The Landau-Kleffner Syndrome

Diagnostic findings and yield of investigations for children with developmental regression

Childhood conditions that feature developmental regression are poorly understood. Phenotype-genotype characterization and diagnostic yield data are needed to inform clinical decision-making. The aim of this study was to report the conditions featuring developmental regression and assess diagnostic yields of investigations. A retrospective chart review of children presenting with developmental regression to a tertiary pediatric genetic clinic between 2018 and 2021 was performed. Of 99 children, 30% (n = 30) had intellectual disability (ID), 21% (n = 21) were autistic, 39% (n = 39) were autistic with ID, and 9% (n = 9) did not have ID or autism. Thirty-two percent (n = 32) of children received a new diagnosis, including eight molecular findings not previously reported to feature developmental regression. Of the children investigated, exome sequencing (ES) provided the highest diagnostic yield (51.1%, n = 24/47), highest (63.6%, n = 14/22) for children with ID, 50% for autistic children with ID (n = 6/12) and children without autism or ID (n = 3/6), and 14.3% (n = 1/7) for autistic children without ID. We highlight the conditions that feature developmental regression and report on novel phenotypic expansions. The high diagnostic yield of ES, regardless of autism or ID diagnosis, indicates the presence of developmental regression as an opportunity to identify the cause, including for genetic differences not previously reported to include regression.

Landau-Kleffner syndrome (LKS) in an 8-year-old girl: a case report and review of the literature

Introduction and importance

Landau-Kleffner syndrome (LKS) is a rare epileptic encephalopathy characterized by language regression and abnormal electroencephalogram (EEG) patterns. This case report highlights the importance of early recognition and intervention in LKS, as well as the challenges in diagnosis and management due to its varied clinical manifestations.

Case presentation

An 8-year-old girl presented with delayed speech, suspected hearing loss, and regression in language skills. Diagnostic tests revealed mild sensorineural hearing loss and EEG abnormalities consistent with LKS. The patient underwent speech therapy and received pharmacological treatment with valproic acid, resulting in significant improvements in language function.

Clinical discussion

This case report provides insights into the typical features of LKS, including language regression and EEG abnormalities. It also highlights uncommon findings such as sensorineural hearing loss and mild intellectual delay. The multidisciplinary approach involving neurology, audiology, speech therapy, and education is crucial in the diagnosis and management of LKS.

Conclusion

Early recognition and intervention, along with tailored pharmacological approaches and a multidisciplinary care approach, are essential in managing LKS. Further research is needed to better understand the pathophysiology, natural history, and optimal treatment of LKS, aiming to improve long-term outcomes for affected children and their families.

Systematic Assessment of Protein C-Termini Mutated in Human Disorders

All proteins have a carboxyl terminus, and we previously summarized eight mutations in binding and trafficking sequence determinants in the C-terminus that, when disrupted, cause human diseases. These sequence elements for binding and trafficking sites, as well as post-translational modifications (PTMs), are called minimotifs or short linear motifs. We wanted to determine how frequently mutations in minimotifs in the C-terminus cause disease. We searched specifically for PTMs because mutation of a modified amino acid almost always changes the chemistry of the side chain and can be interpreted as loss-of-function. We analyzed data from ClinVar for disease variants, Minimotif Miner and the C-terminome for PTMs, and RefSeq for protein sequences, yielding 20 such potential disease-causing variants. After additional screening, they include six with a previously reported PTM disruption mechanism and nine with new hypotheses for mutated minimotifs in C-termini that may cause disease. These mutations were generally for different genes, with four different PTM types and several different diseases. Our study helps to identify new molecular mechanisms for nine separate variants that cause disease, and this type of analysis could be extended as databases grow and to binding and trafficking motifs. We conclude that mutated motifs in C-termini are an infrequent cause of disease.

Auditory phoneme discrimination, articulation, and language disorders in patients with genetic epilepsy with febrile seizures plus: A case-control study

INTRODUCTION

Genetic epilepsy with febrile seizures plus (GEFS+) is an epilepsy syndrome with clinical heterogeneity that was first described in 1997. Central auditory processing (CAP) is defined as the neurophysiological process in decoding sound waves from the outer ear to the auditory cortex. The present study aimed to analyze CAP and phonological disorders in preschool-age children with GEFS+.

MATERIAL AND METHOD

This is a prospective case-control study. Twenty-seven patients diagnosed with GEFS+ aged between 4 years and 6 years and 6 months and 31 healthy controls in the same age range were included in the study. Phonological sensitivity test (SAT) and auditory discrimination test (İAT) were applied to both groups, and the results of both groups were statistically compared.

RESULTS

The SAT and İAT raw and Z scores of the subjects in the study group were found to be significantly higher than those of the control group (p = 0.001; p < 0.01). Electroencephalography (EEG) status of the patients or the duration of antiseizure medication use did not have a statistically significant effect on the outcome.

CONCLUSION

Patients with GEFS+ have a significantly high impairment in both articulation and auditory discrimination of phonemes compared with the healthy population. Early diagnosis and early treatment of this condition can prevent potential literacy problems and the development of dyslexia in the future.

Alternatives to Gold Standard Diagnostic Tools for Distinguishing "Natural Kinds" on the Autism Spectrum

Next-generation sequencing techniques have accelerated the discovery of rare mutations responsible for autism spectrum disorder (ASD) in genes involved in a large number of physiological processes, including the control of gene expression, chromatin remodeling, signaling pathways, synaptic scaffolding, neurotransmitter receptors, and lipid metabolism. Genetic diagnosis provides subjects with an explanation of the cause of their disorder. However, it does not, or at least does not yet, shed light on the psychopathological phenomena specific to the individual. It could be hypothesized that each physiological impact of a mutation corresponds to a specific psychopathological phenomenon of ASD, i.e., "a psychopathological natural kind". We discuss here the difficulties identifying this specificity of underlying psychopathology in individuals with ASD due to a rare mutation with a major effect. A comparison of Newson's pathological demand avoidance and Wing's Asperger's syndrome with Asperger's autistic psychopathy highlights different ways of approaching psychopathological descriptions and diagnosis, by focusing on either common or unusual features. Such a comparison calls into question the principles of clinical research recommended by Falret for characterizing "disease individuality" of ASD due to a rare mutation.

Cerebral dominance in an unusual case of Landau-Kleffner syndrome

Landau-Kleffner syndrome (LKS) is described by the International Classification of Epileptic Syndromes since 1985 as a constellation of clinical and electrographic signs, including acquired aphasia, regression of language milestones and seizures, along with sleep-activated paroxysms on electroencephalogram which can progress to electrographic status epilepticus of sleep. In this case, a 7-year-old boy presented with an atypical history of new-onset aphasia and regression of language milestones with rare seizures. However, there was an electrographic mismatch in the form of right-sided epileptiform activity and continuous spike and wave of sleep pattern. Detailed speech analysis and perusal of the history revealed a possibly ambidextrous child with right hemispheric language dominance, and he was diagnosed with LKS and treated. This report illustrates the many pitfalls in the diagnosis and treatment of this rare epileptic syndrome.

Morphometry and functional connectivity of auditory cortex in school-age children with profound language disabilities: Five comparative case studies

Many neurodevelopmental conditions imply absent or severely reduced language capacities at school age. Evidence from functional magnetic resonance imaging is highly limited. We selected a series of five cases scanned with the same fMRI paradigm and the aim of relating individual language profiles onto underlying patterns of functional connectivity (FC) across auditory language cortex: three with neurogenetic syndromes (Coffin-Siris, Landau-Kleffner, and Fragile-X), one with idiopathic intellectual disability, one with autism spectrum disorder (ASD). Compared to both a group with typical development (TD) and a verbal ASD group (total N = 110), they all showed interhemispheric FC below two standard deviations of the TD mean. Children with higher language scores showed higher intrahemispheric FC between Heschl's gyrus and other auditory language regions, as well as an increase of FC during language stimulation compared to rest. An increase of FC in forward vs. reversed speech in the posterior and middle temporal gyri was seen across all cases. The Coffin-Siris case, the most severe, also had the most anomalous FC patterns and showed reduced myelin content, while the Landau-Kleffner case showed reduced cortical thickness. These results suggest potential for neural markers and mechanisms of severe language processing deficits under highly heterogeneous etiological conditions.

Electroencephalography in Assessment of Autism Spectrum Disorders: A Review

Electroencephalography (EEG) can further out our understanding of autistic spectrum disorders (ASD) neurophysiology. Epilepsy and ASD comorbidity range between 5 and 46%, but its temporal relationship, causal mechanisms and interplay with intellectual disability are still unknown. Epileptiform discharges with or without seizures go as high as 60%, and associate with epileptic encephalopathies, conceptual term suggesting that epileptic activity can lead to cognitive and behavioral impairment beyond the underlying pathology. Seizures and ASD may be the result of similar mechanisms, such as abnormalities in GABAergic fibers or GABA receptor function. Epilepsy and ASD are caused by a number of genetic disorders and variations that induce such dysregulation. Similarly, initial epilepsy may influence synaptic plasticity and cortical connection, predisposing a growing brain to cognitive delays and behavioral abnormalities. The quantitative EEG techniques could be a useful tool in detecting and possibly measuring dysfunctions in specific brain regions and neuronal regulation in ASD. Power spectra analysis reveals a U-shaped pattern of power abnormalities, with excess power in the low and high frequency bands. These might be the consequence of a complicated network of neurochemical changes affecting the inhibitory GABAergic interneurons and their regulation of excitatory activity in pyramidal cells. EEG coherence studies of functional connectivity found general local over-connectivity and long-range under-connectivity between different brain areas. GABAergic interneuron growth and connections are presumably impaired in the prefrontal and temporal cortices in ASD, which is important for excitatory/inhibitory balance. Recent advances in quantitative EEG data analysis and well-known epilepsy ASD co-morbidity consistently indicate a role of aberrant GABAergic transmission that has consequences on neuronal organization and connectivity especially in the frontal cortex.

Acquired epileptiform aphasia: 44 years after diagnosis

We report a case of a 48-year-old woman who was diagnosed with Landau-Kleffner syndrome (LKS) at the age of 4 and reassessed by the same neurologist four decades later. While her seizures abated by the time she was 12 years old, she was left with chronic aphasia, despite receiving optimal care. Although she graduated from high school, started her own family, and was gainfully employed, she was vulnerable in situations that required clear communication. This case reflects successful management of an otherwise debilitating condition and reminds us of the vulnerability of adults with LKS and their need for a life-long support.

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Acquired epileptiform aphasia, and LKS as its variant, has lifelong consequences.

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Even those who recover relatively well from LKS face lifelong social, communication and economic challenges.

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Educational and psychological support with effective social restructuring may be necessary for adults with LKS.

Social cognition and psychopathology in childhood and adolescence

There is a substantial body of research on social cognition in adults with epilepsy, and in broad categories such as focal and generalized epilepsies, but much less has been written about social cognition in children with epilepsy (CWE), and in childhood-onset epilepsy syndromes specifically. In several of these syndromes, autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD), two disorders with social cognitive impairments, are reported. There is strong evidence for social cognitive deficits in juvenile myoclonic epilepsy (JME). There is also a considerable amount of evidence for such deficits in a number of syndromes that may be associated with ASD or ADHD, including West syndrome (WS), Dravet syndrome (DS), and the Landau-Kleffner syndrome (LKS). However, the evidence is of variable quality and incomplete across the range of childhood epilepsy syndromes. In some syndromes, childhood epilepsy substantially increases the risk of severe social cognitive impairment, which may persist after the seizures remit. This paper presents an overview of current research on social cognition in childhood epilepsy, with a particular focus on syndromes with a high prevalence of autistic and behavioral comorbidities. Social cognitive impairments represent a considerable additional challenge for patients and caregivers. Early diagnosis and intervention might significantly improve long-term social cognitive outcomes, highlighting the need for greater awareness among clinicians of this important topic. This article is part of the Special Issue "Epilepsy and social cognition across the lifespan".

Language and behavioral outcomes of treatment with pulse-dose prednisone for electrical status epilepticus in sleep (ESES)

Few studies have examined treatment response in electrical status epilepticus in sleep (ESES), and fewer still have evaluated the effect of corticosteroid treatment employing a pulse-dose regimen. The aim of this study was to examine the effectiveness of pulse-dose prednisone in treating language and behavioral disturbances that often accompany ESES. The sample included 17 patients age 5 to 10 years at time of baseline electroencephalogram (EEG) and neuropsychological assessments. For all patients, focal, multifocal, or generalized spike and wave activity occupied greater than 50% of the nonrapid eye movement (REM) sleep record. Patients were seen for follow-up EEG recording and neuropsychological testing with an average of 10 months following initiation of pulse-dose prednisone. Improvement in language or behavior was examined in relation to resolution of ESES on EEG, age at seizure onset and treatment, duration of ESES, duration of treatment, lesional versus nonlesional epilepsy, history of language or behavioral regression, seizure control at follow-up, and intelligence quotient (IQ). With the exception of a greater likelihood of patients with low IQ to demonstrate improvement in language or behavior, improvement was seen in most patients, irrespective of ESES or other factors.

The inhibitory effect of functional lesions on eloquent brain areas: from research bench to operating bed

Objectives: Functioning, but injured cerebral connections are hypothesized to inhibit cortical plasticity. Study of neural networks can validate this hypothesis, and provide further practical clues for clinical and surgical options to restore function in eloquent brain areas. Material and methods: Cortical lesions in eloquent areas were simulated by means of artificial neural networks. Next, functional restoration of these networks after lesional bypass was studied. Results: The accuracy of network outputs was reduced from 92% to 72% (P-value < 0.001) when logical temporal connections with dysfunctional lesions were established. Restoration of function was almost totally achieved by bypassing the lesion, without any significant changes in network nodal weights. Estimated remaining functional fraction errors were trivial (0.0044%-1.4%). Discussion: Examples of functional decline due to disturbing signals are Todd's paralysis and Landau-Kleffner syndrome. Functional restoration after lesionectomy in eloquent areas of the brain is also practiced. Likewise, injured connections provide routes of influence for disturbing impulses. Conclusion: Herein, the proposed evidences provide theoretical clues to formulate new avenues in restorative functional neurosurgery. They may help to identify suitable lesions and suitable techniques for functional restoration including dissection of disturbing connections, bridging and bypassing lesions that can be corroborated by simulation.

Influence of valproate on language functions in children with epilepsy

The aim of the current study was to assess the influences of valproate (VPA) on the language functions in newly diagnosed pediatric patients with epilepsy. We reviewed medical records of 53 newly diagnosed patients with epilepsy, who were being treated with VPA monotherapy (n=53; 22 male patients and 31 female patients). The subjects underwent standardized language tests, at least twice, before and after the initiation of VPA. The standardized language tests used were The Test of Language Problem Solving Abilities, a Korean version of The Expressive/Receptive Language Function Test, and the Urimal Test of Articulation and Phonology. Since all the patients analyzed spoke Korean as their first language, we used Korean language tests to reduce the bias within the data. All the language parameters of the Test of Language Problem Solving Abilities slightly improved after the initiation of VPA in the 53 pediatric patients with epilepsy (mean age: 11.6±3.2years), but only "prediction" was statistically significant (determining cause, 14.9±5.1 to 15.5±4.3; making inference, 16.1±5.8 to 16.9±5.6; prediction, 11.1±4.9 to 11.9±4.2; total score of TOPS, 42.0±14.4 to 44.2±12.5). The patients treated with VPA also exhibited a small extension in mean length of utterance in words (MLU-w) when responding, but this was not statistically significant (determining cause, 5.4±2.0 to 5.7±1.6; making inference, 5.8±2.2 to 6.0±1.8; prediction, 5.9±2.5 to 5.9±2.1; total, 5.7±2.1 to 5.9±1.7). The administration of VPA led to a slight, but not statistically significant, improvement in the receptive language function (range: 144.7±41.1 to 148.2±39.7). Finally, there were no statistically significant changes in the percentage of articulation performance after taking VPA. Therefore, our data suggested that VPA did not have negative impact on the language function, but rather slightly improved problem-solving abilities.

Autism spectrum disorder and epileptic encephalopathy: common causes, many questions

Epileptic encephalopathies represent a particularly severe form of epilepsy, associated with cognitive and behavioral deficits, including impaired social-communication and restricted, repetitive behaviors that are the hallmarks of autism spectrum disorder (ASD). With the advent of next-generation sequencing, the genetic landscape of epileptic encephalopathies is growing and demonstrates overlap with genes separately implicated in ASD. However, many questions remain about this connection, including whether epileptiform activity itself contributes to the development of ASD symptomatology. In this review, we compiled a database of genes associated with both epileptic encephalopathy and ASD, limiting our purview to Mendelian disorders not including inborn errors of metabolism, and we focused on the connection between ASD and epileptic encephalopathy rather than epilepsy broadly. Our review has four goals: to (1) discuss the overlapping presentations of ASD and monogenic epileptic encephalopathies; (2) examine the impact of the epilepsy itself on neurocognitive features, including ASD, in monogenic epileptic encephalopathies; (3) outline many of the genetic causes responsible for both ASD and epileptic encephalopathy; (4) provide an illustrative example of a final common pathway that may be implicated in both ASD and epileptic encephalopathy. We demonstrate that autistic features are a common association with monogenic epileptic encephalopathies. Certain epileptic encephalopathy syndromes, like infantile spasms, are especially linked to the development of ASD. The connection between seizures themselves and neurobehavioral deficits in these monogenic encephalopathies remains open to debate. Finally, advances in genetics have revealed many genes that overlap in ties to both ASD and epileptic encephalopathy and that play a role in diverse central nervous system processes. Increased attention to the autistic features of monogenic epileptic encephalopathies is warranted for both researchers and clinicians alike.

Vision as a Beachhead

When neural circuits develop abnormally due to different genetic deficits and/or environmental insults, neural computations and the behaviors that rely on them are altered. Computational theories that relate neural circuits with specific quantifiable behavioral and physiological phenomena, therefore, serve as extremely useful tools for elucidating the neuropathological mechanisms that underlie different disorders. The visual system is particularly well suited for characterizing differences in neural computations; computational theories of vision are well established, and empirical protocols for measuring the parameters of those theories are well developed. In this article, we examine how psychophysical and neuroimaging measurements from human subjects are being used to test hypotheses about abnormal neural computations in autism, with an emphasis on hypotheses regarding potential excitation/inhibition imbalances. We discuss the complexity of relating specific computational abnormalities to particular underlying mechanisms given the diversity of neural circuits that can generate the same computation, and we discuss areas of research in which computational theories need to be further developed to provide useful frameworks for interpreting existing results. A final emphasis is placed on the need to extend existing ideas into developmental frameworks that take into account the dramatic developmental changes in neurophysiology (e.g., changes in excitation/inhibition balance) that take place during the first years of life, when autism initially emerges.

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.

Levetiracetam reduces the frequency of interictal epileptiform discharges during NREM sleep in children with ADHD

BACKGROUND

Symptoms of attention deficit hyperactivity disorder (ADHD) are more common in children with epilepsy than in the general paediatric population. Epileptiform discharges in EEG may be seen in children with ADHD also in those without seizure disorders. Sleep enhances these discharges which may be suppressed by levetiracetam.

AIM

To assess the effect of levetiracetam on focal epileptiform discharges during sleep in children with ADHD.

METHOD

In this retrospective study a new semi-automatic quantitative method based on the calculation of spike index in 24-h ambulatory EEG recordings was applied. Thirty-five ADHD children, 17 with focal epilepsy, one with generalised epilepsy, and 17 with no seizure disorder were evaluated. Follow-up 24-h EEG recordings were performed after a median time of four months.

RESULTS

Mean spike index was 50 prior to levetiracetam treatment and 21 during treatment. Seventeen children had no focal interictal epileptiform discharges in EEG at follow-up. Five children had a more than 50% reduction in spike index. Thus, a more than 50% reduction in spike index was found in 22/35 children (63%). Out of these an improved behaviour was noticed in 13 children (59%).

CONCLUSION

This study shows that treatment with levetiracetam reduces interictal epileptiform discharges in children with ADHD. There is a complex relationship between epilepsy, ADHD and epileptiform activity, why it is a need for prospective studies in larger sample sizes, also to ascertain clinical benefits.

Rational treatment options with AEDs and ketogenic diet in Landau-Kleffner syndrome: still waiting after all these years

Antiepileptic drugs (AEDs) remain a first treatment approach in Landau-Kleffner syndrome (LKS) and related syndromes. In the current literature, only class IV evidence is available. Inclusion criteria and outcome parameters are ill-defined. Most commonly, valproate, ethosuximide, and/or benzodiazepines are used. More recent case series show that sulthiame and especially levetiracetam can be considered as effective drugs. Smaller studies also point to the ketogenic diet as a valuable treatment option in LKS.

A child with refractory complex partial seizures, right temporal ganglioglioma, contralateral continuous electrical status epilepticus, and a secondary Landau-Kleffner autistic syndrome

A 7-year-old, right-handed girl started to have seizures at age 1 year 4 months. She developed normally until age 4 when she had worsening of seizures with auditory verbal agnosia, complete aphasia, and a behavioral disorder fulfilling the diagnostic criteria of autism. Medical therapy failed. MRI revealed a right temporal tumor. Video/EEG monitoring at age 7 showed contralateral electrical status epilepticus in wakefulness and sleep and ipsilateral onset of seizures. Resection (ganglioglioma with excessive inflammation) resulted in seizure freedom and marked reduction of the autistic features. This case is unique for being, to our knowledge, (1) the first in which a lesion located in the right, rather than left, temporal lobe resulted in secondary falsely localizing left temporal lobe electrical status epilepticus with a clinical picture of Landau-Kleffner syndrome and autism, and (2) the fourth reported patient with lesional Landau-Kleffner syndrome to respond to resective surgery.

Aphasia: Associated Disturbances in Affect, Behavior, and Cognition in the Setting of Speech and Language Difficulties

Patients with disturbances in affect, behavior, and cognition present a variety of challenges to healthcare providers; their evaluation and treatment becomes especially problematic in the setting of speech and language difficulties. The authors present the case of a man who sustained a left-side cerebrovascular accident with aphasia and discuss the approach to his diagnosis and treatment. Moreover, since a variety of speech and language problems can arise after stroke and since patients and their treaters can become frustrated by impaired communication and diagnostic uncertainties, authors review the clinical manifestations, timing, and treatment of such conditions so that treatment can be improved.

Landau–Kleffner syndrome is not an eponymic badge of ignorance

In a 1992 editorial article, Landau expressed the hope of collective agreement in the medical community about Landau-Kleffner syndrome (LKS) in terms of diagnosis criteria, etiology, pathophysiology and rational therapy. Since then, neurophysiological and neuroimaging studies have led to the view that LKS is an acquired aphasia, secondary to an epileptic disturbance affecting a cortical area involved in verbal processing. This fits with the hypothesis of a "functional ablation" caused by epileptic activity. Under these criteria, epileptic aphasia becomes a subgroup of the continuous spike-waves syndrome in which epileptic discharges originate from the temporal cortex. Genetic predisposition for KLS could be related to hyperexcitability and synchronization of interneurons within the perisylvian cortices, which generate the spike-waves. Activation of these waves during NREM sleep, following thalamo-cortical uncoupling, might then alter the blood brain barrier and provoke an autoimmune reaction. Interneuron hyperactivity might in turn have an antiepileptic protective effect, associated with the inhibition of a specific function, and spike-waves activity over the long term might eventuate in focal atrophy. This morphological defect might explain the poor verbal outcome in some cases of LKS. From this study we recommend a multicenter control study of good design and methodology be carried out to compare the efficacies of early versus delayed (3 months) corticosteroid treatment in patients with typical LKS that is being treated by clobazam (or diazepam) monotherapy.

Landau-Kleffner syndrome with mitochondrial respiratory chain-complex I deficiency

Landau-Kleffner syndrome is characterized by epileptic aphasia associated with electrical status epilepticus of slow wave sleep. A 5-year-old female, who had manifested normal developmental progress, was referred with principal complaints of fluctuating sensory aphasia and bizarre behavior during the preceding 4 months. Landau-Kleffner syndrome was confirmed by clinical and electroencephalographic features; in addition, the patient's mitochondrial respiratory chain-complex I deficiency was confirmed by fibroblast culture with the evidence of energy metabolism disorder. This patient's seizures were intractable to many antiepileptic drugs, adrenocorticotrophic hormone, and intravenous immunoglobulin, with catastrophic cognitive and behavioral decline, but the seizures were successfully controlled by ketogenic diet with supplementary mitochondrial cocktail including coenzyme Q10, riboflavin, L-carnitine, and high-dose multivitamins. The patient finally regained fully normal cognitive functioning. Landau-Kleffner syndrome with mitochondrial respiratory chain-complex I deficiency was controlled in this case by ketogenic diet and supplementary mitochondrial cocktail therapy.

Children with ESES: variability in the syndrome

OBJECTIVE

We undertook a retrospective study of children who present with significant activation of paroxysmal discharges during sleep to examine the clinical spectrum of disorders that present with such an EEG abnormality.

BACKGROUND

Electrical status epilepticus in sleep (ESES) is an electrographic pattern characterized by nearly continuous spike-wave discharges in slow wave sleep, usually with a frequency of 1.5-3 Hz and usually diffuse and bilateral in distribution. A variety of neurocognitive and behavioral problems have been associated with this EEG pattern.

METHODS

We conducted a retrospective review of 1497 EEG records of patients admitted to University of California, Los Angeles (UCLA) for overnight video-EEG monitoring during a 5 year interval. Demographic, clinical and electroencephalographic variables were evaluated.

RESULTS

EEG records for 102 patients meeting criteria were identified. Clinical information was available for 90 of those patients. Eighteen of these patients could be diagnosed with Landau-Kleffner syndrome (LKS). Key findings include: (1) neuroimaging abnormalities were uncommon in our LKS patients; (2) among children who do not fit the specific diagnostic criteria for LKS, a spike-wave index (SWI) >50% was more likely to be associated with global developmental disturbances than SWI < or =50% (p<0.05); (3) Children with generalized discharges were more likely to experience severe or global developmental disturbance than those with focal abnormalities, without reaching statistical significance (p=0.07).

CONCLUSIONS

Severity of ESES can vary over time between and within patients and clinical status does not always directly correlate with SWI. However, the prognosis of LKS is substantially better than CSWS and these two disorders could be classified in a dichotomous manner rather than be seen as two points along a continuum.

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.

Role of interictal epileptiform abnormalities in cognitive impairment

The epileptic encephalopathies are conditions in which neurological deterioration is attributable entirely or partly to epileptic activity and is due to very frequent or severe seizures or severely abnormal electroencephalograms (EEGs), or both. Evidence for the concept that seizures or the abnormal EEGs are responsible for the cognitive deterioration is the observation that patients can improve dramatically when therapy eliminates or reduces seizure frequency and improves or normalizes the EEG. For example, children with the syndrome of continuous spike-wave of sleep (CSWS) have electrical status epilepticus during sleep (ESES) and cognitive regression. Although seizures often occur in the disorder, there are indications that the EEG abnormalities are responsible for the cognitive regression. Interictal spikes, which correspond to a large intracellular depolarization with evoked action potentials, in many ways mimic a "miniseizure." Interictal spikes can result in transitory cognitive impairment with the type of deficit dependent on where in the cortex the spike arises. We suggest that interictal spikes, particularly if frequent and widespread, can impair cognitive abilities, through interference with waking learning and memory, and memory consolidation during sleep.

Converging evidences on language impairment in Landau–Kleffner Syndrome revealed by behavioral and brain activity measures: A case study

OBJECTIVE

To assess the linguistic abilities of a boy having Landau-Kleffner Syndrome, and relate the focal disturbance of brain activity due to epilepsy to the cognitive and linguistic deficits.

METHODS

Several kinds of assessments were carried out, including epileptic source analysis using electronic source localization methods and PET, neuropsychological assessment of cognitive functions, and assessment of speech perception skills (discrimination of phonetic and stress cues) using ERPs.

RESULTS

The source of epileptic activity was localized in the left superior temporal lobe. The neuropsychological assessment showed dissociation between verbal and nonverbal functions, and the performance in former was bellow the normal range. ERPs obtained to the processing of phonetic and stress speech cues indicated that the two cues were processed asymmetrically: the mismatch negativity component (MMN) was obtained for the phoneme difference, but not for the stress pattern difference.

CONCLUSIONS

Our data converged as it showed that the patient presented a selective impairment of the language system, and the verbal working memory system appeared to be especially defective. It is suggested that the language deficit is at least partly due to the focal disturbance of those neural networks that underlie the functioning of the working memory system.

SIGNIFICANCE

LKS is a childhood language disorder that might serve as a model in studying what happens to the language system if, in the course of development, the essential neural circuits are severely disturbed.