Deficits of cognitive function, including language development and learning of complex social skills, typical of mental deficiency and autism, are reported in 4 children with bilateral hippocampal sclerosis and epilepsy followed at Duke University Medical Center, Durham, NC. MRI showed increased signal on T2-weighted images and 25% loss of volume of the hippocampi, pictures consistent with sclerosis. An early normal development was interrupted by episodes of status epilepticus, followed by failure of language development and social deficits. Control of seizures was not accompanied by improved social/adaptive skills. The hippocampus is essential for learning of language and social development in infancy. 
COMMENT. Bilateral hippocampal sclerosis in infancy may result in failure of language development and deficits in behavior and social learning consistent with mental retardation and autism. Normal acquisition of language and learning is not significantly affected by unilateral damage to the hippocampus. Neuronal loss in the hippocampi during prolonged seizures has been linked to excessive release of glutamate.