Jieun Choi

Cellular injury and neuroinflammation in children with chronic intractable epilepsy

ObjectiveTo elucidate the presence and potential involvement of brain inflammation and cell death in neurological morbidity and intractable seizures in childhood epilepsy, we quantified cell death, astrocyte proliferation, microglial activation and cytokine release in brain tissue from patients who underwent epilepsy surgery.MethodsCortical tissue was collected from thirteen patients with intractable epilepsy due to focal cortical dysplasia (6), encephalomalacia (5), Rasmussens encephalitis (1) or mesial temporal lobe epilepsy (1). Sections were processed for immunohistochemistry using markers for neuron, astrocyte, microglia or cellular injury. Cytokine assay was performed on frozen cortices. Controls were autopsy brains from eight patients without history of neurological diseases.ResultsMarked activation of microglia and astrocytes and diffuse cell death were observed in epileptogenic tissue. Numerous fibrillary astrocytes and their processes covered the entire cortex and converged on to blood vessels, neurons and microglia. An overwhelming number of neurons and astrocytes showed DNA fragmentation and its magnitude significantly correlated with seizure frequency. Majority of our patients with abundant cell death in the cortex have mental retardation. IL-1beta, IL-8, IL-12p70 and MIP-1beta were significantly increased in the epileptogenic cortex; IL-6 and MCP-1 were significantly higher in patients with family history of epilepsy.ConclusionsOur results suggest that active neuroinflammation and marked cellular injury occur in pediatric epilepsy and may play a common pathogenic role or consequences in childhood epilepsy of diverse etiologies. Our findings support the concept that immunomodulation targeting activated microglia and astrocytes may be a novel therapeutic strategy to reduce neurological morbidity and prevent intractable epilepsy.

Role of Brain Inflammation in Epileptogenesis

Inflammation is known to participate in the mediation of a growing number of acute and chronic neurological disorders. Even so, the involvement of inflammation in the pathogenesis of epilepsy and seizure-induced brain damage has only recently been appreciated. Inflammatory processes, including activation of microglia and astrocytes and production of proinflammatory cytokines and related molecules, have been described in human epilepsy patients as well as in experimental models of epilepsy. For many decades, a functional role for brain inflammation has been implied by the effective use of anti-inflammatory treatments, such as steroids, in treating intractable pediatric epilepsy of diverse causes. Conversely, common pediatric infectious or autoimmune diseases are often accompanied by seizures during the course of illness. In addition, genetic susceptibility to inflammation correlated with an increased risk of epilepsy. Mounting evidence thus supports the hypothesis that inflammation may contribute to epileptogenesis and cause neuronal injury in epilepsy. We provide an overview of the current knowledge that implicates brain inflammation as a common predisposing factor in epilepsy, particularly childhood epilepsy.

Increased levels of HMGB1 and pro-inflammatory cytokines in children with febrile seizures

ObjectiveFebrile seizures are the most common form of childhood seizures. Fever is induced by pro-inflammatory cytokines during infection, and pro-inflammatory cytokines may trigger the development of febrile seizures. In order to determine whether active inflammation, including high mobility group box-1 (HMGB1) and pro-inflammatory cytokines, occurs in children with febrile seizures or epilepsy, we analyzed cytokine profiles of patients with febrile seizures or epilepsy.MethodsForty-one febrile seizure patients who visited the emergency department of Seoul National University Boramae Hospital from June 2008 to May 2009 were included in this study. Blood was obtained from the febrile seizure child patients within 30 minutes of the time of the seizure; subsequently, serum cytokine assays were performed. Control samples were collected from children with febrile illness without convulsion (N = 41) and similarly analyzed. Serum samples from afebrile status epilepticus attacks in intractable epilepsy children (N = 12), afebrile seizure attacks in generalized epilepsy with febrile seizure plus (GEFSP) children (N = 6), and afebrile non-epileptic controls (N = 7) were also analyzed.ResultsSerum HMGB1 and IL-1β levels were significantly higher in febrile seizure patients than in fever only controls (p < 0.05). Serum IL-6 levels were significantly higher in typical febrile seizures than in fever only controls (p < 0.05). Serum IL-1β levels were significantly higher in status epilepticus attacks in intractable epilepsy patients than in fever only controls (p < 0.05). Serum levels of IL-1β were significantly correlated with levels of HMGB1, IL-6, and TNF-α (p < 0.05).ConclusionsHMGB1 and pro-inflammatory cytokines were significantly higher in febrile seizure children. Although it is not possible to infer causality from descriptive human studies, our data suggest that HMGB1 and the cytokine network may contribute to the generation of febrile seizures in children. There may be a potential role for anti-inflammatory therapy targeting cytokines and HMGB1 in preventing or limiting febrile seizures or subsequent epileptogenesis in the vulnerable, developing nervous system of children.

Clinical and EEG risk factors for subsequent epilepsy in patients with complex febrile seizures

PURPOSE To identify the risk factors for subsequent epilepsy in patients with complex febrile seizures from a single-center retrospective cohort. METHODS The medical records of 1091 patients discharged with a diagnosis of febrile seizures from the Seoul National University Bundang Hospital from February 2004 to October 2009 were reviewed. One hundred eighty-three patients (107 boys and 76 girls) with complex febrile seizures who showed normal neurocognitive development were included in the analysis. Clinical characteristics, including features of complex febrile seizure, initial interictal electroencephalographic findings, and subsequent epilepsy, were reviewed and the odds ratio of subsequent epilepsy was estimated. The mean follow-up duration for subsequent epilepsy was 6.1 years (range, 2.5-8.0 years). RESULTS Complex febrile seizures were observed in 22.6% of all patients with febrile seizures. Among 183 patients with complex febrile seizures, 22 patients (12.0%) developed subsequent epilepsy. Prolonged (>10 min) seizure (p=0.031; odds ratio, 3.04; 95% confidence interval, 1.11-8.32) or the presence of multiple seizures for 24 h (p=0.032; odds ratio, 3.63; 95% confidence interval, 1.12-11.8) was significantly more frequent in patients with subsequent epilepsy, whereas the presence of focal seizure was not significantly different. Epileptiform discharges (focal in all cases) were significantly more frequent in patients with subsequent epilepsy (50% vs. 13%, p=0.002), with an odds ratio of 5.15 (95% confidence interval, 1.84-14.5). CONCLUSION The presence of epileptiform discharges is a significant risk factor for subsequent epilepsy in patients with complex febrile seizures. Electroencephalography should be considered in all patients with complex febrile seizures especially those who had multiple or prolonged seizures.

Comparison of flunarizine and topiramate for the prophylaxis of pediatric migraines

The purpose of this study was to compare the efficacy and tolerability of topiramate and flunarizine for the prophylaxis of pediatric migraines. A retrospective medical-record review of patients who underwent prophylaxis after receiving a diagnosis of migraine with aura and without aura was performed. Only patients who completed at least 3 months of treatment were included in the analysis. Response to treatment was assessed as the total number of headache days/month. Patients with more than 50% reduction in headache days/month were classified as responders. Responder rate, retention rate, and adverse-event rates were also calculated from all patients who started on the prophylaxis. Further analyses were performed using different patient groups with a cut-off age of 12 years. The responder rate was 80% (89/111 patients) for flunarizine and 81% (122/150 patients) for topiramate, based on a comparison among 261 patients. The retention rate was 67% for flunarizine and 63% for topiramate and the adverse-event rate was 6% for flunarizine and 10% for topiramate. The responder rate, the retention rate, and the adverse-event rate were not significantly different between flunarizine and topiramate. These findings were concordant between the preadolescent (6-12 years old) and adolescent (13-18 years old) groups. The efficacy and tolerability of topiramate were not inferior to those of flunarizine for the prophylaxis of pediatric migraines. These findings were observed in preadolescent and adolescent patients.

Epilepsy phenotype associated with a chromosome 2q24.3 deletion involving SCN1A: Migrating partial seizures of infancy or atypical Dravet syndrome?

The deletion of a sodium channel gene cluster located on chromosome 2q24.3 is associated with variable epilepsy phenotypes, including Dravet syndrome and migrating partial seizures of infancy. Although SCN1A is considered as the major contributor to the epilepsy phenotype, the role of other sodium channel genes that map within this cluster has not been delineated. We presented five new cases with a chromosome 2q24.3 deletion involving SCN1A and investigated their epilepsy phenotype in relation to the extent of the deletion. Three cases with deletion of the whole sodium channel gene cluster (SCN3A, SCN2A, SCN1A, SCN9A, and SCN7A) exhibited a complex epilepsy phenotype that was atypical for Dravet syndrome and suggestive of migrating partial seizures of infancy: early seizure onset (before 2 months of age), severe developmental delay from seizure onset, multifocal interictal spikes, polymorphous focal seizures, and acquired microcephaly. Two cases with partial deletion of SCN1A and SCN9A and whole SCN1A deletion had an epilepsy phenotype of Dravet syndrome. A literature review of cases with chromosome 2q24.3 deletion revealed that, in most Dravet syndrome cases, it does not involve SCN2A and SCN3A, whereas a complex epilepsy phenotype that is shared with migrating partial seizures of infancy was associated with cases of deletion of the whole sodium channel gene cluster.

Effectiveness of Intravenous Levetiracetam as an Adjunctive Treatment in Pediatric Refractory Status Epilepticus

Objectives Intravenous levetiracetam (LEV) has been shown to be effective and safe in treating adults with refractory status epilepticus (SE). We sought to investigate the efficacy and safety of intravenous LEV for pediatric patients with refractory SE. Methods We performed a retrospective medical-record review of pediatric patients who were treated with intravenous LEV for refractory SE. Clinical information regarding age, sex, seizure type, and underlying neurological status was collected. We evaluated other anticonvulsants that were used prior to administration of intravenous LEV and assessed loading dose, response to treatment, and any adverse events from intravenous LEV administration. Results Fourteen patients (8 boys and 6 girls) received intravenous LEV for the treatment of refractory SE. The mean age of the patients was 4.4 ± 5.5 years (range, 4 days to 14.6 years). Ten of the patients were neurologically healthy prior to the refractory SE, and the other 4 had been previously diagnosed with epilepsy. The mean loading dose of intravenous LEV was 26 ± 4.6 mg/kg (range, 20–30 mg/kg). Seizure termination occurred in 6 (43%) of the 14 patients. In particular, 4 (57%) of the 7 patients younger than 2 years showed seizure termination. No immediate adverse events occurred during or after infusions. Conclusions The current study demonstrated that the adjunctive use of intravenous LEV was effective and well tolerated in pediatric patients with refractory SE, even in patients younger than 2 years. Intravenous LEV should be considered as an effective and safe treatment option for refractory SE in pediatric patients.

FARS2 mutation and epilepsy: Possible link with early-onset epileptic encephalopathy

Early-onset epileptic encephalopathy (EOEE) consists of a heterogeneous group of epilepsy phenotypes. Recent technological advances in molecular biology have also rapidly expanded the genotype of EOEE. Genes involved in diverse molecular pathways, including ion channels, synaptic structure, transcription regulation, and cellular growth, have been implicated in EOEE. Mitochondrial aminoacyl tRNA synthetase, which plays a key role in mitochondrial protein synthesis by attaching 20 different amino acids to the tRNA tail, has been recently linked with the epilepsy phenotype. Here, we report a novel homozygous c.925G>A (G309S) missense mutation in the gene that encodes the human mitochondrial phenylalanyl-tRNA synthetase (FARS2) in four patients from two nonconsanguineous Korean families. All four patients suffered from intractable seizures that started at the age of 3 and 4 months. Seizure types were variable, including infantile spasms and myoclonic seizures, and often prolonged. Although their initial development seemed to be normal, relentless regression after seizure onset occurred in all patients. An etiologic investigation, including brain imaging and metabolic studies, did not reveal a specific etiology. We reviewed the epilepsy phenotypes of six additional FARS2 mutation-positive patients and suggest that FARS2 can be considered one of the genetic causes of EOEE.

SCN1A mutational analysis in Korean patients with Dravet syndrome

OBJECTIVE The aim of this study was to characterize the SCN1A mutation spectrum in Korean patients with Dravet syndrome. METHODS Twenty-nine patients diagnosed with Dravet syndrome at the Seoul National University Childrens Hospital were included in the study. Direct sequencing and multiplex ligation-dependent probe amplification (MLPA) were used to identify SCN1A mutations. Mutations were classified as either truncation (nonsense and frameshift) or missense mutations. RESULTS Nineteen pathogenic mutations (19/29; 66%) and three unclassified variants were identified. One large deletion mutation spanning exons 1-20 was detected using MLPA. Fifteen of these 19 SCN1A mutations were novel. Eleven mutations were classified as truncations (seven frameshift and four nonsense mutations) and seven were classified as missense mutations. Truncating mutations spanned the whole span of subunits of the SCN1A protein, whereas all missense mutations were localized at either the voltage sensor (S4) or the ion pore (S5-S6) regions. Analysis according to clinical phenotype revealed that SCN1A mutations were more frequent in the classic group than in the borderline group (78% vs. 45%). CONCLUSIONS SCN1A mutational analysis of Korean Dravet syndrome patients resulted in the identification of 15 novel mutations, which could expand the spectrum of SCN1A mutations and confirms the current understanding of genotype-phenotype correlations.

Leigh Syndrome in Childhood: Neurologic Progression and Functional Outcome

Background and Purpose Few studies have analyzed the clinical course and functional outcome in Leigh syndrome (LS). The aim of this study was to determine the clinical, radiological, biochemical, and genetic features of patients with LS, and identify prognostic indicators of the disease progression and neurological outcome. Methods Thirty-nine patients who had been diagnosed with LS at the Seoul National University Childrens Hospital were included. Their medical records, neuroimaging findings, and histological/biochemical findings of skeletal muscle specimens were reviewed. Targeted sequencing of mitochondrial DNA was performed based on mitochondrial respiratory chain (MRC) enzyme defects. Results Isolated complex I deficiency was the most frequently observed MRC defect (in 42% of 38 investigated patients). Mitochondrial DNA mutations were identified in 11 patients, of which 81.8% were MT-ND genes. The clinical outcome varied widely, from independent daily activity to severe disability. Poor functional outcomes and neurological deterioration were significantly associated with early onset (before an age of 1 year) and the presence of other lesions additional to basal ganglia involvement in the initial neuroimaging. Conclusions The neurological severity and outcome of LS may vary widely and be better than those predicted based on previous studies. We suggest that age at onset and initial neuroimaging findings are prognostic indicators in LS.