Subcortical nuclei volumes are associated with cognition in children post-convulsive status epilepticus: Results at nine years follow-up

PURPOSE: The purpose of the present study was to investigate the relationship between subcortical nuclei volume and cognition in children with post-convulsive status epilepticus (CSE). METHODS: Structural T1-weighted magnetic resonance imaging (MRI) scans (Siemens Avanto, 1.5 T) and neuropsychological assessments (full-scale intelligence quotient (FSIQ) and Global Memory Scores (GMS)) were collected from subjects at a mean 8.5 years post-CSE (prolonged febrile seizures (PFS), n = 30; symptomatic/known, n = 28; and other, n = 12) and from age- and sex-matched healthy controls (HC). Subjects with CSE were stratified into those with lower cognitive ability (LCA) (CSE+, n = 22) and those without (CSE-, n = 48). Quantitative volumetric analysis using Functional MRI of the Brain Software Library (FSL) (Analysis Group, FMRIB, Oxford) provided segmented MRI brain volumes. Univariate analysis of covariance (ANCOVA) was performed to compare subcortical nuclei volumes across subgroups. Multivariable linear regression was performed for each subcortical structure and for total subcortical volume (SCV) to identify significant predictors of LCA (FSIQ <85) while adjusting for etiology, age, socioeconomic status, sex, CSE duration, and intracranial volume (ICV); Bonferroni correction was applied for the analysis of individual subcortical nuclei. RESULTS: Seventy subjects (11.8 ± 3.4 standard deviation (SD) years; 34 males) and 72 controls (12.1 ± 3.0SD years; 29 males) underwent analysis. Significantly smaller volumes of the left thalamus, left caudate, right caudate, and SCV were found in subjects with CSE+ compared with HC, after adjustment for intracranial, gray matter (GM), or cortical/cerebellar volume. When compared with subjects with CSE-, subjects with CSE+ also had smaller volumes of the left thalamus, left pallidum, right pallidum, and SCV. Individual subcortical nuclei were not associated, but SCV was associated with FSIQ (p = 0.005) and GMS (p = 0.014). Intracranial volume and etiology were similarly predictive. CONCLUSIONS: Nine years post-CSE, SCV is significantly lower in children who have LCA compared with those that do not. However, in this cohort, we are unable to determine whether the relationship is independent of ICV or etiology. Future, larger scale studies may help tease this out

VARIATIONAL APPROXIMATIONS AND MEAN-FIELD SCALING THEORY

It is shown that ‘mean-field finite-size scaling theory’ can be adjusted and applied to sequences of approximations that do not obey the well known power laws of finite-size scaling. The proposed modification of the theory seems to be well directed to the sequence of Baxter’s variational approximations. This sequence of approximations shows a novel feature according to which exponential laws appear in places where power laws should be expected, but the modified scaling theory still yields relations from which non-classical critical exponents can be estimated. Thus, two techniques for the estimation of the critical exponent beta are suggested from the finite-order variational approximations. These techniques are applied to the zero-field Ising model on the square lattice using the systematic series of the Baxter-Tsang systems and excellent estimates of beta are obtained correct up to 13 significant figures

Long-term prognosis after childhood convulsive status epilepticus: a prospective cohort study

Background: The prognosis of convulsive status epilepticus (CSE), a common childhood medical neurological emergency, is not well characterised. We aimed to investigate the long-term outcomes in a cohort of participants who previously had CSE. Methods: In this prospective study, we followed up a population-based childhood CSE cohort from north London, UK (the north London convulsive status epilepticus surveillance study cohort; NLSTEPSS). We collected data from structured clinical neurological assessment, neurocognitive assessment (Wechsler Abbreviated Scale of Intelligence), brain MRI, medical records, and structured interviews with participants and their parents to determine neurological outcomes, with adverse outcome defined as presence of one or more of epilepsy (active or in remission), motor disability, intellectual disability, or statement of special educational needs. We applied multiple imputation to address missing data and performed binary logistic regression analyses on complete-case and imputed datasets to investigate sociodemographic and CSE factors associated with adverse outcomes. Findings: Of 203 survivors (90% of inception cohort), 134 (66%) were assessed at a median follow-up of 8·9 years (IQR 8·2–9·5). The cumulative incidence of epilepsy was 24·7% (95% CI 16·2–35·6), with most (89%) emerging within 18 months after CSE. The cumulative incidence of epilepsy was lower in patients with prolonged febrile seizures (14·3%, 6·3–29·4) and survivors of acute symptomatic CSE (13·3%, 3·7–37·9) than in those of remote symptomatic CSE (45·5%, 21·3–72·0) and unclassified CSE (50·0%, 25·4–74·6). One participant (2·9%, 0·5–14·5) in the prolonged febrile seizures group developed temporal lobe epilepsy with mesial temporal sclerosis. The absence of fever at CSE was the only predictor of incident epilepsy (odds ratio [OR] 7·5, 95% CI 2·25–25·1). Motor and intellectual disability was seen predominantly in participants who had idiopathic and cryptogenic CSE (seven [36·8%, 95% CI 19·1–59·0] and 16 [84·2%, 62·4–94·5] of 19, respectively) a nd remote symptomatic CSE (33 [62·3%, 48·8–74·1] and 40 [75·5%, 62·4–85·1] of 53), and most of these participants had pre-existing disabilities. Pre-existing epilepsy was the only predictor of intellectual disability (OR 8·0, 95% CI 1·1–59·6). 51·5% (95% CI 43·1–59·8) of those followed up had a statement of special educational needs. Interpretation: Childhood CSE is associated with substantial long-term neurological morbidity, but primarily in those who have epilepsy, neurological abnormalities, or both before the episode of CSE. Survivors without neurological abnormalities before CSE have favourable outcomes. Funding: BUPA Foundation, The Academy of Medical Sciences, Wellcome Trust, National Institute for Health Research, and Young Epilepsy