Low incidence of abnormal (18)FDG-PET in children with new-onset partial epilepsy: a prospective study.

Abstract

Patients with refractory partial epilepsy often exhibit regional hypometabolism. It is unknown whether the metabolic abnormalities are present at seizure onset or develop over time. The authors studied 40 children within 1 year of their third unprovoked partial seizure with EEG, MRI, and [(18)F]-fluorodeoxyglucose ((18)FDG)-PET (mean age at seizure onset = 5.8 years, range 0.9 to 11.9 years; mean epilepsy duration = 1.1 years, range 0.3 to 2.3 years; mean number of seizures = 30, range 3 to 200). The authors excluded children with abnormal structural MRI, except four with mesial temporal sclerosis and two with subtle hippocampal dysgenesis. (18)FDG-PET was analyzed with a region of interest template. An absolute asymmetry index, [AI], greater than 0.15 was considered abnormal. Thirty-three children had a presumptive temporal lobe focus, five frontotemporal, and two frontal. Mean AI for all regions was not different from 10 normal young adults, even when children less likely to have a temporal focus were excluded. Eight of 40 children (20%) had focal hypometabolism, all restricted to the temporal lobe, especially inferior mesial and inferior lateral regions. Abnormalities were ipsilateral to the presumed temporal lobe ictal focus. Abnormalities of glucose utilization may be less common and profound in children with new-onset partial seizures than in adults with chronic partial epilepsy. Although these patients' prognosis is uncertain, resolution of epilepsy after three documented seizures is uncommon. If the subjects develop a higher incidence of hypometabolism in the future with planned follow-up studies, metabolic dysfunction may be related to persistent epilepsy rather than present at seizure onset.