Landau–Kleffner syndrome: a rare childhood epileptic aphasia

Abstract

Landau–Kleffner Syndrome (LKS), a rare epileptic aphasia which occurs at a crucial period for the development of verbal skills, arouses interest and controversy among both clinicians and neuroscientists interested in the development of language. On the one hand, the relationship between epilepsy and aphasia and the poor outcome of epileptic aphasia compared to lesional childhood aphasia is a matter of debate among the clinicians. On the other hand, the severe verbal agnosia experienced during the active period of epilepsy allows one to examine the effect of deprivation of verbal auditory input on further language development. The chronic language impairments observed in most cases following the complete recovery from epilepsy could be either a consequence of a permanent neurophysiological dysfunction (the epileptic focus) during a crucial period of functional differentiation in the brain tissue assigned to language processing (the left superior temporal cortex), or a consequence of a lack of auditory-verbal experience. This paper reviews the clinical and experimental studies of Landau–Kleffner Syndrome with the aim of precisely defining the two main clinical features of the syndrome, the aphasic disorders and the epilepsy and examining their relationship. The recent findings of a cognitive study of the components of the verbal memory system in six LKS patients who recovered from epilepsy and aphasia are presented. These data suggest the possibility of a deficit within the phonological short-term memory system that would account for both the poor vocabulary development and the persisting impairment of verbal comprehension in the late outcome of LKS.