Hemiconvulsion-hemiplegia-epilepsy (HHE) syndrome is a rare pediatric epilepsy syndrome characterized by prolonged focal febrile seizures, postictal hemiparesis, and progressive unilateral brain injury, often followed by chronic epilepsy. We report a previously healthy 10-month-old girl who presented with a prolonged left-sided focal fever-associated seizure. She tested positive for SARS-CoV-2 but did not meet criteria for multisystem inflammatory syndrome in children. On admission, she had left-sided flaccid hemiparesis. Brain MRI showed mild diffusion restriction and marked hyperperfusion of the right hemispheric gray matter, most prominently in the frontal, temporo-occipital, and hippocampal regions. EEG showed high-amplitude slowing over the right hemisphere without epileptiform discharges. No further seizures occurred, and long-term antiseizure treatment was not required. At 9-month follow-up, the patient was seizure-free and developmentally age-appropriate, but the hemiparesis persisted. Serial MRI showed progressive right hemispheric cortical and subcortical atrophy and hippocampal sclerosis. Extensive diagnostic workup found no other structural, infectious, or metabolic cause. This case illustrates the classical biphasic course of HHE syndrome and highlights the diagnostic value of early MRI, EEG, and genetic testing. The patient carried a paternally inherited heterozygous IRF3 variant, a gene essential for innate antiviral immunity. Although causality cannot be established, the temporal association with SARS-CoV-2 infection and an IRF3 variant suggests a possible genetic predisposition to infection-triggered injury. Continued clinical vigilance and long-term follow-up are essential, as epilepsy develops in most children with HHE. Greater awareness of this syndrome may support earlier recognition and timely rehabilitation to optimize functional outcomes.

This case report describes a unique case of hemiconvulsion-hemiplegia-epilepsy syndrome in a paediatric patient with an underlying hypomyelinating leukodystrophy. We present the clinical, neuroimaging and genetic findings of a 3-year-old girl with a myelin deposition disorder who presented with a prolonged febrile status epilepticus, followed by persistent left hemiplegia. Brain magnetic resonance imaging (MRI) revealed a pattern consistent with hemiconvulsion-hemiplegia-epilepsy syndrome, with unilateral cytotoxic oedema and increased cerebral blood flow in the right cerebral hemisphere cortex. The girl was treated with corticosteroid therapy and levetiracetam. Follow-up imaging showed cerebral atrophy ipsilateral to the seizure focus. Incomplete myelination pattern remained unchanged. No prior cases associating hypomyelinating leukodystrophy with hemiconvulsion-hemiplegia-epilepsy syndrome have been reported. This case expands the phenotypic spectrum of hypomyelinating disorders and raises the hypothesis that an underlying white matter vulnerability may predispose to or modify the course of hemiconvulsion-hemiplegia-epilepsy syndrome. Recognition of such associations may have implications for prognosis and management, including seizure control strategies and neurorehabilitation. Further reports are needed to determine the role of myelination in the development of epileptic syndromes.

To develop standardized diagnostic criteria for 'infection-triggered encephalopathy syndrome (ITES)' and five specific clinical syndromes of ITES. The draft definitions were based on existing criteria, standardized, and discussed by a panel of international experts using nominal group technique over 18 months to achieve consensus. All criteria use the same format: (1) presence of infection/fever; (2) clinical features including encephalopathy; (3) neuroradiological features on magnetic resonance imaging; (4) exclusion of other causes. We first highlighted differences between ITES and infectious and autoimmune encephalitis, which is the most important differential diagnosis. Consensus was achieved to define five specific ITESs: acute encephalopathy with biphasic seizures and late reduced diffusion; acute necrotizing encephalopathy; mild encephalopathy with a reversible splenial lesion; acute fulminant cerebral oedema; and acute shock with encephalopathy and multiorgan failure. Two further conditions that are currently classified as epilepsy syndromes but have similar features to ITES, namely febrile infection-related epilepsy syndrome and hemiconvulsion-hemiplegia-epilepsy syndrome, are also discussed. The consensus definition is expected to improve awareness of this disease concept, provide diagnostic framework, and facilitate future international research and clinical trials.

Hemiconvulsion-hemiplegia-epilepsy syndrome is a rare and severe neurological condition that results from prolonged status epilepticus in infancy and early childhood. This syndrome is characterized by unilateral prolonged seizures, primarily clonic in nature, which are followed by transient or permanent ipsilateral hemiplegia. In this report, we present the case of a 3-year-old girl who exhibited persistent left hemiparesis after experiencing an episode of prolonged focal seizures at the age of 2 years. Comprehensive neurological evaluation and brain MRI conducted in our department confirmed the diagnosis of hemiconvulsion-hemiplegia-epilepsy syndrome in its chronic phase.