Ring chromosome 20 epilepsy syndrome in children: Electroclinical features

Ring chromosome 20 mosaicism is associated with dysmorphic features, mental retardation, and intractable seizures, including recurrent episodes of non convulsive status epilepticus. The authors' findings in four children, all without dysmorphic features, indicate that mental deterioration and frequen t subtle nocturnal frontal lobe seizures, associated with a characteristic EEG pattern, represent prominent additional clinical features not previousl y described in this syndrome. This emphasizes the importance of full-night video-EEG in children with frontal lobe seizures and cognitive deterioratio n.