A spectrum of conditions with varied degree of cognitive, language, behavioral, and motor regression associated with marked spike-wave activation in sleep. The regression is seen within weeks of the EEG pattern. This syndrome encompasses the previous syndromes epileptic encephalopathy with continuous spike-wave in sleep and atypical childhood epilepsy with centrotemporal spikes (also previously known as pseudo-Lennox syndrome and atypical benign partial epilepsy). Landau–Kleffner syndrome is a specific subtype of EE-SWAS, where regression affects mainly language, with an acquired auditory agnosia. [ https://www.epilepsydiagnosis.org/syndrome/ee-csws-overview.html ]