Three Cases of Hemiconvulsion-Hemiplegia-Epilepsy Syndrome With Focal Cortical Dysplasia Type IIId.

Hemiconvulsion-hemiplegia-epilepsy syndrome (HHES) is a subset of acute encephalopathy characterized by infantile-onset with acute hemiconvulsive febrile status and subsequent unilateral cerebral atrophy and hemiparesis. In the chronic phase, patients with HHES develop epilepsy, typically displayed as intractable focal seizures. The patients are often intractable with antiepileptic drugs and need surgical treatment. Although viral encephalitis and genetic abnormalities are presumed to be the underlying etiology, the pathogenesis remains mostly unknown. We describe three cases of successful functional hemispherotomy for intractable epilepsy in HHES. Patients developed acute asymmetrical convulsive status following viral infections during the ages of 17-30 months. Their seizures were intractable with antiepileptic drugs and required hemispherotomy. On the basis of the pathological findings, all cases were diagnosed as focal cortical dysplasia (FCD) type IIId. The epileptogenic mild cortical malformations may be the cause of HHES.

A Nationwide Survey of Pediatric-onset Japanese Encephalitis in Japan.

BACKGROUND: Japanese encephalitis (JE) is the leading cause of viral encephalitis with high mortality and morbidity in Asia. In Japan, however, the active recommendation of JE vaccine was retracted in 2005 because of the potential risk of acute disseminated encephalomyelitis. We aimed to determine the recent incidence of childhood-onset JE after the domestic change of vaccination policy in Japan, and to analyze the clinical features of affected children. METHODS: A retrospective nationwide survey was conducted for pediatric patients with JE in Japan from 1995 to 2015. The national surveillance system was used to identify the pediatric patients with JE. Follow-up questionnaires were sent to analyze their clinical and neuroimaging profiles. RESULTS: Among a total of 109 patients registered to the national surveillance, 10 (9%) were less than age 15 years. The annual incidence rate of childhood-onset JE was higher during 2005-15 than that during 1995-2004 (4.3 × 10-3 vs 1.1 × 10-3 per 100000, respectively; P = .04). Endemic regions overlapped with prefectures that farmed pigs harboring antibodies against JE virus with high prevalence. Detailed clinical data were collected from 9 patients. None of them died, but 5 of 9 patients (56%) had neurological sequelae after recovery. One patient who was partially vaccinated with 2 doses of JE vaccine fully recovered from a coma. The age of 3 years or less was associated with unfavorable neurological prognosis. CONCLUSIONS: Our data provide evidence for the importance and prophylactic effect of the JE vaccine in young children in the endemic area.

"Symptomatic" infection-associated acute encephalopathy in children with underlying neurological disorders.

BACKGROUND: Development of infection-associated acute encephalopathy (AE) is precipitated by several factors, including viral agents, age, and genetic polymorphisms. In addition, children with prior underlying neurological disorders can also present with AE. METHOD: We reviewed 55 children with AE who were referred to hospitals participating in the Status Epilepticus Study Group from 1988 to 2013. AE was classified into eight subtypes: acute encephalopathy with biphasic seizures and late reduced diffusion (AESD); hemiconvulsion-hemiplegia syndrome (HH); acute necrotizing encephalopathy; hemorrhagic shock and encephalopathy syndrome (HSES); clinically mild encephalitis/encephalopathy with a reversible splenial lesion; acute encephalitis with refractory, repetitive partial seizures; Reye-like syndrome; and unclassified. RESULT: Of the 55 AE cases, 14 (25.4%) had underlying neurological disorders, including perinatal insults (n=6) and genetic syndrome and/or brain malformations (n=8). These preceding morbidities were relatively common in AESD (6/18, 33.3%), HH (3/9, 33.3%), and HSES (3/6, 50.0%). History of epilepsy or febrile seizures were frequent in HH cases (4/9, 44.4%), whereas they were rare in other AE subtypes. CONCLUSION: Among the AE subgroups, HH, HSES, and AESD frequently emerged in preceding etiologies with augmented neuronal excitability. These subgroups may have distinct pathomechanism from the "cytokine storm" mediated AEs during childhood.