Variations of Resting-State EEG-Based Functional Networks in Brain Maturation From Early Childhood to Adolescence

Background@#and Purpose Alterations in human brain functional networks with maturation have been explored extensively in numerous electroencephalography (EEG) and functional magnetic resonance imaging studies. It is known that the age-related changes in the functional networks occurring prior to adulthood deviate from ordinary trajectories of networkbased brain maturation across the adult lifespan. @*Methods@#This study investigated the longitudinal evolution of resting-state EEG-based functional networks from early childhood to adolescence among 212 pediatric patients (age 12.2± 3.5 years, range 4.4–17.9) in 6 frequency bands using 8 types of functional connectivity measures in the amplitude, frequency, and phase domains. @*Results@#Electrophysiological aspects of network-based pediatric brain maturation were characterized by increases in both functional segregation and integration up to middle adolescence. EEG oscillations in the upper alpha band reflected the age-related increases in mean node strengths and mean clustering coefficients and a decrease in the characteristic path lengths better than did those in the other frequency bands, especially for the phase-domain functional connectivity. The frequency-band-specific age-related changes in the global network metrics were influenced more by volume-conduction effects than by the domain specificity of the functional connectivity measures. @*Conclusions@#We believe that this is the first study to reveal EEG-based functional network properties during preadult brain maturation based on various functional connectivity measures. The findings potentially have clinical applications in the diagnosis and treatment of age-related brain disorders.

First Successful Application of Preimplantation Genetic Diagnosis for Lethal Neonatal Rigidity and Multifocal Seizure Syndrome in Korea: A Case Report

Lethal neonatal rigidity and multifocal seizure syndrome (RMFSL) is a severe autosomal recessive epileptic encephalopathy characterized by rigidity, intractable multifocal seizures, microcephaly, apnea, and bradycardia immediately after birth. RMFSL is related to a mutation in breast cancer 1-associated ataxia telangiectasia mutated activation-1 protein (BRAT1). We report a case of a female infant born to non-consanguineous Korean parents who developed hypertonia, dysmorphic features, progressive encephalopathy with refractory seizures at birth, and worsening intermittent apnea, leading to intubation and death at 137 days of age. The initial repeated electroencephalographic findings were normal; however, a pattern of focal seizures emerged at 35 days of life. Rapid trio whole-exome sequencing revealed heterozygous mutations c.1313_1314delAG p.(Gln438Argfs*51) and c.1276C>T p. (Gln426*) in BRAT1. After genetic counseling for pregnancy planning, a preimplantation genetic diagnosis for targeted BRAT1 mutations was successfully performed, and a healthy baby was born. To our knowledge, this is the first reported case of a Korean patient with compound heterozygous mutations in BRAT1. An early and accurate genetic diagnosis can help provide timely treatment to patients and indicate the need for reproductive counseling for parents for family planning.

Clinical Spectrum of Myelin Oligodendrocyte Glycoprotein-Immunoglobulin G-Associated Disease in Korean Children

Background@#and Purpose: The myelin oligodendrocyte glycoprotein (MOG) antibody is detected at a high rate in childhood acquired demyelinating syndrome (ADS). This study aimed to determine the diagnostic value of the MOG antibody in ADS and the spectrum of MOGantibody-positive demyelinating diseases in children. @*Methods@#This study included 128 patients diagnosed with ADS (n=94) or unexplained encephalitis (n=34). The MOG antibody in serum was tested using an in-house live-cell-based immunofluorescence assay. @*Results@#The MOG antibody was detected in 48 patients (46 ADS patients and 2 encephalitis patients, comprising 23 males and 25 females). Acute disseminated encephalomyelitis (ADEM) (35.4%) was the most-common diagnosis, followed by the unclassified form (17.4%), isolated optic neuritis (ON) (15.2%), neuromyelitis optica spectrum disorder (13.0%), multiple sclerosis (MS) (10.8%), other clinically isolated syndromes [monophasic event except ADEM, isolated ON, or transverse myelitis (TM)] (8.7%), and unexplained encephalitis (4.3%). At the initial presentation, 35 out of the 46 patients with ADS had brain lesions detected in magnetic resonance imaging, and 54% of these 35 patients had encephalopathy. Nine of the 11 patients without brain lesions exhibited only ON. Thirty-nine percent of the patients experienced a multiphasic event during the mean follow-up period of 34.9 months (range 1.4–169.0 months). Encephalopathy at the initial presentation was frequently confirmed in the monophasic group (p= 0.011). @*Conclusions@#MOG antibodies were identified in all pediatric ADS phenotypes except for monophasic TM. Therefore, the MOG antibody test is recommended for all pediatric patients with ADS, especially before a diagnosis of MS and for patients without a clear diagnosis.

Clinical and Genetic Spectrum of ATP1A3-Related Disorders in a Korean Pediatric Population

Erratum to: Elevated Serum Uric Acid in Benign Convulsions with Mild Gastroenteritis in Children

Wide heterogeneity of congenital myasthenic syndromes: analysis of clinical experience in a tertiary center

Purpose@#Congenital myasthenic syndrome (CMS) is a clinically and genetically heterogeneous group of disorders characterized by impaired neuromuscular transmission. This study aims to provide the clue for early diagnosis and improved therapeutic strategies in CMS. @*Materials and Methods@#Through the targeted panel sequencing including twenty CMS causative genes, eleven patients were genetically confirmed and enrolled in this study. A retrospective medical record review was carried out for the clinical and laboratory data analysis. @*Results@#The age of patients ranged from 5 to 23 years, with the median age of 16 years. The peak age at onset of symptoms was the neonatal period. Seven out of the eleven patients were symptomatic at birth. The most commonly reported initial finding was generalized hypotonia with poor sucking and crying. Mean time to accurate diagnosis was 9.3±5.0 years. Total fifteen different variants in seven genes associated with CMS (DOK7, AGRN, RAPSN, CHRNE, COLQ, SLC5A7, and GFPT1) were identified. @*Conclusion@#We describe the clinical and genetic characteristics of CMS patients and treatment outcome in a single tertiary center. High clinical suspicion and timely molecular diagnosis is particularly important for the tailored therapy to maximize clinical improvement in CMS.

Wide heterogeneity of congenital myasthenic syndromes: analysis of clinical experience in a tertiary center

Purpose@#Congenital myasthenic syndrome (CMS) is a clinically and genetically heterogeneous group of disorders characterized by impaired neuromuscular transmission. This study aims to provide the clue for early diagnosis and improved therapeutic strategies in CMS. @*Materials and Methods@#Through the targeted panel sequencing including twenty CMS causative genes, eleven patients were genetically confirmed and enrolled in this study. A retrospective medical record review was carried out for the clinical and laboratory data analysis. @*Results@#The age of patients ranged from 5 to 23 years, with the median age of 16 years. The peak age at onset of symptoms was the neonatal period. Seven out of the eleven patients were symptomatic at birth. The most commonly reported initial finding was generalized hypotonia with poor sucking and crying. Mean time to accurate diagnosis was 9.3±5.0 years. Total fifteen different variants in seven genes associated with CMS (DOK7, AGRN, RAPSN, CHRNE, COLQ, SLC5A7, and GFPT1) were identified. @*Conclusion@#We describe the clinical and genetic characteristics of CMS patients and treatment outcome in a single tertiary center. High clinical suspicion and timely molecular diagnosis is particularly important for the tailored therapy to maximize clinical improvement in CMS.

Antiepileptic Drug Withdrawal after Surgery in Children with Focal Cortical Dysplasia: Seizure Recurrence and Its Predictors

BACKGROUND AND PURPOSE: This study investigated the seizure recurrence rate and potential predictors of seizure recurrence following antiepileptic drug (AED) withdrawal after resective epilepsy surgery in children with focal cortical dysplasia (FCD). METHODS: We retrospectively analyzed the records of 70 children and adolescents with FCD types I, II, and IIIa who underwent resective epilepsy surgery between 2004 and 2015 and were followed for at least 2 years after surgery. RESULTS: We attempted AED withdrawal in 40 patients. The median time of starting the AED reduction was 10.8 months after surgery. Of these 40 patients, 14 patients (35%) experienced seizure recurrence during AED reduction or after AED withdrawal. Half of the 14 patients who experienced recurrence regained seizure freedom after AED reintroduction and optimization. Compared with their preoperative status, the AED dose or number was decreased in 57.1% of patients, and remained unchanged in 14.3% after surgery. A multivariate analysis found that incomplete resection (p=0.004) and epileptic discharges on the postoperative EEG (p=0.025) were important predictors of seizure recurrence after AED withdrawal. Over the mean follow-up duration of 4.5 years after surgery, 34 patients (48.6% of the entire cohort) were seizure-free with and without AEDs. CONCLUSIONS: Children with incomplete resection and epileptic discharges on postoperative EEG are at a high risk of seizure recurrence after drug withdrawal. Complete resection of FCD may lead to a favorable surgical outcome and successful AED withdrawal after surgery.

A familial case of limb-girdle muscular dystrophy with CAV3 mutation

Limb-girdle muscular dystrophy (LGMD) is a group of muscular dystrophies that has extremely heterogeneous clinical features and genetic background. The caveolin-3 gene (CAV3) is one of the causative genes. LGMD appears as a clinical continuum, from isolated skeletal muscle involvement to long QT syndrome. Here we report two patients without apparent muscle weakness in a family with CAV3 mutation.A 7-month-old Korean boy visited our muscle clinic because of an incidental finding of elevated serum creatine kinase (CK) concentration (680 IU/L, reference range, 20-270 IU/L) without clinical symptoms. The patient was born after an uneventful pregnancy and showed normal developmental milestones. He developed pseudohypertrophy of his calf muscle during the follow-up. We obtained a muscle biopsy at age 14 months, which showed size variations and degenerating/regenerating myofibers with endomysial fibrosis and immunohistochemical evidence of normal dystrophin. Under the impression of LGMD, we performed target panel sequencing and identified a heterozygous in-frame mutation of CAV3, c.307_312delGTGGTG (p.Val103_Val104del). Immunohistochemical staining of muscle indicated complete loss of caveolin-3 compared with normal control muscle, which supported the variant's pathogenicity. We performed segregation analysis and found that the patient's mother had the same variant with elevated serum CK level (972 IU/L).We report on autosomal dominant familial caveolinopathy caused by a pathogenic variant in CAV3, which was asymptomatic until the fourth decade. This case highlights the utility of next generation sequencing in the diagnosis of muscular dystrophies and the additive role of muscle biopsy to confirm the variants.

Association of Tumor Necrosis Factor-α Gene Promotor Variant, Not Interleukin-10, with Febrile Seizures and Genetic Epilepsy with Febrile Seizure Plus / 대한소아신경학회지

PURPOSE@#Cytokines demonstrate active roles in the occurrence of febrile seizures (FS). However, whether a genetic predisposition to inflammation is implicated in FS, febrile seizure plus (FS+) or genetic epilepsy with febrile seizure plus (GEFS+) are still unclear. Therefore we perform this study to find the association of promotor variants in pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) genes and anti-inflammatory cytokine interleukin 10 (IL-10) genes either with FS, FS+, and GEFS+ in Korean children.@*METHODS@#Fifty-seven children with FS, 32 FS+, and 12 GEFS+ patients were compared with 108 controls. The allelic and genotypic distributions were compared for TNF-α-238 (rs361525), −308 (rs1800629), −857 (rs1799724), −863 (rs1800630), and IL-10-592 (rs1800872), −819 (rs1800871), −1082 (rs1800896), and −1352 (rs1800893).@*RESULTS@#Allelic and genotypic frequencies of TNF-α and IL-10 promotor variants showed no significant differences between FS, FS+, and GEFS+ versus controls. However, AA genotypes at TNF-α-863 were present only in controls. TNF-α-863 (rs1800630) promoter variants showed an association with FS, FS+, and GEFS+ in a recessive mode of inheritance pattern (P<0.05).@*CONCLUSION@#Our results suggest that AA genotypes at TNF-α-863 may be associated with FS, FS+, and GEFS+, implicating protective roles against to development of FS, FS+, and GEFS+.

Elevated Serum Uric Acid in Benign Convulsions with Mild Gastroenteritis in Children

BACKGROUND AND PURPOSE: To identify whether serum uric acid levels are significantly higher in patients with benign convulsion associated with mild gastroenteritis (CwG) than in patients with acute gastroenteritis. METHODS: This retrospective study compared the serum levels of uric acid between CwG, acute gastroenteritis, and febrile seizure after correcting for the varying degree of mild dehydration using serum HCO3⁻ levels. We also compared the serum uric acid levels between patients with CwG and febrile seizures in order to exclude the effect of seizures on uric acid. RESULTS: This study included 154 CwG patients (age range 0.73–3.19 years), 2,938 patients with acute gastroenteritis, and 154 patients with febrile seizure. The serum uric acid level was significantly higher in CwG patients than in patients with acute gastroenteritis [9.79±2.16 mg/dL vs. 6.04±2.3 mg/dL (mean±SD), p<0.001]. This difference was also significant after correcting for dehydration. The serum uric acid level was significantly higher in CwG patients than in dehydration-corrected acute gastroenteritis patients (9.79±2.16 mg/dL vs. 6.67±2.48 mg/dL, p<0.001). The serum uric acid level was not elevated in patients with febrile seizure. CONCLUSIONS: We have confirmed that serum uric acid is elevated in CwG patients even after correcting for their dehydration status, and that this was not a postictal phenomenon. Highly elevated serum uric acid in CwG could be a useful clinical indicator of CwG in patients with acute gastroenteritis.

Association Analysis of Interleukin-1β, Interleukin-6, and HMGB1 Variants with Postictal Serum Cytokine Levels in Children with Febrile Seizure and Generalized Epilepsy with Febrile Seizure Plus

BACKGROUND AND PURPOSE: Febrile seizure (FS) is a unique type of seizure that only occurs during childhood. Genelized epilepsy with febrile seizure plus (GEFS+) is a familial epilepsy syndrome associated with FS and afebrile seizure (AFS). Both seizure types are related to fever, but whether genetic susceptibility to inflammation is implicated in them is still unclear. To analyze the associations between postictal serum cytokine levels and genetic variants in the cytokine genes interleukin (IL)-1β, IL-6, and high mobility group box-1 (HMGB1) in FS and GEFS+. METHODS: Genotyping was performed in 208 subjects (57 patients with FS, 43 patients with GEFS+, and 108 controls) with the SNaPshot assay for IL-1β-31 (rs1143627), IL-1β-511 (rs16944), IL-6-572 (rs1800796), and HMGB1 3814 (rs2249825). Serum IL-1β, IL-6, and HMGB1 levels were analyzed within 2 hours after seizure attacks using the ELISA in only 68 patients (38 FS, 10 GEFS+, and 20 controls). The allele distribution, genotype distribution, and correlations with serum cytokine levels were analyzed. RESULTS: Near-complete linkage disequilibrium exists between IL-1β-31 and IL-1β-511 variants. CT genotypes of these variants were associated with significantly higher postictal serum IL-1β levels than were CC+TT genotypes in FS (both p<0.05). CT genotypes of IL-1β-31 and IL-1β-511 variants were more strongly associated with FS than were CC+TT genotypes (odds ratio=1.691 and 1.731, respectively). For GEFS+, serum IL-1β levels after AFS for CT genotypes of IL-1β-31 and IL-1β-511 were also higher than for CC+TT genotypes. No significant associations were found for IL-6 and HMGB1. CONCLUSIONS: Genetic variants located in IL-1β-31 and IL-1β-511 promotor regions are correlated with higher postictal IL-1β levels in FS. These results suggest that IL-1 gene cluster variants in IL-1β-31 and IL-1β-511 are a host genetic factor for provoking FS in Korean children.

Resting-State Electroencephalography (EEG) Functional Connectivity Analysis / 대한소아신경학회지

Advances in network science and computer engineering have enabled brain connectivity analysis using clinical big data such as brain magnetic resonance imaging (MRI), electroencephalography (EEG), or magnetoencephalography (MEG). Resting-state functional connectivity analysis aims to reveal the characteristics of functional brain network in various diseases and normal brain maturation using resting-state EEG. Simplified sequence of resting-state functional connectivity analysis methods will be reviewed in this article. The outcomes from EEG resting-state connectivity analysis are comprised of connectivity itself of the specific condition and the network topology measure which describe the characteristics of specific connectivity. An increasing number of studies report the differences in the functional connection itself, global network measures including segregation (connectedness), integration (efficiency), and importance of specific nodes (centrality or node degree). Several issues that are relevant in the resting-state connectivity analysis are obtaining good quality EEG for analysis, consideration of particular features of EEG signal, understanding different types of association measures, and statistics for comparison of connectivities. Well-designed and carefully analyzed EEG resting-state connectivity analysis can provide useful information for patient care in pediatric neurology.

A Unique Mutational Spectrum of MLC1 in Korean Patients With Megalencephalic Leukoencephalopathy With Subcortical Cysts: p.Ala275Asp Founder Mutation and Maternal Uniparental Disomy of Chromosome 22

BACKGROUND: Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare inherited disorder characterized by infantile-onset macrocephaly, slow neurologic deterioration, and seizures. Mutations in the causative gene, MLC1, are found in approximately 75% of patients and are inherited in an autosomal recessive manner. We analyzed MLC1 mutations in five unrelated Korean patients with MLC. METHODS: Direct Sanger sequencing was used to identify MLC1 mutations. A founder effect of the p.Ala275Asp variant was demonstrated by haplotype analysis using single-nucleotide polymorphic (SNP) markers. Multiple ligation-dependent probe amplification (MLPA) and comparative genomic hybridization plus SNP array were used to detect exonic deletions or uniparental disomy (UPD). RESULTS: The most prevalent pathogenic variant was c.824C>A (p.Ala275Asp) found in 7/10 (70%) alleles. Two pathogenic frameshift variants were found: c.135delC (p.Cys46Alafs*12) and c.337_353delinsG (p.Ile113Glyfs*4). Haplotype analysis suggested that the Korean patients with MLC harbored a founder mutation in p.Ala275Asp. The p.(Ile113Glyfs*4) was identified in a homozygous state, and a family study revealed that only the mother was heterozygous for this variant. Further analysis of MLPA and SNP arrays for this patient demonstrated loss of heterozygosity of chromosome 22 without any deletion, indicating UPD. The maternal origin of both chromosomes 22 was demonstrated by haplotype analysis. CONCLUSIONS: This study is the first to describe the mutational spectrum of Korean patients with MLC, demonstrating a founder effect of the p.Ala275Asp variant. This study also broadens our understanding of the mutational spectrum of MLC1 by demonstrating a homozygous p.(Ile113Glyfs*4) variant resulting from UPD of chromosome 22.

Idiopathic Cervicosyringomyelia in 2 year-old Boy

Syringomyelia is a disorder in which a cavity has formed within the spinal cord. Idiopathic syringomyelia is not associated with identifiable causes such as Chari type 1 malformation, spinal cord tumor, vascular malformation, tethered cord, arachnoiditis, hydrocephalus, or previous spinal surgery. The main neurologic symptoms of idiopathic syringomyelia are toe-walking, constipation, incontinence, abnormal reflexes, and lower extremity weakness. Patients may present with various symptoms such as scoliosis, cutaneous markers, pain in the lower extremities or back, or may be asymptomatic. Herein, we report a young child with idiopathic syringomyelia presenting with subtle neck pain. A 23-month-old boy visited the neurologic clinic after 3 months of right occipital area neck pain. He had no history of trauma or central nervous system infection, and neurologic examination results were normal except for right posterior neck hyperesthesia. Brain and spinal magnetic resonance imaging showed an ovoid intramedullary cystic lesion (9.7×5.0×4.7 mm) at C6/7 of the spinal cord. There was no evidence of Chiari malformation or other lesions that can be primary pathologies of syringomyelia. Electromyogram/nerve conduction velocity results were normal. The subject was diagnosed as idiopathic syringomyelia. His symptoms and neurologic/radiologic indications showed no change at a 1-year follow-up. Idiopathic syringomyelia symptoms are varied and may be overlooked by physicians. Pediatricians may consider syringomyelia if patients complain about persistent sensory abnormality. All patients who present with syringomyelia should undergo detailed neuroimaging of the entire neuraxis to elucidate the proximate cause of the lesion.

Factors Associated with Favorable Outcome of Topiramate Migraine Prophylaxis in Pediatric Patients

BACKGROUND AND PURPOSE: There are few studies that have investigated predictive factors related to migraine prophylaxis of which produced inconsistent results. The aim of this study was to identify factors that can predict the treatment response to topiramate prophylaxis in pediatric patients with migraine. METHODS: One hundred and thirteen patients who were older than 7 years and received topiramate for at least 3 months were recruited from the Seoul National University Bundang Hospital outpatient clinic from 2005 to 2014. A positive response was defined as a reduction of more than 50% in the number of migraine episodes after topiramate treatment. Proposed predictive factors such as migraine characteristics including severity and frequency were assessed, as were other data on sex, disease duration, associated symptoms, family history, and impairment of daily activities. RESULTS: Seventy patients (61.9%) responded to prophylactic treatment with topiramate. Patients who experienced significant impairment in daily activities showed significant benefit from the treatment (p=0.004). Sex, the severity, frequency, and duration of migraine episodes, disease duration, treatment duration, age at onset, and associated symptoms were not significantly related to a response to topiramate treatment. CONCLUSIONS: Migraine characteristics and associated symptoms were not significantly related to a response to topiramate treatment. However, patients with significant impairment in daily activities showed significant benefit from the treatment, and so prophylactic topiramate treatment should be strongly encouraged in this patient group.

Clinical and Radiologic Features of Pediatric Cerebral Venous Thrombosis in Korea

PURPOSE: Cerebral venous thrombosis (CVT) is a rare cause of pediatric stroke. Our goal was to describe the clinical CVT features among pediatric patients presenting at a tertiary referral center. METHODS: Patient data was retrospectively collected from the charts of all pediatric patients (newborn to 18 years old) who were diagnosed with CVT at Seoul National University Children's Hospital between 2000 and 2016. Magnetic resonance imaging or venography was conducted for diagnostic confirmation. Modified Rankin Scale (mRS) was used to evaluate neurologic outcome. RESULTS: Twenty patients were diagnosed with CVT during the study period (16 male, 4 female). Median age was 4 years. The most common risk factor was systemic infection (6/20, 30.0%). Twelve patients initially presented with headache or vomiting (12/20, 60.0%). Seizure was in only 3 patients within 48 hours of symptom onset; however, as the clinical course progressed, seizure was the symptom that most frequently led to brain imaging (12/20, 60.0%). Thrombosis in the superior sagittal sinus was frequently associated with intracranial hemorrhage (4/11, 36.4%) and clinical seizure (9/11, 81.8%). Anticoagulation and/or antiplatelet agents were used in 16 patients (16/20, 80%). At the 3-month follow-up, 14 patients (14/20, 70%) had an mRS of 0 or 1, showing that most of these patients had no neurologic impairment. CONCLUSION: Seizure and signs of increased intracranial pressure are the most common manifestation of pediatric CVT. However, clinical features are diverse and include age at symptom onset and underlying risk factors. Despite diagnostic delay, neurologic outcome is favorable in most patients.

Epstein-Barr Virus Infection associated Transverse Myelitis with Brain Involvement in an Immunosuppressed Patient: A Case Report

A 19-year-old girl with immunosuppressive agents of tacrolimus and mychophenolate mofetil following liver transplantation due to glycogen storage disease visited hospital due to lower extremity motor weakness and blurred vision. Motor power was checked as grade II in the upper extremities and grade 0 in the lower extremities with absence of deep tendon reflexes and anal sphincter dysfunction. The magnetic resonance imaging (MRI) showed increased T2 high signal intensity lesions from C4 to L2 level of spinal cord, cerebral cortex, and the left optic nerve. The cerebrospinal fluid (CSF) analysis showed pleocytosis. Epstein-Barr virus (EBV) deoxyribonucleic acid (DNA) was detected as 5,954 copies/mL in CSF whereas all other microbiologic tests were negative. Anti-aquaporin 4 antibody and oligoclonal band were not detected. Intravenous immunoglobulin, methylprednisolone pulse therapy and 3-week course of acyclovir were administered. Although motor power in the upper extremities recovered to grade V, motor power in the lower extremities did not show any improvement. The EBV viral load was not detected in the follow-up CSF examination. EBV infection in an immune-compromised patient could cause extensive demyelinating diseases in central nervous system and result in severe disability.

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 Children's 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.

Efficacy and Tolerability of Valproic Acid Once Daily Dosing for Juvenile Myoclonic Epilepsy

PURPOSE: The purpose of this study was to evaluate the efficacy and tolerability of extended-release valproic acid once daily dosing in juvenile myoclonic epilepsy (JME). METHODS: Medical records of patients who received valproic acid monotherapy for the treatment of JME were retrospectively reviewed. Their clinical information regarding age, gender, seizure types, underlying neurologic status, dosing regimen, response to treatment, and adverse events related to valproic acid, were analyzed. Seizure control, compliance, and adverse events rates were compared between the group of once daily dosing and the group of twice daily dosing. RESULTS: Twenty one patients (11 boys and 10 girls) were included in the study. Twelve patients were taking valproic acid extended-release once daily and nine patients were taking twice a day. More than 50% decrease in myoclonic seizure was achieved in all the patients in both groups. Generalized tonic-clonic seizure was controlled in all the patients who were taking once daily while 3 patients (36%, 3/8 patients) in twice daily group had breakthrough generalized tonic clonic seizures during the 2 year period of treatment. However, there were no statistically significant differences in seizure control, compliance, and adverse event rates between the two groups. CONCLUSION: This study demonstrated that valproic acid extended-release once daily dosing was as effective and tolerable as twice daily in the treatment of JME. Once daily dosing of valproic acid would be convenient which improve patient compliance and consequently bring better outcome in treatment of JME.