The clinical syndrome of early-life bilateral hippocampal sclerosis.

Four infants had bilateral hippocampal sclerosis by magnetic resonance scans, including oblique coronal fast spin echo images of the temporal lobes; [18F]fluorodeoxyglucose-positron emission tomographic scans, done in 2 infants, showed isolated bilateral anterior temporal lobe hypometabolism. All had epilepsy with episodes of status epilepticus. Despite adequate motor and sensory functions, all failed to develop language (or lost attained language), social skills, and complex purposive or adaptive activity, even after epilepsy was controlled. Bilateral hippocampal dysfunction in early life appears to be associated with a profound failure of cognitive capacities, including language learning and learning of complex social and adaptive skills in general. The deficits correspond to the cognitive deficits of severe infantile autism. Hippocampal function, or more generally medial temporal lobe function, appears necessary for language learning in the infant, as well as for complex social and adaptive learning.