[The Landau-Kleffner syndrome. Infantile "acquired" aphasia, paroxysmal electroencephalographic changes and epileptic seizures].

Since the initial description by Landau and Kleffner, in 1957, of a syndrome occurring exclusively in children and consisting of aphasia, paroxysmal changes in E.E.G. and, frequently, epileptic seizures, 80 cases have been reported. The acquired speech disorder, sometimes associated with auditory agnosia, differs in symptomatology and development from the usual forms of infantile aphasia. The prognosis, based on the regression or persistence of the aphasia, is favourable in 60% of the cases and unfavourable in 40%. None of the various antiepileptic drugs is consistently effective. The cause of the syndrome remains unknown.