Successful Treatment of Refractory Landau-Kleffner Syndrome with Memantine in a Child with GRIN2A Gain-of-Function Variant.

Landau-Kleffner syndrome and related epilepsy-aphasia spectrum disorders are characterized by childhood-onset language regression, sleep-activated epileptiform activity, and frequently refractory seizures. This case report describe a boy with normal early development who developed progressive aphasia and non-motor seizures around age three, with electroencephalographic findings consistent with spike-wave activation during slow sleep, while neuroimaging and metabolic evaluations were normal. Standard antiseizure medications and repeated immunotherapy provided no sustained benefit. Genetic testing at age 12 identified a pathogenic heterozygous GRIN2A gain-of-function missense variant (p.T531M), guiding initiation of targeted therapy with memantine, and an NMDA receptor antagonist. Following memantine treatment, the patient showed marked improvement in speech and social interaction together with reduced sleep-related epileptiform discharges, although some deficits persisted. This case underscores the value of early genetic evaluation in refractory epilepsy-aphasia syndromes and supports the potential role of precision NMDA-modulating therapy in GRIN2A-associated epileptic encephalopathy.