Early-onset progressive encephalopathy with migrant continuous myoclonus

Early-onset progressive encephalopathy with migrant continuous myoclonus (also known as early infantile epileptic encephalopathy with migrating focal seizures, or migrating partial seizures of infancy) is a rare and severe neurological disorder that typically presents in the first months of life. It is characterized by nearly continuous seizure activity that appears to migrate from one brain region to another, involving different cortical areas in succession. The myoclonic and focal seizures are typically refractory to conventional antiepileptic medications. The condition primarily affects the central nervous system, leading to progressive deterioration of brain function. Affected infants usually develop normally for a brief period before the onset of seizures, which are often multifocal and intractable. Key clinical features include progressive psychomotor regression, severe intellectual disability, hypotonia or spasticity, and loss of previously acquired developmental milestones. Electroencephalography (EEG) characteristically shows migrating ictal discharges that shift from one hemisphere or region to another. Some cases have been associated with mutations in genes such as KCNT1, SCN1A, SCN2A, SLC25A22, PLCB1, and TBC1D24, among others, reflecting genetic heterogeneity. The treatment landscape remains challenging, as seizures in this condition are typically resistant to standard antiepileptic drugs. Management is largely supportive and symptomatic, focusing on seizure reduction, nutritional support, and physical therapy. Quinidine has been explored as a targeted therapy in cases with KCNT1 mutations, though results have been variable. The prognosis is generally poor, with significant neurodevelopmental impairment and reduced life expectancy in many cases.

Common questions about Early-onset progressive encephalopathy with migrant continuous myoclonus