The thalamus and basal ganglia are smaller in children with epilepsy after perinatal stroke

Background

Epilepsy is one of the most serious consequences of perinatal stroke. Epilepsy itself has been proposed as a risk factor for impaired cognitive, language, and behavioral functioning. It is still unclear which children develop epilepsy after perinatal stroke. The current study aimed to evaluate the volume of the thalamus and the basal ganglia in children after perinatal stroke in relation to poststroke epilepsy.

Methods

The follow-up study included 29 children with perinatal arterial ischemic stroke (AIS), 33 children with presumed periventricular venous infarction (PVI), and 46 age- and sex-matched healthy controls. Magnetic resonance imaging was performed in children between the ages of 4 and 18 years, and volumetric analysis by segmentation was used to evaluate the size of the thalamus, caudate nucleus, putamen, globus pallidus, hippocampus, amygdala, and nucleus accumbens.

Results

During a median follow-up time of 12.8 years [interquartile range (IQR): 10.8-17.3] in the AIS group and 12.5 years (IQR: 9.3-14.8) in the PVI group (p = 0.32), epilepsy developed in 10 children (34.5%) with AIS and in 4 (12.1%) children with PVI, p = 0.036 [odds ratio (OR) = 3.8, 95%, confidence interval (CI): 1.04-14]. Epilepsy and interictal epileptiform discharges (IEDs) without clinical seizures were more often expressed in children with AIS (n = 16, 55%) than in children with PVI (n = 7, 21.2%), p = 0.0057 (OR = 3.8 95% CI: 1.04-14). In the AIS group, the ipsilesional and contralesional thalamus, ipsilesional caudate nucleus, and nucleus accumbens were significantly smaller in children with epilepsy compared to children without epilepsy. In the PVI group, the ipsilesional thalamus, caudate nucleus, and nucleus accumbens were smaller in the pooled group of epilepsy plus IED alone compared to children without epilepsy.

Conclusion

In children with AIS, epilepsy or IED occurred more often compared to children with PVI. Both patients with AIS and PVI with severe damage to the basal ganglia and the thalamus have a higher risk of developing poststroke epilepsy and should be monitored more closely throughout childhood to initiate timely antiseizure medication and rehabilitation.

The gain of function SCN1A disorder spectrum: novel epilepsy phenotypes and therapeutic implications

Brain voltage-gated sodium channel NaV1.1 (SCN1A) loss-of-function variants cause the severe epilepsy Dravet syndrome, as well as milder phenotypes associated with genetic epilepsy with febrile seizures plus. Gain of function SCN1A variants are associated with familial hemiplegic migraine type 3. Novel SCN1A-related phenotypes have been described including early infantile developmental and epileptic encephalopathy with movement disorder, and more recently neonatal presentations with arthrogryposis. Here we describe the clinical, genetic and functional evaluation of affected individuals. Thirty-five patients were ascertained via an international collaborative network using a structured clinical questionnaire and from the literature. We performed whole-cell voltage-clamp electrophysiological recordings comparing sodium channels containing wild-type versus variant NaV1.1 subunits. Findings were related to Dravet syndrome and familial hemiplegic migraine type 3 variants. We identified three distinct clinical presentations differing by age at onset and presence of arthrogryposis and/or movement disorder. The most severely affected infants (n = 13) presented with congenital arthrogryposis, neonatal onset epilepsy in the first 3 days of life, tonic seizures and apnoeas, accompanied by a significant movement disorder and profound intellectual disability. Twenty-one patients presented later, between 2 weeks and 3 months of age, with a severe early infantile developmental and epileptic encephalopathy and a movement disorder. One patient presented after 3 months with developmental and epileptic encephalopathy only. Associated SCN1A variants cluster in regions of channel inactivation associated with gain of function, different to Dravet syndrome variants (odds ratio = 17.8; confidence interval = 5.4-69.3; P = 1.3 × 10-7). Functional studies of both epilepsy and familial hemiplegic migraine type 3 variants reveal alterations of gating properties in keeping with neuronal hyperexcitability. While epilepsy variants result in a moderate increase in action current amplitude consistent with mild gain of function, familial hemiplegic migraine type 3 variants induce a larger effect on gating properties, in particular the increase of persistent current, resulting in a large increase of action current amplitude, consistent with stronger gain of function. Clinically, 13 out of 16 (81%) gain of function variants were associated with a reduction in seizures in response to sodium channel blocker treatment (carbamazepine, oxcarbazepine, phenytoin, lamotrigine or lacosamide) without evidence of symptom exacerbation. Our study expands the spectrum of gain of function SCN1A-related epilepsy phenotypes, defines key clinical features, provides novel insights into the underlying disease mechanisms between SCN1A-related epilepsy and familial hemiplegic migraine type 3, and identifies sodium channel blockers as potentially efficacious therapies. Gain of function disease should be considered in early onset epilepsies with a pathogenic SCN1A variant and non-Dravet syndrome phenotype.

Language lateralization and outcome in perinatal stroke patients with different vascular types

Perinatal stroke affects child's language development and can change language lateralization. Language generation and comprehension tasks in functional magnetic resonance imaging were used to determine language lateralization in term born children with perinatal left-side arterial ischemic stroke (AIS) (n = 9, mean age (SD) 13.4 (3.1) y.) and periventricular venous infarction (PVI) (n = 12, 11.8 (2.8) y.), and in healthy right-handed controls (n = 30, 11.6 (2.6) y.). Lateralization index was calculated for the Broca and Wernicke areas and correlated with language and cognitive outcomes measured by the Kaufman Assessment Battery for Children II ed. Language outcome in children with perinatal stroke is poorer compared to healthy controls. Children with small AIS lesions and most children with PVI showed left-side language activation. Most children with large AIS lesions and one child with large PVI had language activation reorganized to the right hemisphere. Language reorganization to the unlesioned right hemisphere did not ensure normal language outcome.

Structural mapping of GABRB3 variants reveals genotype-phenotype correlations

PURPOSE

Pathogenic variants in GABRB3 have been associated with a spectrum of phenotypes from severe developmental disorders and epileptic encephalopathies to milder epilepsy syndromes and mild intellectual disability (ID). In this study, we analyzed a large cohort of individuals with GABRB3 variants to deepen the phenotypic understanding and investigate genotype-phenotype correlations.

METHODS

Through an international collaboration, we analyzed electro-clinical data of unpublished individuals with variants in GABRB3, and we reviewed previously published cases. All missense variants were mapped onto the 3-dimensional structure of the GABRB3 subunit, and clinical phenotypes associated with the different key structural domains were investigated.

RESULTS

We characterized 71 individuals with GABRB3 variants, including 22 novel subjects, expressing a wide spectrum of phenotypes. Interestingly, phenotypes correlated with structural locations of the variants. Generalized epilepsy, with a median age at onset of 12 months, and mild-to-moderate ID were associated with variants in the extracellular domain. Focal epilepsy with earlier onset (median: age 4 months) and severe ID were associated with variants in both the pore-lining helical transmembrane domain and the extracellular domain.

CONCLUSION

These genotype-phenotype correlations will aid the genetic counseling and treatment of individuals affected by GABRB3-related disorders. Future studies may reveal whether functional differences underlie the phenotypic differences.

Incidence of Childhood Epilepsy in Estonia

The aim of this prospective epidemiological study was to establish the incidence rate of childhood epilepsy in Estonia, to describe the clinical spectrum and to identify etiology of childhood epilepsy. The overall incidence rate was 86.3/100 000. The incidence rate was the highest (141.9/100 000) in the age group from 5 to 9 years. Specific electroclinical syndromes were identified in 22.8% of cases. Structural or metabolic etiology was identified in 20.0% of cases, presumed genetic origin was identified in 33.9% of cases, and in 46.1% of cases the cause of epilepsy remained unknown. The incidence rate of childhood epilepsy in Estonia (86.3/100 000) is similar to the other European countries. In comparison with the results of the first epidemiological study of childhood epilepsy in Estonia (incidence rate 45/100 000; Beilmann et al), the incidence rate in this study is almost 2 times higher, what can be explained with better case collection and improved diagnostic modalities in Estonia.

Epilepsy after perinatal stroke with different vascular subtypes

Objective

With an incidence up to 63 per 100,000 live births, perinatal stroke is an important cause of childhood epilepsy. The aim of the study was to find the prevalence of and predictive factors for epilepsy, and to describe the course of epilepsy in children with perinatal stroke with different vascular subtypes.

Methods

Patients were retrieved from the Estonian Paediatric Stroke Database with follow‐up time at least 24 months. Patients were divided into 5 perinatal stroke syndromes: neonatal arterial ischemic stroke (AIS), neonatal hemorrhagic stroke, neonatal cerebral sinovenous thrombosis, presumed AIS, and presumed periventricular venous infarction.

Results

The final study group included 73 children with perinatal stroke (39 boys). With a median follow‐up time of 8.6 years, epilepsy was diagnosed in 21/73 (29%) children, most of whom had AIS (17/21, 81%). The 18‐year cumulative poststroke epilepsy risk according to the Kaplan‐Meier estimator was 40.8% (95% confidence interval [CI] 20.7–55.9%). The median age at epilepsy diagnosis was 50 months (range 1 month to 18.4 years). Children with neonatal AIS had the highest risk of epilepsy, but children with presumed AIS more often had severe epilepsy syndromes. Cortical lesions (odds ratio [OR] 19.7, 95% CI 2.9–133), and involvement of thalamus (OR 9.8, 95% CI 1.8–53.5) and temporal lobe (OR 8.3, 95% CI 1.8–39.6) were independently associated with poststroke epilepsy.

Significance

The risk for poststroke epilepsy after perinatal stroke depends on the vascular subtype. Patients with perinatal AIS need close follow‐up to detect epilepsy and start with antiepileptic treatment on time.

Mutations in GABRB3: From febrile seizures to epileptic encephalopathies

OBJECTIVE

To examine the role of mutations in GABRB3 encoding the β₃ subunit of the GABA_A receptor in individual patients with epilepsy with regard to causality, the spectrum of genetic variants, their pathophysiology, and associated phenotypes.

METHODS

We performed massive parallel sequencing of GABRB3 in 416 patients with a range of epileptic encephalopathies and childhood-onset epilepsies and recruited additional patients with epilepsy with GABRB3 mutations from other research and diagnostic programs.

RESULTS

We identified 22 patients with heterozygous mutations in GABRB3, including 3 probands from multiplex families. The phenotypic spectrum of the mutation carriers ranged from simple febrile seizures, genetic epilepsies with febrile seizures plus, and epilepsy with myoclonic-atonic seizures to West syndrome and other types of severe, early-onset epileptic encephalopathies. Electrophysiologic analysis of 7 mutations in Xenopus laevis oocytes, using coexpression of wild-type or mutant β₃, together with α₅ and γ_2s subunits and an automated 2-microelectrode voltage-clamp system, revealed reduced GABA-induced current amplitudes or GABA sensitivity for 5 of 7 mutations.

CONCLUSIONS

Our results indicate that GABRB3 mutations are associated with a broad phenotypic spectrum of epilepsies and that reduced receptor function causing GABAergic disinhibition represents the relevant disease mechanism.

CDKL5 Gene-Related Epileptic Encephalopathy in Estonia: Four Cases, One Novel Mutation Causing Severe Phenotype in a Boy, and Overview of the Literature

Cyclin-dependent kinase-like 5 (CDKL5) gene mutations have mainly been found in females with early infantile epileptic encephalopathy (EIEE), severe intellectual disability, and Rett-like features. To date, only 22 boys have been reported, presenting with far more severe phenotypic features. We report the first cases of CDKL5 gene-related EIEE in Estonia diagnosed using panels of epilepsy-associated genes and describe the phenotype-genotype correlations in three male and one female patient. One of the mutations, identified in a male patient, was a novel de novo hemizygous frameshift mutation (NM_003159.2:c.2225_2228del (p.Glu742Afs*41)) in exon 15 of CDKL5. All boys have a more severe phenotype than the female patient. In boys with early onset of seizures and poor development with absent or poor eye contact, CDKL5 gene-related EIEE can be suspected and epilepsy-associated genes should be analyzed for early etiological diagnosis. Early genetic diagnosis would be the cornerstone in personalized treatment in the future.

Gene Panel Testing in Epileptic Encephalopathies and Familial Epilepsies

In recent years, several genes have been causally associated with epilepsy. However, making a genetic diagnosis in a patient can still be difficult, since extensive phenotypic and genetic heterogeneity has been observed in many monogenic epilepsies. This study aimed to analyze the genetic basis of a wide spectrum of epilepsies with age of onset spanning from the neonatal period to adulthood. A gene panel targeting 46 epilepsy genes was used on a cohort of 216 patients consecutively referred for panel testing. The patients had a range of different epilepsies from benign neonatal seizures to epileptic encephalopathies (EEs). Potentially causative variants were evaluated by literature and database searches, submitted to bioinformatic prediction algorithms, and validated by Sanger sequencing. If possible, parents were included for segregation analysis. We identified a presumed disease-causing variant in 49 (23%) of the 216 patients. The variants were found in 19 different genes including SCN1A, STXBP1, CDKL5, SCN2A, SCN8A, GABRA1, KCNA2, and STX1B. Patients with neonatal-onset epilepsies had the highest rate of positive findings (57%). The overall yield for patients with EEs was 32%, compared to 17% among patients with generalized epilepsies and 16% in patients with focal or multifocal epilepsies. By the use of a gene panel consisting of 46 epilepsy genes, we were able to find a disease-causing genetic variation in 23% of the analyzed patients. The highest yield was found among patients with neonatal-onset epilepsies and EEs.

Clinical Phenotype of De Novo GNAO1 Mutation: Case Report and Review of Literature

Mutations in the guanine nucleotide-binding protein (G protein), α activating activity polypeptide O (GNAO1) gene have recently been described in 6 patients with early infantile epileptic encephalopathies. In the present study, we report the phenotype and the clinical course of a 4-year-old female with an epileptic encephalopathy (Ohtahara syndrome) and profound intellectual disability due to a de novo GNAO1 mutation (c.692A>G; p.Tyr231Cys). Ohtahara syndrome is a devastating early infantile epileptic encephalopathy that can be caused by mutations in different genes, now also including GNAO1. The mutation was found using a targeted next generation sequencing gene panel and demonstrates targeted sequencing as a powerful tool for identifying mutations in genes where only a few de novo mutations have been identified.

De novo SCN8A mutation identified by whole-exome sequencing in a boy with neonatal epileptic encephalopathy, multiple congenital anomalies, and movement disorders

Epileptic encephalopathies represent a clinically and genetically heterogeneous group of disorders, majority of which are of unknown etiology. We used whole-exome sequencing of a parent-offspring trio to identify the cause of early infantile epileptic encephalopathy in a boy with neonatal seizures, movement disorders, and multiple congenital anomalies who died at the age of 17 months because of respiratory illness and identified a de novo heterozygous missense mutation (c.3979A>G; p.Ile1327Val) in SCN8A (voltage-gated sodium-channel type VIII alpha subunit) gene. The variant was confirmed in the proband with Sanger sequencing. Because the clinical phenotype associated with SCN8A mutations has previously been identified only in a few patients with or without epileptic seizures, these data together with our results suggest that mutations in SCN8A can lead to early infantile epileptic encephalopathy with a broad phenotypic spectrum. Additional investigations will be worthwhile to determine the prevalence and contribution of SCN8A mutations to epileptic encephalopathies.

Monosomy 1p36 - a multifaceted and still enigmatic syndrome: four clinically diverse cases with shared white matter abnormalities

Monosomy 1p36 is the most common subtelomeric deletion syndrome seen in humans. Uniform features of the syndrome include early developmental delay and consequent intellectual disability, muscular hypotonia, and characteristic dysmorphic facial features. The gene-rich nature of the chromosomal band, inconsistent deletion sizes and overlapping clinical features have complicated relevant genotype-phenotype correlations. We describe four patients with isolated chromosome 1p36 deletions. All patients shared white matter abnormalities, allowing us to narrow the critical region for white matter involvement to the deletion size of up to 2.5 Mb from the telomere. We hypothesise that there might be a gene(s) responsible for myelin development in the 1p36 subtelomeric region. Other significant clinical findings were progressive spastic paraparesis, epileptic encephalopathy, various skeletal anomalies, Prader-Willi-like phenotype, neoplastic changes - a haemangioma and a benign skin tumour, and in one case, sleep myoclonus, a clinical entity not previously described in association with 1p36 monosomy. Combined with prior studies, our results suggest that the clinical features seen in monosomy 1p36 have more complex causes than a classical contiguous gene deletion syndrome.

Cerebral blood-flow velocities in predicting outcome of asphyxiated newborn infants

AIM

To evaluate the role of early (up to 12 h) changes in cerebral blood-flow (CBF) velocity in predicting the severity of hypoxic-ischaemic encephalopathy (HIE) and long-term outcome in asphyxiated term infants.

METHODS

CBF velocities were investigated by colour Doppler ultrasonography in 81 healthy and 60 asphyxiated term infants at least three times during the first 5 d of life. The psychomotor development of infants was followed up to 18 mo.

RESULTS

No differences in CBF velocities were found at the age of 2-6 h between infants with severe and mild-moderate HIE, mean CBF velocity [mean (95% CI of mean CBF velocity)] in anterior cerebral artery [14.9 (1.4-28.4)cm/s] and [13.9 (11.1-16.7) cm/s], respectively, and between infants with poor outcome (death or severe disability) and with normal development/mild impairments. By the age of 12 h infants with mild-moderate HIE and infants with normal development/mild impairments had decreased CBF velocity in the anterior cerebral artery, and infants with severe HIE or poor outcome had increased mean CBF velocity in anterior, medial cerebral and basilar artery compared to the control group.

CONCLUSION

The value of CBF velocity changes to predict poor outcome in asphyxiated infants is low 2-6 h after asphyxia, but increases by the age of 12 ho.

Four siblings with Hallervorden-Spatz disease

We reported four cases of Hallervorden-Spatz disease. All four siblings (three males and one female) in the family are affected. The first symptoms of the disease were spastic paraparesis and optic atrophy followed by trunkal dystonia and lower motor neurone involvement. The average age of the onset was 4.25 years. The diagnosis was made at the ages of 17, 14, 11 and 10 years. The diagnosis was confirmed clinically, electrophysiologically and by MRI. On MRI scans all patients demonstrated hypointense areas in globus pallidus. There is neither specific treatment nor prenatal diagnosis.