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Magnetic resonance imaging (MRI) was performed after complex febrile convulsions (CFCs) in 27 infants. Definite MRI abnormalities were seen in 6 of the 15 infants with focal or lateralized CFCs and in none of the 12 infants with generalized CFCs. In 2 of the 6 infants with lateralized CFCs and abnormal MRIs, the MR images showed preexisting bilateral hippocampal atrophy consistent with the history of perinatal insults in these infants. However, the remaining 4 infants with MRI abnormalities and lateralized CFCs had significantly longer seizures than other infants and had MRI changes suggesting acute edema with increased hippocampal T2-weighted signal intensity and increased volume predominantly in the hippocampus in the hemisphere of seizure origin. Of those with acute edema, 1 had electrographical seizure activity recorded in the temporal region and another had a choroid fissure cyst displacing the affected hippocampus; both infants had follow-up MRIs showing that hippocampal atrophy had developed. These patients demonstrate that prolonged and focal CFCs can occasionally produce acute hippocampal injury that evolves to hippocampal atrophy. Finally, evidence of preexisting hippocampal abnormalities in several infants and electrographical temporal lobe seizure activity in 1 suggests the possibility that CFCs actually originated in the temporal lobes in some patients.

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.

Neurological endemic cretinism, resulting from severe iodine deficiency, is characterized by mental deficiency, deafmutism, and a spastic-rigid motor disorder. Its neuropathology and pathophysiology have been investigated very little. We report the clinical and magnetic resonance imaging brain scan findings of 3 adult Chinese cretins. All show an apparent magnetic resonance imaging abnormality in the globus pallidus and substantia nigra, with hyperintensity on T1-weighted images and hypointensity on T2-weighted images. The motor abnormality, characterized by truncal and proximal limb-girdle rigidity and spasticity, with relative sparing of the hands and feet, is analogous to other extrapyramidal disorders. Endemic cretinism is a unique form of cerebral palsy of potential interest for students of human neuromotor development.