Epilepsy of infancy with migrating focal seizures: A scoping review of clinical features, diagnostic testing including genetics, long-term outcomes, mortality, and current and emerging therapeutic strategies.
Abstract
Background
Epilepsy of infancy with migrating focal seizures (EIMFS) is among the most severe developmental and epileptic encephalopathies (DEEs), marked by intractable multifocal seizures migrating across both hemispheres, profound developmental arrest, and high early mortality. Advances in next-generation sequencing have revealed a heterogeneous genetic architecture dominated by KCNT1 gain-of-function variants across more than 30 implicated genes, creating opportunities for precision therapeutics.
Objective
To systematically map published evidence on the clinical, electrophysiological, neuroimaging, genetic, and therapeutic landscape of EIMFS, and to delineate critical knowledge gaps and future research priorities.
Methods
A scoping review was conducted following the Arksey and O'Malley framework, searching PubMed, Ovid MEDLINE, Embase, Cochrane Library/CENTRAL, and ClinicalTrials.gov.
Results
Of 643 articles screened, 89 met inclusion criteria. Beyond confirmation of the canonical electroclinical phenotype, several gaps emerged: neonatal versus post-neonatal onset stratification by genetic etiology remains largely uncharacterized; genotype-specific EEG biomarkers are lacking except for a single small KCNT1 study; and the clinical significance of atypical EEG features-including burst suppression and hypsarrhythmia-is undefined. Neuroimaging literature documents progressive cerebral atrophy and myelination abnormalities without quantitative volumetry, diffusion tractography markers, or attribution to seizure burden, medication effects, or underlying etiology. Genetic diagnostic yield was 70-80%, with KCNT1 accounting for 30-50% of solved cases; however, genotype-outcome stratification is limited. Seizures were broadly refractory; potassium bromide, ketogenic diet, cannabidiol, and quinidine (in KCNT1-confirmed cases) showed partial efficacy. Emerging precision approaches include sodium channel blockers for SCN2A gain-of-function variants, novel small molecules, fluoxetine, antisense oligonucleotides, and divalent siRNA targeting KCNT1. Systemic-to-pulmonary collateral circulation causing severe cardiopulmonary complications was reported across multiple cases, yet no consensus screening protocol exists.
Conclusions
EIMFS remains one of the most refractory epilepsy syndromes of infancy. Precision genetic diagnosis is essential to guide targeted therapy. International collaborative registries, standardized outcome measures, genotype-stratified biomarker studies, and rapid point-of-care genomic testing are urgently needed to advance evidence-based care for this highly vulnerable population.