The role of PET in childhood epilepsy.

Functional brain imaging with positron emission tomography (PET) has led to significant advances in the diagnosis and management of various forms of childhood epilepsy. Interictal PET in temporal lobe epilepsy typically shows decreased glucose utilization (hypometabolism) in one or both temporal lobes. Children with early-onset refractory extratemporal lobe epilepsy who do not manifest structural abnormalities on magnetic resonance imaging often show single or multiple cortical foci of hypometabolism indicating underlying microdysgenesis that corresponds to the area of epileptogenicity. The findings of focal cortical metabolic lesions and metabolic activation of subcortical structures (brain stem and lenticular nuclei) in patients with infantile spasms have allowed many infants with intractable spasms to be treated surgically with cortical resection, and have altered our concepts regarding the pathophysiology of these seizures. New observations in Lennox-Gastaut syndrome, Sturge-Weber syndrome, tuberous sclerosis, hemimegalencephaly, Landau-Kleffner syndrome, and other pediatric epilepsy syndromes have been documented with PET and have improved our understanding of these disorders. Recent PET studies of several neurotransmitter receptors in adult epileptic patients suggest that this approach holds great promise in the study of childhood epilepsy. The current guidelines indicating which patients with epilepsy should be referred for a PET study are outlined.