Pathophysiological aspects of Landau-Kleffner syndrome: From the active epileptic phase to recovery

In their original description of the syndrome of “acquired aphasia with convulsive disorder,” Landau and Kleffner (1957) suggested “that persistent convulsive discharges in brain tissue largely concerned with linguistic communication result in the functional ablation of these areas for normal linguistic behavior.” In further case studies, the observation of continuous epileptic discharges in electroencephalograms (EEGs) recorded during sleep agreed with this early suggestion. Although several group studies emphasized the almost parallel fluctuation of aphasic disorders and EEG abnormalities, the causal relationship between epileptiform EEG discharges and the language defect remains a matter of debate. Another subject of discussion concerns the outcome of aphasia after recovery of epilepsy that typically occurs at the beginning of adolescence. In the Landau-Kleffner syndrome (LKS), the prognosis of aphasia varies in a manner opposite that observed after structural lesions of the left hemisphere. To further elucidate the pathophysiological basis of aphasia and its poor outcome in LKS, this chapter reexamines five clinical studies of LKS with particular emphasis on electrophysiological and metabolic findings and their relationship to neuropsychological deficits. The data presented and discussed covers a follow-up period extending for each case from the active period to the late recovery phase of epilepsy lasting from 7 to 15 years. The chapter summarizes the clinical histories and neuropsychological findings gathered during the period when the children were aphasic and epileptic and after recovery and focuses on the experimental data supporting focal or regional cerebral dysfunction underlying this particular acquired childhood aphasia.