Genetic and biologic classification of infantile spasms

Common genes and recurrent causative variants in 957 Asian patients with pediatric epilepsy

OBJECTIVE

We aimed to identify common genes and recurrent causative variants in a large group of Asian patients with different epilepsy syndromes and subgroups.

METHODS

Patients with unexplained pediatric-onset epilepsy were identified from the in-house Severance Neurodevelopmental Disorders and Epilepsy Database. All patients underwent either exome sequencing or multigene panels from January 2017 to December 2019, at Severance Children's Hospital in Korea. Clinical data were extracted from the medical records.

RESULTS

Of the 957 patients studied, 947 (99.0%) were Korean and 570 were male (59.6%). The median age at testing was 4.91 years (interquartile range, 1.53-9.39). The overall diagnostic yield was 32.4% (310/957). Clinical exome sequencing yielded a diagnostic rate of 36.9% (134/363), whereas the epilepsy panel yielded a diagnostic rate of 29.9% (170/569). Diagnostic yield differed across epilepsy syndromes. It was high in Dravet syndrome (87.2%, 41/47) and early infantile developmental epileptic encephalopathy (60.7%, 17/28), but low in West syndrome (21.8%, 34/156) and myoclonic-atonic epilepsy (4.8%, 1/21). The most frequently implicated genes were SCN1A (n = 49), STXBP1 (n = 15), SCN2A (n = 14), KCNQ2 (n = 13), CDKL5 (n = 11), CHD2 (n = 9), SLC2A1 (n = 9), PCDH19 (n = 8), MECP2 (n = 6), SCN8A (n = 6), and PRRT2 (n = 5). The recurrent genetic abnormalities included 15q11.2 deletion/duplication (n = 9), Xq28 duplication (n = 5), PRRT2 deletion (n = 4), MECP2 duplication (n = 3), SCN1A, c.2556+3A>T (n = 3), and 2q24.3 deletion (n = 3).

SIGNIFICANCE

Here we present the results of a large-scale study conducted in East Asia, where we identified several common genes and recurrent variants that varied depending on specific epilepsy syndromes. The overall genetic landscape of the Asian population aligns with findings from other populations of varying ethnicities.

Genetic Advancements in Infantile Epileptic Spasms Syndrome and Opportunities for Precision Medicine

Infantile epileptic spasms syndrome (IESS) is a devastating developmental epileptic encephalopathy (DEE) consisting of epileptic spasms, as well as one or both of developmental regression or stagnation and hypsarrhythmia on EEG. A myriad of aetiologies are associated with the development of IESS; broadly, 60% of cases are thought to be structural, metabolic or infectious in nature, with the remainder genetic or of unknown cause. Epilepsy genetics is a growing field, and over 28 copy number variants and 70 single gene pathogenic variants related to IESS have been discovered to date. While not exhaustive, some of the most commonly reported genetic aetiologies include trisomy 21 and pathogenic variants in genes such as TSC1, TSC2, CDKL5, ARX, KCNQ2, STXBP1 and SCN2A. Understanding the genetic mechanisms of IESS may provide the opportunity to better discern IESS pathophysiology and improve treatments for this condition. This narrative review presents an overview of our current understanding of IESS genetics, with an emphasis on animal models of IESS pathogenesis, the spectrum of genetic aetiologies of IESS (i.e., chromosomal disorders, single-gene disorders, trinucleotide repeat disorders and mitochondrial disorders), as well as available genetic testing methods and their respective diagnostic yields. Future opportunities as they relate to precision medicine and epilepsy genetics in the treatment of IESS are also explored.

Increased propensity for infantile spasms and altered neocortical excitation-inhibition balance in a mouse model of down syndrome carrying human chromosome 21

Children with Down syndrome (DS, trisomy of chromosome 21) have an increased risk of infantile spasms (IS). As an epileptic encephalopathy, IS may further impair cognitive function and exacerbate neurodevelopmental delays already present in children with DS. To investigate the pathophysiology of IS in DS, we induced IS-like epileptic spasms in a genetic mouse model of DS that carries human chromosome 21q, TcMAC21, the animal model most closely representing gene dosage imbalance in DS. Repetitive extensor/flexor spasms were induced by the GABA_B receptor agonist γ-butyrolactone (GBL) and occurred predominantly in young TcMAC21 mice (85%) but also in some euploid mice (25%). During GBL application, background electroencephalographic (EEG) amplitude was reduced, and rhythmic, sharp-and-slow wave activity or high-amplitude burst (epileptiform) events emerged in both TcMAC21 and euploid mice. Spasms occurred only during EEG bursts, but not every burst was accompanied by a spasm. Electrophysiological experiments revealed that basic membrane properties (resting membrane potential, input resistance, action-potential threshold and amplitude, rheobase, input-output relationship) of layer V pyramidal neurons were not different between TcMAC21 mice and euploid controls. However, excitatory postsynaptic currents (EPSCs) evoked at various intensities were significantly larger in TcMAC21 mice than euploid controls, while inhibitory postsynaptic currents (IPSCs) were similar between the two groups, resulting in an increased excitation-inhibition (E-I) ratio. These data show that behavioral spasms with epileptic EEG activity can be induced in young TcMAC21 DS mice, providing proof-of-concept evidence for increased IS susceptibility in these DS mice. Our findings also show that basic membrane properties are similar in TcMAC21 and euploid mice, while the neocortical E-I balance is altered to favor increased excitation in TcMAC21 mice, which may predispose to IS generation.

Efficacy analysis of oral dexamethasone in the treatment of infantile spasms and infantile spasms related Lennox-Gastaut syndrome

OBJECTIVE

Treatment with adrenocorticotropic hormone (ACTH) or a corticosteroid is the first choice for infantile spasms (IS), and vigabatrin is the first choice for children with tuberous sclerosis. Although corticosteroids may be also effective against IS and IS-related Lennox-Gastaut syndrome (LGS), the use of dexamethasone (DEX), a kind of corticosteroid, for these diseases has been rarely reported. This retrospective study aimed to evaluate the efficacy and tolerability of DEX for the treatment of IS and IS-related LGS.

METHODS

Patients diagnosed as having IS (including patients whose condition evolved to LGS after the failure of early treatment) in our hospital between May 2009 and June 2019 were treated with dexamethasone after failure of prednisone treatment. The oral dose of DEX was 0.15-0.3 mg/kg/d. Thereafter, the clinical efficacy, electroencephalogram (EEG) findings, and adverse effects were observed every 4-12 weeks depending on the individual patient's response. Then, the efficacy and safety of DEX in the treatment of IS and IS-related LGS were retrospectively evaluated.

RESULTS

Among 51 patients (35 cases of IS; 16 cases of IS-related LGS), 35 cases (68.63%) were identified as responders to DEX treatment, comprising 20 cases (39.22%) and 15 cases (29.41%) with complete control and obvious control, respectively. To discuss the syndromes individually, complete control and obvious control were achieved in 14/35 and 9/35 IS cases and in 6/16 and 6/16 IS-related LGS cases, respectively. During DEX withdrawal, 11 of the 20 patients with complete control relapsed (9/14 IS; 2/6 LGS). The duration of dexamethasone treatment (including weaning) in most of the 35 responders was less than 1 year. However, 5 patients were treated with prolonged, low-dose maintenance therapy, which continued for more than 1.5 years. These 5 patients showed complete control, and 3 patients had no recurrence. Except for one child who died of recurrent asthma and epileptic status 3 months after stopping DEX, there were no serious or life-threatening adverse effects during DEX treatment.

CONCLUSION

Oral DEX is effective and tolerable for IS and IS-related LGS. all LGS patients were evolved from IS in this study. The conclusion may not apply to patients with other etiology and courses of LGS. Even when prednisone or ACTH is failed, DEX may still be considered as a treatment option. For children who respond to DEX but do not show complete control after 6 months of treatment, prolonged treatment with low-dose DEX administered in the morning might be considered.

Heterozygous GABAA receptor β3 subunit N110D knock-in mice have epileptic spasms

OBJECTIVE

Infantile spasms is an epileptic encephalopathy of childhood, and its pathophysiology is largely unknown. We generated a heterozygous knock-in mouse with the human infantile spasms-associated de novo mutation GABRB3 (c.A328G, p.N110D) to investigate its molecular mechanisms and to establish the Gabrb3+/N110D knock-in mouse as a model of infantile spasms syndrome.

METHODS

We used electroencephalography (EEG) and video monitoring to characterize seizure types, and a suite of behavioral tests to identify neurological and behavioral impairment in Gabrb3+/N110D knock-in mice. Miniature inhibitory postsynaptic currents (mIPSCs) were recorded from layer V/VI pyramidal neurons in somatosensory cortex, and extracellular multi-unit recordings from the ventral basal nucleus of the thalamus in a horizontal thalamocortical slice were used to assess spontaneous thalamocortical oscillations.

RESULTS

The infantile spasms-associated human de novo mutation GABRB3 (c.A328G, p.N110D) caused epileptic spasms early in development and multiple seizure types in adult Gabrb3+/N110D knock-in mice. Signs of neurological impairment, anxiety, hyperactivity, social impairment, and deficits in spatial learning and memory were also observed. Gabrb3+/N110D mice had reduced cortical mIPSCs and increased duration of spontaneous oscillatory firing in the somatosensory thalamocortical circuit.

SIGNIFICANCE

The Gabrb3+/N110D knock-in mouse has epileptic spasms, seizures, and other neurological impairments that are consistent with infantile spasms syndrome in patients. Multiple seizure types and abnormal behaviors indicative of neurological impairment both early and late in development suggest that Gabrb3+/N110D mice can be used to study the pathophysiology of infantile spasms. Reduced cortical inhibition and increased duration of thalamocortical oscillatory firing suggest perturbations in thalamocortical circuits.

Long-Term Outcome of Adrenocorticotropic Hormone Therapy in Children With New-Onset Infantile Spasms

BACKGROUND

To investigate for pretreatment clinical variables to predict the outcome of new-onset epileptic spasms after adrenocorticotropic hormone (ACTH) therapy and to identify risk factors for poor long-term outcome.

METHODS

We retrospectively studied 129 consecutive patients with infantile spasms syndrome (ISS). These patients received ACTH with antiseizure medication therapy for the first time and were regularly followed up for more than six months at our hospital. The response to treatment was assessed after two weeks of ACTH injection. Kaplan-Meier survival analysis and the multivariate Cox proportional hazard regression model were used.

RESULTS

Among the 129 patients, 61 (47.3%) had a good response after two weeks of ACTH treatment. At the time of the latest follow-up, 71 (55%) patients were seizure-free (International League Against Epilepsy class1). The univariate analysis revealed that normal neurodevelopment (P = 0.018), time lag of less than one month (P = 0.026), no hypsarrhythmia on EEG (P = 0.004), and serum calcium level ≥2.50 mmol/L (P = 0.035) were significantly associated with a good response. Only a good response to ACTH therapy was significantly associated with a positive long-term outcome. The Kaplan-Meier survival analysis showed that serum calcium level ≧2.50 mmol/L was significantly associated with a positive long-term outcome (P = 0.030). Multivariate analysis confirmed that no response to ACTH therapy was an independent variable that predicted long-term seizure recurrence (P < 0.001, hazard ratio = 4.602, confidence interval = 2.252 to 9.406).

CONCLUSIONS

A good response to ACTH therapy had a significant predictive value for long-term seizure outcomes. Calcium may play an important role in the treatment of ISS with ACTH.

Cortical Parvalbumin-Positive Interneuron Development and Function Are Altered in the APC Conditional Knockout Mouse Model of Infantile and Epileptic Spasms Syndrome

Infantile and epileptic spasms syndrome (IESS) is a childhood epilepsy syndrome characterized by infantile or late-onset spasms, abnormal neonatal EEG, and epilepsy. Few treatments exist for IESS, clinical outcomes are poor, and the molecular and circuit-level etiologies of IESS are not well understood. Multiple human IESS risk genes are linked to Wnt/β-catenin signaling, a pathway that controls developmental transcriptional programs and promotes glutamatergic excitation via β-catenin's role as a synaptic scaffold. We previously showed that deleting adenomatous polyposis coli (APC), a component of the β-catenin destruction complex, in excitatory neurons (APC cKO mice, APCfl/fl x CaMKIIαCre) increased β-catenin levels in developing glutamatergic neurons and led to infantile behavioral spasms, abnormal neonatal EEG, and adult epilepsy. Here, we tested the hypothesis that the development of GABAergic interneurons (INs) is disrupted in APC cKO male and female mice. IN dysfunction is implicated in human IESS, is a feature of other rodent models of IESS, and may contribute to the manifestation of spasms and seizures. We found that parvalbumin-positive INs (PV+ INs), an important source of cortical inhibition, were decreased in number, underwent disproportionate developmental apoptosis, and had altered dendrite morphology at P9, the peak of behavioral spasms. PV+ INs received excessive excitatory input, and their intrinsic ability to fire action potentials was reduced at all time points examined (P9, P14, P60). Subsequently, GABAergic transmission onto pyramidal neurons was uniquely altered in the somatosensory cortex of APC cKO mice at all ages, with both decreased IPSC input at P14 and enhanced IPSC input at P9 and P60. These results indicate that inhibitory circuit dysfunction occurs in APC cKOs and, along with known changes in excitation, may contribute to IESS-related phenotypes.SIGNIFICANCE STATEMENT Infantile and epileptic spasms syndrome (IESS) is a devastating epilepsy with limited treatment options and poor clinical outcomes. The molecular, cellular, and circuit disruptions that cause infantile spasms and seizures are largely unknown, but inhibitory GABAergic interneuron dysfunction has been implicated in rodent models of IESS and may contribute to human IESS. Here, we use a rodent model of IESS, the APC cKO mouse, in which β-catenin signaling is increased in excitatory neurons. This results in altered parvalbumin-positive GABAergic interneuron development and GABAergic synaptic dysfunction throughout life, showing that pathology arising in excitatory neurons can initiate long-term interneuron dysfunction. Our findings further implicate GABAergic dysfunction in IESS, even when pathology is initiated in other neuronal types.

Biochemical mechanisms in pathogenesis of infantile epileptic spasm syndrome

The molecular mechanisms leading to infantile epileptic spasm syndrome (IESS) remain obscure. The only common factor seems to be that the spasms are restricted to a limited period of infancy, during a certain maturational state. Here the current literature regarding the biochemical mechanisms of brain maturation in IESS is reviewed, and various hypotheses of the pathophysiology are put together. They include: (1) imbalance of inhibitory (NGF, IGF-1, ACTH, GABA) and excitatory factors (glutamate, nitrites) which distinguishes the different etiological subgroups, (2) abnormality of the hypothalamic pituitary adrenal (HPA) axis linking insults and early life stress, (3) inflammation (4) yet poorly known genetic and epigenetic factors, and (5) glucocorticoid and vigabatrin action on brain development, pinpointing at molecular targets of the pathophysiology from another angle. An altered maturational process may explain why so many, seemingly independent etiological factors lead to the same clinical syndrome and frequently to developmental delay. Understanding these factors can provide ideas for novel therapies.

Genotype and phenotype characteristics of West syndrome in 20 Vietnamese children: Two novel variants detected by next-generation sequencing

BACKGROUND

In children with West syndrome (WS), whose treatment is challenging due to drug resistance and poor prognosis, investigation of genetic etiology and genotype-phenotype characteristics might assist in treatment optimization and genetic counseling.

OBJECTIVE

In this study, we aimed to present the results of genetic analysis and the corresponding phenotypes in a cohort of twenty children with WS in Vietnam.

METHODS

Our study was designed as a single-institution retrospective case series, in which consecutive sampling was used to select WS children having undergone genetic testing. Identified variants were investigated individually or as a variant combination by bioinformatics platforms. Clinical data were used to establish the genotype-phenotype correlation and compare clinical characteristics between groups of genetic causes and unknown causes.

RESULTS

Genetic testing identified at least one variant in 17/20 children. According to ACMG 2015, of all variants, one variant (3.9%) was classified as a benign variant, 16 variants (61.5%) were variants of uncertain significance, 4 (15.4%) were likely pathogenic variants, and 5 (19.2%) were pathogenic variants. These 26 variants belonged to 21 genes, of which eight candidate genes were CREBBP, MED25, HDAC8, SCN3A, ABCD1, TSC2, COL4A1, and NDUFA10. Two novel variants of SCN3A and TSC2 were found. Predicted pathogenic variant combinations were identified in two cases. Compared to three children of unknown etiology, five children with genetic causes had a higher rate of abnormal brain structures, developmental delay, and treatment resistance.

CONCLUSIONS

WS has a genetically heterogeneous etiology, and some cases might be polygenically susceptible. Our findings expand the disease's genotype-phenotype spectrum and support previous literature results that genetic etiology poses an unfavorable outcome in WS.

Animal Models in Epileptic Spasms and the Development of Novel Treatment Options

SUMMARY

The infantile spasms (IS) syndrome is a catastrophic developmental epileptic encephalopathy syndrome characterized by an age-specific expression of epileptic spasms that are associated with extremely abnormal, oftentimes described as chaotic, interictal EEG pattern known as hypsarrhythmia. Patients with IS generally have poor neurodevelopmental outcomes, in large part because of the frequent epileptic spasms and interictal EEG abnormalities. Current first-line treatments such as adrenocorticotropic hormone or vigabatrin are often ineffective and are associated with major toxic side effects. There is therefore a need for better and safer treatments for patients with IS, especially for the intractable population. Hope is on the horizon as, over the past 10 years, there has been robust progress in the development of etiology-specific animal models of IS. These models have been used to identify potential new treatments for IS and are beginning to provide some important insights into the pathophysiological substrates for this disease. In this review, we will highlight strengths and weaknesses of the currently available animal models of IS in addition to new insights into the pathophysiology and treatment options derived from these models.

Decreased cerebrospinal fluid kynurenic acid in epileptic spasms: A biomarker of response to corticosteroids

Background

Epileptic (previously infantile) spasms is the most common epileptic encephalopathy occurring during infancy and is frequently associated with abnormal neurodevelopmental outcomes. Epileptic spasms have a diverse range of known (genetic, structural) and unknown aetiologies. High dose corticosteroid treatment for 4 weeks often induces remission of spasms, although the mechanism of action of corticosteroid is unclear. Animal models of epileptic spasms have shown decreased brain kynurenic acid, which is increased after treatment with the ketogenic diet. We quantified kynurenine pathway metabolites in the cerebrospinal fluid (CSF) of infants with epileptic spasms and explored clinical correlations.

Methods

A panel of nine metabolites in the kynurenine pathway (tryptophan, kynurenine, kynurenic acid, 3-hydroxykynurenine, xanthurenic acid, anthranilic acid, 3-hydroxyanthranilic acid, quinolinic acid, and picolinic acid) were measured using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). CSF collected from paediatric patients less than 3 years of age with epileptic spasms (n=34, 19 males, mean age 0.85, median 0.6, range 0.3–3 yrs) were compared with other epilepsy syndromes (n=26, 9 males, mean age 1.44, median 1.45, range 0.3–3 yrs), other non-inflammatory neurological diseases (OND) (n=29, 18 males, mean age 1.47, median 1.6, range 0.1–2.9 yrs) and inflammatory neurological controls (n=12, 4 males, mean age 1.80, median 1.80, range 0.8–2.5 yrs).

Findings

There was a statistically significant decrease of CSF kynurenic acid in patients with epileptic spasms compared to OND (p<0.0001). In addition, the kynurenic acid/kynurenine (KYNA/KYN) ratio was lower in the epileptic spasms subgroup compared to OND (p<0.0001). Epileptic spasms patients who were steroid responders or partial steroid responders had lower KYNA/KYN ratio compared to patients who were refractory to steroids (p<0.005, p<0.05 respectively).

Interpretation

This study demonstrates decreased CSF kynurenic acid and KYNA/KYN in epileptic spasms, which may also represent a biomarker for steroid responsiveness. Given the anti-inflammatory and neuroprotective properties of kynurenic acid, further therapeutics able to increase kynurenic acid should be explored.

Funding

Financial support for the study was granted by Dale NHMRC Investigator grant APP1193648, Petre Foundation, Cerebral Palsy Alliance and Department of Biochemistry at the Children's Hospital at Westmead. Prof Guillemin is funded by NHMRC Investigator grant APP1176660 and Macquarie University.

Lesional Intractable Epileptic Spasms in Children: Electroclinical Localization and Postoperative Outcomes

To analyze the influence of seizure semiology, electroencephalography (EEG) features and magnetic resonance imaging (MRI) change on epileptogenic zone localization and surgical prognosis in children with epileptic spasm (ES) were assessed. Data from 127 patients with medically intractable epilepsy with ES who underwent surgical treatment were retrospectively analyzed. ES semiology was classified as non-lateralized, bilateral asymmetric, and focal. Interictal epileptiform discharges were divided into diffusive or multifocal, unilateral, and focal. MRI results showed visible local lesions for all patients, while the anatomo-electrical-clinical value of localization of the epileptogenic zone was dependent on the surgical outcome. During preoperative video EEG monitoring, among all 127 cases, 53 cases (41.7%) had ES only, 46 (36.2%) had ES and focal seizures, 17 (13.4%) had ES and generalized seizures, and 11 (8.7%) had ES with focal and generalized seizures. Notably, 35 (27.6%) and 92 cases (72.4%) showed simple and complex ES, respectively. Interictal EEG showed that 22 cases (17.3%) had bilateral multifocal discharges or hypsarrhythmia, 25 (19.7%) had unilateral dominant discharges, and 80 (63.0%) had definite focal or regional discharges. Ictal discharges were generalized/bilateral in 71 cases (55.9%) and definite/lateralized in 56 cases (44.1%). Surgically resected lesions were in the hemisphere (28.3%), frontal lobe (24.4%), temporal lobe (16.5%), temporo-parieto-occipital region (14.2%), and posterior cortex region (8.7%). Seizure-free rates at 1 and 4 years postoperatively were 81.8 and 72.7%, respectively. There was no significant difference between electroclinical characteristics of ES and seizure-free rate. Surgical treatment showed good outcomes in most patients in this cohort. Semiology and ictal EEG change of ES had no effect on localization, while focal or lateralized epileptiform discharges of interictal EEG may affect lateralization and localization. Complete resection of epileptogenic lesions identified via MRI was the only factor associated with a positive surgical outcome.

Epilepsy: Expert opinion on emerging drugs in phase 2/3 clinical trials

INTRODUCTION

Despite the existence of over 30 anti-seizure medications (ASM), including 20 over the last 30 years, a third of patients with epilepsy remain refractory to treatment, with no disease-modifying or preventive therapies until very recently. The development of new ASMs with new mechanisms of action is therefore critical. Recent clinical trials of new treatments have shifted focus from the traditional common epilepsies to rare, genetic epilepsies with known mechanistic targets for treatment and disease-specific animal models.

AREAS COVERED

ASMs in phase 2a/b and 3 clinical trials target cholesterol, serotonin, sigma-1 receptors, potassium channels and metabotrobic glutamate receptors. Neuroinflammation, protein misfolding, abnormal thalamocortical firing, and molecular deficiencies are among the targeted pathways. Clinically, the current phase 2a/b-3 agents hold promise for variety of epilepsy conditions, from developmental epileptic encephalopathies (Dravet Syndrome, Lennox-Gastaut syndrome, CDKL5 and PCDH19, Rett's Syndrome), Infantile Spasms, Tuberous Sclerosis as well as focal and idiopathic generalized epilepsies and acute rescue therapy for cluster seizures.

EXPERT OPINION

New delivery mechanisms increase potency and site-specificity of existing drugs. Novel mechanisms of action involve cholesterol degradation, mitochondrial pathways, anti-inflammation and neuro-regeneration. Earlier identification of genetic conditions through genetic testing will allow for earlier use of disease specific and disease-modifying therapies.

Comparison of Efficacy and Safety of Low- Versus High-Dose Oral Prednisolone in Infantile Spasm (IS): An Open Label Randomized Controlled Trial at the Children’s Hospital & Institute of Child Health, Multan, Pakistan

Background: Infantile spasm (IS) is an epileptic syndrome characterized by epileptic spasms, hypsarrhythmia on electroencephalography (EEG), and high risk of neurodevelopmental regression. This study was done to compare the efficacy and safety of the high versus the usual dose in children with IS.

Methodology: This open label randomized controlled trial was conducted at Department of Pediatric Neurology, The Children’s Hospital & Institute of Child Health, Multan, Pakistan, from January 1, 2020 to December 31, 2020. A total of 62 children (31 in each group) aged three months to two years presenting with epileptic spasms (at least one cluster per day) with EEG evidence of hypsarrhythmia were included. All 62 children were randomized to receive either high-dose prednisolone (10mg per dose four times a day) or the usual-dose prednisolone (2mg/kg/day thrice a day) for 14 days. Primary outcome measure was noted in terms of proportion of children who achieved complete, partial, or no response. Secondary outcome measure was proportion of children with adverse effects.

Results: In a total of 62 children, there were 34 (54.8%) male. Overall, mean age was noted to be 9.1±3.4 months. The most common etiology of IS was noted to be hypoxic-ischemic encephalopathy (HIE) in 28 children (45.2%). Significantly better clinical efficacy was reported in high-dose prednisolone group when compared to low-dose prednisolone cases as complete response, partial response and no response were noted in nine (29.0%), eight (25.8%), and 14 (45.2%) patients of low-dose group versus 18 (58.1%), eight (25.8%), and five (16.1%) patients in high-dose group, respectively (p=0.0265). Weight gain was the most frequently reported adverse effects noted in 11 (17.7%) cases. Overall, no statistically significant difference in the frequency of adverse effects (p=0.9573).

Conclusion: In comparison to low-dose prednisolone, high-dose prednisolone was found to be significantly more efficacious among cases of IS. Adverse effect in both treatment groups were relatively low and similar.

2-deoxyglucose and β-hydroxybutyrate fail to attenuate seizures in the betamethasone-NMDA model of infantile spasms

Infantile spasms (IS) is an epileptic encephalopathy with a poor neurodevelopmental prognosis, and limited, often ineffective treatment options. The effectiveness of metabolic approaches to seizure control is being increasingly shown in a wide variety of epilepsies. This study investigates the efficacy of the glycolysis inhibitor 2‐deoxyglucose (2‐DG) and the ketone body β‐hydroxybutyrate (BHB) in the betamethasone‐NMDA model of rat IS. Prenatal rats were exposed to betamethasone on gestational day 15 (G15) and NMDA on postnatal day 15 (P15). Video‐electroencephalography (v‐EEG) was used to monitor spasms. NMDA consistently induced hyperflexion spasms associated with interictal sharp‐slow wave EEG activity and ictal flattening of EEG signals, reminiscent of hypsarrhythmia and electrodecrement, respectively. 2‐DG (500 mg/kg, i.p), BHB (200 mg/kg, i.p.), or both were administered immediately after occurrence of the first spasm. No experimental treatment altered significantly the number, severity, or progression of spasms compared with saline treatment. These data suggest that metabolic inhibition of glycolysis or ketogenesis does not reduce infantile spasms in the NMDA model. The study further validates the betamethasone‐NMDA model in terms of its behavioral and electrographic resemblance to human IS and supports its use for preclinical drug screening.

Classifying etiology of infantile spasms syndrome in resource-limited settings: A study from the South Asian region

Objective

Etiological classification of infantile spasms syndrome (ISS) is important, considering the influence on prognosis based on the presence or absence of a known etiology. This study was performed to describe the limitations and difficulties experienced within the South Asian region when classifying the etiology of ISS according to the current recommendation.

Method

Data on healthcare indices and facilities related to management of ISS for the nine countries in the South Asian region were gathered by the South Asian West Syndrome Research Group. A Google survey was performed among three hundred and thirty pediatric neurologists in the region. The capacity within each country for investigating etiology of ISS according to current described benchmarks was evaluated. The difficulties experienced in this regard and the potential solutions were investigated.

Results

One hundred and sixty pediatric neurologists (response rate 48%) from Bangladesh (19/25), India (94/255), Myanmar (11/11), Nepal (6/8), Pakistan (19/25), and from Sri Lanka (7/8) responded. Three countries had no pediatric neurology services. Fifty‐six percent attempted to classify ISS etiology according to classification outlined by International League Against Epilepsy in 2017. The facilities to perform metabolic, genetic, and immunological investigations were very limited. Lack of funding for investigations and poor laboratory support were the two most frequent barriers encountered. Sixty percent indicated that a separate classification is suitable for low‐income setting; 78% suggested inclusion of separate category as “incompletely investigated” as an alternative solution to mitigate the barrier of achieving a better understanding of the etiological subtypes seen more frequently in this region.

Significance

The resources in South Asian region are limited to meet the recommendations for investigating etiology of ISS. Including the etiological subcategory “incompletely investigated” is proposed as an alternative to understand the true proportions of children in this region, with a definite known etiology and those with an unknown etiology.

Efficacy, tolerability, and safety of zonisamide in children with epileptic spasms: A systematic review and meta-analysis

BACKGROUND

Valproate, levetiracetam, benzodiazepines, and topiramate are antiseizure medications (ASMs) considered to have definite efficacy in reducing the frequency of epileptic spasm frequency, apart from ketogenic dietary therapies. Although zonisamide has also been shown to have efficacy as second-line ASM for epileptic spasms, various studies have conflicting results in literature. This systematic review aims to summarize clinical studies regarding the efficacy of zonisamide for epileptic spasms.

METHODS

We conducted a systematic literature search collating all available literature. The primary objective was to determine efficacy in terms of proportion with complete spasm resolution, we also intended to determine proportion with at least 50% spasm reduction, hypsarrhythmia resolution, and nature/frequency of adverse effects. All prospective/retrospective, controlled/uncontrolled studies describing the use of zonisamide with epileptic spasms were included in the qualitative review excluding case reports, but for metanalysis pertaining to key outcomes, we included studies with at least 10 participants.

RESULTS

A total of nineteen publications were found eligible for inclusion in the qualitative review, out of 101 search items. A total of 401 children with epileptic spasms were tried up to a maximum of 9.9-35 mg/kg/day dose with only mild adverse effects in a few patients. Total 20.8% (95% CI-11.4%-29.2%) and 23.4% (95% CI-17.8%-29.1%) patients had complete cessation of spasms and at least a 50% reduction in total spasm frequency as compared to baseline after starting zonisamide. Similarly, 20.3% (95% CI-10.1%-30.5%) had resolution of hypsarrhythmia in EEG after starting zonisamide.

CONCLUSION

Zonisamide can reduce spasms in 21% of children with epileptic spasms, without major adverse effects. But there are only limited studies on epileptic spasms of sufficient quality to give high confidence in meta-analysis. Large controlled trials are needed in this regard to provide high-quality evidence favoring/disfavoring its use in patients with epileptic spasms.

Early 17β-estradiol treatment reduces seizures but not abnormal behaviour in mice with expanded polyalanine tracts in the Aristaless related homeobox gene (ARX)

Children with severe intellectual disability have an increased prevalence of refractory seizures. Steroid treatment may improve seizure outcomes, but the mechanism remains unknown. Here we demonstrate that short term, daily delivery of an exogenous steroid 17β-estradiol (40 ng/g) in early postnatal life significantly reduced the number and severity of seizures, but did not improve behavioural deficits, in mice modelling mutations in the Aristaless-related homeobox gene (ARX), expanding the first (PA1) or second (PA2) polyalanine tract. Frequency of observed seizures on handling (n = 14/treatment/genotype) were significantly reduced in PA1 (32% reduction) and more modestly reduced in PA2 mice (14% reduction) with steroid treatment compared to vehicle. Spontaneous seizures were assessed (n = 7/treatment/genotype) at 7 weeks of age coinciding with a peak of seizure activity in untreated mice. PA1 mice treated with steroids no longer present with the most severe category of prolonged myoclonic seizures. Treated PA2 mice had an earlier onset of seizures coupled with a subsequent reduction in seizures later in postnatal life, with a complete absence of any seizures during the analysis at 7 weeks of age. Despite the reduction in seizures, 17β-estradiol treated mice showed no improvement in behavioural or cognitive outcomes in adulthood. For the first time we show that these deficits due to mutations in Arx are already present before seizure onset and do not worsen with seizures. ARX is a transcription factor and Arx PA mutant mice have deregulated transcriptome profiles in the developing embryonic brain. At postnatal day 10, treatment completion, RNAseq identified 129 genes significantly deregulated (Log2FC > ± 0.5, P-value<0.05) in the frontal cortex of mutant compared to wild-type mice. This list reflects genes deregulated in disease and was particularly enriched for known genes in neurodevelopmental disorders and those involved in signalling and developmental pathways. 17β-estradiol treatment of mutant mice significantly deregulated 295 genes, with only 23 deregulated genes overlapping between vehicle and steroid treated mutant mice. We conclude that 17β-estradiol treatment recruits processes and pathways to reduce the frequency and severity of seizures in the Arx PA mutant mice but does not precisely correct the deregulated transcriptome nor improve mortality or behavioural and cognitive deficits.

Quality of life at 6 years in children treated for West syndrome with hormonal therapy

INTRODUCTION

West syndrome is a severe epileptic encephalopathy occurring in infancy. Majority of affected children suffer from poor epilepsy control in later life and are dependent on care-givers for daily living. There is no previous study evaluating the Quality of Life (QOL) in children suffered from WS.

METHOD

A prospective cohort study was performed at six years in a group of children with West syndrome, followed up in the Sri Lanka Infantile Spasm Study (SLISS). The quality of life was evaluated using Sri Lankan Health-Related Quality-of-Life Index for school children (SLHRQ-S), an age-specific, primary caregiver proxy-rated, validated questionnaire for Sri Lankan children with epilepsy. Information on epilepsy, medication, and daily activities was obtained from the parents.

RESULTS

Fifty parents of initial 97 children treated for WS participated. The majority had no ongoing epilepsy (56%) at time of evaluation. The mean QOL was 67.22 (SD 15.68). Mean QOL scores for individual domains showed that physical domain was the worst affected (58.51 (SD = 22.11)). Psychological and social function domains were 68.73 (SD = 17.74) and 75.2 (SD = 14.87), respectively. Male sex (0.02), using multiple anti-seizure medications (0.00) and lower ILAE epilepsy control scale (0.02) were significantly associated with a poor quality of life. Age at onset, delay in treatment, and early spasm control were among the factors that did not influence quality of life.

CONCLUSION

Despite having control of their epilepsy in the majority, these children suffered from poor quality of life. The greater impact on the physical domain possibly is related to the effect of underlying pathologies.

A novel variant of CDK19 causes a severe neurodevelopmental disorder with infantile spasms

Infantile spasms are a potentially catastrophic form of epilepsy syndrome that are usually associated with substantial developmental delay and commonly occur in children younger than 1 yr. Recent reports on four cases revealed that variants harbored in a novel gene CDK19 were causative for the syndrome. We report a fifth affected individual, a 10-mo-old male patient who presented with a neurodevelopmental syndrome characterized by infantile spasms. We identified a novel de novo missense variant c.92C > A (p.Thr31Asn) in CDK19 that was classified as a likely pathogenic disease-causing variant. The characterized clinical phenotypes of the proband were similar to the previously reported four patients, but he had few variable features including earlier seizure onset age and earlier occurring developmental abnormality. Protein structure modeling analysis revealed that CDK19 variants may disable its kinase activity, which would further impede the transcriptional regulation, thus leading to detrimental pathologies. Our report expanded CDK19 genotype spectrum and further demonstrated that a CDK19 missense variant was causative of neurodevelopmental disorder clinically marked by infantile spasms.

Insights into Potential Targets for Therapeutic Intervention in Epilepsy

Epilepsy is a chronic brain disease that affects approximately 65 million people worldwide. However, despite the continuous development of antiepileptic drugs, over 30% patients with epilepsy progress to drug-resistant epilepsy. For this reason, it is a high priority objective in preclinical research to find novel therapeutic targets and to develop effective drugs that prevent or reverse the molecular mechanisms underlying epilepsy progression. Among these potential therapeutic targets, we highlight currently available information involving signaling pathways (Wnt/β-catenin, Mammalian Target of Rapamycin (mTOR) signaling and zinc signaling), enzymes (carbonic anhydrase), proteins (erythropoietin, copine 6 and complement system), channels (Transient Receptor Potential Vanilloid Type 1 (TRPV1) channel) and receptors (galanin and melatonin receptors). All of them have demonstrated a certain degree of efficacy not only in controlling seizures but also in displaying neuroprotective activity and in modifying the progression of epilepsy. Although some research with these specific targets has been done in relation with epilepsy, they have not been fully explored as potential therapeutic targets that could help address the unsolved issue of drug-resistant epilepsy and develop new antiseizure therapies for the treatment of epilepsy.

Effects of febrile seizures in mesial temporal lobe epilepsy with hippocampal sclerosis on gene expression using bioinformatical analysis

Background

To investigate the effect of long-term febrile convulsions on gene expression in mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) and explore the molecular mechanism of MTLE-HS.

Methods

Microarray data of MTLE-HS were obtained from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) between MTLE-HS with and without febrile seizure history were screened by the GEO2R software. Pathway enrichment and gene ontology of the DEGs were analyzed using the DAVID online database and FunRich software. Protein–protein interaction (PPI) networks among DEGs were constructed using the STRING database and analyzed by Cytoscape.

Results

A total of 515 DEGs were identified in MTLE-HS samples with a febrile seizure history compared to MTLE-HS samples without febrile seizure, including 25 down-regulated and 490 up-regulated genes. These DEGs were expressed mostly in plasma membrane and synaptic vesicles. The major molecular functions of those genes were voltage-gated ion channel activity, extracellular ligand-gated ion channel activity and calcium ion binding. The DEGs were mainly involved in biological pathways of cell communication signal transduction and transport. Five genes (SNAP25, SLC32A1, SYN1, GRIN1,andGRIA1) were significantly expressed in the MTLE-HS with prolonged febrile seizures.

Conclusion

The pathogenesis of MTLE-HS involves multiple genes, and prolonged febrile seizures could cause differential expression of genes. Thus, investigations of those genes may provide a new perspective into the mechanism of MTLE-HS.

West syndrome: a comprehensive review

Since its first clinical description (on his son) by William James West (1793–1848) in 1841, and the definition of the classical triad of (1) infantile spasms; (2) hypsarrhythmia, and (3) developmental arrest or regression as “West syndrome”, new and relevant advances have been recorded in this uncommon disorder. New approaches include terminology of clinical spasms (e.g., infantile (IS) vs. epileptic spasms (ES)), variety of clinical and electroencephalographic (EEG) features (e.g., typical ictal phenomena without EEG abnormalities), burden of developmental delay, spectrum of associated genetic abnormalities, pathogenesis, treatment options, and related outcome and prognosis. Aside the classical manifestations, IS or ES may present with atypical electroclinical phenotypes (e.g., subtle spasms; modified hypsarrhythmia) and may have their onset outside infancy. An increasing number of genes, proteins, and signaling pathways play crucial roles in the pathogenesis. This condition is currently regarded as a spectrum of disorders: the so-called infantile spasm syndrome (ISs), in association with other causal factors, including structural, infectious, metabolic, syndromic, and immunologic events, all acting on a genetic predisposing background. Hormonal therapy and ketogenic diet are widely used also in combination with (classical and recent) pharmacological drugs. Biologically targeted and gene therapies are increasingly studied. The present narrative review searched in seven electronic databases (primary MeSH terms/keywords included West syndrome, infantile spasms and infantile spasms syndrome and were coupled to 25 secondary clinical, EEG, therapeutic, outcomes, and associated conditions terms) including MEDLINE, Embase, Cochrane Central, Web of Sciences, Pubmed, Scopus, and OMIM to highlight the past knowledge and more recent advances.

Modeling epileptic spasms during infancy: Are we heading for the treatment yet?

Infantile spasms (IS or epileptic spasms during infancy) were first described by Dr. William James West (aka West syndrome) in his own son in 1841. While rare by definition (occurring in 1 per 3200-3400 live births), IS represent a major social and treatment burden. The etiology of IS varies - there are many (>200) different known pathologies resulting in IS and still in about one third of cases there is no obvious reason. With the advancement of genetic analysis, role of certain genes (such as ARX or CDKL5 and others) in IS appears to be important. Current treatment strategies with incomplete efficacy and serious potential adverse effects include adrenocorticotropin (ACTH), corticosteroids (prednisone, prednisolone) and vigabatrin, more recently also a combination of hormones and vigabatrin. Second line treatments include pyridoxine (vitamin B6) and ketogenic diet. Additional treatment approaches use rapamycin, cannabidiol, valproic acid and other anti-seizure medications. Efficacy of these second line medications is variable but usually inferior to hormonal treatments and vigabatrin. Thus, new and effective models of this devastating condition are required for the search of additional treatment options as well as for better understanding the mechanisms of IS. Currently, eight models of IS are reviewed along with the ideas and mechanisms behind these models, drugs tested using the models and their efficacy and usefulness. Etiological variety of IS is somewhat reflected in the variety of the models. However, it seems that for finding precise personalized approaches, this variety is necessary as there is no "one-size-fits-all" approach possible for both IS in particular and epilepsy in general.

De Novo Variants in CDK19 Are Associated with a Syndrome Involving Intellectual Disability and Epileptic Encephalopathy

We identified three unrelated individuals with de novo missense variants in CDK19, encoding a cyclin-dependent kinase protein family member that predominantly regulates gene transcription. These individuals presented with hypotonia, global developmental delay, epileptic encephalopathy, and dysmorphic features. CDK19 is conserved between vertebrate and invertebrate model organisms, but currently abnormalities in CDK19 are not known to be associated with a human disorder. Loss of Cdk8, the fly homolog of CDK19, causes larval lethality, which is suppressed by expression of human CDK19 reference cDNA. In contrast, the CDK19 p.Tyr32His and p.Thr196Ala variants identified in the affected individuals fail to rescue the loss of Cdk8 and behave as null alleles. Additionally, neuronal RNAi-mediated knockdown of Cdk8 in flies results in semi-lethality. The few eclosing flies exhibit severe seizures and a reduced lifespan. Both phenotypes are fully suppressed by moderate expression of the CDK19 reference cDNA but not by expression of the two variants. Finally, loss of Cdk8 causes an obvious loss of boutons and synapses at larval neuromuscular junctions (NMJs). Together, our findings demonstrate that human CDK19 fully replaces the function of Cdk8 in the fly, the human disease-associated CDK19 variants behave as strong loss-of-function variants, and deleterious CDK19 variants underlie a syndromic neurodevelopmental disorder.

Treatment of infantile spasms: why do we know so little?

INTRODUCTION

Infantile spasm (IS) is an epileptic syndrome with typical onset within the first 2 years of life. This condition might be caused by several etiologies. IS is associated with pathological neuronal networks; however, definite hypotheses on neurobiological processes are awaited.

AREAS COVERED

Changes in NMDA and GABA_B receptors and increase of Ca²⁺ conductance are some of the possible pathophysiological mechanisms. Animal models can help, but most have only some features of IS. Outcome is strongly affected by etiology and the timing of treatment, which relies still on ACTH, oral steroids, and vigabatrin. No significant differences in terms of efficacy have been documented, though a combination of ACTH and vigabatrin seems to be associated with better long-term outcomes. Despite the increasing knowledge about the etiology and pathophysiology of IS, in the last years, no new treatment approaches have been recognized to be able to modify the neurobiological process underlying IS. Precision medicine has far to come in IS.

EXPERT OPINION

Recently, no new therapeutic options for IS have emerged, probably due to the lack of reliable animal models and to the extreme variability in etiologies. Consequently, the outlook for patients and families is poor and early recognition and intervention remain research priorities.

Antiepileptic Drug Carbamazepine Binds to a Novel Pocket on the Wnt Receptor Frizzled-8

Misregulation of Wnt signaling is common in human cancer. The development of small molecule inhibitors against the Wnt receptor, frizzled (FZD), may have potential in cancer therapy. During small molecule screens, we observed binding of carbamazepine to the cysteine-rich domain (CRD) of the Wnt receptor FZD8 using surface plasmon resonance (SPR). Cellular functional assays demonstrated that carbamazepine can suppress FZD8-mediated Wnt/β-catenin signaling. We determined the crystal structure of the complex at 1.7 Å resolution, which reveals that carbamazepine binds at a novel pocket on the FZD8 CRD. The unique residue Tyr52 discriminates FZD8 from the closely related FZD5 and other FZDs for carbamazepine binding. The first small molecule-bound FZD structure provides a basis for anti-FZD drug development. Furthermore, the observed carbamazepine-mediated Wnt signaling inhibition may help to explain the phenomenon of bone loss and increased adipogenesis in some patients during long-term carbamazepine treatment.

Infantile Spasms: An Update on Pre-Clinical Models and EEG Mechanisms

Infantile spasms (IS) is an epileptic encephalopathy with unique clinical and electrographic features, which affects children in the middle of the first year of life. The pathophysiology of IS remains incompletely understood, despite the heterogeneity of IS etiologies, more than 200 of which are known. In particular, the neurobiological basis of why multiple etiologies converge to a relatively similar clinical presentation has defied explanation. Treatment options for this form of epilepsy, which has been described as “catastrophic” because of the poor cognitive, developmental, and epileptic prognosis, are limited and not fully effective. Until the pathophysiology of IS is better clarified, novel treatments will not be forthcoming, and preclinical (animal) models are essential for advancing this knowledge. Here, we review preclinical IS models, update information regarding already existing models, describe some novel models, and discuss exciting new data that promises to advance understanding of the cellular mechanisms underlying the specific EEG changes seen in IS—interictal hypsarrhythmia and ictal electrodecrement.

GRIN2A -Related Severe Epileptic Encephalopathy Treated with Memantine: An Example of Precision Medicine

Epileptic spasm (ES) is one of the seizure types which is difficult to treat. Next-generation sequencing has facilitated rapid gene discovery that is linked to ES and GRIN2A being one of them. Genotype-driven precision medicine is on the horizon and is a targeted treatment approach toward the precise molecular cause of the disease. GRIN2A gene encodes for a subunit of N-methyl-D-aspartate (NMDA) receptor and it has been suggested from in vitro studies and few case reports that memantine, a NMDA receptor antagonist, was shown to reduce seizures in patients with GRIN2A mutations. Here, we describe a patient with a novel GRIN2A mutation and severe drug-resistant ES who became seizure free with memantine.

A novel VARS2 gene variant in a patient with epileptic encephalopathy

Background: Mitochondrial disorders are heterogeneous clinical syndromes caused by defective activity in the mitochondrial respiratory chain, resulting in a faulty oxidative phosphorylation system. These inherited disorders are individually rare, and furthermore they are phenotypic variables. The genetically characterized mitochondrial disorders are rarely associated with epileptic encephalopathies.Case presentation: We present the clinical phenotype, biochemical analysis, and electrographic and neuro-radiological features of a 5-month-old girl with epileptic encephalopathy, microcephaly, severe psychomotor delay, hypertrophic cardiomyopathy, and abnormal MRI scan. Using whole-genome sequencing technique, compound heterozygous mutations of the VARS2 gene were revealed, with one previously unreported frameshift mutation.Conclusion: Our report extends the phenotypic spectrum of VARS2-related disorders with an initial presentation of epileptic encephalopathy and early death due to malignant arrhythmia.

Effectiveness of corticosteroids versus adrenocorticotropic hormone for infantile spasms: a systematic review and meta-analysis

Objective

To compare the therapeutic effectiveness of oral corticosteroids with that of adrenocorticotrophic hormone for infantile spasms.

Methods

PubMed, Embase, Scopus, and the Cochrane library were searched to retrieve studies published before December 2018 to identify pediatric patients with a diagnosis of infantile spasms. The interventions of oral corticosteroids and adrenocorticotrophic hormone were compared. We included only randomized controlled trials that reported the cessation of spasms as treatment response. The primary outcome was clinical spasm cessation on day 13 or 14. The secondary outcomes were the resolution of hypsarrhythmia, side effects, continued spasm control, spasm relapse rate, and subsequent epilepsy rate. Following the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses, the study‐level quality assessment was conducted using the Cochrane risk‐of‐bias tool.

Results

After extensive review, 39 articles were included for meticulous evaluation. Five randomized controlled trials with a total of 239 individuals were eligible for further analysis. No significant difference was detected between the corticosteroids and adrenocorticotrophic hormone in the cessation of clinical spasms (odds ratio [OR]: 0.54; 95% confidence interval [CI]: 0.16 to 1.81; P = 0.32). The subgroups of high‐dose prednisolone versus adrenocorticotrophic hormone and low‐dose prednisone versus adrenocorticotrophic hormone also exhibited no significant difference. Furthermore, the two subgroups did not differ in terms of hypsarrhythmia resolution, side effects, relapse rate, or subsequent epilepsy rate.

Interpretation

This meta‐analysis suggests that high‐dose prednisolone is not inferior to adrenocorticotrophic hormone and that it be considered a safe and effective alternative treatment.

The underlying etiology of infantile spasms (West syndrome): Information from the International Collaborative Infantile Spasms Study (ICISS)

OBJECTIVE

To determine the underlying etiologies in a contemporary cohort of infants with infantile spasms and to examine response to treatment.

METHODS

Identification of the underlying etiology and response to treatment in 377 infants enrolled in a clinical trial of the treatment of infantile spasms between 2007 and 2014 using a systematic review of history, examination, and investigations. They were classified using the pediatric adaptation of International Classification of Diseases, Tenth Revision (ICD-10).

RESULTS

A total of 219 of 377 (58%) had a proven etiology, of whom 128 (58%) responded, 58 of 108 (54%) were allocated hormonal treatment, and 70 of 111 (63%) had combination therapy. Fourteen of 17 (82%, 95% confidence interval [CI] 59% to 94%) infants with stroke and infarct responded (compared to 114 of 202 for the rest of the proven etiology group (56%, 95% CI 48% to 62%, chi-square 4.3, P = .037): the better response remains when treatment allocation and lead time are taken into account (odds ratio 5.1, 95% CI 1.1 to 23.6, P = .037). Twenty of 37 (54%, 95% CI 38% to 70%) infants with Down syndrome had cessation of spasms compared to 108 of 182 (59%, 95% CI 52% to 66%, chi-square 0.35, P = .55) for the rest of the proven etiology group. The lack of a significant difference remains after taking treatment modality and lead-time into account (odds ratio 0.8, 95% CI 0.4 to 1.7, P = .62). In Down syndrome infants, treatment modality did not appear to affect response: 11 of 20 (55%) allocated hormonal therapy responded, compared to 9 of 17 (53%) allocated combination therapy.

SIGNIFICANCE

This classification allows easy comparison with other classifications and with our earlier reports. Stroke and infarct have a better outcome than other etiologies, whereas Down syndrome might not respond to the addition of vigabatrin to hormonal treatment.

Increased electroencephalography connectivity precedes epileptic spasm onset in infants with tuberous sclerosis complex

OBJECTIVE

To identify whether abnormal electroencephalography (EEG) connectivity is present before the onset of epileptic spasms (ES) in infants with tuberous sclerosis complex (TSC).

METHODS

Scalp EEG recordings were collected prospectively in infants diagnosed with TSC in the first year of life. This study compared the earliest recorded EEG from infants prior to ES onset (n = 16) and from infants who did not develop ES (n = 28). Five minutes of stage II or quiet sleep was clipped and filtered into canonical EEG frequency bands. Mutual information values between each pair of EEG channels were compared directly and used as a weighted graph to calculate graph measures of global efficiency, characteristic path length, average clustering coefficient, and modularity.

RESULTS

At the group level, infants who later developed ES had increased EEG connectivity in sleep. They had higher mutual information values between most EEG channels in all frequency bands adjusted for age. Infants who later developed ES had higher global efficiency and average clustering coefficients, shorter characteristic path lengths, and lower modularity across most frequency bands adjusted for age. This suggests that infants who went on to develop ES had increased local and long-range EEG connectivity with less segregation of graph regions into distinct modules.

SIGNIFICANCE

This study suggests that increased neural connectivity precedes clinical ES onset in a cohort of infants with TSC. Overconnectivity may reflect progressive pathologic network synchronization culminating in generalized ES. Further research is needed before scalp EEG connectivity measures can be used as a potential biomarker of ES risk and treatment response in pre-symptomatic infants with TSC.

De novo PHACTR1 mutations in West syndrome and their pathophysiological effects

Trio-based whole exome sequencing identified two de novo heterozygous missense mutations [c.1449T > C/p.(Leu500Pro) and c.1436A > T/p.(Asn479Ile)] in PHACTR1, encoding a molecule critical for the regulation of protein phosphatase 1 (PP1) and the actin cytoskeleton, in unrelated Japanese individuals with West syndrome (infantile spasms with intellectual disability). We then examined the role of Phactr1 in the development of mouse cerebral cortex and the pathophysiological significance of these two mutations and others [c.1561C > T/p.(Arg521Cys) and c.1553T > A/p.(Ile518Asn)], which had been reported in undiagnosed patients with intellectual disability. Immunoprecipitation analyses revealed that actin-binding activity of PHACTR1 was impaired by the p.Leu500Pro, p.Asn479Ile and p.Ile518Asn mutations while the p.Arg521Cys mutation exhibited impaired binding to PP1. Acute knockdown of mouse Phactr1 using in utero electroporation caused defects in cortical neuron migration during corticogenesis, which were rescued by an RNAi-resistant PHACTR1 but not by the four mutants. Experiments using knockdown combined with expression mutants, aimed to mimic the effects of the heterozygous mutations under conditions of haploinsufficiency, suggested a dominant negative effect of the mutant allele. As for dendritic development in vivo, only the p.Arg521Cys mutant was determined to have dominant negative effects, because the three other mutants appeared to be degraded with these experimental conditions. Electrophysiological analyses revealed abnormal synaptic properties in Phactr1-deficient excitatory cortical neurons. Our data show that the PHACTR1 mutations may cause morphological and functional defects in cortical neurons during brain development, which is likely to be related to the pathophysiology of West syndrome and other neurodevelopmental disorders.

Infantile Spasms of Unknown Cause: Predictors of Outcome and Genotype-Phenotype Correlation

BACKGROUND

No large-scale studies have specifically evaluated the outcomes of infantile spasms (IS) of unknown cause, previously known as cryptogenic or idiopathic. The Epilepsy Phenome/Genome Project aimed to characterize IS of unknown cause by phenotype and genotype analysis.

METHODS

We undertook a retrospective multicenter observational cohort of 133 individuals within the Epilepsy Phenome/Genome Project database met criteria for IS of unknown cause with at least six months of follow-up data. Clinical medical records, imaging, and electroencephalography were examined.

RESULTS

Normal development occurred in only 15% of IS of unknown cause. The majority (85%) had clinically documented developmental delay (15% mild, 20% moderate, and 50% severe) at last assessment (median 2.7 years; interquartile interval 1.71-6.25 years). Predictors of positive developmental outcomes included no delay prior to IS (P < 0.001), older age of IS onset (median six months old), and resolution of IS after initial treatment (P < 0.001). Additional seizures after IS occurred in 67%, with predictors being seizures prior to IS (P = 0.018), earlier age of IS onset (median five months old), and refractory IS (P = 0.008). On a research basis, whole exome sequencing identified 15% with de novo variants in known epilepsy genes. Individuals with a genetic finding were more likely to have poor developmental outcomes (P = 0.035).

CONCLUSIONS

The current study highlights the predominately unfavorable developmental outcomes and that subsequent seizures are common in children with IS of unknown cause. Ongoing genetic evaluation of IS of seemingly unknown cause is likely to yield a diagnosis and provide valuable prognostic information.

Epileptic Encephalopathies

PURPOSE OF REVIEW

This article reviews the manifestations and treatment of the epileptic encephalopathies, which are a heterogeneous group of disorders characterized by both seizures and neurocognitive impairment.

RECENT FINDINGS

Next-generation (exome- and genome-based) sequencing technologies are revolutionizing the identification of single-gene causes of epileptic encephalopathy but have only had a modest impact on patient-specific treatment decisions. The treatment of most forms of epileptic encephalopathy remains a particularly challenging endeavor, with therapeutic decisions chiefly driven by the electroclinical syndrome classification. Most antiseizure drugs are ineffective in the treatment of these disorders, and treatments that are effective often entail significant risk and cost.

SUMMARY

The epileptic encephalopathies continue to pose a major challenge in diagnosis and treatment, with most patients experiencing very poor outcomes, although a significant minority of patients respond to, or are even cured by, specific therapies.

Wnt/β-catenin signaling as a potential target for novel epilepsy therapies

Epilepsy is one of the most common neurological disorders, and yet many afflicted individuals are resistant to all available therapeutic treatments. Existing pharmaceutical treatments function primarily to reduce hyperexcitability and prevent seizures, but fail to influence the underlying pathophysiology of the disorder. Recently, research efforts have focused on identifying alternative mechanistic targets for anti-epileptogenic therapies that can prevent the development of chronic epilepsy. The Wnt/β-catenin pathway, one possible target, has been demonstrated to be disrupted in both acute and chronic phases of epilepsy. Wnt/β-catenin signaling can regulate many seizure-induced changes in the brain, including neurogenesis and neuronal death, as well as can influence seizure susceptibility and potentially the development of chronic epilepsy. Several genome-wide studies and in vivo knockout animal models have provided evidence for an association between disrupted Wnt/β-catenin signaling and epilepsy. Furthermore, approved pharmaceutical drugs and other small molecule compounds that target components of the β-catenin destruction complex or antagonize endogenous inhibitors of the pathway have shown to be protective following seizures. However, additional studies are needed to determine the optimal time period in which modulation of the pathway may be most beneficial. Overall, disrupted molecular networks such as Wnt/β-catenin signaling, could be a promising anti-epileptogenic target for future epilepsy therapies.

Clinical characteristics of two cohorts of infantile spasms: response to pyridoxine or topiramate monotherapy

BACKGROUND

Infantile spasms (IS) was an epileptic disease with varied treatment widely among clinicians. Here, we aimed to compare and analyze the clinical characteristics of IS response to pyridoxine or topiramate monotherapy (TPM control IS).

METHODS

The clinical manifestations, treatment processes and outcomes were analyzed in 11 pyridoxine responsive IS and 17 TPM-control IS.

RESULTS

Of the 11 patients with pyridoxine responsive IS, nine were cryptogenic/idiopathic. Age of seizure onset was 5.36 ± 1.48 months. Spasms were controlled within a week in most of the patients. At the last follow-up, EEG returned to normal in 8. Psychomotor development was normal in 6, mild delay in 3, severe delay in 2. Of the 17 patients with TPM-control IS, 10 were cryptogenic/idiopathic. The age of seizure onset was 5.58 ± 2.09 months. All patients were controlled within a month. At the last follow-up, EEG was normal in 10. Psychomotor development was normal in 8, mild delay in 5, severe delay in 4. Genetic analysis did not show any meaningful results.

CONCLUSIONS

The clinical characteristics and disease courses of pyridoxine responsive IS and TPM-control IS were similar, which possibly clued for a same pathogenic mechanism. Pyridoxine should be tried first in all IS patients, even in symptomatic cases. If patients were not responsive to pyridoxine, TPM could be tried.

Benign and severe early-life seizures: a round in the first year of life

BACKGROUND

At the onset, differentiation between abnormal non-epileptic movements, and epileptic seizures presenting in early life is difficult as is clinical diagnosis and prognostic evaluation of the various seizure disorders presenting at this age. Seizures starting in the first year of life including the neonatal period might have a favorable course, such as in infants presenting with benign familial neonatal epilepsy, febrile seizures simplex or acute symptomatic seizures. However, in some cases, the onset of seizures at birth or in the first months of life have a dramatic evolution with severe cerebral impairment. Seizure disorders starting in early life include the "epileptic encephalopathies", a group of conditions characterized by drug resistant seizures, delayed developmental skills, and intellective disability. This group of disorders includes early infantile epileptic encephalopathy also known as Ohtahara syndrome, early myoclonic encephalopathy, epilepsy of infancy with migrating focal seizures, infantile spasms syndrome (also known as West syndrome), severe myoclonic epilepsy in infancy (also known as Dravet syndrome) and, myoclonic encephalopathies in non-progressive disorder. Here we report on seizures manifesting in the first year of life including the neonatal period. Conditions with a benign course, and those with severe evolution are presented. At this early age, clinical identification of seizures, distinction of each of these disorders, type of treatment and prognosis is particularly challenging. The aim of this report is to present the clinical manifestations of each of these disorders and provide an updated review of the conditions associated with seizures in the first year of life.

Detailed Magnetic Resonance Imaging (MRI) Analysis in Infantile Spasms

PURPOSE

To evaluate initial magnetic resonance imaging (MRI) abnormalities in infantile spasms, correlate them to clinical characteristics, and describe repeat imaging findings.

METHODS

A retrospective review of infantile spasm patients was conducted, classifying abnormal MRI into developmental, acquired, and nonspecific subgroups.

RESULTS

MRIs were abnormal in 52 of 71 infantile spasm patients (23 developmental, 23 acquired, and 6 nonspecific) with no correlation to the clinical infantile spasm characteristics. Both developmental and acquired subgroups exhibited cortical gray and/or white matter abnormalities. Additional abnormalities of deep gray structures, brain stem, callosum, and volume loss occurred in the structural acquired subgroup. Repeat MRI showed better definition of the extent of existing malformations.

CONCLUSION

In structural infantile spasms, developmental/acquired subgroups showed differences in pattern of MRI abnormalities but did not correlate with clinical characteristics.

Deep Learning Meets Biomedical Ontologies: Knowledge Embeddings for Epilepsy

While biomedical ontologies have traditionally been used to guide the identification of concepts or relations in biomedical data, recent advances in deep learning are able to capture high-quality knowledge from textual data and represent it in graphical structures. As opposed to the top-down methodology used in the generation of ontologies, which starts with the principled design of the upper ontology, the bottom-up methodology enabled by deep learning encodes the likelihood that concepts share certain relations, as evidenced by data. In this paper, we present a knowledge representation produced by deep learning methods, called Medical Knowledge Embeddings (MKE), that encode medical concepts related to the study of epilepsy and the relations between them. Many of the epilepsy-relevant medical concepts from MKE are not yet available in existing biomedical ontologies, but are mentioned in vast collections of epilepsy-related medical records which also imply their relationships. The evaluation of the MKE indicates high accuracy of the medical concepts automatically identified from clinical text as well as promising results in terms of correctness and completeness of relations produced by deep learning.

Cognitive and Social Outcomes of Epileptic Encephalopathies

The term "epileptic encephalopathy" denotes a disorder in which seizures or frequent interictal discharges exacerbate neurocognitive dysfunction beyond what would be expected on the basis of underlying etiology. However, many underlying causes of epileptic encephalopathy also result in neurocognitive deficits, and it can be challenging to discern to what extent these deficits can be improved with better seizure control. Additionally, as seizures in these conditions are typically refractory, children are often exposed to high doses of multiple antiepileptic drugs which further exacerbate these comorbidities. This review will summarize the neurocognitive and social outcomes in children with various epileptic encephalopathies. Prompt, accurate diagnosis of epilepsy syndrome and etiology allows selection of optimal therapy to maximize seizure control, limiting the impact of ongoing seizures and frequent epileptiform abnormalities on the developing brain. Furthermore, mandatory screening for comorbidities allows early recognition and focused therapy for these commonly associated conditions to maximize neurocognitive outcome.

Identification of De Novo DNMT3A Mutations That Cause West Syndrome by Using Whole-Exome Sequencing

Epileptic encephalopathies (EEs) are a group of severe neurodevelopmental disorders with extreme genetic heterogeneity. Recent trio-based whole-exome sequencing (WES) studies have demonstrated that de novo mutations (DNMs) play prominent roles in severe EE. In this study, we searched for potential causal DNMs by using high-coverage WES of four unrelated Chinese parent-offspring trios affected by West syndrome. Through extensive bioinformatic analysis, we identified three novel DNMs in DNMT3A, CDKL5, and MAMDC2 in three trios and two compound heterozygous mutations in KMT2A in one trio. The DNMs in CDKL5 and DNMT3A were considered to be deleterious on the basis of the consensus of several genetic damage prediction tools. In addition, spatiotemporal expression patterns revealed a high level of DNMT3A expression during the early embryonic stage in nearly all brain regions. We also observed that certain high-confidence genes for epilepsy were shared among the co-expression and genetic interaction networks of DNMT3A, CDKL5, and KMT2A. Furthermore, all the candidate epilepsy genes in the co-expression network of DNMT3A were significantly enriched in the early developmental stages of the brain according to a rank-based enrichment test. In particular, we found that the DNMs of DNMT3A were shared among EE, autism spectrum disorder (ASD), and intellectual disability (ID) and mainly occurred in the functional domain of DNMT3A. Together, our findings support an association between DNMT3A mutations and EE susceptibility and suggest a shared molecular pathophysiology among EE and other neuropsychiatric disorders.

Whole-exome sequencing identifies a novel de novo mutation in DYNC1H1 in epileptic encephalopathies

Epileptic encephalopathies (EE) are a group of severe childhood epilepsy disorders characterized by intractable seizures, cognitive impairment and neurological deficits. Recent whole-exome sequencing (WES) studies have implicated significant contribution of de novo mutations to EE. In this study, we utilized WES for identifying causal de novo mutations in 4 parent-offspring trios affected by West syndrome. As a result, we found two deleterious de novo mutations in DYNC1H1 and RTP1 in two trios. Expression profile analysis showed that DYNC1H1 and RTP1 are expressed in almost all brain regions and developmental stages. Interestingly, co-expression and genetic interaction network analyses suggested that DYNC1H1 and RTP1 are tightly associated with known epilepsy genes. Furthermore, we observed that the de novo mutations of DYNC1H1 were identified in several different neuropsychiatric disorders including EE, autism spectrum disorders and intellectual disabilities by previous studies, and these mutations primarily occurred in the functional domain of the protein. Taken together, these results demonstrate DYNC1H1 as a strong candidate and RTP1 as a potential candidate on the onset of EE. In addition, this work also proves WES as a powerful tool for the molecular genetic dissection of children affected by sporadic EE.