Childhood seizures and their consequences for the hippocampus.

Abstract

Both idiopathic generalized epilepsy and focal epilepsy may be associated with seizures in early childhood (Hamati‐Haddad and Abou‐Khalil, 1998). The majority of adults with refractory epilepsy have focal epilepsy, with a temporal lobe epileptic focus in ∼60–70% of which hippocampal (mesial temporal) sclerosis is the causative lesion in ∼80% (Van Paesschen et al ., 1995). In newly diagnosed focal epilepsy the prevalence of hippocampal sclerosis is ∼11% (Van Paesschen et al ., 1998). The aetiology of this common cause of focal epilepsy remains enigmatic. One of the few clues is its association with early childhood convulsion (ECC), particularly complicated ECC (usually defined as lasting >15 min, associated with focal neurological deficit or recurrent within 24 h). Approximately half of patients with hippocampal sclerosis report a history of complicated ECC (Kuks et al ., 1993), and 90% of patients with temporal lobe epilepsy and a history of complicated ECC have hippocampal sclerosis (Grunewald et al , 1994). ECCs affect between 2 and 4% of the population and are usually benign. However, after an ECC a small minority of children continue to have seizures or develop epilepsy later. The Child Health and Education Study, a birth cohort study, demonstrated that the risk of epilepsy depends on the type of seizure, being higher for complicated than simple ECCs, (4–6% versus 1–1.5% risk of epilepsy in the first 10 years of …