Low incidence of abnormal 18FDG-PET in children with new-onset partial epilepsy A prospective study

Objective: 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. Methods: 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. Results: 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. Conclusions: 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.