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Background: Seizures are commonly reported in patients with myelin oligodendrocyte glycoprotein antibody-associated cerebral cortical encephalitis (MOG-CCE). However, seizure management during the acute phase has not been established., Case Report: A 9-year-old previously healthy boy presented with fever persisting for approximately 6 days, along with headache and altered consciousness. Plain T2-weighted and fluid-attenuated inversion recovery imaging showed swelling and abnormal hyperintense lesions in the bilateral frontal, parietal, temporal, and insular cortices with left hemisphere predominance. Consciousness disturbance persisted, and focal myoclonic seizures clustered hourly. Seizures were arrested by titrating the thiopental dose but recurred with dose reduction, and the patient exhibited super refractory status epilepticus. Adverse effects due to long-term use of thiopental became apparent. Hence, continuous infusion of ketamine and intrathecal dexamethasone therapy (IT-DEX) was started. After administration of ketamine and IT-DEX, his seizure was arrested promptly. The cerebrospinal fluid and serum at the time of transfer were clear positive for ani-MOG antibody; therefore, the patient was diagnosed with MOG-CCE. The patient received three courses of intravenous methylprednisolone pulse therapy, followed by oral prednisolone gradually tapered over 6 months. He did not experience any relapse for 6 months., Conclusion: In MOG-CCE, some cases may present with super-refractory status epilepticus (SRSE) in the acute phase and be refractory to anti-seizure medication, analogous to febrile infection-related epilepsy syndrome. IT-DEX and continuous infusion ketamine are useful for seizure control in MOG-CCE., Competing Interests: Declaration of competing interest The authors declare no financial relationships relevant to this article. There was no honorarium, grant, or other form of payment to produce the manuscript., (Copyright © 2024. Published by Elsevier B.V.)

Objectives: Acute encephalopathy is an acute brain dysfunction after preceding infection, consisting of multiple syndromes. Some syndromes, such as acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), are severe with poor outcome, whereas others, such as clinically mild encephalitis/encephalopathy with reversible splenial lesion (MERS), are mild with favorable outcome. Previous study reported the association of the thermolabile polymorphism in Carnitine Palmitoyltransferase 2 (CPT2) gene and severe syndromes of acute encephalopathy. To further explore the pathogenetic role of CPT2 in acute encephalopathy, we conducted a case-control association study of a typical thermolabile CPT2 polymorphism, rs2229291, in 416 patients of acute encephalopathy, including both severe and mild syndromes., Methods: The case cohort consisted of 416 patients, including AESD, MERS, and other syndromes. The control subjects were 100 healthy Japanese. rs2229291 was genotyped by Sanger sequencing. Genetic distribution was compared between the patients and controls using Cochran-Armitage trend test., Results: Minor allele frequency of rs2229291 was significantly higher in AESD (p = 0.044), MERS (p = 0.015) and entire acute encephalopathy (p = 0.044) compared to the controls. The polymorphism showed no significant association with influenza virus, or with outcome., Conclusions: This study provided evidence that CPT2 is a susceptibility gene for overall acute encephalopathy, including both severe and mild syndromes, and suggested that impairment of mitochondrial metabolism is common to various syndromes of acute encephalopathy., (Copyright © 2019 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Background: Cerebellar ataxia, Areflexia, Pes cavus, Optic atrophy and Sensorineural hearing loss (CAPOS) syndrome is a known ATP1A3-related disorder, but little has been elucidated regarding its pathophysiology. We now report two new patients, a Japanese boy and his mother with a pathogenic mutation (c.2452G>A) in ATP1A3, who were diagnosed with CAPOS syndrome., Methods: After febrile illnesses at 7 months of age, and again at 22 months of age, the boy had a reduced level of consciousness, truncal ataxia and eye movement-disorders. The patient's 32-year-old mother may have experienced an episode of acute encephalopathy in her childhood and sustained sensorineural hearing loss. In the present study, we demonstrated chronological dynamic changes in cerebral blood flow (CBF) in the son, using serial single-photon emission computed tomography (SPECT)., Results: The serial CBF-SPECT findings using statistical methods showed progressive hyperperfusion in the frontal lobes, basal ganglia and thalamus, and hypoperfusion in the occipital and temporal lobes during the acute and subacute phases. Thereafter, the dynamic changes of CBF improved in the chronic but hypoperfusion in thalamus appeared to the chronic phase., Conclusion: The abnormal cortico-subcortical CBF may contribute to an acute encephalopathy-like condition in the acute stage of CAPOS syndrome. CAPOS syndrome is not often reported, and is possibly an under-recognized syndrome in clinically mild cases., (Copyright © 2019 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Sjögren syndrome (SS) is a systemic inflammatory and autoimmune disease characterized by systemic disorders of the exocrine glands, predominantly the salivary and lacrimal glands. Here, we report a 4-year-old boy who presented with the repetition of generalized tonic-clonic seizures for 1-2 min. Initially, he was diagnosed with idiopathic autoimmune encephalitis and was treated with steroids. He was eventually diagnosed with SS based on the examination results, such as inflammatory cell infiltration into the minor salivary glands and positive serum anti-SSA/Ro antibody. Although central nervous system complications are rare in pediatric SS, this condition should be considered in the differential diagnosis when a patient presents with idiopathic autoimmune encephalitis of unknown cause. Furthermore, SS can occur in relatively young children and can present without imaging abnormalities., (Copyright © 2018 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Objectives: Acute encephalopathy has been observed with acute brain swelling (ABS) that is characterized by rapid progression to whole-brain swelling. The objective of this study was to describe the clinical characteristics of ABS., Methods: We encountered four patients with ABS and retrospectively investigated their clinical data with a medical chart review., Results: Three patients had seizure clustering or status epilepticus in the clinical course. Signs of elevated intracranial pressure (ICP) appeared 3-9 h after the first convulsive attack in three patients. In all patients, signs of brainstem involvement appeared 1-8 h after signs of elevated ICP. Mild hyponatremia that progressed after signs of elevated ICP appeared was noted in three patients. Brain CT revealed mild brain swelling in the initial phase, which rapidly progressed to whole-brain swelling. No focal abnormalities were detected on brain MRI in one patient. Continuous electroencephalography was initially normal, but in two patients, high-amplitude slow waves appeared with rapid changes before signs of brainstem involvement. Although recovery was achieved without sequelae in two patients, outcome was fatal for the other two., Conclusions: The pathogenesis of ABS has yet to be clarified, but clinical features in our patients are not consistent with any established subtypes of acute encephalopathy. Therefore, we believe that ABS should be recognized as a new type of acute encephalopathy., (Copyright © 2018 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Tuberous sclerosis complex (TSC) is a multisystem genetic disorder that activates mammalian target of rapamycin and produces tumor growth in several organs. We present five patients younger than 12 months who were diagnosed with TSC and treated with everolimus (EVL), after which congenital subependymal giant astrocytoma (cSEGA) promptly regressed in all patients. All patients achieved at least 50% reduction in the volume of cSEGA within 6 months. The most rapid reduction of cSEGA volume (79.1%) was found during the initial 3 months of EVL treatment. Patients underwent EVL treatment for an average of 27 months (range: 4-55 months). Mean EVL maintenance dose was 1.35 mg per day. EVL blood trough concentrations ranged from 2.0 to 11.7 ng/ml. The cSEGA became larger after discontinuing EVL in two patients. In all four patients who had multiple cardiac rhabdomyomas (CRMs), the CRMs showed accelerated regression after receiving EVL. Adverse events were noted in four patients: infection, stomatitis, and increased triglycerides. Four patients had febrile status epilepticus, which occurred during acute encephalopathy in a patient, and after discontinuing EVL in another. Three patients were still receiving EVL at their latest evaluations. Maintenance therapy with EVL is an effective therapeutic option for patients with cSEGA, and moreover may have additional favorable effects on other complications, even in early infancy; however, adverse effects should be carefully monitored., (Copyright © 2018 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

We diagnosed a 3-year-old girl with acute transverse myelitis (ATM). She presented with weakness of the limbs and developed urination difficulty and respiratory disturbance. Magnetic resonance imaging revealed a symmetric area of high signal intensity on T2-weighted images involving the lower end of the medulla oblongata to the level of the fourth thoracic vertebra. Anti-aquaporin-4 antibody was negative. She was treated with intravenous methylprednisolone pulse therapy, immunoglobulin therapy, and plasmapheresis; however, her clinical symptoms did not change. At 10 and 20days after symptom onset, cardiac arrest occurred on postural change, requiring cardiopulmonary resuscitation. A permanent pacemaker was implanted 23days after onset. In the presence of sympathetic nerve hypofunction, relative hyperactivity of the parasympathetic nerves may have led to severe bradycardia and cardiac arrest in the presence of an inducer, such as a postural change. This is the first reported case of pacemaker implantation for management of ATM., (Copyright © 2017 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

An 11-year-old boy presented with progressive leg hypesthesia but no history of trauma. Dysuria and constipation appeared subsequent to gait difficulty. He was admitted 8days after onset. Spinal magnetic resonance imaging (MRI) revealed longitudinal hyperintensity with cord swelling and hypointensity on T2-weighted images, suggesting severe inflammation and microbleeding change, respectively. Gadolinium contrast-enhanced MRI demonstrated mild enhancement in the lesions. Platelet count and coagulation findings were normal, and cerebrospinal fluid analysis showed no pleocytosis. He was diagnosed with idiopathic acute transverse myelitis (ATM), and intravenous methylprednisolone pulse therapy and plasmapheresis were initiated. On day 14, motor dysfunction aggravated suddenly, accompanied by expanding hemorrhagic lesions. Thereafter, administration of intravenous immunoglobulin, repeated intravenous methylprednisolone pulse therapy and prednisolone for one month resulted in complete recovery four months later. Both anti-aquaporin-4 and anti-myelin oligodendrocyte glycoprotein antibodies were negative. We presented the first pediatric case showing hemorrhagic spinal lesions in the clinical course of ATM. This severe complication should be recognized in the management of ATM., (Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

The KCNT1 gene encodes the sodium-dependent potassium channel, with quinidine being a partial antagonist of the KCNT1 channel. Gain-of-function KCNT1 mutations cause early onset epileptic encephalopathies including migrating partial seizures of infancy (MPSI). At 5months of age, our patient presented with epileptic spasms and hypsarrhythmia by electroencephalogram. Psychomotor retardation was observed from early infancy. The patient was diagnosed with West syndrome. Consequently, various anti-epileptic drugs, adrenocorticotropic hormone therapy (twice), and ketogenic diet therapy were tried. However, the epileptic spasms were intractable. Whole exome sequencing identified a KCNT1 mutation (c.1955G>T; p.G652V). At 2years and 6months, the patient had daily epileptic spasms despite valproate and lamotrigine treatment, and was therefore admitted for quinidine therapy. With quinidine therapy, decreased epileptic spasms and decreased epileptiform paroxysmal activity were observed by interictal EEG. Regarding development, babbling, responsiveness, oral feeding and muscle tone were ameliorated. Only transient diarrhea was observed as an adverse effect. Thus, quinidine therapy should be attempted in patients with West syndrome caused by KCNT1 mutations, as reported for MPSI., (Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Background: Clinical phenotypic expression of SSADH deficiency is highly heterogeneous, and some infants may develop refractory secondary generalized seizures., Patient: A 9-month-old boy manifested partial seizures, developing severe status epilepticus, and conventional antiepileptic drugs were ineffective. Use of ketamine contributed to the control of status epilepticus, achieving a reduction in frequency of partial seizures, and improving EEG findings without apparent complications. Diffusion-weighted images showed hyperintensities in the bilateral basal ganglia and fornix, and multiple T2 hyperintensity lesions were detected. (123)I-iomazenil (IMZ) SPECT revealed a decrease in binding of (123)I-iomazenil predominantly in the left temporal region by the 18th day of hospitalization. However, repeated IMZ-SPECT on the 46th day of hospitalization demonstrated almost no accumulation across a broad region, sparing the left temporal region. The patient showed rapid regression, refractory myoclonus, and severe progressive brain atrophy., Conclusion: IMZ-SPECT findings demonstrated reduced benzodiazepine receptor binding and its dynamic changes in an SSADH-deficient patient. Considering the down regulation of the GABAA receptor, ketamine should be included in pharmacotherapeutic strategies for treatment of refractory status epilepticus in SSADH-deficient patients., (Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Autoimmune autonomic ganglionopathy (AAG) is an acquired immune-mediated disorder that leads to systemic autonomic failure. Autoantibodies to the ganglionic nicotinic acetylcholine receptor (gAChR) are detected in 50% of AAG patients. We report the first pediatric case of AAG presenting with acute encephalitis. The patient was a 13-year-old boy who presented with orthostatic hypotension, followed by rapidly progressing disturbance of consciousness. Cerebrospinal fluid analysis revealed significant pleocytosis and increased neopterin concentration. Head MRI showed hyperintensities in bilateral caudate nuclei, putamen, hippocampus, and insula cortex. Severe autonomic dysfunctions such as severe orthostatic hypotension, bradycardia, dysuria, prolonged constipation and vomiting appeared. These symptoms were successfully controlled by repeated immunomodulating therapy with intravenous methylprednisolone pulse therapy and intravenous immunoglobulin. Autoantibodies to the α3 subunit of gAChR were detected at neurological onset, but were undetectable five months later. This observation indicates that AAG should be suspected in patients manifesting acute encephalitis characterized by preceding and prolonged autonomic symptoms, and immunomodulating therapy from an early stage can be effective., (Copyright © 2015 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)