Diagnosis and management of epileptic encephalopathies in children

128 The Association Between Serum Levels of Glial Biomarkers, Clinical Severity and Electro-encephalography Features in Idiopathic West and Lennox-Gastaut Syndromes

Introduction

Although the contribution of enhanced glial activity in seizure induction is increasingly recognized, the role of glia-induced neuroinflammation in the physiopathology of epileptic encephalopathy (EE) has been scarcely investigated.

Methods

To delineate the contribution of glial activity in EE, we measured levels of glia-derived mediators with previously described biomarker value, including glial fibrillary acidic protein (GFAP), high mobility group box 1 (HMGB1), chitinase-3-like protein 1 (CHI3L1), soluble CD163 (sCD163) and triggering receptor expressed on myeloid cells 2 (TREM2) by ELISA in sera of patients with idiopathic West syndrome (WS, n=18), idiopathic Lennox-Gastaut syndrome (LGS, n=13) and healthy controls (n=31).

Results

Patients with EE showed significantly higher CHI3L1 levels compared to healthy controls. Levels of HMGB1, CHI3L1, sCD163 and TREM2 were higher in LGS patients than WS patients and/or healthy controls. One or more of the investigated mediators were associated with treatment responsiveness, disease severity and presence of pathological features on electroencephalography (EEG).

Conclusions

To our knowledge, our findings provide the initial patient-based evidence that astrocyte- and microglia-mediated neuroinflammation might be involved in the pathogenesis of LGS and WS. Moreover, glial mediators may serve as prognostic biomarkers in patients with idiopathic EE.

GABRG1 variant as a potential novel cause of epileptic encephalopathy, hypotonia, and global developmental delay

Epileptic encephalopathies (EEs) are severe brain disorders with excessive ictal (seizure) and interictal (electrographic epileptiform discharges) activity in developing brain which may result in progressive cognitive and neuropsychological deterioration. In contrast to regular epilepsy where the treatment goal is to prevent the seizure (ictal) recurrence, in patients with EE the goal is to treat both ictal as well as interictal activity to prevent further progression. With the introduction of genetic sequencing technologies over the past 20 years, there is growing recognition of the genetic basis of EE, with the majority due to monogenic causes. Monogenic etiologies of EE include pathogenic variants in the γ-aminobutyric acid type A receptor (GABA-A) encoding gene family. We present a 2-year-old patient with EE, hypotonia, and global developmental delays. Clinical trio exome sequencing showed a novel, de novo variant in GABRG1. GABRG1 encodes the γ1 subunit of the GABA-A receptor. To date, there has not been an association of EE with pathogenic variants in GABRG1. This variant is predicted to be damaging to protein structure and function, and the patient's phenotype is similar to those with pathogenic variants in other members of the GABA-A receptor encoding gene family.

Novel dominant and recessive variants in human ROBO1 cause distinct neurodevelopmental defects through different mechanisms

The Roundabout (Robo) receptors, located on growth cones of neurons, induce axon repulsion in response to the extracellular ligand Slit. The Robo family of proteins controls midline crossing of commissural neurons during development in flies. Mono- and bi-allelic variants in human ROBO1 (HGNC: 10249) have been associated with incomplete penetrance and variable expressivity for a breath of phenotypes, including neurodevelopmental defects such as strabismus, pituitary defects, intellectual impairment, as well as defects in heart and kidney. Here, we report two novel ROBO1 variants associated with very distinct phenotypes. A homozygous missense p.S1522L variant in three affected siblings with nystagmus; and a monoallelic de novo p.D422G variant in a proband who presented with early-onset epileptic encephalopathy. We modeled these variants in Drosophila and first generated a null allele by inserting a CRIMIC T2A-GAL4 in an intron. Flies that lack robo1 exhibit reduced viability but have very severe midline crossing defects in the central nervous system. The fly wild-type cDNA driven by T2A-Gal4 partially rescues both defects. Overexpression of the human reference ROBO1 with T2A-GAL4 is toxic and reduces viability, whereas the recessive p.S1522L variant is less toxic, suggesting that it is a partial loss-of-function allele. In contrast, the dominant variant in fly robo1 (p.D413G) affects protein localization, impairs axonal guidance activity and induces mild phototransduction defects, suggesting that it is a neomorphic allele. In summary, our studies expand the phenotypic spectrum associated with ROBO1 variant alleles.

Nordic treatment guidelines for rare epileptic conditions: A literature review

INTRODUCTION

The onset of severe, drug-resistant seizures in early childhood is characteristic of the rare epileptic disorders Lennox-Gastaut syndrome (LGS), Dravet syndrome (DS), and CDKL5 deficiency disorder (CDD) and is frequently observed in the rare genetic conditions tuberous sclerosis complex (TSC) and Rett syndrome (RTT). High-quality treatment guidelines are needed for optimal management of these conditions. This review aimed to assess content, availability, and development of treatment guidelines for these disorders in the Nordics region (Denmark, Finland, Iceland, Norway, and Sweden).

METHODS

A targeted literature review (TLR) was therefore conducted in November/December 2020 by manually searching online rare disease and guideline databases in addition to relevant health technology assessment and regulatory agency websites to identify pharmacological treatment guidelines for DS, LGS, TSC, RTT, and CDD. Search terms for each disorder were translated to identify country-specific guidelines. Treatment recommendations, geographical focus, and guideline development methodology was extracted into a predetermined extraction grid.

RESULTS

Most of the 24 eligible guidelines identified (16/24; 66%) were specific to particular countries; Sweden was the most represented (7/24 [29%] guidelines), while no guidelines were identified for Iceland. Guideline development methodologies were heterogeneous, including systematic literature reviews/TLRs and expert consultation; several methodologies did not report details on the evidence sources used (7/24 [29%] guidelines). Treatment recommendation availability was variable across disorders, ranging from 126 treatment recommendations (LGS) to none (RTT, CDD).

CONCLUSION

Comprehensive, consensus-based treatment guidance developed via international collaboration within the Nordics region is necessary to optimize patient care in these five rare epileptic conditions.

Treatment Guidelines for Rare, Early-Onset, Treatment-Resistant Epileptic Conditions: A Literature Review on Dravet Syndrome, Lennox-Gastaut Syndrome and CDKL5 Deficiency Disorder

Background: Dravet syndrome (DS), Lennox-Gastaut syndrome (LGS) and CDKL5 deficiency disorder (CDD) are rare epileptic conditions, characterised by drug-resistant seizures. Seizure management in these patients requires careful therapy selection. This targeted literature review (TLR) aimed to collate and synthesise information from country-specific and international treatment guidelines for DS, LGS and CDD. Methods: A TLR was performed between 25th January and 11th March 2021. Online rare diseases and guideline databases were manually searched in addition to websites of national health technology assessment bodies for the following countries: Australia, Canada, France, Germany, Israel, Italy, Japan, Spain, Switzerland, UK and US, as defined by pre-specified eligibility criteria. Search terms, developed for each condition, were translated into local languages where appropriate. Descriptive analyses were performed to examine the geographical distribution of included guidelines; methodologies used to develop guidelines; cross-referencing of treatment recommendations made within other guidelines; patterns of treatment recommendations. An author map was created using R version 3.5.1, to visualise the extent of collaboration between authors. Results: Forty total guidelines were included, of which 29, 34 and 0 contained recommendations for DS, LGS and CDD, respectively (some provided recommendations for ≥1 condition). Most were country-specific, with guideline authors predominantly publishing in regional groups. Five guidelines were classified as "International" and displayed connections between author groups in the US, UK, France and Italy. Reported guideline development processes were lacking [43% (17 guidelines) had unclear/absent literature review methodologies] and those reported were variable, including both systematic and targeted literature reviews. Use of expert consultation was also variable. A high degree of heterogeneity was observed in the availability of treatment recommendations across disorders, with 271 and 190 recommendations for LGS and DS, respectively, and contradictory positive and negative treatment recommendations for several drugs in each indication [35% (11/31) and 22% (6/27) in LGS and DS, respectively]. Conclusions: This review highlights the need for further high-quality international consensus-based treatment guidelines for LGS, DS, and particularly for CDD (for which no treatment guidelines were identified). Supra-national consensus guidance based on findings from a wider geographical range may improve resource allocation and establish an improved world-wide standard of care.

Exome and genome sequencing for pediatric patients with congenital anomalies or intellectual disability: an evidence-based clinical guideline of the American College of Medical Genetics and Genomics (ACMG)

PURPOSE

To develop an evidence-based clinical practice guideline for the use of exome and genome sequencing (ES/GS) in the care of pediatric patients with one or more congenital anomalies (CA) with onset prior to age 1 year or developmental delay (DD) or intellectual disability (ID) with onset prior to age 18 years.

METHODS

The Pediatric Exome/Genome Sequencing Evidence-Based Guideline Work Group (n = 10) used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) evidence to decision (EtD) framework based on the recent American College of Medical Genetics and Genomics (ACMG) systematic review, and an Ontario Health Technology Assessment to develop and present evidence summaries and health-care recommendations. The document underwent extensive internal and external peer review, and public comment, before approval by the ACMG Board of Directors.

RESULTS

The literature supports the clinical utility and desirable effects of ES/GS on active and long-term clinical management of patients with CA/DD/ID, and on family-focused and reproductive outcomes with relatively few harms. Compared with standard genetic testing, ES/GS has a higher diagnostic yield and may be more cost-effective when ordered early in the diagnostic evaluation.

CONCLUSION

We strongly recommend that ES/GS be considered as a first- or second-tier test for patients with CA/DD/ID.

Basics of modern epilepsy classification and terminology

BACKGROUND

The terminology and classification of seizures and epilepsy has undergone multiple revisions in the last several decades, which can lead to confusion and miscommunication amongst physicians and researchers. In 2017, the International League Against Epilepsy (ILAE) revised the classification of both seizures and epilepsy types in an effort to use less ambiguous terminology. Over time, definitions for status epilepticus, febrile seizures, and neonatal seizures have also evolved, as has the delineation of various epilepsy syndromes by age.

METHODS

Review of the literature for old and new terminology and various epilepsy syndromes was accomplished using the PubMed database system.

RESULTS

In the following article, we review old terminology for classifying seizures and epilepsy as compared to the new (2017) ILAE guidelines. We discuss neonatal seizures, status epilepticus, febrile seizures, autoimmune epilepsy and various epilepsy syndromes by age of onset.

CONCLUSION

Adopting a classification system that uses plain language allows for more effective and efficient communication between individuals and across specialties. Definitions of various syndromes and seizure types have evolved over time and are reviewed.

Oxidative Stress, a Crossroad Between Rare Diseases and Neurodegeneration

Oxidative stress is an imbalance between production and accumulation of oxygen reactive species and/or reactive nitrogen species in cells and tissues, and the capacity of detoxifying these products, using enzymatic and non-enzymatic components, such as glutathione. Oxidative stress plays roles in several pathological processes in the nervous system, such as neurotoxicity, neuroinflammation, ischemic stroke, and neurodegeneration. The concepts of oxidative stress and rare diseases were formulated in the eighties, and since then, the link between them has not stopped growing. The present review aims to expand knowledge in the pathological processes associated with oxidative stress underlying some groups of rare diseases: Friedreich’s ataxia, diseases with neurodegeneration with brain iron accumulation, Charcot-Marie-Tooth as an example of rare neuromuscular disorders, inherited retinal dystrophies, progressive myoclonus epilepsies, and pediatric drug-resistant epilepsies. Despite the discrimination between cause and effect may not be easy on many occasions, all these conditions are Mendelian rare diseases that share oxidative stress as a common factor, and this may represent a potential target for therapies.

Systematic evidence-based review: outcomes from exome and genome sequencing for pediatric patients with congenital anomalies or intellectual disability

Purpose

Exome and genome sequencing (ES/GS) are performed frequently in patients with congenital anomalies, developmental delay, or intellectual disability (CA/DD/ID), but the impact of results from ES/GS on clinical management and patient outcomes is not well characterized. A systematic evidence review (SER) can support future evidence-based guideline development for use of ES/GS in this patient population.

Methods

We undertook an SER to identify primary literature from January 2007 to March 2019 describing health, clinical, reproductive, and psychosocial outcomes resulting from ES/GS in patients with CA/DD/ID. A narrative synthesis of results was performed.

Results

We retrieved 2654 publications for full-text review from 7178 articles. Only 167 articles met our inclusion criteria, and these were primarily case reports or small case series of fewer than 20 patients. The most frequently reported outcomes from ES/GS were changes to clinical management or reproductive decision-making. Two studies reported on the reduction of mortality or morbidity or impact on quality of life following ES/GS.

Conclusion

There is evidence that ES/GS for patients with CA/DD/ID informs clinical and reproductive decision-making, which could lead to improved outcomes for patients and their family members. Further research is needed to generate evidence regarding health outcomes to inform robust guidelines regarding ES/GS in the care of patients with CA/DD/ID.

GRIN2D/GluN2D NMDA receptor: Unique features and its contribution to pediatric developmental and epileptic encephalopathy

N-methyl-d-aspartate receptors (NMDARs), a subset of ligand-gated ionotropic glutamate receptors, are critical for learning, memory, and neuronal development. However, when NMDAR subunits are mutated, a host of neuropathological conditions can occur, including epilepsy. Recently, genetic variation within the GRIN2D gene, which encodes the GluN2D subunit of the NMDAR, has been associated with a set of early-onset neurological diseases, notably developmental and epileptic encephalopathy (DEE). Importantly, patients with GRIN2D variants are largely refractory to conventional anti-epileptic drug (AED) treatment, highlighting the need to further understand the distinctive characteristics of GluN2D in neurological and pathological functions. In this review, we first summarize GluN2D's unique spatial and temporal expression patterns, electrophysiological profiles, and contributions to both pre- and postsynaptic signaling. Next, we review thirteen unique case studies from DEE patients harboring ten different causal GRIN2D variants. These patients are highly heterogenous, manifesting multiple seizure types, electroencephalographic recordings, and neurological and developmental outcomes. Lastly, this review concludes by highlighting the difficulty in treating patients with DEE-associated GRIN2D variants, and stresses the need for selective therapeutic agents delivered within a precise time window.

Arfgef1 haploinsufficiency in mice alters neuronal endosome composition and decreases membrane surface postsynaptic GABAA receptors

ARFGEF1 encodes a guanine exchange factor involved in intracellular vesicle trafficking, and is a candidate gene for childhood genetic epilepsies. To model ARFGEF1 haploinsufficiency observed in a recent Lennox Gastaut Syndrome patient, we studied a frameshift mutation (Arfgef1^fs) in mice. Arfgef1^fs/+ pups exhibit signs of developmental delay, and Arfgef1^fs/+ adults have a significantly decreased threshold to induced seizures but do not experience spontaneous seizures. Histologically, the Arfgef1^fs/+ brain exhibits a disruption in the apical lining of the dentate gyrus and altered spine morphology of deep layer neurons. In primary hippocampal neuron culture, dendritic surface and synaptic but not total GABA_A receptors (GABA_AR) are reduced in Arfgef1^fs/+ neurons with an accompanying decrease in the number of GABA_AR-containing recycling endosomes in cell body. Arfgef1^fs/+ neurons also display differences in the relative ratio of Arf6⁺:Rab11⁺:TrfR⁺ recycling endosomes. Although the GABA_AR-containing early endosomes in Arfgef1^fs/+ neurons are comparable to wildtype, Arfgef1^fs/+ neurons show an increase in the number of GABA_AR-containing lysosomes in dendrite and cell body. Together, the altered endosome composition and decreased neuronal surface GABA_AR results suggests a mechanism whereby impaired neuronal inhibition leads to seizure susceptibility.

Non-traumatic Infantile Slipped Capital Femoral Epiphysis following an Epileptic Seizure - A Case Report

Introduction:

Slipped capital femoral epiphysis (SCFE) is a rather uncommon fracture, occurring usually in adolescence, during a period of rapid growth. Various pathogenetic risk factors contributing to its development have been identified. We present the case of a 10-month-old male infant who developed SCFE in his left hip following an epileptic seizure. To the best of our knowledge, this is the first such case report in the English literature.

Case Report:

A 10-month-old male infant, with a known medical history of epileptic encephalopathy, was referred to the accident and emergency department of our hospital. The parents of the youngster reported inability of the child to move his left lower limb and inconsolable crying following several epileptic seizures. A radiograph revealed the existence of SCFE in the left hip. The fracture was reduced (with gentle closed traction under general anesthesia) and a hip spicacast was applied. It was removed at 8 weeks. Physical examination at this stage revealed a painless hip with a full range of motion. Painless hip range of motion was retained during all follow-up visits throughout the next 22 months. Amagnetic resonance imaging scan at 2 years post-reduction showed normal shape and size of the affected femoral head, with no signs of physeal arrest and/or avascular necrosis.

Conclusion:

This unique case of a 10-month-old infant who developed SCFE following an epileptic seizure shows that this rare fracture may occur even in very young children. Although it is not currently indicated for the treatment of the vast majority of patients with SCFE, closed reduction and immobilization in a hip spicacast may be considered as an alternative treatment option in carefully selected patients.

Munc18-1 haploinsufficiency impairs learning and memory by reduced synaptic vesicular release in a model of Ohtahara syndrome

Ohtahara syndrome, also known as type 4 of Early Infantile Epileptic Encephalopathy with suppression bursts (EIEE-4) is currently an untreatable disorder that presents with seizures and impaired cognition. EIEE-4 patients have mutations most frequently in the STXBP1 gene encoding a Sec protein, munc18-1. The exact molecular mechanism of how these munc18-1 mutations cause impaired cognition, remains elusive. The leading haploinsufficiency hypothesis posits that mutations in munc18-1 render the protein unstable leading to its degradation. Expression driven by the healthy allele is not sufficient to maintain the physiological function resulting in haploinsufficiency. The aim of this study has been to understand how munc18-1 haploinsufficiency causes cognitive impairment seen in EIEE-4. Here we present results from behavioral to cellular effects from a mouse model of munc18-1 haploinsufficiency. Munc18-1 heterozygous knock-out mice showed impaired spatial learning and memory in behavior tests as well as reduced synaptic plasticity in hippocampal CA1 long-term potentiation. Cultured munc18-1 heterozygous hippocampal neurons had significantly slower rate of synaptic vesicle release and decreased readily releasable vesicle pool compared to wild-type control neurons in fluorescent FM dye assays. These results demonstrate that reduced munc18-1 levels are sufficient to impair learning and memory by reducing neurotransmitter release. Therefore, our study implicates munc18-1 haploinsufficiency as a primary cause of cognitive impairment seen in EIEE-4 patients.

Inborn Errors of Metabolism and Epilepsy: Current Understanding, Diagnosis, and Treatment Approaches

Inborn errors of metabolism (IEM) are a rare cause of epilepsy, but seizures and epilepsy are frequently encountered in patients with IEM. Since these disorders are related to inherited enzyme deficiencies with resulting effects on metabolic/biochemical pathways, the term “metabolic epilepsy” can be used to include these conditions. These epilepsies can present across the life span, and share features of refractoriness to anti-epileptic drugs, and are often associated with co-morbid developmental delay/regression, intellectual, and behavioral impairments. Some of these disorders are amenable to specific treatment interventions; hence timely and appropriate diagnosis is critical to improve outcomes. In this review, we discuss those disorders in which epilepsy is a dominant feature and present an approach to the clinical recognition, diagnosis, and management of these disorders, with a greater focus on primarily treatable conditions. Finally, we propose a tiered approach that will permit a clinician to systematically investigate, identify, and treat these rare disorders.

Neonatal hypoglycemic brain injury is a cause of infantile spasms

Neonatal hypoglycemic brain injury is one of the causes of infantile spasms. In the present study, the clinical history and auxiliary examination results of 18 patients who developed infantile spasms several months after neonatal hypoglycemia were retrospectively analyzed. Among the 666 patients with infantile spasms admitted to two pediatric centers between January 2008 and October 2012, 18 patients developed infantile spasms after being diagnosed with neonatal hypoglycemia, defined as a whole blood glucose concentration of <2.6 mmol/l. These patients developed infantile spasms from between 2 and 10 months (mean, 4.9 months) following the diagnosis of neonatal hypoglycemia. All 18 patients had abnormal electroencephalographic findings with either classical or modified hypsarrhythmia. Upon examination using brain magnetic resonance imaging (MRI), 10 patients (55.6%) exhibited abnormalities. The MRI results principally showed a disproportional involvement of parietal and occipital cortices and sub-cortical white matter lesions. In conclusion, the results of this study indicate that neonatal hypoglycemic brain injury is associated with the subsequent development of infantile spasms.

Refractory epilepsy in children

Refractory epilepsy, estimated to affect 10-20% children with epilepsy, can have profound effect on the education, social and cognitive functioning and recreational activities of the child. The definitions are still evolving. A detailed clinical evaluation may reveal an accurate syndromic and etiological diagnosis. The recent advances in neuroimaging and electrophysiology have revolutionized the management of children with refractory epilepsy and supplement the clinical evaluation. Genetic and metabolic evaluation may be indicated in selected cases. The rational use of anti-epileptic drugs, epilepsy surgery and dietary therapies are the mainstay in the management. Various experimental treatment options and pharmacogenetics offer hope for future.