As first-line therapies for treatment of ESES display inadequate efficacy and confer substantial risk, we set out to describe our center's experience with amantadine in the treatment of ESES. METHODS: Patients with video-EEG-confirmed ESES who received amantadine were retrospectively identified in a clinical EEG database. Spike-wave index, before and after amantadine exposure, was compared in a pairwise fashion. In an exploratory analysis, we cataloged reported changes in language functioning, cognition, and autistic features, which accompanied treatment. RESULTS: We identified 20 patients with ESES-associated syndromes. Median cumulative weighted average amantadine dosage was 2.1 mg/kg/d (interquartile range (IQR): 1.1, 4.5), and median duration of therapy was 11.5 months (IQR: 7.8, 26.6). In comparison with median baseline spike-wave index (76%), post-amantadine spike-wave index (53%) was reduced, with P = 0.01. Six (30%) patients exhibited complete (or nearly complete) resolution of ESES. A majority of patients exhibited subjective cognitive, linguistic, or behavioral benefit. Amantadine was generally well-tolerated despite substantial dosage and duration of therapy. CONCLUSIONS: This study suggests that amantadine may be effective in the treatment of ESES-associated syndromes but warrants replication in a more rigorous study.

Neurocognitive and behavioral profiles of children with Landau-Kleffner syndrome.

This is a retrospective study of 14 cases of children with Landau-Kleffner syndrome (LKS), the most prominent feature of which is acquired aphasia. These children were followed at a tertiary care pediatric epilepsy center. From the research data base, all LKS cases with neuropsychological evaluation were extracted. Children ranged in age from 6 to 13 years (M = 9.12; SD = 2.19) at the time of assessment (1 to 10 years post-onset). The majority of the children were white males, and all but one continued to experience seizure activity. Global intellectual functioning ranged from 59 to 101 (M = 82.07; SD = 12.14). Across the 14 cases reviewed, the neuropsychological profiles are considered in the context of neurological and syndrome-related factors. For these cases, 86% demonstrated continued expressive, and 50% had receptive language problems with 57% exhibiting poor auditory processing. Furthermore, 50 to 57% had deficits in auditory working memory and verbal memory. Academically, the majority had poor reading fluency and comprehension; 50% exhibited difficulty with mathematics. Finally, 57% evidenced attentional or other behavioral problems. Better understanding of LKS can assist in targeted assessment and intervention planning.

The Impact of 3:1 Ketogenic Diet on Cardiac Repolarization Changes in Children with Refractory Seizures: A Prospective Follow-Up Study.

Background The association between ketogenic diet (KD) and prolonged QT interval, life-threatening ventricular arrhythmias, and sudden death is controversial. Aim We aimed to prospectively evaluate the effect of KD on electrocardiography (ECG) measures in children with refractory epilepsy. Method A total of 70 children with drug-resistant epilepsy who received a KD for at least 12 months were included in the study. The standard 12-lead electrocardiography was performed in all patients before the beginning and in the 12th month of KD. Heart rate, P-wave duration and dispersion, corrected QT interval and QT dispersion, and Tp-e interval were measured. Results All ECG-derived parameters, but P-wave dispersion increased after 12 months of KD compared with the baseline values. However, these changes were not statistically significant. Conclusion A 12-month long 3:1 KD treatment exerts no deleterious effect on cardiac repolarization measures.

Cortical interneuron dysfunction in epilepsy associated with autism spectrum disorders.

Autism and epilepsy are two associated disorders that are highly prevalent, share common developmental origins, and demonstrate substantial heritability. In this review, cross-disciplinary data in a rapidly evolving field that bridges neurology and psychiatry are synthesized to identify shared biologic mechanisms. The relationship between these debilitating, lifelong conditions is examined at the clinical, genetic, and neurophysiologic levels in humans and in animal models. Scopus and PubMed searches were used to identify relevant literature. Clinical observations have prompted speculation about the interdependence of autism and epilepsy, but causal relationships have proved difficult to determine. Despite their heritability, the genetic basis of autism spectrum disorder (ASD) and epilepsy has remained largely elusive until the advent of next-generation sequencing. This approach has revealed that mutations that are either causal or confer an increased disease risk are found in numerous different genes, any one of which accounts for only a small percentage of cases. Conversely, even cases with identical clinical phenotypes can be genetically heterogeneous. Candidate gene identification has facilitated the development of mouse genetic models, which in parallel with human studies have implicated shared brain regions and circuits that mediate disease expression. Diverse genetic causes of ASD and epilepsy converge on cortical interneuron circuits as one important mediator of both disorders. Cortical interneurons are among the most diverse cell types in the brain and their unique chemical and electrical coupling exert a powerful inhibitory influence on excitatory neurons via the release of the neurotransmitter, γ-aminobutyric acid (GABA). These multifaceted approaches have validated theories derived from the field of developmental neurobiology, which propose that the neurologic and neuropsychiatric manifestations are caused by an altered ratio of excitation to inhibition in the cortex.

Episodic epileptic verbal auditory agnosia in Landau Kleffner syndrome treated with combination diazepam and corticosteroids.

We report 2 pediatric patients who presented initially with seizures followed by subacute language regression characterized by a verbal auditory agnosia. These previously normal children had no evidence of expressive aphasia during their symptomatic periods. Further, in both cases, auditory agnosia was associated with sleep-activated electroencephalographic (EEG) epileptiform activity, consistent with Landau-Kleffner syndrome. However, both cases are unique since the episodic auditory agnosia and sleep-activated EEG epileptiform activity rapidly responded to combination therapy with pulse benzodiazepine and corticosteroids. Further, in each case, recurrences were characterized by similar symptoms, EEG findings, and beneficial responses to the pulse benzodiazepine and corticosteroid therapy. These observations suggest that pulse combination high-dose corticosteroid and benzodiazepine therapy may be especially effective in Landau-Kleffner syndrome.

BECTS evolving to Landau-Kleffner Syndrome and back by subsequent recovery: a longitudinal language reorganization case study using fMRI, source EEG, and neuropsychological testing.

By means of a longitudinal case study, we demonstrated the course of cerebral reorganization of language representation due to epilepsy in a child with benign epilepsy with centro-temporal spikes (BECTS) evolving to Landau-Kleffner Syndrome (LKS) and returning to BECTS. The child underwent the following procedures at the ages of 8.2, 8.6, and 9.3 years: 3D source EEG imaging, language fMRI (sentence generation and reading), and neuropsychological testing. He had a follow-up testing at the age of 10.8 years. Further, 24-h EEGs were regularly performed. At the age of around 8 years, the child was diagnosed initially with left-hemispheric BECTS, which evolved to LKS with continuous bilateral discharges. In addition, 3D source imaging data revealed a left anterior temporal focus with a spreading to the right parietal and left centro-parietal areas. The patient had verbal agnosia with poor verbal yet good performance indices. Functional magnetic resonance imaging (fMRI) showed a left-hemispheric reading network but sentence generation was impossible to perform. After initiation of adequate treatment, continuous discharges disappeared, and only very rare left-hemispheric centro-temporal spikes remained. Verbal IQ and performance IQ increased at the age of 8.6 years. Functional magnetic resonance imaging showed, at this time, a right-hemispheric language activation pattern for sentence generation and reading. At the ages of 9.3 and 10.8 years, language tasks remained right-hemispheric and verbal IQ remained stable, but right-hemispheric non-verbal functions decreased due to possible crowding-out mechanisms.

Acquired auditory agnosia in childhood and normal sleep electroencephalography subsequently diagnosed as Landau-Kleffner syndrome: a report of three cases.

AIM: We report three cases of Landau-Kleffner syndrome (LKS) in children (two females, one male) in whom diagnosis was delayed because the sleep electroencephalography (EEG) was initially normal. METHOD: Case histories including EEG, positron emission tomography findings, and long-term outcome were reviewed. RESULTS: Auditory agnosia occurred between the age of 2 years and 3 years 6 months, after a period of normal language development. Initial awake and sleep EEG, recorded weeks to months after the onset of language regression, during a nap period in two cases and during a full night of sleep in the third case, was normal. Repeat EEG between 2 months and 2 years later showed epileptiform discharges during wakefulness and strongly activated by sleep, with a pattern of continuous spike-waves during slow-wave sleep in two patients. Patients were diagnosed with LKS and treated with various antiepileptic regimens, including corticosteroids. One patient in whom EEG became normal on hydrocortisone is making significant recovery. The other two patients did not exhibit a sustained response to treatment and remained severely impaired. INTERPRETATION: Sleep EEG may be normal in the early phase of acquired auditory agnosia. EEG should be repeated frequently in individuals in whom a firm clinical diagnosis is made to facilitate early treatment.

Changing perspectives on Landau-Kleffner syndrome.

Landau-Kleffner syndrome (LKS) is a childhood disorder characterized by an acquired aphasia that emerges in association with epileptiform electroencephalographic abnormalities. The language loss is often characterized by a severe disturbance of auditory language comprehension (verbal auditory agnosia) combined with a substantial disruption of expressive language. Comorbid behavioral disturbances commonly involve hyperactivity and attentional problems but sometimes encompass a more pervasive pattern of difficulties resembling an autism spectrum disorder. Now one the most frequently described forms of acquired aphasia in children, LKS has had a profound influence on both neurological practice and cognitive neuroscience. Here, we review current conceptualizations of LKS, consider its pleomorphic manifestations and discuss existing and future diagnostic issues and dilemmas. The potential relevance of LKS to understanding other disorders, including autistic regression, is considered.

Landau-Kleffner syndrome in Norway: long-term prognosis and experiences with the health services and educational systems.

We have conducted a retrospective study based on the medical records of 19 children with Landau-Kleffner syndrome and semistructured interviews of their parents. There was considerable heterogeneity in the children's symptoms. Eleven children were followed for more than 10 years (mean=14.4 years); four have normal language, four have moderate language problems, and three have no functional verbal language today. Late-onset language decline, short duration of the initial aphasic period, and marked fluctuations in speech abilities appeared to be associated with a positive outcome with respect to future language skills. The parents reported having to argue strongly with the health authorities and educational system to obtain a correct diagnosis and receive adequate help. Their main concern was not being taken seriously when they expressed their worries, and they expressed a strong wish for someone who could ensure that appropriate support measures were implemented and who could coordinate assistance.

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.

Landau-Kleffner syndrome: a rare auditory processing disorder series of cases and review of the literature.

OBJECTIVE: To describe the clinical presentation and treatment of 3 children with an Auditory Processing Disorder with an identifiable neurological cause: Landau-Kleffner syndrome. This classical syndrome is well recognized in pediatric neurology but the diagnosis is less well known to Pediatric Otolaryngology, Speech Language Pathology and Audiology services. METHODS: Retrospective chart review of three patients with Landau-Kleffner syndrome. RESULTS: In all cases, pharmacological intervention led to clinical and electroencephalographic improvement, but all patients had long-term difficulty with understanding sounds in a noisy environment. Magnetic Resonance Imaging (MRI) of the brain was normal in all three patients. Their language disturbance improved over time. Speech language intervention was helpful in addressing communication difficulties arising from the auditory processing/receptive and expressive language disorder. CONCLUSION: A multidisciplinary assessment is the key for early diagnosis, treatment and follow-up in patients with this syndrome.

Nocturnal epileptiform EEG discharges, nocturnal epileptic seizures, and language impairments in children: review of the literature.

This review addresses the effect on language function of nocturnal epileptiform EEG discharges and nocturnal epileptic seizures in children. In clinical practice, language impairment is frequently reported in association with nocturnal epileptiform activity. Vice versa, nocturnal epileptiform EEG abnormalities are a common finding in children with specific language impairment. We suggest a spectrum that is characterized by nocturnal epileptiform activity and language impairment ranging from specific language impairment to rolandic epilepsy, nocturnal frontal lobe epilepsy, electrical status epilepticus of sleep, and Landau-Kleffner syndrome. In this spectrum, children with specific language impairment have the best outcome, and children with electrical status epilepticus of sleep or Landau-Kleffner syndrome, the worst. The exact nature of this relationship and the factors causing this spectrum are unknown. We suggest that nocturnal epileptiform EEG discharges and nocturnal epileptic seizures during development will cause or contribute to diseased neuronal networks involving language. The diseased neuronal networks are less efficient compared with normal neuronal networks. This disorganization may cause language impairments.

Landau-Kleffner syndrome: long-term follow-up.

PURPOSE: Landau-Kleffner syndrome (LKS) is a rare entity characterized by epilepsy and aphasia. It occurs in previously normal children, usually between three and seven years of age. The long-term outcome of LKS is not completely clear. The aim of this study is to verify the long-term follow-up of a group of patients with LKS, focusing on clinical and electroencephalographic (EEG) aspects, and quality of life. METHODS: This was a transversal study. Between November 2006 and April 2007 seven patients with previous diagnosis of LKS were interviewed. They had had a follow-up of three to 16 years after their disease onset. They were all males between the ages of eight and 27 years old. All patients had normal MRI. Parents and/or patients were interviewed by one of the authors using a structured questionnaire. The Vineland Adaptive Behavior Scales, the Conner's Rating Scales-Revised, and Short-Form Health Survey (SF 36) were used. Each patient had a prolonged interictal EEG recording. All patients had normal MRI. RESULTS: The present investigation revealed that two patients still have seizures several years after epilepsy onset. One patient had total and three others had partial remission of language disturbance, while three patients still have aphasia and verbal auditory agnosia. With respect to quality of life, only one of our patients has a normal life at present. The remaining six patients with some sort of limitation consider the aphasia/agnosia to be the main difficulty in their lives. Five patients have normal EEGs. CONCLUSIONS: The long-term follow-up of patients with LKS shows that epilepsy and EEG abnormalities do not always disappear. Language disturbances tend to persist in most patients. The age of onset of language dysfunction does not seem to correlate with the prognosis for recovery of language function. Patients with LKS have an overall poor quality of life, mostly due to language difficulties.