Ferreira, JoanaLopes, SofiaCarmona Lopes, JoséFerreira, CristinaMagalhães, Catarina2021-11-022021-11-022021-06Ferreira J, Lopes S, Carmona-Lopes J, Ferreira C, Magalhães C, Nascer e Crescer - Birth and Growth Medical Journal 2021;30(2): 99-104. doi:10.25753/BirthGrowthMJ.v30.i2.175012183-9417http://hdl.handle.net/10400.16/2524Introduction: Childhood epileptic encephalopathies are age-dependent brain disorders in which ictal and interictal epileptogenic activity is the apparent cause of progressive cognitive and neuro-psychological impairment. Case report: A previously healthy four-year-old boy presented to the Emergency Department with a history of receptive and expressive language regression with four days of evolution, associated with seizure onset. Clinical features and electroencephalographic findings led to diagnosis of Landau-Kleffner syndrome. The boy was treated with valproate, clobazam, and prednisolone, with language improvement. Discussion/Conclusion: Landau-Kleffner syndrome is a rare epileptic encephalopathy with pathognomonic sudden aphasia, epilepsy, and paroxysmal electroencephalographic abnormalities. The condition should be suspected in children with normal development who show a deterioration of established language skills. Early diagnosis and treatment are important to improve outcome.engcognitionepilepsyepileptic syndromesLandau-Kleffner syndromejournal article10.25753/BirthGrowthMJ.v30.i2.17501