Brain injury with prolonged seizures in children and adults.

Some retrospective studies have suggested that there is a relationship between seizures early in life and the development of hippocampal damage (mesial temporal lobe hippocampal sclerosis) leading to intractable temporal lobe epilepsy in late childhood or adulthood. Recent prospective epidemiologic studies have not confirmed such a relationship, however, and many questions remain. Some of these questions are being addressed by animal studies. In adult rats, experimental seizures produce varying degrees of hippocampal damage and subsequent spontaneous seizures; the older the rat, the greater the hippocampal injury. The preponderance of available data indicate that such seizure-induced hippocampal damage may not occur in normally developing rats up to a certain age that may correspond to late childhood in humans. However, if the brain is already compromised, seizures early in life may produce hippocampal damage, depending on the nature of the initial lesion. Thus, the consequences of seizures appear to be age and etiology specific. Additional clinical and basic science studies are needed to clarify the neurobiology of seizure-induced hippocampal damage in children.