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Early childhood convulsions (ECCs) are epileptic fits in children between the ages of 6 months and 5 years and occur in 2%-5% of the population. 1 They are probably heterogeneous in aetiology. Hippocampal sclerosis is the commonest single cause of medically refractory temporal lobe epilepsy in adults. 2 Patients with hippocampal sclerosis, identified either histopathologically after epilepsy surgery, or by MRI, are much more likely than those with other types of localisation related epilepsy to report a history of prolonged or complicated ECC. 3-5 A complicated ECC is usually defined as a focal seizure, one that is recurrent within 24 hours, one which lasts longer than 20-30 minutes, or one associated with postictal neurological deficit. The severity of the pathology has been reported to be greater the younger the child when the first convulsion occurs. 6 More severe ECCs are especially associated with the development of localisation related epilepsy and hippocampal sclerosis in later life. 7
Development of hippocampal sclerosis after ECC does not necessarily imply a cause and effect relation; it may be that pre-existing damage to the hippocampus (for example, hippocampal dysgenesis, anterior or end folium sclerosis, or frank hippocampal sclerosis) predisposes to severe ECC. Many patients with hippocampal sclerosis do not have a history of ECC, 8 so such convulsions may not be the only cause of hippocampal sclerosis, although they may be one cause. Patients with idiopathic generalised epilepsy or benign childhood partial epilepsy are more likely to have had a febrile convulsion (usually simple) but do not seem to develop hippocampal sclerosis. 5 Even recurrent ECCs do not necessarily produce hippocampal damage, and it may be the structural brain or metabolic abnormalities present at the time of the ECC which determine whether hippocampal damage ensues. We tested the hypothesis that complicated ECCs may be associated with structural abnormality of the brain, including the hippocampus, which might lead to hippocampal sclerosis and later development of temporal lobe epilepsy.
Methods
The South Sheffield research ethics committee and all participating District General Hospitals' ethics committees approved the protocol for the study. Parents or guardians of all participating children provided informed consent for inclusion in the study.
Subjects presenting with first febrile or non-febrile complicated early childhood convulsion were studied. A complicated ECC was...