Early childhood epilepsies:epidemiology, classification, aetiology, and socio-economic determinants

Epilepsies of early childhood are frequently resistant to therapy and often associated with cognitive and behavioural comorbidity. Aetiology focused precision medicine, notably gene-based therapies, may prevent seizures and comorbidities. Epidemiological data utilizing modern diagnostic techniques including whole genome sequencing and neuroimaging can inform diagnostic strategies and therapeutic trials. We present a 3-year, multicentre prospective cohort study, involving all children under 3 years of age in Scotland presenting with epilepsies. We used two independent sources for case identification: clinical reporting and EEG record review. Capture-recapture methodology was then used to improve the accuracy of incidence estimates. Socio-demographic and clinical details were obtained at presentation, and 24 months later. Children were extensively investigated for aetiology. Whole genome sequencing was offered for all patients with drug-resistant epilepsy for whom no aetiology could yet be identified. Multivariate logistic regression modelling was used to determine associations between clinical features, aetiology, and outcome. Three hundred and ninety children were recruited over 3 years. The adjusted incidence of epilepsies presenting in the first 3 years of life was 239 per 100 000 live births [95% confidence interval (CI) 216–263]. There was a socio-economic gradient to incidence, with a significantly higher incidence in the most deprived quintile (301 per 100 000 live births, 95% CI 251–357) compared with the least deprived quintile (182 per 100 000 live births, 95% CI 139–233), χ2 odds ratio = 1.7 (95% CI 1.3–2.2). The relationship between deprivation and incidence was only observed in the group without identified aetiology, suggesting that populations living in higher deprivation areas have greater multifactorial risk for epilepsy. Aetiology was determined in 54% of children, and epilepsy syndrome was classified in 54%. Thirty-one per cent had an identified genetic cause for their epilepsy. We present novel data on the aetiological spectrum of the most commonly presenting epilepsies of early childhood. Twenty-four months after presentation, 36% of children had drug-resistant epilepsy (DRE), and 49% had global developmental delay (GDD). Identification of an aetiology was the strongest determinant of both DRE and GDD. Aetiology was determined in 82% of those with DRE, and 75% of those with GDD. In young children with epilepsy, genetic testing should be prioritized as it has the highest yield of any investigation and is most likely to inform precision therapy and prognosis. Epilepsies in early childhood are 30% more common than previously reported. Epilepsies of undetermined aetiology present more frequently in deprived communities. This likely reflects increased multifactorial risk within these populations

Effects of antenatal inflammation and postnatal oxygen fluctuation on developing white matter in a rodent model of prematurity

Inflammation and oxidative stress are increasingly recognised as important independent mediators of preterm brain injury and have been implicated in the pathogenesis of cerebral palsy and cognitive impairment. Such exposures are common for the premature infant in whom infection and inflammatory morbidities occur in around 60%. Furthermore, many preterm infants require oxygen therapy and respiratory support due to lung immaturity. Epidemiological and experimental studies indicate that in addition to the independent effects of inflammation and extreme hyperoxia on the developing brain, inflammation preconditions the developing brain resulting in variable injury when exposed to subsequent hypoxia-ischaemia. However experimental studies employing exposure to more modest oxygen fluctuations are lacking. This thesis characterises a clinically relevant model of prematurity where the developing brain is exposed to low grade inflammation and oxygen fluctuation around a hyperoxic mean. We hypothesise that antenatal inflammation and postnatal oxygen fluctuation, both alone and in combination, have detrimental effects on developing white matter. Pregnant dams received intraperitoneal lipopolysaccharide (LPS) or saline on G18 and G19. Dams and their pups were then reared in room air or fluctuating hyperoxia (circa 10kPa) for seven days. We measured longitudinal brain and body growth in different experimental groups to 12 weeks. Whole brains were examined for mRNA expression of inflammatory cytokines (TNFα, IL-1β, IL-6 and IL-10) and markers of oxidative injury (iNOS, SOD2). To determine the effect of perinatal insults on developing white matter, we analysed the expression of myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) in the internal and external capsule. We also examined white matter tracts for differences in microglia (CD68), oligodendrocyte progenitor cells (NG2), oligodendroglial cells (Olig2) and cell death (cleaved caspase3). Behavioural studies (Morris Watermaze Test, Elevated Plus Test and Open Field Test) were undertaken at 12 weeks of age to detect any long-term functional difference between the groups. Antenatal inflammation reduces both brain and body growth at P7. This normalises by P14 unless this inflammatory insult has been followed by postnatal oxygen fluctuation, where brain and body growth restriction persists until P14. We defined our inflammatory response at P1 following antenatal inflammation and did not observe elevation of mRNA at P1. We demonstrated increased SOD2 at this time point, indicating a reparative process. At P7 we observed a significant reduction in the oxidative response following combined exposure to antenatal inflammation and postnatal oxygen fluctuation, indicating a potential limit to, or suppression of, the reparative process. In terms of white matter injury, antenatal inflammation reduces myelination at P7. There is no synergistic effect of inflammation and oxygen fluctuation on MBP immunohistochemistry at P7. However, MBP mRNA expression is increased in pups exposed to both insults compared to those exposed to inflammation alone suggesting that the oxygen fluctuation may stimulate MBP production in response to oxidative injury. MBP mRNA levels and protein expression have all normalised by P14. We observed a reduction in total cell number in the external capsule and corpus callosum in the dual insult group, without an increase in caspase. In keeping with other studies we detected no effect of our perinatal insults on NG2+ve oligodendrocytes. Olig2+ve cell numbers were also consistent between experimental groups. In further characterisation of the cellular response, antenatal inflammation followed by postnatal oxygen fluctuation resulted in a decrease in GFAP mRNA at P7, an effect which was reversed and significantly increased by P14 suggesting delayed activation of the innate immune system. No difference was observed in microglial numbers between experimental groups. There was however, increased microglial cell death (CD68 + caspase) in the group exposed to antenatal inflammation. When this insult was combined with postnatal oxygen fluctuation there was a comparative decrease in microglial cell death, which may reflect an earlier peak of microglial cell death, due to an increased and sustained inflammatory stimulus. Morris Watermaze testing demonstrated that pups exposed to both insults took longer than controls to locate the hidden platform on day 1, which is a measure of spatial learning. The Elevated Plus Test and Open Field Test demonstrated that pups exposed to both insults were less anxious and took more risks than pups exposed to single insults. In conclusion, within a clinically relevant preterm model, antenatal inflammation transiently disrupts both brain and body growth and myelination of the motor tracts of the developing brain. Moreover, when combined with postnatal oxygen fluctuation, detrimental effects on growth are amplified and sustained. Decreased cell numbers are also observed within white matter tracts. In terms of long term functionality, these pups display disinhibition of behaviour as young adults. Collectively, this thesis demonstrates that synergistic actions of common low-grade perinatal insults may alter normal neurodevelopment, and that this may carry a risk of neurodevelopmental sequelae for preterm infants

Pre-discharge "car seat challenge" for preventing morbidity and mortality in preterm infants

BACKGROUND: Physiological monitoring studies indicate that some preterm infants experience episodes of oxygen desaturation, apnoea, or bradycardia when seated in standard car safety seats. The American Academy of Pediatrics recommends that all preterm infants should be assessed for cardiorespiratory stability in their car seat prior to discharge - the "car seat challenge". We aimed to assess the evidence to support this practice, specifically to determine whether the use of the car seat challenge prevents morbidity and mortality in preterm infants. OBJECTIVES: To assess the available evidence from randomised controlled trials that pre-discharge cardiorespiratory monitoring in a car safety seat prevents morbidity and mortality in preterm infants. SEARCH STRATEGY: We used the standard search strategy of the Cochrane Neonatal Review Group. This included searches of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2005), MEDLINE (1966 - September 2005), EMBASE (1980 - September 2005), CINAHL (1982 - September 2005), conference proceedings, and previous reviews. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials that compared pre-discharge cardiorespiratory monitoring in a car seat versus no monitoring in preterm infants in the week prior to planned discharge from hospital. DATA COLLECTION AND ANALYSIS: The standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by two review authors, and synthesis of data using relative risk, risk difference and weighted mean difference. MAIN RESULTS: We did not find any randomised controlled trials that fulfilled the eligibility criteria. AUTHORS' CONCLUSIONS: It is unclear whether undertaking a pre-discharge car seat challenge is beneficial or harmful to preterm infants. Further studies are needed to determine whether the car seat challenge accurately predicts the risk of clinically significant adverse events in preterm infants travelling in car seats. If this is shown to be the case then a large randomised controlled trial is needed to provide an unbiased assessment of its utility in pre-discharge assessment

Interactions formed by individually expressed TAP1 and TAP2 polypeptide subunits

The transporter associated with antigen processing (TAP) supplies peptides into the lumen of the endoplasmic reticulum (ER) for binding by major histocompatibility complex (MHC) class I molecules. TAP comprises two polypeptides, TAP1 and TAP2, each a 'half-transporter' encoding a transmembrane domain and a nucleotide-binding domain. Immunoprecipitation of rat TAP1 and TAP2 expressed individually in the human TAP-deficient cell line, T2, revealed that both bound the endogenously expressed HLA-A2 and -B51 class I molecules. Using HLA-encoding recombinant vaccinia viruses HLA-A*2501, -B*2704, -B*3501 and -B*4402, alleles also associated with both TAP1 and TAP2. Thus, TAP1 and TAP2 do not appear to differ in their ability to interact with MHC class I alleles. Single TAP polypeptide subunits also formed MHC class I peptide-loading complexes, and their nucleotide-binding domains retained the ability to interact with ATP, and may permit the release of peptide-loaded MHC class I molecules in the absence of a peptide transport cycle. It is also demonstrated by chemical cross-linking that TAP2, but not TAP1, has the ability to form a homodimer complex both in whole cells and in detergent lysates. Together these data indicate that single TAP polypeptide subunits possess many of the features of the TAP heterodimer, demonstrating them to be useful models in the study of ATP-binding cassette (ABC) transporters

Neuronal antibody prevalence in children with seizures under 3 years:a prospective national cohort

Objective: To report the prevalence of anti-neuronal antibodies in a prospectively whole nation cohort of children presenting with seizures before their third birthday. Methods: This was a prospective population-based national cohort study involving all children presenting with new onset epilepsy or complex febrile seizures before their 3rd birthday over a three-year period. Patients with previously identified structural, metabolic or infectious cause for seizures were excluded. Serum samples were obtained at first presentation and tested for seven neuronal antibodies using live cell-based assays. Clinical data were collected using structured proformas at recruitment, and 24 months after presentation. In addition, patients with seizures and clinically suspected autoimmune encephalitis were independently identified by reviewing the case records of all children < 3 years in Scotland who had undergone electroencephalography (EEG). Results: 298 patients were identified, recruited and underwent autoantibody testing. Antibody positivity was identified in 18/298 (6.0%). The antibodies identified were: GABABR (n = 8, 2.7%), CASPR2 (n = 4, 1.3%), GlyR (n = 3, 1.0%), LGI1 (n = 2, 0.7%), NMDAR (n = 1, 0.3%), and GABAAR (n = 1, 0.3%). None of these patients had a clinical picture of autoimmune encephalitis. Seizure classification and clinical phenotype did not correlate with antibody positivity. Conclusions: Autoimmune encephalitis is very rare in early childhood. However serum neuronal antibodies are identified in 6.4% of children presenting with seizures < 3 years. Antibody testing should not be a routine clinical test in early childhood-onset epilepsy as in the absence of other features of autoimmune encephalitis antibody-positivity is of doubtful clinical significance. Antibody testing should be reserved for patients with additional features of encephalitis